In the initial period of industrialization a great deal of land is needed for Chinese industry development as well as land resource per person of China is much lower than the average value in the world, thus it is nec...In the initial period of industrialization a great deal of land is needed for Chinese industry development as well as land resource per person of China is much lower than the average value in the world, thus it is necessary to save land in Chinese urban constrUction. This paper mainly discussed the features of urban land use in economic developed coastal cities: one is that the index of urban land per person in middle-small cities was higher than in large cities; another is that urban land has not been used highly and strongly; the third is that the industrial land occupied an irrationally large percentage of whole urban land; the final is that rural enterprises took up a quantity of land. Thereafter, this paper put forward five land-saving measures: first, to adopt the idea of saving land; next, to adjust the land-use structure when redeveloping the old city and alternate some land use when adjusting the industry structure of the city; the third, to develop the system of payment for using land and the management of urban planning; finally to enhance the effective regional plan and the urban landuse plan.展开更多
A continuously stratified nonlinear model is set up to study the impact of topographical character on the generation of internal solitary waves over a sill by tidal flow.One of the reasons why almost all of the genera...A continuously stratified nonlinear model is set up to study the impact of topographical character on the generation of internal solitary waves over a sill by tidal flow.One of the reasons why almost all of the generated internal solitary waves propagate westward in the northern South China Sea is explained.The model simulations describe the generation and propagation of internal waves well.When the strength of imposed barotropic tides and the water stratification stay unchanged,the steepness of the sill slope can control both(a) whether or not the waves induced over a sill by tidal flow are linear internal waves or nonlinear internal solitary waves,and(b) the amplitude of the internal solitary waves generated.If the steepness of the sill is asymmetric,the nonlinear internal solitary waves may be induced on the steeper side of the sill.These conclusions are supported by a numerical experiment with a monthly-mean stratification and an actual seafloor topography from the Luzon Strait.展开更多
AIM To explore the association between Helicobacter pylori(H. pylori) infection and obesity/weight gain in a Chinese population.METHODS Our primary outcome was the change in body mass index(BMI). The generalized linea...AIM To explore the association between Helicobacter pylori(H. pylori) infection and obesity/weight gain in a Chinese population.METHODS Our primary outcome was the change in body mass index(BMI). The generalized linear models were used to explore the association between H. pylori infection and the change of BMI, and the logistic regression models were used to explore the association between H. pylori infection and obesity.RESULTS A total of 3039 subjects were recruited and analyzed, of which 12.8% were obese. The prevalence of H. pylori infection was 53.9%(1639/3039) overall and 54.6%(212/388) in the obese subjects. The change of BMI in the H. pylori(+) group was not significantly higher than that in the H. pylori(-) group after adjustment for potential confounding factors [RR = 0.988, 95%CI:0.924-1.057, P = 0.729]. The prevalence of obesity decreased 1.1% in the H. pylori(+) group and 0.5% in the H. pylori(-) group. The RR of H. pylori infection for obesity was 0.831(95%CI: 0.577-1.197, P = 0.321) after the adjustment.CONCLUSION H. pylori infection was not associated with overweight/obesity observed from the retrospective study in this Chinese population.展开更多
Tropical cyclones(TCs)in the South China Sea(SCS)cause serious disasters and loss every year to the coastal and inland areas of southern China.The types of TCs are usually difficult to forecast,and studies on the unde...Tropical cyclones(TCs)in the South China Sea(SCS)cause serious disasters and loss every year to the coastal and inland areas of southern China.The types of TCs are usually difficult to forecast,and studies on the understanding of the TCs affecting the SCS are lacking.In this study,the authors use the TC data during 1965–2017 from two best-track datasets to analyse the climatic characteristics in terms of the frequency,the track activity,and the influencing indexes of the TCs affecting the SCS and investigate the possible causes.The results show that,during 1965–2017,there were 535 TCs affecting the SCS,mainly occurring from June to November of each year,with the annual average frequency exhibiting a significant downward trend.Meanwhile,the frequency of the track activity in most areas of the SCS also demonstrate a remarkable decreasing trend but an increase in the Gulf of Tonkin and the Taiwan Strait.The large-scale environmental anomalous westerlies and the decrease of humidity in the mid-and low-level over the northern part of the SCS are likely the main causes for the decrease in frequency and the track activity.In addition,the analysis using the cyclone activity index shows that the influence of the before mentioned TCs in southern China gradually decreases,while the influence of TCs in the SCS show a decreasing trend during past decades.展开更多
