China has resolved its overall regional poverty in 2020 by attaining moderate societal prosperity.The country has entered a new development stage designed to achieve its second centenary goal.However,ecological fragil...China has resolved its overall regional poverty in 2020 by attaining moderate societal prosperity.The country has entered a new development stage designed to achieve its second centenary goal.However,ecological fragility and risk susceptibility have increased the risk of returning to ecological poverty.In this paper,the Liupan Mountain Region of China was used as a case study,and the counties were used as the scale to reveal the spatiotempora differentiation and influcing factors of the risk of returning to poverty in study area.The indicator data for returning to ecological poverty from 2011-2020 were collected and summarized in three dimensions:ecological,economic and social.The autoregressive integrated moving average model(ARIMA)time series and exponential smoothing method(ES)were used to predict the multidimensional indicators of returning to ecological poverty for 61 counties(districts)in the Liupan Mountain Region for 2021-2030.The back propagation neural network(BPNN)and geographic information system(GIS)were used to generate the spatial distribution and time variation for the index of the risk of returning to ecological poverty(RREP index).The results show that 1)ecological factors were the main factors in the risk of returning to ecological poverty in Liupan Mountain Region.2)The RREP index for the 61 counties(districts)exhibited a downward trend from 2021-2030.The RREP index declined more in medium-and high-risk areas than in low-risk areas.From 2021 to 2025,the RREP index exhibited a slight downward trend.From 2026 to2030,the RREP index was expected to decline faster,especially from 2029-2030.3)Based on the RREP index,it can be roughly divided into three types,namely,the high-risk areas,the medium-risk areas,and the low-risk areas.The natural resource conditions in lowrisk areas of returning to ecological poverty,were better than those in medium-and high-risk areas.展开更多
A novel indicator called price-citation was proposed.Based on the company integrated patent database of China listed companies of common stocks(A-shares)with the stock price and the stock return rate data,more than tw...A novel indicator called price-citation was proposed.Based on the company integrated patent database of China listed companies of common stocks(A-shares)with the stock price and the stock return rate data,more than two thousand of A-shares from 2017 to 2020 were selected.The effect of the traditional patent forward citation and the price-citation for discriminating the stock return rate was thoroughly analyzed via ANOVA.The A-shares of forward citation counts above the average showed higher stock return rate means than the A-shares having patents but receiving no forward citations.The price-citation,combining both the financial and patent attributes,defined as the multiplication of the current stock price and the currently receiving forward citation count,showed its excellence in discriminating the stock return rate.The A-shares of higher price-citation showed significantly higher stock return rate means while the A-shares of lower price-citation showed significantly lowest stock return rate means.The price-citation effect had not been changed by COVID-19 though COVID-19 affected the social and economic environment to a considerable extent in 2020.展开更多
Increasing populations are causing an increase in food demands, and the area of cultivated land expands every year. Inappropriate land transition from ecology to production results in the constant decline of the ecolo...Increasing populations are causing an increase in food demands, and the area of cultivated land expands every year. Inappropriate land transition from ecology to production results in the constant decline of the ecological security level and influences the regional sustainable development. Adjusting unreasonable land use mode and reconstructing natural land cover are important ways to maintain and improve the ecological environment. Also reclaiming farmland as areas for forests and grasslands (FRFG) is another way. Successful implementation of FRFG in China is the result of comprehensive effect of the multi-scales driving forces. This paper analyses the driving forces of FRFG in China on a national (country) –regional (province) – local (county) – household (farmer) level scale, and the results are: driving forces at the national scale include ecological and food security and the western development of China; at the regional scale, ecological and economic benefits become the main factors to influence the dimension of FRFG under the same policy. The driving forces can be divided into 6 types: industrial structure adjustment, water source protection, flood prevention, the Three-Gorge Project protection, reduction of the amount of sediment flowing into the Yellow River and wind erosion desertification prevention. The driving forces at the local scale can be divided into 12 types with developing leading industries, increasing farmers’ income and improving agricultural production conditions as the main types; at the household scale, the nationalpolicy meeting farmers’ demands and the optimization of individual interests are all driving forces.展开更多
