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Short-term Association of Meteorological Elements on COVID-19 Pandemic in a Semi-arid City of Northwest China,2021-2022
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作者 FENG Feng Liu MA Yu Xia +3 位作者 CHENG Bo Wen LIU Zong Rui ZHAO Yu Han YANG Jie 《Biomedical and Environmental Sciences》 SCIE CAS CSCD 2024年第5期537-542,共6页
The coronavirus disease 2019(COVID-19)outbreak in late 2019 significantly impacted global health.The virus’s rapid spread,with its long incubation period and high infection level,caused substantial disruption to regu... The coronavirus disease 2019(COVID-19)outbreak in late 2019 significantly impacted global health.The virus’s rapid spread,with its long incubation period and high infection level,caused substantial disruption to regular social frameworks,production,and lifestyles^([1]).COVID-19 is primarily transmitted through close contact,long-range contaminants,and airborne routes. 展开更多
关键词 northwest COV primarily
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Climate and topography regulate the spatial pattern of soil salinization and its effects on shrub community structure in Northwest China
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作者 DU Lan TIAN Shengchuan +5 位作者 ZHAO Nan ZHANG Bin MU Xiaohan TANG Lisong ZHENG Xinjun LI Yan 《Journal of Arid Land》 SCIE CSCD 2024年第7期925-942,共18页
Soil salinization may affect biodiversity and species composition,leading to changes in the plant community structure.However,few studies have explored the spatial pattern of soil salinization and its effects on shrub... Soil salinization may affect biodiversity and species composition,leading to changes in the plant community structure.However,few studies have explored the spatial pattern of soil salinization and its effects on shrub community structure at the ecosystem scale.Therefore,we conducted a transect sampling of desert shrublands in Northwest China during the growing season(June–September)in 2021.Soil salinization(both the degree and type),shrub community structure(e.g.,shrub density and height),and biodiversity parameters(e.g.,Simpson diversity,Margalf abundance,Shannon-Wiener diversity,and Pielou evenness indices)were used to assess the effects of soil salinization on shrub community structure.The results showed that the primary degree of soil salinization in the study area was light salinization,with the area proportion of 69.8%.Whereas the main type of soil salinization was characterized as sulfate saline soil,also accounting for 69.8%of the total area.Notably,there was a significant reduction in the degree of soil salinization and a shift in the type of soil salinization from chloride saline soil to sulfate saline soil,with an increase in longitude.Regional mean annual precipitation(MAP),mean annual evapotranspiration(MAE),elevation,and slope significantly contributed to soil salinization and its geochemical differentiation.As soil salinization intensified,shrub community structure displayed increased diversity and evenness,as indicated by the increases in the Simpson diversity,Shannon-Wiener diversity,and Pielou evenness indices.Moreover,the succulent stems and leaves of Chenopodiaceae and Tamaricaceae exhibited clear advantages under these conditions.Furthermore,regional climate and topography,such as MAP,MAE,and elevation,had greater effects on the distribution of shrub plants than soil salinization.These results provide a reference for the origin and pattern of soil salinization in drylands and their effects on the community structure of halophyte shrub species. 展开更多
关键词 soil salinization HALOPHYTES SHRUBLAND climate change BIODIVERSITY DRYLANDS northwest China
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Evaluating the Impact of the Universal Test and Treat Strategy on the Survival of Patients in the Northwest Region of Cameroon
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作者 Emmanuel Mboh Nshom Bereynuy Jude Cholong +9 位作者 Kum Kang Walter Khan Eveline Mboh Keng Vitalis Noela F. Ijang Gwendoline Nkenu Nsom Mirabel Mbueh Vifeme Esther Bonje Kuni Monju Johnson Vishi Gladys Enih Fosah Pius Muffih Tih 《World Journal of AIDS》 2024年第3期45-60,共16页