AIM To explore the association between Helicobacter pylori (H. pylori) infection status, intestinal metaplasia (IM), and colorectal adenomas. METHODS We retrospectively reviewed 1641 individuals aged >= 40 years wh...AIM To explore the association between Helicobacter pylori (H. pylori) infection status, intestinal metaplasia (IM), and colorectal adenomas. METHODS We retrospectively reviewed 1641 individuals aged >= 40 years who underwent physical examination, laboratory testing, C-13-urea breath testing, gastroscopy, colonoscopy, and an interview to ascertain baseline characteristics and general state of health. Histopathological results were obtained by gastric and colorectal biopsies. RESULTS The prevalence of H. pylori infection and adenomas was 51.5% (845/1641) and 18.1% (297/1641), respectively. H. pylori infection was significantly correlated with an increased risk of colorectal adenomas (crude OR = 1.535, 95% CI: 1.044-1.753, P = 0.022; adjusted OR = 1.359, 95% CI: 1.035-1.785, P = 0.028). Individuals with IM had an elevated risk of colorectal adenomas (crude OR = 1.664, 95% CI: 1.216-2.277, P = 0.001; adjusted OR = 1.381, 95% CI: 0.998-1.929, P = 0.059). Stratification based on H. pylori infection stage and IM revealed that IM accompanied by H. pylori infection was significantly associated with an increased risk of adenomas (crude OR = 2.109, 95% CI: 1.383-3.216, P = 0.001; adjusted OR = 1.765, 95% CI: 1.130-2.757, P = 0.012). CONCLUSION H. pylori-related IM is associated with a high risk of colorectal adenomas in Chinese individuals.展开更多
Based on the National Land Use/Cover Database of China(NLUD-C) in the end of the 1980s(the 1980s,hereafter), 1995, 2000, 2005, and 2010, 665 cities were selected to study the size distribution and its changes of urban...Based on the National Land Use/Cover Database of China(NLUD-C) in the end of the 1980s(the 1980s,hereafter), 1995, 2000, 2005, and 2010, 665 cities were selected to study the size distribution and its changes of urban lands in China. In this study, the spatiotemporal evolutions of urban land size distribution as well as the influence of administrative-level on these cities were explored by combining urban spatial positions and administrative-levels. Results indicate that: 1) City size distribution using urban lands was more practical and reasonable than using non-agricultural population. 2) In the 1980s, cities with ascending urban land rank were centralized in Eastern China, specially the Changjiang(Yangtze) River Delta, the Zhujiang(Pearl) River Delta, and Beijing-Tianjin-Hebei region. Cities in Central, Western, and Northeast China mainly indicated descending urban land rank. 3) The transfer of national development focus resulted in cities with ascending urban land rank becoming evenly distributed nationwide; however, this trend was slightly centralized around Chengdu, Chongqing, and Wuhan in different periods. 4) During the 1980s to 2010, the proportion of cities with ascending urban land rank in provincial capitals, municipalities, and special administrative regions(high-level cities, hereafter) was consistently higher than those in prefecture- and county-level cities except for 2005–2010. The ranks of the majority of the prefecture- and county-level cities were mainly descending, supported by ascending; the proportion of cities with unchanged rank is small. This study breaks through the bottleneck of traditional research in the area of city size distribution by examining urban land replacing the non-agricultural population. The current study also provides scientific explanation for the healthy and reasonable development of urban land as well as the coordinated development of population urbanization and land urbanization.展开更多
In the era of globalization,English as an international language(EIL) is also the medium of intercultural communication for the international community.Based on the theory of cultural linguistics(CL),which regards lan...In the era of globalization,English as an international language(EIL) is also the medium of intercultural communication for the international community.Based on the theory of cultural linguistics(CL),which regards language as culture-oriented rather than structure-oriented,Sharifian(2009,p.4) has proposed that varieties of English which constitute EIL result from the interaction between the English language and different local cultures.CL suggests that China English(CE) should be understood in this light:It is not a substandard interlanguage,but a variety of English with its own cultural value and right.This paper intends to systemically analyze the nature of CE and its value in intercultural communication so as to better understand current intercultural education.Over a long time,much emphasis has been laid on the importance of adapting to the target language culture to the neglect of home language culture in our College English classrooms,thus resulting in what is known as Chinese cultural aphasia.In the light of CL,intercultural communication competence(ICC) encompasses not only knowing English and adapting to its culture,but also using CE to introduce the native culture in which CE plays an irreplaceable role.Therefore,CE is undoubtedly a key remedy for Chinese cultural aphasia.More research on CL should be conducted as it provides felicitous disciplinary guidance for our college intercultural education.展开更多
