期刊文献+
共找到7,531篇文章
< 1 2 250 >
每页显示 20 50 100
Research on the Digital Economy's Impact on China's Economic Growth:Based on the Variations in Urbanization Levels Across China's Eastern,Central,and Western Regions and Sectoral Heterogeneity
1
作者 Qiu Jin Yan Hong 《Contemporary Social Sciences》 2024年第3期27-44,共18页
This paper uses inter-provincial panel data from 2011 to 2017,a linear regression model,and a threshold model to conduct empirical analyses of the impact of the digital economy on China's overall economic growth a... This paper uses inter-provincial panel data from 2011 to 2017,a linear regression model,and a threshold model to conduct empirical analyses of the impact of the digital economy on China's overall economic growth and the three main sectors of industry.The paper then investigates the impact and effects the digital economy has had on the economic growth of the three main sectors of industry in China's eastern,central,and western regions.Finally,the paper investigates the most significant differences among the various regions and the threshold effects of urbanization levels on the relationship between the digital economy and economic growth.The findings indicate a significantly positive correlation between the digital economy and regional economic growth.Moreover,geographical factors notably influence this correlation.The digital economy exerts a positive effect on all sectors of industry.It may not substantially impact industrial development in regions with highly developed infrastructure.Regarding the other regions,the digital economy exhibits varying degrees of impact due to the differences in the specific indicators.The conclusion drawn by the threshold model is that the magnitude of the threshold effect correlates with geographic factors.No threshold effect was observed in the eastern region,while the threshold effect occurred in the central region when the urbanization levels for the provinces were below 0.6645.Similarly,the threshold effect was noted in the western region when the urbanization level was below 0.3931.Considering all of this,the study also offers policy recommendations that will help balance the regional development of digital economies,accelerate the digital transformation of traditional industries,enhance digital infrastructure construction,refine the formulation and implementation of data policy,and establish relevant incentive mechanisms. 展开更多
关键词 digital economy economic growth regional differences urbanization level threshold models
下载PDF
Susceptibility-weighted imaging is suitable for evaluating signal strength in different brain regions of a rabbit model of acute hemorrhagic anemia 被引量:1
2
作者 Jun Xia Ni Xie +3 位作者 Anyu Yin Guozhao Teng Fan Lin Yi Lei 《Neural Regeneration Research》 SCIE CAS CSCD 2014年第9期990-992,共3页
Acute hemorrhagic anemia can decrease blood flow and oxygen supply to brain, and affect its physiological function. While detecting changes in brain function in patients with acute hemorrhagic anemia is helpful for pr... Acute hemorrhagic anemia can decrease blood flow and oxygen supply to brain, and affect its physiological function. While detecting changes in brain function in patients with acute hemorrhagic anemia is helpful for preventing neurological complications and evaluating therapeutic effects, clinical changes in the nervous systems of these patients have not received much attention. In part, this is because current techniques can only indirectly detect changes in brain function following onset of anemia, which leads to lags between real changes in brain function and their detection. 展开更多
关键词 Susceptibility-weighted imaging is suitable for evaluating signal strength in different brain regions of a rabbit model of acute hemorrhagic anemia Figure
下载PDF
Changes of evoked potential in different hippocampal regions induced by electrostimulation at medial mamillary nucleus of rats
3
作者 Xinxin Li Lihong Shang +1 位作者 Liang Zhang Fengzhi Cui 《Neural Regeneration Research》 SCIE CAS CSCD 2006年第1期87-89,共3页
BACKGROUND: Morphological data have shown that the most important afferent fibers of papillary body come from hippocampal structure.OBJECTIVE: To observe the changes of evoked potential in hippocampus and the signif... BACKGROUND: Morphological data have shown that the most important afferent fibers of papillary body come from hippocampal structure.OBJECTIVE: To observe the changes of evoked potential in hippocampus and the significance after electrostimulation at medial mamillary nucleus. DESIGN: An observational control experiment.SETTING: Department of Physiology, Shenyang Medical College.MATERIALS : Twenty-three male or female Wistar rats, 3-4 months old, weighing 270-350 g, were provided by bhe animal room of Shenyang Medical College [the license number was scxk(Liao)2003-0016]. METHODS: The Wistar rats were anaesthetized by intraperintoneal injection of 20% urethane (1 g/kg), tracheal intubation was also given. The self-made double-pole metal stimulating electrode with the point diameter of 1 mm was inserted into medial