Taking Shunping County of Hebei Province as an example,according to the relevant survey data in the year 2008 after returning cultivated land and data in the year 2001 before returning cultivated land, the thesis anal...Taking Shunping County of Hebei Province as an example,according to the relevant survey data in the year 2008 after returning cultivated land and data in the year 2001 before returning cultivated land, the thesis analyzes the impact of implementation of project of returning cultivated land to forests on local land use structure, three industrial added value and famers' per capita income. The results show that returning cultivated land has played a certain positive role on the local economic development and the improvement of people's life level.However, there are also some shortcomings: although famers' income is increasing with low growth rate, a large portion of famers still have not shaken off poverty; the farmers depends on subsidies greatly and the compensation mechanism of returning cultivated land is not considered well. China should further perfect the ecological compensation plan, and build rational ecological compensation mechanism in order to make the areas of returning cultivated land have self-blood-producing function; Shunping County should make full use of the location advantage in areas around Beijing-Tianjin, develop deep processing based on fruit trees industry, strengthen farmers' skill training, and increase input in the agricultural infrastructure construction to propel the sustainable development of agriculture.展开更多
The women's liberation movement in China started after the first opium war and it took shape with the aim of protecting the race and salvaging the country. Doubtlessly, the emergence of modern feminism opened the pre...The women's liberation movement in China started after the first opium war and it took shape with the aim of protecting the race and salvaging the country. Doubtlessly, the emergence of modern feminism opened the precedent in the theory of women's liberation in China and exerted a profound and far-reaching influence on women's liberation afterwards. But we must face up to the fact that there was some traps or misunderstanding of modern feminism, which were unfavorable for realizing women's rights and such influence was long, so much so that till today we are still seeing its existence. It is, therefore, necessary to have a full reflection of modem feminism, unveil the original meaning of women's rights and make women's rights return to human rights in order to make the development of women's fights continue.展开更多
It is an important way for realizing sustainable development of sweet corn production to stabilize and improve soil fertility of cultivated land in sweet corn production region.Through the test of sweet corn straw dir...It is an important way for realizing sustainable development of sweet corn production to stabilize and improve soil fertility of cultivated land in sweet corn production region.Through the test of sweet corn straw directly returning to the field after 6seasons for 3years,the results showed that continuous single application of chemical fertilizer is not conducive to the stability of soil fertility and yield improvement,and implementation of straw returning could receive fertility,improve soil acidic conditions,and enhance the yield of sweet corn.Compared with before the test,the single application of chemical fertilizer increased soil available phosphorus,while the contents of soil organic matter,available nitrogen and available potassium decreased by 1.08,1.18 and 2.47mg/kg respectively,and the soil pH decreased by 0.15.Under the same fertilizer conditions,organic matter contents of single and double-season straw returning increased by 0.71 and 1.29g/kg,available nitrogen increased by 17.15 and 28.27mg/kg,available phosphorus increased by 0.96 and 1.73mg/kg,available potassium increased by 2.41 and 5.92mg/kg,the soil pH increased by 0.16 and 0.2.Compared with the single application of chemical fertilizer,the average yields of single and double-season straw returning increased by 7.5%and 11.8%,and their average income increased by 87.3and 117.1yuan of per mu(667m^2)respectively.展开更多
Our research on private placement of equity on China capital market reveals that firms prefer to equity financing when their stock price is overvalued and investor sentiment is high,following the market timing hypothe...Our research on private placement of equity on China capital market reveals that firms prefer to equity financing when their stock price is overvalued and investor sentiment is high,following the market timing hypothesis.However,after private issuance,we document a significant positive abnormal return within three years.We believe firms choose to polish their financial statement before the exit of institutional investors and controlling shareholders.Through manipulation of discretional accruals,firms improve the profitability and market valuation,and help institutional investors and controlling shareholders obtain the abnormal return after private placement of equity.Nevertheless,such manipulation cannot be sustained and will do harm to other investors in the long-term.展开更多
The paper discloses the current situation of migrant workers returning home to start business by making a survey of the total number of returning migrant workers. The paper also points out the main difficulties the mi...The paper discloses the current situation of migrant workers returning home to start business by making a survey of the total number of returning migrant workers. The paper also points out the main difficulties the migrant workers who returning home to start business facing. The first is the old fashioned and backward concepts of development in some local departments; the second is lacking of powerful supports of policies; the third is the still bad environment to start business; the fourth is the lower qualities of people who are going to start business. Based on these situations, the official policies are put forward to encourage and support migrant workers to return home to start business. Such as strategies activating migrant workers to return home to start business should be positively operated; the management services should be further standardized and the environment should be perfected for starting business; the programs and items to start business by migrant workers returning home should be guided and favored; beneficial tax policies should be improved further; financial services should be further perfected; the land using problems of migrant workers should be firstly solved; the demonstration project of migrant workers returning back to start business should be continuously carried on; the organizing and leading jobs for starting business of migrant workers should be further strengthened.展开更多