Introduction: The main outcome of efficiently implemented universal test and treat (UTT) program is improved survival. UTT implementation has been ongoing in Cameroon since 2016 but evaluation data are scarce. This st... Introduction: The main outcome of efficiently implemented universal test and treat (UTT) program is improved survival. UTT implementation has been ongoing in Cameroon since 2016 but evaluation data are scarce. This study aims to assess the survival of antiretroviral therapy (ART) patients initiated under UTT in Northwest region of Cameroon. Methods: This retrospective cohort study included HIV-positive patients initiated in 2016 at 27 purposefully selected sites and followed until 2021. Data was anonymously abstracted from ART registers and patients’ charts. Kaplan-Meier survival estimates and Cox model were used to compare the survival of patients initiated under UTT with those initiated otherwise, using stata version 14.0. Results: In total, 2490 HIV-positive patients (median age 42.7 years, 94.7% adults, and 69.0% female) participated in the study. Of 1389 patients with viral load (VL) test results, 55% were initiated on ART late. The VL suppression rate of patients initiated late and those initiated early were similar. During follow-up, 1020 (40.9%) participants censored. The survival curves of patients initiated early on ART and those initiated late were similar during the first 2.5 years of follow-up but significantly (p Conclusions: This study confirms the expected impact of UTT. Programs only need to close existing implementation gaps along the critical pathways (diagnosis and treatment) of UTT, focusing more on males. 展开更多
关键词 Universal Test and Treat Viral Load SURVIVAL northwest Cameroon
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Spatiotemporal variability of rain-on-snow events in the arid region of Northwest China
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作者 YANG Zhiwei CHEN Rensheng +3 位作者 LIU Zhangwen ZHAO Yanni LIU Yiwen WU Wentong 《Journal of Arid Land》 SCIE CSCD 2024年第4期483-499,共17页
Rain-on-snow(ROS)events involve rainfall on snow surfaces,and the occurrence of ROS events can exacerbate water scarcity and ecosystem vulnerability in the arid region of Northwest China(ARNC).In this study,using dail... Rain-on-snow(ROS)events involve rainfall on snow surfaces,and the occurrence of ROS events can exacerbate water scarcity and ecosystem vulnerability in the arid region of Northwest China(ARNC).In this study,using daily snow depth data and daily meteorological data from 68 meteorological stations provided by the China Meteorological Administration National Meteorological Information Centre,we investigated the spatiotemporal variability of ROS events in the ARNC from 1978 to 2015 and examined the factors affecting these events and possible changes of future ROS events in the ARNC.The results showed that ROS events in the ARNC mainly occurred from October to May of the following year and were largely distributed in the Qilian Mountains,Tianshan Mountains,Ili River Valley,Tacheng Prefecture,and Altay Prefecture,with the Ili River Valley,Tacheng City,and Altay Mountains exhibiting the most occurrences.Based on the intensity of ROS events,the areas with the highest risk of flooding resulting from ROS events in the ARNC were the Tianshan Mountains,Ili River Valley,Tacheng City,and Altay Mountains.The number and intensity of ROS events in the ARNC largely increased from 1978 to 2015,mainly influenced by air temperature and the number of rainfall days.However,due to the snowpack abundance in areas experiencing frequent ROS events in the ARNC,snowpack changes exerted slight impact on ROS events,which is a temporary phenomenon.Furthermore,elevation imposed lesser impact on ROS events in the ARNC than other factors.In the ARNC,the start time of rainfall and the end time of snowpack gradually advanced from the spring of the current year to the winter of the previous year,while the end time of rainfall and the start time of snowpack gradually delayed from autumn to winter.This may lead to more ROS events in winter in the future.These results could provide a sound basis for managing water resources and mitigating related disasters caused by ROS events in the ARNC. 展开更多