mamillary nucleus, the wanted hippocampal guidance spot was found within the rang of the hippocampal region at the same side of tee mamillary body range (CA1-CA4), inserted with same-core guidance electrode, a sole square-wave stimulation of wave wide 0.2 ms stimulated with electrodes at the applied intensity of 7-9 V, the evoked potential was induced through guidance electrodes, and then input to the ATAC-350 data-processing machine for memory showing wave processing, the memory recorded wave recording graph was separately drawn up by the X-Y recording instrument to observe the latency, time procedure and amplitude of the evoked potential in each hippocampal region of the rats and calculate the percentage of the evoked potential in each hippocampal region. Totally 78 guidance spots in hippocampus were recorded, including 30 positive reaction spots and 48 negative ones. MAIN OUTCOME MEASURES: ① Latency, time procedure and amplitude of the evoked potentials in each hippocampal region of rats; ②percentage of the evoked potentials in each hippocampal region; ③ the wave shapes of the evoked potentials in each hippocampal region from different arrangement in the same positive reaction spot. RESULTS :① Of the 30 recorded positive reactions, 9 positive spots fused into the stimulated false marks because of the short latency. The analysis of variance showed that the latency had significant difference (P 〈 0.05), time procedure had highly significant difference (P 〈 0.01 ), but there was no significant difference in the amplitude (P 〉 0.05) among the hippampal regions.② Among the 30 positive spots, the percentage of evoked potential in the hippocampal regions were 34.5% for CA1, 2.0% for CA2, 24.1% for CA3 and 22.4% for CA4. ③ In different levels of the same positive spot, different changes of the evoked potential wave shapes could be observed, and the most obvious change was that of positive wave amplitude. At different positive spots, evoked potentials of positive phase, negative and the double-phase could be observed. CONCLUSION: There are nerve associations between mamillary body and hippocampus, afferent fibers of mamillary body come from hippocampal CA1 region are a little more. 展开更多
关键词 Changes of evoked potential in different hippocampal regions induced by electrostimulation at medial mamillary nucleus of rats body
下载PDF
Regional differences in gully network connectivity based on graph theory:a case study on the Loess Plateau,China
4
作者 CHENG Jian-hua LUO Lan-hua +2 位作者 LI Fa-yuan LIU Lu-lu CUI Ling-zhou 《Journal of Mountain Science》 SCIE CSCD 2023年第4期1035-1050,共16页
Material exchange frequently occurs in gullies,and thus the relationship between a gullynetwork structure and sediment transport potential has attracted considerable interest.However,previous researches ignored the di... Material exchange frequently occurs in gullies,and thus the relationship between a gullynetwork structure and sediment transport potential has attracted considerable interest.However,previous researches ignored the difficulty of material transport from sources to sinks,and did not quantify the connectivity of a network structure.In this study,we used a graph model structure to model gully networks of six typical sample areas in the Loess Plateau of China and quantified gully network connectivity using four indexes:average node strength,accessibility from sources to sinks,potential flow,and network structural connectivity index.Results show that:(1)Reflected by different quantitative indexes,the trends of gully network connectivity in different regions are similar.From north to south,the connectivity of a sample area first increases and then decreases.(2)The more mature gullies have stronger network connectivity.Small resistance is conducive to material transport in the gullies.(3)The node connectivity index of the gully network shows a significant aggregation distribution in space,and node connectivity on the main channel is often stronger than that on the branch trench.These results not only deepen the understanding of the process and mechanism of loess gully geomorphic development and evolution but also provide a reference for geomorphic studies. 展开更多
关键词 Graph theory Gully network Loess Plateau CONNECTIVITY regional difference
下载PDF
China’s urban green innovation:Regional differences,distribution dynamics,and convergence
5
作者 Yuting Xue Shumin Dong +1 位作者 Guixiu Ren Kai Liu 《Chinese Journal of Population,Resources and Environment》 2023年第4期239-248,共10页
Urban green innovation(UGI)is essential to environmental protection,ecological conservation,and high quality economic growth.Using green patents,our study assessed the level of UGI of 287 Chinese cities at and above t... Urban green innovation(UGI)is essential to environmental protection,ecological conservation,and high quality economic growth.Using green patents,our study assessed the level of UGI of 287 Chinese cities at and above the prefecture level.Then,using the Dagum Gini coefficient,kernel density estimation(KDE),and con‐vergence models,we examined regional differences,distribution dynamics,and convergence of UGI across China.The study’s findings are as follows:(1)Overall,regional differences in UGI tended to narrow,and the main contributor to these differences was the difference between economic zones.(2)KDE showed that the level of UGI was rising,which was polarized within each economic zone.(3)The national UGI in economic zones other than the Northeast and Middle Yellow River Economic Zones featured significantσconvergence,while each economic zone showed absolute and conditionalβconvergence. 展开更多