In the context of global climate change and rapid urbanization,climate governance has become one of the unavoidable challenges of human society.Therefore,climate engineering is increasingly mentioned in the internatio...In the context of global climate change and rapid urbanization,climate governance has become one of the unavoidable challenges of human society.Therefore,climate engineering is increasingly mentioned in the international climate negotiations.For solar radiation management with the most controversy in climate engineering method,based on two scenarios of climate engineering (G4) and non climate engineering (RCP4.5) of BNU-ESM model,95% and 99% percentiles of daily rainfall data during 2010-2099 were taken as thresholds of heavy rainfall and extreme rainfall events.The data of over threshold sampling (POT) were fitted by Weibull distribution to diagnose the heavy rainfall and extreme rainfall in 10,20,50 and 100 years of return period.The results showed that:in two scenarios,strength of heavy rainfall and extreme rainfall enhanced with return period increased,and they showed a southeast high-northwest low spatial characteristics.Climate engineering,in general,contributes to the increase in heavy rainfall and extreme rainfall in China,as well as spatial heterogeneity,which represents the suppression of heavy rainfall and extreme rainfall in parts of the country.This research is of great significance for the future global climate control and regional climate adaptation.展开更多
This year marks the40th anniversary of China’s opening up to the world.One of the key decisions during the early period after opening-up was the restoration of the national college entrance exam.As of today,China has...This year marks the40th anniversary of China’s opening up to the world.One of the key decisions during the early period after opening-up was the restoration of the national college entrance exam.As of today,China has produced nearly100million college students and6million overseas students,which provided a solid human resource background for China’s opening-up and economic growth.展开更多
Future changes in the 50-yr return level for temperature and precipitation extremes over China's Mainland are investigated based on a CMIP5 multi-model ensemble for RCP2.6, RCP4.5 and RCP8.5 scenarios. The followi...Future changes in the 50-yr return level for temperature and precipitation extremes over China's Mainland are investigated based on a CMIP5 multi-model ensemble for RCP2.6, RCP4.5 and RCP8.5 scenarios. The following indices are analyzed: TXx and TNn (the annual maximum and minimum of daily annual maximum consecutive 5-day precipitation) and CDD maximum and minimum surface temperature), RX5day (the (maximum annual number of consecutive dry days). After first validating the model performance, future changes in the 50-yr return values and return periods for these indices are investigated along with the inter-model spread. Multi-model median changes show an increase in the 50-yr return values of TXx and a decrease for TNn, more specifically, by the end of the 21st century under RCP8.5, the present day 50-yr return period of warm events is reduced to 1.2 yr, while extreme cold events over the country are projected to essentially disappear. A general increase in RX5day 50-yr return values is found in the future. By the end of the 21st century under RCP8.5, events of the present RX5day 50-yr return period are projected to reduce to 〈 10 yr over most of China. Changes in CDD-50 show a dipole pattern over China, with a decrease in the values and longer return periods in the north, and vice versa in the south. Our study also highlights the need for further improvements in the representation of extreme events in climate models to assess the future risks and engineering design related to large-scale infrastructure in China.展开更多
Upland red soils have been identified as major CO2 and N2O sources induced by human activities such as fertilization. To monitor characteristics of soil surface CO2 and N2O fluxes in cropland ecosystems after continuo...Upland red soils have been identified as major CO2 and N2O sources induced by human activities such as fertilization. To monitor characteristics of soil surface CO2 and N2O fluxes in cropland ecosystems after continuous fertilizer applications over decades and to separate the respective contributions of root and heterotrophic respiration to the total soil CO2 and N2O fluxes, the measurements of soil surface CO2 and N2O fluxes throughout the maize growing season in 2009 were carried out based on a fertilization experiment (from 1990) through of the maize (Zea mays L.) growing season in red soil in southern China. Five fertilization treatments were chosen from the experiment for study: zero-fertilizer application (CK), nitrogen-phosphorus- potassium (NPK) fertilizer application only, pig manure (M), NPK plus pig manure (NPKM) and NPK with straw (NPKS). Six chambers were installed in each plot. Three of them are in the inter-row soil (NR) and the others are in the soil within the row (R). Each fertilizer treatment received the same amount of N (300 kg ha-1 yr-1). Results showed that cumulative soil CO2 fluxes in NR or R were both following the order: NPKS〉M, NPKM〉NPK〉CK. The contributions of root respiration to soil CO2 fluxes was 40, 44, 50, 47 and 35% in CK, NPK, NPKM, M and NPKS treatments, respectively, with the mean value of 43%. Cumulative soil N2O fluxes in NR or R were both following the order: NPKS, NPKM〉M〉NPK〉CK, and soil N2O fluxes in R were 18, 20 and 30% higher than that in NR in NPKM, M and NPKS treatments, respectively, but with no difference between NR and R in NPK treatment. Furthermore, combine with soil temperature at -5 cm depth and soil moisWxe (0-20 cm) together could explain 55-70% and 42-59% of soil CO2 and N2O emissions with root interference and 62- 78% and 44-63% of that without root interference, respectively. In addition, soil CO2 and N2O flUXeS per unit yield in NPKM (0.55 and 0.10 kg C t^-1) and M (0.65 and 0.13 g N t^-1) treatments were lower than those in other treatments. Therefore, manure application could be a preferred fertilization strategy in red soils in South China.展开更多