Due to high intensity agricultural exploitation since the middle of the 20 th century, farmland gullies have become a pervasive form of water erosion in Northeast China. Yet few researches are concentrated on how topo...Due to high intensity agricultural exploitation since the middle of the 20 th century, farmland gullies have become a pervasive form of water erosion in Northeast China. Yet few researches are concentrated on how topography and land use affect long-term gully development in this region. In this study, gully distribution in a village with an area of 24.2 km^2 in the central Mollisols area of Northeast China in different times were compared by Aerial photography(1968), Quickbird image(2009) and field survey, and factors affecting gully development including land use and topography were analyzed. The results showed that the total gully number decreased from 104 to 69, while occupying area rose from 34.8 ha to 78.4 ha from 1968 to 2009. Fundamental gully distribution had been formed by 1968 as most of 2009′s gullies were evolved from 1968′s gullies′ merge and width expansion process, and new gullies those initiated after 1968 occupied only 7% of total gully area in 2009. Gully area increasing ratio in grassland was the highest and that in forestland was the lowest. The threshold catchment area between simple and complex gully development was around 15 ha to 25 ha. This threshold value sets apart catchment areas that will develop simple or complex gullies in areas with similar environmental conditions. Gully control measurements were urgent because if appropriate gully control implements would not be applied, present gully erosion crisis could be doubled within 50 years.展开更多
In the last two decades, China has become one of the areas that have the greatest potential in industrial production, thus it has ranked second only to USA in the flow of international capital. By the end of 1998, the...In the last two decades, China has become one of the areas that have the greatest potential in industrial production, thus it has ranked second only to USA in the flow of international capital. By the end of 1998, the real value of FDI (Foreign Direct Investment) in China has utilized has added up to $268.1 billion. The big flow of FDI has not only promoted the development of social economy, but also worsened the existing regional difference by choosing spatial location. Under this circumstance, China’s economy faces new restrictions and opportunities while adjusting its regional structure and industrial structure. So it is more and more important for us how to seize the opportunity, to seek the regularity of FDI in choosing location from the aspect of space, to set up relevant strategy to direct FDI at inland regions (areas deficient of capital), and to make appropriate policies, esp. the industrial and regional policies so as for FDI to exert positive influence and avoid negative influence on China and its regional economy and society. Based on the latest domestic and overseas materials and data of the FDI in China, combining with the investigation of the enterprises, this paper has systematically revealed the progress of development of the FDI in China and the developing conditions of the main enterprises directly invested by foreign capital since the reform and opening-up in China. The characters of FDI such as spatial concentration, transference as time goes on, change of the technical content and up-gradation of industrial structure and their forming mechanism have been studied. Then the basic conclusions have been made as follows. Firstly, FDI has been highly concentrated in space. But as time goes by, it has been transferring from coastal regions to inland ones, from big cities to their surrounding districts, and the degree of concentration is decreasing. Secondly, the technical content of the invested projects has gradually increased and the up-gradation of the industrial structure is obvious. Thirdly, the regional choice of the FDI in China is mainly affected by labor and other productive factors. The relative change of the cost of productive factors in different regions since the reform and opening-up is one of the main factors that have caused the spatial transference of the FDI in China. Fourthly, as people’s income increases and the accumulation of the capacity of the technique and labor advances, FDI whose aim is to get more market has increased and tended to transfer from coastal regions to inland ones. Fifthly, the changes of the industrial structure of the main areas and countries who have directly invested in China and the changes of inter-regional industries and regional policies in China are also the important factors that affect the industries directly invested by foreign capital and their spatial transference.展开更多