关键词 Urban green innovation regional difference Distribution dynamic CONVERGENCE Green patent
下载PDF
Analysis of Regional Differences in Bone Mineral Density Acquisition Factors in Young Women
6
作者 Norie Funaki Fumihiro Omasu +5 位作者 Asami Endo Minami Mashiko Kana Okazaki Natsuki Ogata Kosuke Hiruma Tomomi Gotoh 《Journal of Biosciences and Medicines》 2023年第11期108-122,共15页
Purpose: Obtaining high peak bone mass (PBM) and maintaining bone mass is important for the prevention of osteoporosis. This study aimed to examine the regional differences in bone mineral density and factors associat... Purpose: Obtaining high peak bone mass (PBM) and maintaining bone mass is important for the prevention of osteoporosis. This study aimed to examine the regional differences in bone mineral density and factors associated with its acquisition from exercise. Design: The study population included 75 women of 18 - 22 years of age in East Japan and 104 women of 18 - 27 years of age in West Japan. The speed of sound (SOS) of the calcaneus was measured, and the young adult mean (%YAM) was calculated from the SOS. The subjects’ medical history, family history of osteoporosis, and exercise habits were examined using a self-administered questionnaire. Results: There were a significantly greater number of subjects with low %YAM in West Japan. The exercise history and exercise time were significantly higher in West Japan, and the exercise intensity score tended to be higher in East Japan during junior high and high school. A multiple regression analysis by region revealed that the following factors had a significant positive association with the SOS: exercise intensity at elementary school and outdoor sports at junior high school in East Japan;and exercise time at elementary school, muscle mass, and outdoor sports at junior high school in West Japan. On the other hand, exercise time in junior high school in West Japan showed a negative association with the SOS. Conclusions: Regional differences in bone mineral density existed, suggesting a trend toward lower bone mineral density in West Japan. Exercise history and time tended to be higher in West Japan, and exercise intensity scores tended to be higher in East Japan, suggesting that exercise intensity may be more important than exercise time for obtaining bone mineral density. 展开更多
关键词 Bone Mineral Density Exercise Intensity region differences Young Women
下载PDF
Regional difference and dynamic evolution of development quality of power industry in China
7
作者 Sha Yu Yongjian Pu +2 位作者 Lefeng Shi Hao Yu Yixiang Huang 《Chinese Journal of Population,Resources and Environment》 2023年第1期1-12,共12页
To achieve the goals of carbon peaking and carbon neutrality and maintain high-quality economic growth,China is currently striving to improve the quality of development of its power sector.In this regard,revealing the... To achieve the goals of carbon peaking and carbon neutrality and maintain high-quality economic growth,China is currently striving to improve the quality of development of its power sector.In this regard,revealing the regional differences and evolutionary trends in the development quality of China’power sector has a high value to inspire the next improvement direction toward how to integrate regional power recourses to an overall optimization level.Motived by this purpose,this paper uses the entropy method to evaluate the com‐prehensive and subsystem indices of the development quality of the power industry,and reveals their re‐gional differences and evolutionary trends with the help of the Dagum Gini coefficient and Kernel density es‐timation methods.The findings show that:There are obvious regional differences in the development quality of China’s power industry,and the differences are steadily declining in all regions except the West.Regional differences are mainly derived from inter-regional differences,with the largest inter-regional differences in the East-Northeast region.Intra-regional differences show a distribution pattern of East>West>North‐east>Center. 展开更多
关键词 Development quality of power industry regional difference The Dagum Gini Dynamic evolution Kernel density
下载PDF
Study on Comprehensive Efficiency Evaluation of Rural Power Grid under Rural Revitalization Strategy Considering Regional Differences
8
作者 Huiru Zhao Manyu Yao +3 位作者 Zhenqi Bai Yue Zhang Zhihua Ding Zhenda Hu 《Energy Engineering》 EI 2023年第10期2211-2231,共21页