关键词 rain-on-snow events SNOWPACK SNOWMELT climate change Spearman's rank correlation arid region of northwest China
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Ecological Network Resilience of Shiyang River Basin: An Arid Inland Watershed of Northwest China
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作者 HE Yangxi LIU Chunfang +1 位作者 NI Bowen LIAN Hugang 《Chinese Geographical Science》 SCIE CSCD 2024年第5期951-966,共16页
Due to the uncertainties posed by climate change,resilience has become an increasingly important variable for evaluating regional ecosystem stability.The assessment of Ecological Network Resilience(ENR)is crucial for ... Due to the uncertainties posed by climate change,resilience has become an increasingly important variable for evaluating regional ecosystem stability.The assessment of Ecological Network Resilience(ENR)is crucial for establishing mitigation strategies and sustainable socioeconomic development in arid regions.Shiyang River Basin is an arid watershed in Northwest China with complex characteristics,its ENR and spatial differentiation characteristics in 2020 were investigated in this work based on the Complex Adaptive System(CAS)theory.The results indicated that the mean Ecological Network Resilience Index(ENRI)value for the Shiyang River Basin was 0.390 in 2020,and the mean values in the southern mountainous,middle oasis,and northern desert regions of the basin were 0.598,0.461,and 0.237,respectively,demonstrating evident spatial differences.Additionally,the ENR of the basin exhibited distinct distribution characteristics across different dimension,whereas the trend of the integrated ENR of the basin was consistent with that of elemental,structural,and functional resilience,indicating the constructed three-region ENR model based on the logical relationship of element-structure-function was suitable for evaluation of the ENR in arid inland river watersheds.Furthermore,strategies for enhancing regional ENR were proposed from the perspective of adapting to climate change. 展开更多
关键词 Ecological Network Resilience(ENR) Complex Adaptive System(CAS) element-structure-function Shiyang River Basin northwest China
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Predicting changes in the suitable habitats of six halophytic plant species in the arid areas of Northwest China
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作者 YANG Ao TU Wenqin +9 位作者 YIN Benfeng ZHANG Shujun ZHANG Xinyu ZHANG Qing HUANG Yunjie HAN Zhili YANG Ziyue ZHOU Xiaobing ZHUANG Weiwei ZHANG Yuanming 《Journal of Arid Land》 SCIE CSCD 2024年第10期1380-1408,共29页
In the context of changes in global climate and land uses,biodiversity patterns and plant species distributions have been significantly affected.Soil salinization is a growing problem,particularly in the arid areas of... In the context of changes in global climate and land uses,biodiversity patterns and plant species distributions have been significantly affected.Soil salinization is a growing problem,particularly in the arid areas of Northwest China.Halophytes are ideal for restoring soil salinization because of their adaptability to salt stress.In this study,we collected the current and future bioclimatic data released by the WorldClim database,along with soil data from the Harmonized World Soil Database(v1.2)and A Big Earth Data Platform for Three Poles.Using the maximum entropy(MaxEnt)model,the potential suitable habitats of six halophytic plant species(Halostachys caspica(Bieb.)C.A.Mey.,Halogeton glomeratus(Bieb.)C.A.Mey.,Kalidium foliatum(Pall.)Moq.,Halocnemum strobilaceum(Pall.)Bieb.,Salicornia europaea L.,and Suaeda salsa(L.)Pall.)were assessed under the current climate conditions(average for 1970-2000)and future(2050s,2070s,and 2090s)climate scenarios(SSP245 and SSP585,where SSP is the Shared Socio-economic Pathway).The results revealed that all six halophytic plant species exhibited the area under the receiver operating