Based on the daily rainfall datasets of 743 stations in China and the NCEP/NCAR monthly reanalysis data during the period of 1960-2003,the relationship between the anomalous extreme precipitation(EP) in the south of C...Based on the daily rainfall datasets of 743 stations in China and the NCEP/NCAR monthly reanalysis data during the period of 1960-2003,the relationship between the anomalous extreme precipitation(EP) in the south of China and atmospheric circulation in the Southern Hemisphere is analyzed.The phenomenon of opposite changes in the sea level pressure and geopotential height anomalies over the Ross Sea and New Zealand is defined as RN,and the index which describes this phenomenon is expressed as RNI.The results show that the RN has barotropic structure and the RNI in May is closely related to the June EP amount in the south of China(SCEP) and the East Asian summer monsoon(EASM).The positive correlations between the May RNI at each level and the June SCEP are significant,and the related simultaneous correlations between the RNI and the June SCEP are also positive,suggesting that the potential impact of RN on the SCEP persists from May to June.Therefore,RN in May can be taken as one of the predictive factors for the June SCEP.Furthermore,one possible physical mechanism by which the RN affects the June SCEP is a barotropic meridional teleconnection emanating from the Southern Hemisphere to the western North Pacific.展开更多
AIM To assess the efficacy and safety of combined directly acting antivirals(DAAs) for the treatment of Chinese chronic hepatitis C(CHC) patients in a real-world setting.METHODS Hospitalized CHC patients who were trea...AIM To assess the efficacy and safety of combined directly acting antivirals(DAAs) for the treatment of Chinese chronic hepatitis C(CHC) patients in a real-world setting.METHODS Hospitalized CHC patients who were treated with DAAs at Peking University First Hospital between January 2015 and December 2016 were enrolled. Samples and clinical data were collected at 0 wk, 2 wk, 4 wk, 8 wk, 12 wk, or 24 wk during DAAs treatment and at 4 wk, 12 wk, and 24 wk after the end of treatment. RESULTS Fifty-four patients who underwent DAAs treatment were included in our study, of whom 83.3%(45/54) achieved rapid virological response at 2 wk after treatment initiation(RVR 2) and 94.4%(51/54)achieved sustained virological response at 24 wk after the end of treatment(SVR 24). Serum creatinine and uric acid levels at the end of treatment were significantly increased compared with baseline levels(83.6 ± 17.9 vs 88.8 ± 19.4, P 01 < 0.001; 320.8 ± 76.3 vs 354.5 ± 87.6, P 01 < 0.001), and no significant improvements were observed at 24 w after the end of treatment(83.6 ± 17.9 vs 86.8 ± 19.1, P 02 = 0.039; 320.8 ± 76.3 vs 345.9 ± 89.4, P 02 = 0.001). The total frequency of adverse events(AEs) during treatment was 33.3%(18/54), with major AEs being fatigue(16.7%), headache(7.4%), anorexia(7.4%), and insomnia(5.6%). CONCLUSION Though based in a small cohort of patients, the abnormal changes in renal function indices and relative high frequency of AEs during combined DAAs treatment should be taken as a note of caution.展开更多
China is a country with many nationalities. Each of them has formed its own special culture, which is different from the mainstream of majority Han nationality, by adapting to geo-environment during history. Due to di...China is a country with many nationalities. Each of them has formed its own special culture, which is different from the mainstream of majority Han nationality, by adapting to geo-environment during history. Due to different backgrounds, the regional developmental model of minorities in the western China is different from the Han nationality and western countries. Combining a knowledge-based civilization and sustainable development, the minority areas can seek the systematic integration of culture-economy-ecology. Based on this, the paper suggests that the minority areas in western China should take the way of emphasizing developmental quality rather than developmental quantity for a harmonious system of culture-economy-ecology. Some approaches for developing minority areas in western China have been put foreword.展开更多
文摘In the initial period of industrialization a great deal of land is needed for Chinese industry development as well as land resource per person of China is much lower than the average value in the world, thus it is necessary to save land in Chinese urban constrUction. This paper mainly discussed the features of urban land use in economic developed coastal cities: one is that the index of urban land per person in middle-small cities was higher than in large cities; another is that urban land has not been used highly and strongly; the third is that the industrial land occupied an irrationally large percentage of whole urban land; the final is that rural enterprises took up a quantity of land. Thereafter, this paper put forward five land-saving measures: first, to adopt the idea of saving land; next, to adjust the land-use structure when redeveloping the old city and alternate some land use when adjusting the industry structure of the city; the third, to develop the system of payment for using land and the management of urban planning; finally to enhance the effective regional plan and the urban landuse plan.