As an essential infrastructure,the rural power grid is vital in promoting agricultural and rural carbon sequestration and improving rural energy electrification.It is necessary to carry out in-depth research on its co... As an essential infrastructure,the rural power grid is vital in promoting agricultural and rural carbon sequestration and improving rural energy electrification.It is necessary to carry out in-depth research on its comprehensive efficiency.Based on the requirements of“double carbon”and rural revitalization strategy for the rural Power Grid,this paper focuses on the modernization and low-carbon transformation of the rural Power Grid.It constructs an input-output index system for the investment efficiency of the rural Power Grid in China under the new situation.It uses the primary data of the rural Power Grid of 30 prefecture-level cities in China from 2019 to 2021 to evaluate the investment efficiency of the rural Power Grid in China through a three-stage DEA model.The empirical results show that:considering the regional differences,the comprehensive efficiency of the rural Power Grid in backward areas is significantly improved;that is,the three-stage DEA method can more objectively evaluate the comprehensive efficiency of the rural Power Grid.In the context of the continued promotion of the rural revitalization strategy,to improve the comprehensive efficiency of the rural Power Grid,it is necessary to improve the technical level of the rural Power Grid further and appropriately expand the scale of investment in the rural Power Grid. 展开更多
关键词 regional difference rural revitalization rural power grid three-stage DEA efficiency of investment
下载PDF
Simulation analysis of regional surface mass anomalies inversion based on different types of constraints 被引量:2
9
作者 Bo Zhong Jiangtao Tan +2 位作者 Qiong Li Xianpao Li Tao Liu 《Geodesy and Geodynamics》 CSCD 2021年第4期298-307,共10页
Surface mass anomalies estimated by mass concentration(mascon)approach using Gravity Recovery and Climate Experiment(GRACE)observations with regularization constraints generally present higher spatial resolution than ... Surface mass anomalies estimated by mass concentration(mascon)approach using Gravity Recovery and Climate Experiment(GRACE)observations with regularization constraints generally present higher spatial resolution than the spheric harmonic(SH)solutions.To analyze the influence of different types of constraints on the estimation of mascon solutions,we carried out a closed-loop simulation experiment to estimate surface mass anomalies over South America based on simulated GRACE intersatellite geopotential differences.Tikhonov regularization with spatial constraint(SC),uniform weighting constraint(UWC),and a prior information constraint(APC)were employed to stabilize the mascon solutions,and the corresponding optimal regularization parameters were determined based on the minimum residual root-mean-square(RMS)criterion.The results show that mascon solutions estimated under different types of constraints are consistent and equivalent when the optimal regularization parameters are selected.The spatial distributions and main characteristics of regional surface mass anomalies estimated by the three types of constraints agree well,and the values of residual RMS with different constraints are very close.But due to the smoothing effect of regularization,the signal strength of mascon solutions is a bit weaker than that of original true signal,especially in the regions with strong signals.In addition,due to the ill-conditioned problem is more serious for higher grid resolution,the relative contribution of the three types of constraints to the final mascon solutions would be stronger.The results show that the averages of relative contribution percentages of these constraints for 2°×2° mascon grids are 80%-90%,while the corresponding values for 4°×4° mascon grids are 30%-60%.However,based on the minimum residual RMS criterion,the accuracy of estimation results is not affected by the type of constraints and their relative contribution to the final mascon solutions. 展开更多
关键词 regional surface mass anomalies Regularization constraints Intersatellite geopotential differences GRACE mascon solutions Simulation analysis
下载PDF
Differential Neutrophil Infiltration Contributes to Regional Differences in Brain Infiammation in the Substantia Nigra Pars Compacta and Cortex 被引量:1
10
作者 KYUNG-AE JI MI YOUNG EU +3 位作者 SEUNG-HEE KANG BYOUNG JOO GWAG ILO JOU EUN-HYE JOE 《神经损伤与功能重建》 2008年第4期265-273,共9页
脑的炎症反应是神经退行性疾病的危险因素之一。有趣的是,黑质密部(SNpc)严重的炎性反应会加速帕金森病的发作和进展。本研究通过比较SNpc与皮质的炎性过程来检测SNpc严重炎性反应的潜在机制。在完整的脑组织中,SNpc和皮质的CD11b+小胶... 脑的炎症反应是神经退行性疾病的危险因素之一。有趣的是,黑质密部(SNpc)严重的炎性反应会加速帕金森病的发作和进展。本研究通过比较SNpc与皮质的炎性过程来检测SNpc严重炎性反应的潜在机制。在完整的脑组织中,SNpc和皮质的CD11b+小胶质细胞密度是相似的。但是,脂多糖注射可增加SNpc的CD11b+细胞数目,而不能增加皮质中的。以前作者曾报道内毒素注射之后,黑质密部有CD11b和MPO双阳性的中性粒细胞浸润(GLIA55:1577-1588)。值得注意的是,MPO+中性粒细胞数量在SNpc中显著增加,而在皮质中只有轻微提高。中性粒细胞浸润的范围与神经元损伤相关。作者证实,内毒素注射后,中性粒细胞减少大鼠的SNpc中的神经元丢失较正常大鼠显著减少。此外,完整的SNpc中的星形胶质细胞密度明显低于皮质。而且,内毒素注射后,SNpc的内皮细胞和星形胶质细胞的损害以及血脑屏障的通透性均有显著变化。这些结果都提示,过度的中性粒细胞浸润和环境因子,例如低星形胶质细胞浓度和高血脑屏障通透性,会导致SNpc的重度炎症和神经元死亡。 展开更多
关键词 中性粒细胞 脑炎症 区域差异