characteristic curve values higher than 0.80 based on the MaxEnt model,indicating the excellent performance of the MaxEnt model.The suitability of the six halophytic plant species significantly varied across regions in the arid areas of Northwest China.Under different future climate change scenarios,the suitable habitat areas for the six halophytic plant species are expected to increase or decrease to varying degrees.As global warming progresses,the suitable habitat areas of K.foliatum,S.salsa,and H.strobilaceum exhibited an increasing trend.In contrast,the suitable habitat areas of H.glomeratus,S.europaea,and H.caspica showed an opposite trend.Furthermore,considering the ongoing global warming trend,the centroids of the suitable habitat areas for various halophytic plant species would migrate to different degrees,and four halophytic plant species,namely,S.salsa,H.strobilaceum,H.glomeratus,and H.capsica,would migrate to higher latitudes.Temperature,precipitation,and soil factors affected the possible distribution ranges of these six halophytic plant species.Among them,precipitation seasonality(coefficient of variation),precipitation of the warmest quarter,mean temperature of the warmest quarter,and exchangeable Na+significantly affected the distribution of halophytic plant species.Our findings are critical to comprehending and predicting the impact of climate change on ecosystems.The findings of this study hold significant theoretical and practical implications for the management of soil salinization and for the utilization,protection,and management of halophytes in the arid areas of Northwest China. 展开更多
关键词 HALOPHYTES climate change global warming maximum entropy(MaxEnt)model soil salinization suitable habitats northwest China
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Effect of CO_(2)flooding in an oil reservoir with strong bottom-water drive in the Tahe Oilfield,Tarim Basin,Northwest China
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作者 Li Zhang Haiying Liao Maolei Cui 《Energy Geoscience》 EI 2024年第1期230-233,共4页
The dissolution and diffusion of CO_(2)in oil and water and its displacement mechanism were investigated by laboratory experiment and numerical simulation for Block 9 in the Tahe oilfield,a sandstone oil reservoir wit... The dissolution and diffusion of CO_(2)in oil and water and its displacement mechanism were investigated by laboratory experiment and numerical simulation for Block 9 in the Tahe oilfield,a sandstone oil reservoir with strong bottom-water drive in Tarim Basin,Northwest China.Such parameters were analyzed as solubility ratio of CO_(2)in oil,gas and water,interfacial tension,in-situ oil viscosity distribution,remaining oil saturation distribution,and oil compositions.The results show that CO_(2)flooding could control water coning and increase oil production.In the early stage of the injection process,CO_(2)expanded vertically due to gravity differentiation,and extended laterally under the action of strong bottom water in the intermediate and late stages.The CO_(2)got enriched and extended at the oil-water interface,forming a high interfacial tension zone,which inhibited the coning of bottom water to some extent.A miscible region with low interfacial tension formed at the gas injection front,which reduced the in-situ oil viscosity by about 50%.The numerical simulation results show that enhanced oil recovery(EOR)is estimated at 5.72%and the oil exchange ratio of CO_(2)is 0.17 t/t. 展开更多
关键词 Strong bottom-water drive reservoir CO_(2)flooding Enhanced oil recovery Coning of bottom water Tahe oilfield Tarim Basin northwest China
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Synthetic analysis of meteorological elements for the sea fogs occurred in northwest the Yellow Sea under low pressure control and comparison with sea fogs occurred under high pressure control in summer
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作者 WANG Kaiyue MA Zheng +3 位作者 MIAO Qingsheng ZHAO Binru ZHANG Zengjian LI Cheng 《Marine Science Bulletin》 2024年第1期1-18,共18页