Based on hourly rainfall observational data from 442 stations during 1960-2014, a regional frequency analysis of the annual maxima (AM) sub-daily rainfall series (1-, 2-, 3-, 6-, 12-, and 24-h rainfall, using a mov...Based on hourly rainfall observational data from 442 stations during 1960-2014, a regional frequency analysis of the annual maxima (AM) sub-daily rainfall series (1-, 2-, 3-, 6-, 12-, and 24-h rainfall, using a moving window approach) for eastern China was conducted. Eastern China was divided into 13 homogeneous regions: Northeast (NE1, NE2), Central (C), Central North (CN1, CN2), Central East (CE1, CE2, CE3), Southeast (SE1, SE2, SE3, SE4), and Southwest (SW). The generalized extreme value performed best for the AM series in regions NE, C, CN2, CE1, CE2, SE2, and SW, and the generalized logistic distribution was appropriate in the other regions. Maximum return levels were in the SE4 region, with value ranges of 80-270 mm (1-h to 24-h rainfall) and 108-390 mm (1-h to 24-h rainfall) for 20- and 100 yr, respectively. Minimum return levels were in the CN1 and NE1 regions, with values of 37-104 mm and 53-140 mm for 20 and 100 yr, respectively. Comparing return levels using the optimal and commonly used Pearson-III distribution, the mean return-level differences in eastern China for 1-24-h rainfall varied from -3-4 mm to -23-11 mm (- 10%-10%) for 20-yr events, reaching -6-26 mm (-10%-30%) and -10-133 mm (-10%-90%) for 100-yr events. In view of the large differences in estimated return levels, more attention should be given to frequency analysis of sub-daily rainfall over China, for improved water management and disaster reduction.展开更多
Wave fields of the South China Sea (SCS) from 1976 to 2005 were simulated using WAVEWATCH III by inputting high-resolution reanalysis wind field datasets assimilated from several meteorological data sources. Compari...Wave fields of the South China Sea (SCS) from 1976 to 2005 were simulated using WAVEWATCH III by inputting high-resolution reanalysis wind field datasets assimilated from several meteorological data sources. Comparisons of wave heights between WAVEWATCH III and TOPEX/Poseidon altimeter and buoy data show a good agreement. Our results show seasonal variation of wave direction as follows: 1. During the summer monsoon (April-September), waves from south occur from April through September in the southern SCS region, which prevail taking about 40% of the time; 2. During the winter monsoon (December-March), waves from northeast prevail throughout the SCS for 56% of the period; 3. The dominant wave direction in SCS is NE. The seasonal variation of wave height Hs in SCS shows that in spring, Hs〉l m in the central SCS region and is less than 1 m in other areas. In summer, Hs is higher than in spring. During September- November, influenced by tropical cyclones, Hs is mostly higher than 1 m. East of Hainan Island, Hs〉2 m. In winter, Hs reaches its maximum value influenced by the north-east monsoon, and heights over 2 m are found over a large part of SCS. Finally, we calculated the extreme wave parameters in SCS and found that the extreme wind speed and wave height for the 100-year return period for SCS peaked at 45 m/s and 19 m, respectively, SE of Hainan Island and decreased from north to south.展开更多
Based on the overview of concept of returning-home migrant workers' entrepreneurship,the thesis has introduced the features of migrant workers' entrepreneurship,as against other types of entrepreneurship,as fo...Based on the overview of concept of returning-home migrant workers' entrepreneurship,the thesis has introduced the features of migrant workers' entrepreneurship,as against other types of entrepreneurship,as follows. Starting from a low base and multi-level perspective;conducting entrepreneurship in manifold industries,mainly in those labor-intensive enterprises;conspicuous mutual interaction and reversibility are embodied in the group characteristics;the strong driving force of returning-home migrant workers' entrepreneurship comes from their affection for hometown. The process of returning-home migrant workers' entrepreneurship can be divided into three stages,namely returning rush,investing rush,and entrepreneurship rush,on which we give the analysis respectively in terms of the continuous change of social mobility,transformation on the part of the main body of entrepreneurship,and the expansion of industry field concerning entrepreneurship. More over,we have discussed the methods of constructing the legal support system for the returning-home migrant workers' entrepreneurship. Firstly,it needs institutionalization,which is the basis of constructing the legal support system for the returning-home migrant workers' entrepreneurship;secondly,it needs definite guiding ideology as the premise of constructing the legal support system for the returning-home migrant workers' entrepreneurship;thirdly,it needs the precise orientation of target group as the key of constructing the legal support system for the returning-home migrant workers' entrepreneurship;finally,appropriate support methods are the pivot of constructing the legal support system for the returning-home migrant workers' entrepreneurship.展开更多