下载PDF
Study on the Influence of Lanzhou-Urumqi High-Speed Railway on Regional Accessibility and Economic Development
11
作者 Lili Ma Xiaolong Han Miao Gong 《Proceedings of Business and Economic Studies》 2024年第2期22-31,共10页
The Lanzhou-Urumqi high-speed railway is an important part of the railway network connecting Gansu,Qinghai,and Xinjiang,and it is of far-reaching significance in facilitating China’s western development.An accessibil... The Lanzhou-Urumqi high-speed railway is an important part of the railway network connecting Gansu,Qinghai,and Xinjiang,and it is of far-reaching significance in facilitating China’s western development.An accessibility model and a double difference model were built to analyze the impact of the Lanzhou-Urumqi high-speed railway on regional accessibility and economic development of the areas along the line before(2012-2014)and after(2017-2019)its opening.The results show that the regional accessibility remains unchanged before and after the operation of this railway line.However,there is a spatial difference in improvement,that of central cities being better.The opening of the high-speed railway is conducive to driving the overall economic development of the region and promoting the comprehensive and coordinated development of regional economies. 展开更多
关键词 Lanzhou-Urumqi high-speed railway regional economy Double difference model Accessibility model Empirical analysis
下载PDF
Regional differences of water conservation in Beijing’s forest ecosystem 被引量:10
12
作者 ZHANG Biao XIE Gao-di YAN Yu-ping YANG Yan-gang 《Journal of Forestry Research》 SCIE CAS CSCD 2011年第2期295-300,共6页
The water conservation capacities of main forests in Beijing,China were estimated through the quantitative analysis.Various methods developed in published papers on forest hydrology were employed.The forests in Huairo... The water conservation capacities of main forests in Beijing,China were estimated through the quantitative analysis.Various methods developed in published papers on forest hydrology were employed.The forests in Huairou,Yanqing,Miyun,Mentougou and Fangshan districts are the main contributors to water conservation(the cumulative ratio reaches 65%),and the forests in Tongzhou,Chaoyang,Shunyi and Daxing districts have the highest water conservation capacity(3000 m3/ha).Altitude and slope are the key factors to affect the water conservation capacity.The forests located in Plain Area,Hilly Area,Low Mountain,and Middle Mountain contributes 27%,28%,24% and 21% of the conserved water,respectively.The water conservation capacity of forests in Plain Area(2 948 m3/ha),is superior to the forests in other regions.And the forests situated on Flat Slope,Moderate Slope and Gentle Slope constitute the largest proportion(nearly 93%) of water conservation,while the forests on Flat Slope has the highest water conservation capacity(2 797 m3/ha),and the forest on Steep slope has the lowest water conservation capacity(948 m3/ha). 展开更多
关键词 forest ecosystem regional difference water conservation BEIJING
下载PDF
Regional Differences and Characteristics of Soil Organic Carbon Density Between Dry Land and Paddy Field in China 被引量:5
13
作者 XU Quan RUI Wen-yi BIAN Xin-min ZHANG Wei-jian 《Agricultural Sciences in China》 CAS CSCD 2007年第8期981-987,共7页
Study on the regional characteristics of soil organic carbon (SOC) density in farmland will not only contribute greatly to the technique of soil productivity enhancement, but also give evidences of technique selecti... Study on the regional characteristics of soil organic carbon (SOC) density in farmland will not only contribute greatly to the technique of soil productivity enhancement, but also give evidences of technique selection and policy making for carbon sequestration in soils. Based on the second national soil survey of China, the situation of SOC density in the plow layer of farmland was analyzed under different land use patterns. Results showed that SOC density in the plow layer was about 3.15 kg m^-2 in average ranging from 0.81 to 12.68 kg m^-2. The highest density was found in the southeastern region with an average of 3.63 kg ma, while the lowest occurring in the northwestern region with an average of 3.00 kg m^-2. The variation coefficient of SOC density in the plow layer of farmland was 57%, which was 35% lower than that of non-farmland soils. Compared to SOC density in the dry land, SOC density in paddy soils was 13% higher with a lower variation coefficient between different regions. In addition, the relationships between the climatic factors (annual average temperature and precipitation) and SOC density were lower in farmland than those in non-farmland soils, as well as lower in paddy soils than those in dry land of farmland. These results suggest that anthropogenic disturbances have great impacts on SOC density in farmland soils, especially in paddy soils, indicating that Chinese rice cropping may contribute greatly to the SOC stability and sequestration in paddy field. 展开更多
关键词 land use pattern organic carbon density carbon sequestration regional difference global change