基金Supported by the Knowledge Innovation Program of Chinese Academy of Sciences (No.KZCX1-YW-12-03),(China National Funds for Distinguished Young Scientists)the National High Technology Research and Development Program of China (863 Program) (Nos.2008AA09Z112, 2008AA09A402)+1 种基金the National Natural Science Foundation of China (No.40676021)Chinese Oceanic Association (No.DYXM-115-02-4-02)
文摘A continuously stratified nonlinear model is set up to study the impact of topographical character on the generation of internal solitary waves over a sill by tidal flow.One of the reasons why almost all of the generated internal solitary waves propagate westward in the northern South China Sea is explained.The model simulations describe the generation and propagation of internal waves well.When the strength of imposed barotropic tides and the water stratification stay unchanged,the steepness of the sill slope can control both(a) whether or not the waves induced over a sill by tidal flow are linear internal waves or nonlinear internal solitary waves,and(b) the amplitude of the internal solitary waves generated.If the steepness of the sill is asymmetric,the nonlinear internal solitary waves may be induced on the steeper side of the sill.These conclusions are supported by a numerical experiment with a monthly-mean stratification and an actual seafloor topography from the Luzon Strait.
基金Supported by the State Key Laboratory of Pathogen and Biosecurity(Academy of Military Medical Science)No.SKLPBS1442the Youth Talent Support Program of the School of Public Health,Peking University
文摘AIM To explore the association between Helicobacter pylori(H. pylori) infection and obesity/weight gain in a Chinese population.METHODS Our primary outcome was the change in body mass index(BMI). The generalized linear models were used to explore the association between H. pylori infection and the change of BMI, and the logistic regression models were used to explore the association between H. pylori infection and obesity.RESULTS A total of 3039 subjects were recruited and analyzed, of which 12.8% were obese. The prevalence of H. pylori infection was 53.9%(1639/3039) overall and 54.6%(212/388) in the obese subjects. The change of BMI in the H. pylori(+) group was not significantly higher than that in the H. pylori(-) group after adjustment for potential confounding factors [RR = 0.988, 95%CI:0.924-1.057, P = 0.729]. The prevalence of obesity decreased 1.1% in the H. pylori(+) group and 0.5% in the H. pylori(-) group. The RR of H. pylori infection for obesity was 0.831(95%CI: 0.577-1.197, P = 0.321) after the adjustment.CONCLUSION H. pylori infection was not associated with overweight/obesity observed from the retrospective study in this Chinese population.
基金This work was jointly supported by General Project of Technological Innovation and Application Demonstration of Chongqing Municipality[cstc2018jscx-msybX0165]Special Project for Development of Key Technology for Meteorological Forecast Service of China Meteorological Administration[YBGJXM(2018)04-08]+1 种基金National Natural Science Foundation of China[41875111]Innovation Team Project of Intelligent Meteorological Technology of Chongqing Meteorological Bureau[ZHCXTD-201804].