Based on the principle of transient perturbation analysis,in this paper,a method to objectively determine the weather pattern formed by sea fog is provided.On the basis of the classification results,the circulation si... Based on the principle of transient perturbation analysis,in this paper,a method to objectively determine the weather pattern formed by sea fog is provided.On the basis of the classification results,the circulation situation,divergence and vertical velocity field,and the vertical profile of temperature and humidity are synthesized and analyzed.The basic characteristics of the circulation and physical field of sea fog under low pressure control(L type sea fog)are obtained,and the results are compared with the sea fog under the control of high pressure(H type sea fog):a)L type sea fogs potential height anomaly disturbance is mainly manifested in the low layer,and its average value is-65.66 gpm,gradually weakening upward;b)L type sea fogs inversion structure is weaker than H type sea fogs when it occurs,the fog layer is thicker and the high relative humidity level is high over the fog layer,while the H type sea fogs fog layer has a relatively obvious dry layer;c)L sea fog has three layers of structure at the vertical direction.The first layer 1000-950 hPa is convergence accompanied by weak rise and subsidence,the second layer 950-850 hPa is divergence accompanied by weak subsidence,and the third layer 850 to 500hPa is gradually strengthened.While there are two layer structures of the H type sea fog.1000 hPa is divergence accompanied by weak rising and sinking movement,950-500 hPa is a uniform subsidence movement.d)Probability density statistical analysis further quantified the vertical movement of L and H type sea fog and the distribution of relative humidity in each layer.These conclusions provide an important reference for forecasting the sea fog in the northwest of the Yellow Sea under the condition of low pressure circulation in summer. 展开更多
关键词 sea fog under the low pressure control sea fog under the high pressure control northwest of the Yellow Sea synthetic analysis transient method
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Comprehensive applicability evaluation of four precipitation products at multiple spatiotemporal scales in Northwest China
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作者 WANG Xiangyu XU Min +3 位作者 KANG Shichang LI Xuemei HAN Haidong LI Xingdong 《Journal of Arid Land》 SCIE CSCD 2024年第9期1232-1254,共23页
Precipitation plays a crucial role in the water cycle of Northwest China.Obtaining accurate precipitation data is crucial for regional water resource management,hydrological forecasting,flood control and drought relie... Precipitation plays a crucial role in the water cycle of Northwest China.Obtaining accurate precipitation data is crucial for regional water resource management,hydrological forecasting,flood control and drought relief.Currently,the applicability of multi-source precipitation products for long time series in Northwest China has not been thoroughly evaluated.In this study,precipitation data from 183 meteorological stations in Northwest China from 1979 to 2020 were selected to assess the regional applicability of four precipitation products(the fifth generation of European Centre for Medium-Range Weather Forecasts(ECMWF)atmospheric reanalysis of the global climate(ERA5),Global Precipitation Climatology Centre(GPCC),Climatic Research Unit gridded Time Series Version 4.07(CRU TS v4.07,hereafter CRU),and Tropical Rainfall Measuring Mission(TRMM))based on the following statistical indicators:correlation coefficient,root mean square error(RMSE),relative bias(RB),mean absolute error(MAE),probability of detection(POD),false alarm ratio(FAR),and equitable threat score(ETS).The results showed that precipitation in Northwest China was generally high in the east and low in the west,and exhibited an increasing trend from 1979 to 2020.Compared with the station observations,ERA5 showed a larger spatial distribution difference than the other products.The overall overestimation of multi-year average precipitation was approximately 200.00 mm and the degree of overestimation increased with increasing precipitation