下载PDF
Regional differences in global glacier retreat from 1980 to 2015 被引量:11
14
作者 LI Yao-Jun DING Yong-Jian +1 位作者 SHANGGUAN Dong-Hui WANG Rong-Jun 《Advances in Climate Change Research》 SCIE CSCD 2019年第4期203-213,共11页
Global warming triggers shrinking and thinning of glaciers worldwide,with potentially severe implications for human society.However,regional differences in glacier retreat and its relationship with climatic characteri... Global warming triggers shrinking and thinning of glaciers worldwide,with potentially severe implications for human society.However,regional differences in glacier retreat and its relationship with climatic characteristics have not been conclusively demonstrated.In this study,regional changes in global glaciers based on two primary features,area change and mass balance,were investigated on the basis of data collected from published research on glacier changes.Results show that during the period 1980—2015,the rate of global glacier area shrinkage was 0.18%per year and that of global glacier mass loss was 0.25 m w.e.per year.Retreat of glaciers located at low and middle latitudes was characterized by severe area shrinkage and mass loss.Correspondingly,in the Arctic,deglaciation was characterized by ice thinning due to a low area reduction but relatively high mass loss rate.However,glaciers in high southern latitudes were in a relatively stable status.High Mountain Asia exhibited the lowest rate of area shrinkage and mass loss among glaciers located at low and middle latitudes,and a slower rate of mass loss compared with the global average.Glaciers in the Tropical Andes exhibited the fastest rate of glacier area shrinkage(—1.6%per year),whereas Antarctic and Subantarctic glaciers showed the lowest rate(—0.11%per year).For mass balance,the most negative occurred at Southern Andes(—0.81 m w.e.per year),followed by Alaska(-0.74 m w.e.per year).Only the Antarctic and Subantarctic experienced small mass gain(0.04 m w.e.per year).High levels of correlation are found between the rates of glacier retreat and annual average temperature and annual total precipitation instead of their trends.The variability of the surface climate conditions in the glacier environment plays a key role in driving these regional differences in global glacier retreat. 展开更多
关键词 Glacier retreat regional differences Climate change
下载PDF
Identification of necrophagous fly species from 12 different cities in China using ISSR and SCAR markers 被引量:2
15
作者 Xueli Zheng Jialin Hu +1 位作者 Santhosh Puthiya Kunnon Chen Xiaoguang 《Asian Pacific Journal of Tropical Medicine》 SCIE CAS 2010年第7期510-514,共5页
Objective:To identify necrophagous fly speies from different regions in China using inter simple sequenc repeat(ISSR) and sequence-characterized amplified region(SCAR) melocular markers and to analyze their gene diffe... Objective:To identify necrophagous fly speies from different regions in China using inter simple sequenc repeat(ISSR) and sequence-characterized amplified region(SCAR) melocular markers and to analyze their gene difference and genetic relationship.Methods:Five carrion fly species were collected from 12 cities and regions in China,including Musca domestica(M.domestica), Lucilia sericata(L.sericata),Chrysomya megacephala(C.megacephala),Helicophagella melanura(H.melanura),Boethcherisca peregrina,and they were studied using ISSR and SCAR markers.Results:Eight ISSR primers were used for amplification of 121 samples.679 clear and stable bands were identified,of which 516 bands were polymorphic.Several species-specific ISSR fragment were cloned and sequenced as an initial effort to derive the SCAR markers.Using M.domestica SCAR specific primers,SCAR-PCR amplification was performed for 8 M.domestca population sample DNA from different regions in China as well as L sericata,C.megacephala, H.melanura and Lucillia cupirina.The result showed only M.domestica produced specificalty 600 bp fragment,but L sericata,C.megacephala,H.melanura and Lucillia cupirina did not produce the same specific fragment.Clustering analysis showed clustering of most flies of M. domestica,C.megacephala and L sericata.M.domestica samples from different regions in China yielded different banding patterns.Conclusions:Application of ISSR-PCR and SCAR markers to identify necrophagous fly species from 12 cities and regions in China is first reported.ISSR-PCR and SCAR markers provide a quick reliable molecular marker technique for the identification of different species of necrophagous fly. 展开更多
关键词 Forensic INSECTS Necrophagous FLIES different population Molecular MARKERS Inter-simple SEQUENCE REPEAT Sequence-characterized amplified region
下载PDF
Spatial-temporal differences in in-stream flow requirement based on GIS: A case study of Yan'an region, northern Shaanxi 被引量:2
16
作者 WANG Lixia REN Zhiyuan 《Journal of Geographical Sciences》 SCIE CSCD 2008年第1期107-114,共8页