文摘Tropical cyclones(TCs)in the South China Sea(SCS)cause serious disasters and loss every year to the coastal and inland areas of southern China.The types of TCs are usually difficult to forecast,and studies on the understanding of the TCs affecting the SCS are lacking.In this study,the authors use the TC data during 1965–2017 from two best-track datasets to analyse the climatic characteristics in terms of the frequency,the track activity,and the influencing indexes of the TCs affecting the SCS and investigate the possible causes.The results show that,during 1965–2017,there were 535 TCs affecting the SCS,mainly occurring from June to November of each year,with the annual average frequency exhibiting a significant downward trend.Meanwhile,the frequency of the track activity in most areas of the SCS also demonstrate a remarkable decreasing trend but an increase in the Gulf of Tonkin and the Taiwan Strait.The large-scale environmental anomalous westerlies and the decrease of humidity in the mid-and low-level over the northern part of the SCS are likely the main causes for the decrease in frequency and the track activity.In addition,the analysis using the cyclone activity index shows that the influence of the before mentioned TCs in southern China gradually decreases,while the influence of TCs in the SCS show a decreasing trend during past decades.
文摘AIM To explore the association between Helicobacter pylori (H. pylori) infection status, intestinal metaplasia (IM), and colorectal adenomas. METHODS We retrospectively reviewed 1641 individuals aged >= 40 years who underwent physical examination, laboratory testing, C-13-urea breath testing, gastroscopy, colonoscopy, and an interview to ascertain baseline characteristics and general state of health. Histopathological results were obtained by gastric and colorectal biopsies. RESULTS The prevalence of H. pylori infection and adenomas was 51.5% (845/1641) and 18.1% (297/1641), respectively. H. pylori infection was significantly correlated with an increased risk of colorectal adenomas (crude OR = 1.535, 95% CI: 1.044-1.753, P = 0.022; adjusted OR = 1.359, 95% CI: 1.035-1.785, P = 0.028). Individuals with IM had an elevated risk of colorectal adenomas (crude OR = 1.664, 95% CI: 1.216-2.277, P = 0.001; adjusted OR = 1.381, 95% CI: 0.998-1.929, P = 0.059). Stratification based on H. pylori infection stage and IM revealed that IM accompanied by H. pylori infection was significantly associated with an increased risk of adenomas (crude OR = 2.109, 95% CI: 1.383-3.216, P = 0.001; adjusted OR = 1.765, 95% CI: 1.130-2.757, P = 0.012). CONCLUSION H. pylori-related IM is associated with a high risk of colorectal adenomas in Chinese individuals.
基金the Young Scientist Fund of National Nature Science Foundation of China(No.41101148)
文摘Based on the National Land Use/Cover Database of China(NLUD-C) in the end of the 1980s(the 1980s,hereafter), 1995, 2000, 2005, and 2010, 665 cities were selected to study the size distribution and its changes of urban lands in China. In this study, the spatiotemporal evolutions of urban land size distribution as well as the influence of administrative-level on these cities were explored by combining urban spatial positions and administrative-levels. Results indicate that: 1) City size distribution using urban lands was more practical and reasonable than using non-agricultural population. 2) In the 1980s, cities with ascending urban land rank were centralized in Eastern China, specially the Changjiang(Yangtze) River Delta, the Zhujiang(Pearl) River Delta, and Beijing-Tianjin-Hebei region. Cities in Central, Western, and Northeast China mainly indicated descending urban land rank. 3) The transfer of national development focus resulted in cities with ascending urban land rank becoming evenly distributed nationwide; however, this trend was slightly centralized around Chengdu, Chongqing, and Wuhan in different periods. 4) During the 1980s to 2010, the proportion of cities with ascending urban land rank in provincial capitals, municipalities, and special administrative regions(high-level cities, hereafter) was consistently higher than those in prefecture- and county-level cities except for 2005–2010. The ranks of the majority of the prefecture- and county-level cities were mainly descending, supported by ascending; the proportion of cities with unchanged rank is small. This study breaks through the bottleneck of traditional research in the area of city size distribution by examining urban land replacing the non-agricultural population. The current study also provides scientific explanation for the healthy and reasonable development of urban land as well as the coordinated development of population urbanization and land urbanization.