Features and effects of returned migrant workers' entrepreneurship in Shaanxi Province are analyzed.Returned migrant workers' entrepreneurship in Shaanxi Province depends on traditional agriculture to develop ...Features and effects of returned migrant workers' entrepreneurship in Shaanxi Province are analyzed.Returned migrant workers' entrepreneurship in Shaanxi Province depends on traditional agriculture to develop the quantitative business of planting and breeding,local resources to develop the processing of building materials and agricultural products,small towns to develop service industry such as catering and tourism and the capital accumulated when working in the outside to achieve the transformation from an ordinary worker to an entrepreneur.Returned migrant workers' entrepreneurship in Shaanxi Province promotes the employment and expends ways of transferring rural labor force and increasing incomes.Advantageous recourses are attracted to the rural and underdeveloped areas,which is beneficial to narrowing the gap between the urban and rural areas.It can also promote the transformation of agricultural developmental methods and speed the pace of building modern agriculture.And a group of talents with higher qualities are provided for new rural construction through the modeling and leading role.Entrepreneurship and urbanization are combined together to advance the process of rural urbanization.展开更多
基金Under the auspices of National Natural Science Foundation of China(No.42071230)。
文摘China has resolved its overall regional poverty in 2020 by attaining moderate societal prosperity.The country has entered a new development stage designed to achieve its second centenary goal.However,ecological fragility and risk susceptibility have increased the risk of returning to ecological poverty.In this paper,the Liupan Mountain Region of China was used as a case study,and the counties were used as the scale to reveal the spatiotempora differentiation and influcing factors of the risk of returning to poverty in study area.The indicator data for returning to ecological poverty from 2011-2020 were collected and summarized in three dimensions:ecological,economic and social.The autoregressive integrated moving average model(ARIMA)time series and exponential smoothing method(ES)were used to predict the multidimensional indicators of returning to ecological poverty for 61 counties(districts)in the Liupan Mountain Region for 2021-2030.The back propagation neural network(BPNN)and geographic information system(GIS)were used to generate the spatial distribution and time variation for the index of the risk of returning to ecological poverty(RREP index).The results show that 1)ecological factors were the main factors in the risk of returning to ecological poverty in Liupan Mountain Region.2)The RREP index for the 61 counties(districts)exhibited a downward trend from 2021-2030.The RREP index declined more in medium-and high-risk areas than in low-risk areas.From 2021 to 2025,the RREP index exhibited a slight downward trend.From 2026 to2030,the RREP index was expected to decline faster,especially from 2029-2030.3)Based on the RREP index,it can be roughly divided into three types,namely,the high-risk areas,the medium-risk areas,and the low-risk areas.The natural resource conditions in lowrisk areas of returning to ecological poverty,were better than those in medium-and high-risk areas.
基金support from Ministry of Science and Technology,Taiwan,R.O.C.under Grant No.MOST 109-2410-H-011-021-MY3.
文摘A novel indicator called price-citation was proposed.Based on the company integrated patent database of China listed companies of common stocks(A-shares)with the stock price and the stock return rate data,more than two thousand of A-shares from 2017 to 2020 were selected.The effect of the traditional patent forward citation and the price-citation for discriminating the stock return rate was thoroughly analyzed via ANOVA.The A-shares of forward citation counts above the average showed higher stock return rate means than the A-shares having patents but receiving no forward citations.The price-citation,combining both the financial and patent attributes,defined as the multiplication of the current stock price and the currently receiving forward citation count,showed its excellence in discriminating the stock return rate.The A-shares of higher price-citation showed significantly higher stock return rate means while the A-shares of lower price-citation showed significantly lowest stock return rate means.The price-citation effect had not been changed by COVID-19 though COVID-19 affected the social and economic environment to a considerable extent in 2020.
文摘Increasing populations are causing an increase in food demands, and the area of cultivated land expands every year. Inappropriate land transition from ecology to production results in the constant decline of the ecological security level and influences the regional sustainable development. Adjusting unreasonable land use mode and reconstructing natural land cover are important ways to maintain and improve the ecological environment. Also reclaiming farmland as areas for forests and grasslands (FRFG) is another way. Successful implementation of FRFG in China is the result of comprehensive effect of the multi-scales driving forces. This paper analyses the driving forces of FRFG in China on a national (country) –regional (province) – local (county) – household (farmer) level scale, and the results are: driving forces at the national scale include ecological and food security and the western development of China; at the regional scale, ecological and economic benefits become the main factors to influence the dimension of FRFG under the same policy. The driving forces can be divided into 6 types: industrial structure adjustment, water source protection, flood prevention, the Three-Gorge Project protection, reduction of the amount of sediment flowing into the Yellow River and wind erosion desertification prevention. The driving forces at the local scale can be divided into 12 types with developing leading industries, increasing farmers’ income and improving agricultural production conditions as the main types; at the household scale, the nationalpolicy meeting farmers’ demands and the optimization of individual interests are all driving forces.