Although water has the central function of the bloodstream in the biosphere especially in arid or semi-arid regions such as Yah'an region in northwestern China, yet the very limited attention is paid to the role of t... Although water has the central function of the bloodstream in the biosphere especially in arid or semi-arid regions such as Yah'an region in northwestern China, yet the very limited attention is paid to the role of the water-related processes in ecosystem. In this research, based on continuous nearly 50-year data including runoff volume, sediment discharge as well as sediment accretion from hydrographic stations, and 10-year information of water quality from pollution monitoring stations, the method for measuring in-stream flow requirement has been put forward supported by experiential models and GIS spatial analysis. Additionally, the changes of in-stream flow requirement for environment and economic development have been addressed from spatial-temporal dimensions. The results show that: (1) According to the central streams in Yan'an region, mean annual in-stream flow requirement reaches 1.0619 billion m^3, and the surface water for economic exploitation is 0.2445 billion m3 (2) Mean annual in-stream flow requirement for sediment transfers in flood period occupies over 80% of the integrated volume in a year. (3) From the 1950s to 1970s, in-stream flow requirement for sediment transfers is comparatively higher, while from the 1980s to 1990s, this requirement presents a decreasing tendency. 展开更多
关键词 GIS spatial analysis Yan'an region in-stream flow requirement spatial-temporal differences
下载PDF
Regional difference and dynamic mechanism of locality of the Chinese farming-pastoral ecotone based on geotagged photos from Panoramio 被引量:1
17
作者 WANG Fang LI Yixi +1 位作者 DONG Ying ZHU Xiaohua 《Journal of Arid Land》 SCIE CSCD 2018年第2期316-333,共18页
Cross-regional locality research reflects the influences of natural environment and the human activities due to the abundant land types and the multiple landscape combinations in related regions. The Chinese farming-p... Cross-regional locality research reflects the influences of natural environment and the human activities due to the abundant land types and the multiple landscape combinations in related regions. The Chinese farming-pastoral ecotone is a typical large-scale region but few studies were conducted. This research contributed to the understanding of cross-regional locality of the Chinese farming-pastoral ecotone from different scales, including national, sectional, and provincial administrative units by utilizing geotagged photos(GTPs) obtained from the Panoramio website. The major results were as follows:(1) the locality elements of the Chinese farming-pastoral ecotone included 52 free nodes classified into 8 types of scene attributes;(2) there were huge differences between locality elements of different regions, and there was a negative correlation between the similarity degree of elements of different provinces and their spatial distances;(3) the Chinese farming-pastoral ecotone could be divided into the northern, central and southern sections, whose localities had differences in element constitution, association structure and the strength of elements, system stability and the anti-interference capability; and(4) the evolution of the localities of the northern and central sections was mainly influenced by human activities, while the locality of southern section retained more natural features. On a theoretical level, this research aimed to establish the research methodology of locality from the perspective of open data on the web with strong operability and replicability. On a practical level, this research could enrich the structuring recognition of the locality of the Chinese farming-pastoral ecotone and the comprehension of its dynamic mechanism. The results provide a reference for locality differentiation protection and the development of a cross-regional scale. 展开更多
关键词 administrative units geotagged photos LANDSCAPE LOCALITY NETWORKS regional differences
下载PDF
Temporal-spatial change and driving mechanism for regional difference of domestic tourism in China 被引量:1
18
作者 Degen Wang Tian Chen 《Chinese Journal of Population,Resources and Environment》 2013年第1期69-78,共10页
By using the variation coefficient,Gini coefficient and Theil coefficient,this paper makes preliminary exploration of temporalspatial change features and driving mechanism for regional differences of domestic tourism ... By using the variation coefficient,Gini coefficient and Theil coefficient,this paper makes preliminary exploration of temporalspatial change features and driving mechanism for regional differences of domestic tourism in China from 1995 to 2009.According to the results,we drew the following conclusions:(1)The regional difference of domestic tourism in China tends to be narrowing generally,and is less than that of inbound tourism,playing an important role in narrowing the overall gap of regional tourism in China.