文摘In the era of globalization,English as an international language(EIL) is also the medium of intercultural communication for the international community.Based on the theory of cultural linguistics(CL),which regards language as culture-oriented rather than structure-oriented,Sharifian(2009,p.4) has proposed that varieties of English which constitute EIL result from the interaction between the English language and different local cultures.CL suggests that China English(CE) should be understood in this light:It is not a substandard interlanguage,but a variety of English with its own cultural value and right.This paper intends to systemically analyze the nature of CE and its value in intercultural communication so as to better understand current intercultural education.Over a long time,much emphasis has been laid on the importance of adapting to the target language culture to the neglect of home language culture in our College English classrooms,thus resulting in what is known as Chinese cultural aphasia.In the light of CL,intercultural communication competence(ICC) encompasses not only knowing English and adapting to its culture,but also using CE to introduce the native culture in which CE plays an irreplaceable role.Therefore,CE is undoubtedly a key remedy for Chinese cultural aphasia.More research on CL should be conducted as it provides felicitous disciplinary guidance for our college intercultural education.
基金National Natural Science Foundation of China(No.41601289,41571264)
文摘Due to high intensity agricultural exploitation since the middle of the 20 th century, farmland gullies have become a pervasive form of water erosion in Northeast China. Yet few researches are concentrated on how topography and land use affect long-term gully development in this region. In this study, gully distribution in a village with an area of 24.2 km^2 in the central Mollisols area of Northeast China in different times were compared by Aerial photography(1968), Quickbird image(2009) and field survey, and factors affecting gully development including land use and topography were analyzed. The results showed that the total gully number decreased from 104 to 69, while occupying area rose from 34.8 ha to 78.4 ha from 1968 to 2009. Fundamental gully distribution had been formed by 1968 as most of 2009′s gullies were evolved from 1968′s gullies′ merge and width expansion process, and new gullies those initiated after 1968 occupied only 7% of total gully area in 2009. Gully area increasing ratio in grassland was the highest and that in forestland was the lowest. The threshold catchment area between simple and complex gully development was around 15 ha to 25 ha. This threshold value sets apart catchment areas that will develop simple or complex gullies in areas with similar environmental conditions. Gully control measurements were urgent because if appropriate gully control implements would not be applied, present gully erosion crisis could be doubled within 50 years.
基金the important project of National Natural Science Foundation of China (49831003)and the important project of the Ninth Five-Year
文摘In the last two decades, China has become one of the areas that have the greatest potential in industrial production, thus it has ranked second only to USA in the flow of international capital. By the end of 1998, the real value of FDI (Foreign Direct Investment) in China has utilized has added up to $268.1 billion. The big flow of FDI has not only promoted the development of social economy, but also worsened the existing regional difference by choosing spatial location. Under this circumstance, China’s economy faces new restrictions and opportunities while adjusting its regional structure and industrial structure. So it is more and more important for us how to seize the opportunity, to seek the regularity of FDI in choosing location from the aspect of space, to set up relevant strategy to direct FDI at inland regions (areas deficient of capital), and to make appropriate policies, esp. the industrial and regional policies so as for FDI to exert positive influence and avoid negative influence on China and its regional economy and society. Based on the latest domestic and overseas materials and data of the FDI in China, combining with the investigation of the enterprises, this paper has systematically revealed the progress of development of the FDI in China and the developing conditions of the main enterprises directly invested by foreign capital since the reform and opening-up in China. The characters of FDI such as spatial concentration, transference as time goes on, change of the technical content and up-gradation of industrial structure and their forming mechanism have been studied. Then the basic conclusions have been made as follows. Firstly, FDI has been highly concentrated in space. But as time goes by, it has been transferring from coastal regions to inland ones, from big cities to their surrounding districts, and the degree of concentration is decreasing. Secondly, the technical content of the invested projects has gradually increased and the up-gradation of the industrial structure is obvious. Thirdly, the regional choice of the FDI in China is mainly affected by labor and other productive factors. The relative change of the cost of productive factors in different regions since the reform and opening-up is one of the main factors that have caused the spatial transference of the FDI in China. Fourthly, as people’s income increases and the accumulation of the capacity of the technique and labor advances, FDI whose aim is to get more market has increased and tended to transfer from coastal regions to inland ones. Fifthly, the changes of the industrial structure of the main areas and countries who have directly invested in China and the changes of inter-regional industries and regional policies in China are also the important factors that affect the industries directly invested by foreign capital and their spatial transference.