基金Supported by the State Social Science Fund Program(09CSH014)
文摘Taking Shunping County of Hebei Province as an example,according to the relevant survey data in the year 2008 after returning cultivated land and data in the year 2001 before returning cultivated land, the thesis analyzes the impact of implementation of project of returning cultivated land to forests on local land use structure, three industrial added value and famers' per capita income. The results show that returning cultivated land has played a certain positive role on the local economic development and the improvement of people's life level.However, there are also some shortcomings: although famers' income is increasing with low growth rate, a large portion of famers still have not shaken off poverty; the farmers depends on subsidies greatly and the compensation mechanism of returning cultivated land is not considered well. China should further perfect the ecological compensation plan, and build rational ecological compensation mechanism in order to make the areas of returning cultivated land have self-blood-producing function; Shunping County should make full use of the location advantage in areas around Beijing-Tianjin, develop deep processing based on fruit trees industry, strengthen farmers' skill training, and increase input in the agricultural infrastructure construction to propel the sustainable development of agriculture.
文摘The women's liberation movement in China started after the first opium war and it took shape with the aim of protecting the race and salvaging the country. Doubtlessly, the emergence of modern feminism opened the precedent in the theory of women's liberation in China and exerted a profound and far-reaching influence on women's liberation afterwards. But we must face up to the fact that there was some traps or misunderstanding of modern feminism, which were unfavorable for realizing women's rights and such influence was long, so much so that till today we are still seeing its existence. It is, therefore, necessary to have a full reflection of modem feminism, unveil the original meaning of women's rights and make women's rights return to human rights in order to make the development of women's fights continue.
基金Supported by Huizhou Science and Technology Support Item(2011B040010010)
文摘It is an important way for realizing sustainable development of sweet corn production to stabilize and improve soil fertility of cultivated land in sweet corn production region.Through the test of sweet corn straw directly returning to the field after 6seasons for 3years,the results showed that continuous single application of chemical fertilizer is not conducive to the stability of soil fertility and yield improvement,and implementation of straw returning could receive fertility,improve soil acidic conditions,and enhance the yield of sweet corn.Compared with before the test,the single application of chemical fertilizer increased soil available phosphorus,while the contents of soil organic matter,available nitrogen and available potassium decreased by 1.08,1.18 and 2.47mg/kg respectively,and the soil pH decreased by 0.15.Under the same fertilizer conditions,organic matter contents of single and double-season straw returning increased by 0.71 and 1.29g/kg,available nitrogen increased by 17.15 and 28.27mg/kg,available phosphorus increased by 0.96 and 1.73mg/kg,available potassium increased by 2.41 and 5.92mg/kg,the soil pH increased by 0.16 and 0.2.Compared with the single application of chemical fertilizer,the average yields of single and double-season straw returning increased by 7.5%and 11.8%,and their average income increased by 87.3and 117.1yuan of per mu(667m^2)respectively.
文摘Our research on private placement of equity on China capital market reveals that firms prefer to equity financing when their stock price is overvalued and investor sentiment is high,following the market timing hypothesis.However,after private issuance,we document a significant positive abnormal return within three years.We believe firms choose to polish their financial statement before the exit of institutional investors and controlling shareholders.Through manipulation of discretional accruals,firms improve the profitability and market valuation,and help institutional investors and controlling shareholders obtain the abnormal return after private placement of equity.Nevertheless,such manipulation cannot be sustained and will do harm to other investors in the long-term.
基金Supported by Project of Social Scientific Department and Social Security Department of Shaanxi Province (2009A004)
文摘The paper discloses the current situation of migrant workers returning home to start business by making a survey of the total number of returning migrant workers. The paper also points out the main difficulties the migrant workers who returning home to start business facing. The first is the old fashioned and backward concepts of development in some local departments; the second is lacking of powerful supports of policies; the third is the still bad environment to start business; the fourth is the lower qualities of people who are going to start business. Based on these situations, the official policies are put forward to encourage and support migrant workers to return home to start business. Such as strategies activating migrant workers to return home to start business should be positively operated; the management services should be further standardized and the environment should be perfected for starting business; the programs and items to start business by migrant workers returning home should be guided and favored; beneficial tax policies should be improved further; financial services should be further perfected; the land using problems of migrant workers should be firstly solved; the demonstration project of migrant workers returning back to start business should be continuously carried on; the organizing and leading jobs for starting business of migrant workers should be further strengthened.
基金Supported by the National Basic Research Program of China(2018YFC0806900)the National Natural Science Foundation of China(41801064,71790611)the Central Asia Atmospheric Science Research Fund(CAAS201804)
文摘In the context of global climate change and rapid urbanization,climate governance has become one of the unavoidable challenges of human society.Therefore,climate engineering is increasingly mentioned in the international climate negotiations.For solar radiation management with the most controversy in climate engineering method,based on two scenarios of climate engineering (G4) and non climate engineering (RCP4.5) of BNU-ESM model,95% and 99% percentiles of daily rainfall data during 2010-2099 were taken as thresholds of heavy rainfall and extreme rainfall events.The data of over threshold sampling (POT) were fitted by Weibull distribution to diagnose the heavy rainfall and extreme rainfall in 10,20,50 and 100 years of return period.The results showed that:in two scenarios,strength of heavy rainfall and extreme rainfall enhanced with return period increased,and they showed a southeast high-northwest low spatial characteristics.Climate engineering,in general,contributes to the increase in heavy rainfall and extreme rainfall in China,as well as spatial heterogeneity,which represents the suppression of heavy rainfall and extreme rainfall in parts of the country.This research is of great significance for the future global climate control and regional climate adaptation.