(2)The regional internal difference features:inter-provincial difference in the eastern region and difference among the eastern,central and western regions are comparatively obvious and demonstrate a significantly shrinking tendency,the change tendency is consistent with the change tendency of overall difference and exercises a decisive role in overall difference,whereas the inter-provincial difference in the central and western regions is small and relatively stable,having less influence on the overall difference.(3)The temporal-spatial change in regional difference is featured by:low-level provinces occupy a majority and are concentrated in the central and western regions,showing a tendency of narrowing difference;high-level provinces are concentrated in the eastern region,showing a tendency of spreading to the central and western regions;spatial pattern of regional difference demonstrates 4 types,i.e."proliferation type","polarization type","quiescence type"and"collapse type."(4)The driving force for regional difference of domestic tourism in China comes down to 3 aspects:regional socio-economic attribute,regional transport accessibility level and regional development policy. 展开更多
关键词 DOMESTIC TOURISM regionAL differENCE temporal-spatial CHANGE driving mechanism China
下载PDF
Regional Differences of China′s Urban Expansion from Late 20th to Early 21st Century Based on Remote Sensing Information 被引量:35
19
作者 LIU Jiyuan ZHANG Qian HU Yunfeng 《Chinese Geographical Science》 SCIE CSCD 2012年第1期1-14,共14页
This study investigated the regional differences of China′s urban land expansion from the late 1980s to the year of 2008, based on the spatio-temporal analysis of CLCD (China′s land cover/land use database) datasets... This study investigated the regional differences of China′s urban land expansion from the late 1980s to the year of 2008, based on the spatio-temporal analysis of CLCD (China′s land cover/land use database) datasets which were mainly produced from remote sensing imagery data. A newly defined urbanization level index (UI), based on urban land area, is proposed to describe Chinese urban expansion process at 1 kilometer, provincial, regional, and na-tional scales, together with the absolute urban expansion index (UEa) and the relative urbanization expansion index (UEr). The results indicate that the percentages of total land area occupied by urban in the late 1980s, 1995, 2000, 2005, and 2008 were approximately 0.25%, 0.32%, 0.33%, 0.43% and 0.52% of China′s total land area, respectively. Between the late 1980s and 2008, the total urban expansion in the mainland of China was 2.645 × 104 km2, resulting in an annual urban expansion area of about 1322.7 km2/yr, with the UEr of 111.9%. This study also finds that there has been an obvious spatial gradient of urbanization ratio running from the east coast to the west inland, and the urbanization gaps among different regions have persisted over the past two decades. The study also reveals obvious temporal varia-tions of the urbanization rates. There was very little urban growth during the period of 1995-2000 due to the governmental policy factors. 展开更多
关键词 中国内地 城市扩展 区域差异 遥感信息 后期 城市化水平 土地利用数据库 基础
下载PDF
IMPROVEMENT OF REGIONAL PREDICTION OF SEA FOG ON GUANGDONG COASTLAND USING THE FACTOR OF TEMPERATURE DIFFERENCE IN THE NEAR-SURFACE LAYER 被引量:1
20
作者 黄辉军 黄健 +2 位作者 刘春霞 毛伟康 毕雪岩 《Journal of Tropical Meteorology》 SCIE 2016年第1期66-73,共8页
The relationship between the factor of temperature difference of the near-surface layer(T_(1000 hPa)-T_(2m))and sea fog is analyzed using the NCEP reanalysis with a horizontal resolution of l°xl°(2000 to 201... The relationship between the factor of temperature difference of the near-surface layer(T_(1000 hPa)-T_(2m))and sea fog is analyzed using the NCEP reanalysis with a horizontal resolution of l°xl°(2000 to 2011) and the station observations(2010 to 2011).The element is treated as the prediction variable factor in the GRAPES model and used to improve the regional prediction of sea fog on Guangdong coastland.(1) The relationship between this factor and the occurrence of sea fog is explicit:When the sea fog happens,the value of this factor is always large in some specific periods,and the negative value of this factor decreases significantly or turns positive,suggesting the enhancement of warm and moist advection of air flow near the surface,which favors the development of sea fog.(2) The transportation of warm and moist advection over Guangdong coastland is featured by some stages and the jumping among these states.It also gets stronger over time.Meanwhile,the northward propagation of warm and moist advection is quite consistent with the northward advancing of sea fog from south to north along the coastland of China.(3) The GRAPES model can well simulate and realize the factor of near-surface temperature difference.Besides,the accuracy of regional prediction of marine fog,the relevant threat score and Heidke skill score are all improved when the factor is involved. 展开更多
关键词 weather prediction regional prediction of marine fog Guangdong coastland GRAPES model factor of near-surface temperature difference
下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部