基金National Basic Research Program of China (2004CB418300, 2010CB833406)National Natural Science Foundation of China (40675042, 40890054, 40871007)
文摘Based on the daily rainfall datasets of 743 stations in China and the NCEP/NCAR monthly reanalysis data during the period of 1960-2003,the relationship between the anomalous extreme precipitation(EP) in the south of China and atmospheric circulation in the Southern Hemisphere is analyzed.The phenomenon of opposite changes in the sea level pressure and geopotential height anomalies over the Ross Sea and New Zealand is defined as RN,and the index which describes this phenomenon is expressed as RNI.The results show that the RN has barotropic structure and the RNI in May is closely related to the June EP amount in the south of China(SCEP) and the East Asian summer monsoon(EASM).The positive correlations between the May RNI at each level and the June SCEP are significant,and the related simultaneous correlations between the RNI and the June SCEP are also positive,suggesting that the potential impact of RN on the SCEP persists from May to June.Therefore,RN in May can be taken as one of the predictive factors for the June SCEP.Furthermore,one possible physical mechanism by which the RN affects the June SCEP is a barotropic meridional teleconnection emanating from the Southern Hemisphere to the western North Pacific.
基金Supported by National Natural Science Foundation of China,No.81373056Beijing Municipal Committee of Science and Technology,No.D161100002716003National Major Project for Infectious Diseases Control,No.2012ZX10002003-004-003
文摘AIM To assess the efficacy and safety of combined directly acting antivirals(DAAs) for the treatment of Chinese chronic hepatitis C(CHC) patients in a real-world setting.METHODS Hospitalized CHC patients who were treated with DAAs at Peking University First Hospital between January 2015 and December 2016 were enrolled. Samples and clinical data were collected at 0 wk, 2 wk, 4 wk, 8 wk, 12 wk, or 24 wk during DAAs treatment and at 4 wk, 12 wk, and 24 wk after the end of treatment. RESULTS Fifty-four patients who underwent DAAs treatment were included in our study, of whom 83.3%(45/54) achieved rapid virological response at 2 wk after treatment initiation(RVR 2) and 94.4%(51/54)achieved sustained virological response at 24 wk after the end of treatment(SVR 24). Serum creatinine and uric acid levels at the end of treatment were significantly increased compared with baseline levels(83.6 ± 17.9 vs 88.8 ± 19.4, P 01 < 0.001; 320.8 ± 76.3 vs 354.5 ± 87.6, P 01 < 0.001), and no significant improvements were observed at 24 w after the end of treatment(83.6 ± 17.9 vs 86.8 ± 19.1, P 02 = 0.039; 320.8 ± 76.3 vs 345.9 ± 89.4, P 02 = 0.001). The total frequency of adverse events(AEs) during treatment was 33.3%(18/54), with major AEs being fatigue(16.7%), headache(7.4%), anorexia(7.4%), and insomnia(5.6%). CONCLUSION Though based in a small cohort of patients, the abnormal changes in renal function indices and relative high frequency of AEs during combined DAAs treatment should be taken as a note of caution.
基金Under the auspices of the National Natural Science Foundation of China (No.49261001).
文摘China is a country with many nationalities. Each of them has formed its own special culture, which is different from the mainstream of majority Han nationality, by adapting to geo-environment during history. Due to different backgrounds, the regional developmental model of minorities in the western China is different from the Han nationality and western countries. Combining a knowledge-based civilization and sustainable development, the minority areas can seek the systematic integration of culture-economy-ecology. Based on this, the paper suggests that the minority areas in western China should take the way of emphasizing developmental quality rather than developmental quantity for a harmonious system of culture-economy-ecology. Some approaches for developing minority areas in western China have been put foreword.