文摘This year marks the40th anniversary of China’s opening up to the world.One of the key decisions during the early period after opening-up was the restoration of the national college entrance exam.As of today,China has produced nearly100million college students and6million overseas students,which provided a solid human resource background for China’s opening-up and economic growth.
基金supported by the National Key R&D Program of China (Grant No. 2017YF0605004)the National Natural Science Foundation of China (Grant No. 41675069)the Climate Change Specific Fund of China (Grant No. CCSF201731)
文摘Future changes in the 50-yr return level for temperature and precipitation extremes over China's Mainland are investigated based on a CMIP5 multi-model ensemble for RCP2.6, RCP4.5 and RCP8.5 scenarios. The following indices are analyzed: TXx and TNn (the annual maximum and minimum of daily annual maximum consecutive 5-day precipitation) and CDD maximum and minimum surface temperature), RX5day (the (maximum annual number of consecutive dry days). After first validating the model performance, future changes in the 50-yr return values and return periods for these indices are investigated along with the inter-model spread. Multi-model median changes show an increase in the 50-yr return values of TXx and a decrease for TNn, more specifically, by the end of the 21st century under RCP8.5, the present day 50-yr return period of warm events is reduced to 1.2 yr, while extreme cold events over the country are projected to essentially disappear. A general increase in RX5day 50-yr return values is found in the future. By the end of the 21st century under RCP8.5, events of the present RX5day 50-yr return period are projected to reduce to 〈 10 yr over most of China. Changes in CDD-50 show a dipole pattern over China, with a decrease in the values and longer return periods in the north, and vice versa in the south. Our study also highlights the need for further improvements in the representation of extreme events in climate models to assess the future risks and engineering design related to large-scale infrastructure in China.
基金financially supported by the National Basic Research Program of China (2011CB100501)the National Nonprofit Institute Research Grant of Chinese Academy of Agricultural Sciences (IARRP-2012-25, IARRP-2013-22)the National Natural Science Foundation of China (41001175, 41171239 and 41201219)
文摘Upland red soils have been identified as major CO2 and N2O sources induced by human activities such as fertilization. To monitor characteristics of soil surface CO2 and N2O fluxes in cropland ecosystems after continuous fertilizer applications over decades and to separate the respective contributions of root and heterotrophic respiration to the total soil CO2 and N2O fluxes, the measurements of soil surface CO2 and N2O fluxes throughout the maize growing season in 2009 were carried out based on a fertilization experiment (from 1990) through of the maize (Zea mays L.) growing season in red soil in southern China. Five fertilization treatments were chosen from the experiment for study: zero-fertilizer application (CK), nitrogen-phosphorus- potassium (NPK) fertilizer application only, pig manure (M), NPK plus pig manure (NPKM) and NPK with straw (NPKS). Six chambers were installed in each plot. Three of them are in the inter-row soil (NR) and the others are in the soil within the row (R). Each fertilizer treatment received the same amount of N (300 kg ha-1 yr-1). Results showed that cumulative soil CO2 fluxes in NR or R were both following the order: NPKS〉M, NPKM〉NPK〉CK. The contributions of root respiration to soil CO2 fluxes was 40, 44, 50, 47 and 35% in CK, NPK, NPKM, M and NPKS treatments, respectively, with the mean value of 43%. Cumulative soil N2O fluxes in NR or R were both following the order: NPKS, NPKM〉M〉NPK〉CK, and soil N2O fluxes in R were 18, 20 and 30% higher than that in NR in NPKM, M and NPKS treatments, respectively, but with no difference between NR and R in NPK treatment. Furthermore, combine with soil temperature at -5 cm depth and soil moisWxe (0-20 cm) together could explain 55-70% and 42-59% of soil CO2 and N2O emissions with root interference and 62- 78% and 44-63% of that without root interference, respectively. In addition, soil CO2 and N2O flUXeS per unit yield in NPKM (0.55 and 0.10 kg C t^-1) and M (0.65 and 0.13 g N t^-1) treatments were lower than those in other treatments. Therefore, manure application could be a preferred fertilization strategy in red soils in South China.
基金supported by the National Basic Research(973)Program of China(Grant Nos.2013CB430205 and 2012CB955903)the National Natural Science Foundation of China(Grant Nos.41171406,41375099,41561124014 and 91337108)
文摘Based on hourly rainfall observational data from 442 stations during 1960-2014, a regional frequency analysis of the annual maxima (AM) sub-daily rainfall series (1-, 2-, 3-, 6-, 12-, and 24-h rainfall, using a moving window approach) for eastern China was conducted. Eastern China was divided into 13 homogeneous regions: Northeast (NE1, NE2), Central (C), Central North (CN1, CN2), Central East (CE1, CE2, CE3), Southeast (SE1, SE2, SE3, SE4), and Southwest (SW). The generalized extreme value performed best for the AM series in regions NE, C, CN2, CE1, CE2, SE2, and SW, and the generalized logistic distribution was appropriate in the other regions. Maximum return levels were in the SE4 region, with value ranges of 80-270 mm (1-h to 24-h rainfall) and 108-390 mm (1-h to 24-h rainfall) for 20- and 100 yr, respectively. Minimum return levels were in the CN1 and NE1 regions, with values of 37-104 mm and 53-140 mm for 20 and 100 yr, respectively. Comparing return levels using the optimal and commonly used Pearson-III distribution, the mean return-level differences in eastern China for 1-24-h rainfall varied from -3-4 mm to -23-11 mm (- 10%-10%) for 20-yr events, reaching -6-26 mm (-10%-30%) and -10-133 mm (-10%-90%) for 100-yr events. In view of the large differences in estimated return levels, more attention should be given to frequency analysis of sub-daily rainfall over China, for improved water management and disaster reduction.
基金Supported by the South China Sea Institute of Oceanology,Chinese Academy of Sciences
文摘Wave fields of the South China Sea (SCS) from 1976 to 2005 were simulated using WAVEWATCH III by inputting high-resolution reanalysis wind field datasets assimilated from several meteorological data sources. Comparisons of wave heights between WAVEWATCH III and TOPEX/Poseidon altimeter and buoy data show a good agreement. Our results show seasonal variation of wave direction as follows: 1. During the summer monsoon (April-September), waves from south occur from April through September in the southern SCS region, which prevail taking about 40% of the time; 2. During the winter monsoon (December-March), waves from northeast prevail throughout the SCS for 56% of the period; 3. The dominant wave direction in SCS is NE. The seasonal variation of wave height Hs in SCS shows that in spring, Hs〉l m in the central SCS region and is less than 1 m in other areas. In summer, Hs is higher than in spring. During September- November, influenced by tropical cyclones, Hs is mostly higher than 1 m. East of Hainan Island, Hs〉2 m. In winter, Hs reaches its maximum value influenced by the north-east monsoon, and heights over 2 m are found over a large part of SCS. Finally, we calculated the extreme wave parameters in SCS and found that the extreme wind speed and wave height for the 100-year return period for SCS peaked at 45 m/s and 19 m, respectively, SE of Hainan Island and decreased from north to south.
文摘Based on the overview of concept of returning-home migrant workers' entrepreneurship,the thesis has introduced the features of migrant workers' entrepreneurship,as against other types of entrepreneurship,as follows. Starting from a low base and multi-level perspective;conducting entrepreneurship in manifold industries,mainly in those labor-intensive enterprises;conspicuous mutual interaction and reversibility are embodied in the group characteristics;the strong driving force of returning-home migrant workers' entrepreneurship comes from their affection for hometown. The process of returning-home migrant workers' entrepreneurship can be divided into three stages,namely returning rush,investing rush,and entrepreneurship rush,on which we give the analysis respectively in terms of the continuous change of social mobility,transformation on the part of the main body of entrepreneurship,and the expansion of industry field concerning entrepreneurship. More over,we have discussed the methods of constructing the legal support system for the returning-home migrant workers' entrepreneurship. Firstly,it needs institutionalization,which is the basis of constructing the legal support system for the returning-home migrant workers' entrepreneurship;secondly,it needs definite guiding ideology as the premise of constructing the legal support system for the returning-home migrant workers' entrepreneurship;thirdly,it needs the precise orientation of target group as the key of constructing the legal support system for the returning-home migrant workers' entrepreneurship;finally,appropriate support methods are the pivot of constructing the legal support system for the returning-home migrant workers' entrepreneurship.
基金Supported by " Studies on Problems in Migrant Workers' Entrepreneurship in Shaanxi Province" launched by Shaanxi Association of Social Sciences,Provincial Human Resources and Department of Labor and Social Secuity(2009A004)
文摘Features and effects of returned migrant workers' entrepreneurship in Shaanxi Province are analyzed.Returned migrant workers' entrepreneurship in Shaanxi Province depends on traditional agriculture to develop the quantitative business of planting and breeding,local resources to develop the processing of building materials and agricultural products,small towns to develop service industry such as catering and tourism and the capital accumulated when working in the outside to achieve the transformation from an ordinary worker to an entrepreneur.Returned migrant workers' entrepreneurship in Shaanxi Province promotes the employment and expends ways of transferring rural labor force and increasing incomes.Advantageous recourses are attracted to the rural and underdeveloped areas,which is beneficial to narrowing the gap between the urban and rural areas.It can also promote the transformation of agricultural developmental methods and speed the pace of building modern agriculture.And a group of talents with higher qualities are provided for new rural construction through the modeling and leading role.Entrepreneurship and urbanization are combined together to advance the process of rural urbanization.