intensity.The multi-year average precipitation of GPCC and CRU was relatively close to that of station observations.The trend of annual precipitation of TRMM was overestimated in high-altitude regions and the eastern part of Lanzhou with more precipitation.At the monthly scale,GPCC performed well but underestimated precipitation in the Tarim Basin(RB=-4.11%),while ERA5 and TRMM exhibited poor accuracy in high-altitude regions.ERA5 had a large bias(RB≥120.00%)in winter months and a strong dispersion(RMSE≥35.00 mm)in summer months.TRMM showed a relatively low correlation with station observations in winter months(correlation coefficients≤0.70).The capture performance analysis showed that ERA5,GPCC,and TRMM had lower POD and ETS values and higher FAR values in Northwest China as the precipitation intensity increased.ERA5 showed a high capture performance for small precipitation events and a slower decreasing trend of POD as the precipitation intensity increased.GPCC had the lowest FAR values.TRMM was statistically ineffective for predicting the occurrence of daily precipitation events.The findings provide a reference for data users to select appropriate datasets in Northwest China and for data developers to develop new precipitation products in the future. 展开更多
关键词 precipitation products the fifth generation of European Centre for Medium-Range Weather Forecasts(ECMWF)atmospheric reanalysis of the global climate(ERA5) Global Precipitation Climatology Centre(GPCC) Climatic Research Unit gridded Time Series(CRU TS) Tropical Rainfall Measuring Mission(TRMM) applicability evaluation northwest China
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藏西北绒山羊子宫内膜容受性相关基因和可变剪接事件的综合分析
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作者 德吉 索朗达 +6 位作者 魏宇辰 王斌 阿旺措吉 仁青措姆 崔久增 张磊 巴贵 《中国组织工程研究》 CAS 北大核心 2025年第7期1429-1436,共8页
背景:藏西北绒山羊子宫内膜容受性是胚胎植入的关键因素,目前对于藏西北绒山羊子宫内膜容受性相关基因表达及可变剪接的认识还未明确。目的:分析并挖掘藏西北绒山羊子宫内膜容受性相关的基因和可变剪接事件。方法:在妊娠第5天和第15天(... 背景:藏西北绒山羊子宫内膜容受性是胚胎植入的关键因素,目前对于藏西北绒山羊子宫内膜容受性相关基因表达及可变剪接的认识还未明确。目的:分析并挖掘藏西北绒山羊子宫内膜容受性相关的基因和可变剪接事件。方法:在妊娠第5天和第15天(分别代表容受前子宫内膜组和容受性子宫内膜组),分别随机选取3只藏西北绒山羊,采集子宫内膜组织,苏木精-伊红染色观察组织形态,免疫组织化学检测子宫内膜容受性标志蛋白白血病抑制因子、血管内皮生长因子的表达水平;提取子宫内膜组织总RNA,质量检测合格后进行转录组测序,寻找差异表达的mRNA、长链非编码RNA、环状RNA和miRNA,进行功能预测,并分析与子宫内膜容受性相关的可变剪接mRNA和长链非编码RNA。结果与结论:(1)与容受前子宫内膜组比较,容受性子宫内膜组子宫内膜组织中白血病抑制因子和血管内皮生长因子蛋白的表达水平明显升高;(2)测序结果显示,差异表达基因多为mRNA和长链非编码RNA,包括250个上调的mRNA、193个上调的长链非编码RNA、135个下调的mRNA和123个下调的长链非编码RNA,显著富集于Wnt、Hedgehog和Hippo信号通路;(3)可变剪接事件分析显示有8个差异表达的可变剪接转录本,均为mRNA分子,其中2个下调、6个上调,与血管内皮生长因子受体信号、细胞运动和胚胎发育有关。 展开更多
关键词 藏西北绒山羊 子宫内膜容受性 转录组测序 差异表达基因 可变剪接 白血病抑制因子 血管内皮生长因子
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Evaluation on Service Function of Plain Forest Ecosystem in Northwest China 被引量:5
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作者 岳丹 马青 +2 位作者 法科宇 鲁肃 黄守科 《Agricultural Science & Technology》 CAS 2011年第4期584-587,共4页
[Objective] The paper aimed to evaluate the plain forestry' service function in Northwest China.[Method] Based on general and representative investigations with county used as the minimum unit,evaluation on service f... [Objective] The paper aimed to evaluate the plain forestry' service function in Northwest China.[Method] Based on general and representative investigations with county used as the minimum unit,evaluation on service function of plain forestry ecosystem in Northwest China was carried out by measuring the quality and quantity.[Result] In 2005,the plain forestry in Northwest China plays a profound role in water and soil conversation,carbon sequestration by vegetation and soil,oxygen release by plants,sulfur dioxide absorption and and so on.[Conclusion] This paper laid foundation for research on service function of plain forest ecosystem in Northwest China. 展开更多
关键词 northwest China Plain forestry Ecosystem services EVALUATION
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Impact of Dry Warming on Economic and Characteristic Crop and Coping Technology in Northwest of China 被引量:4
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作者 邓振镛 倾继祖 +3 位作者 杨启国 宁惠芳 黄蕾诺 徐金强 《Agricultural Science & Technology》 CAS 2010年第4期124-129,共6页
Based on the state of characteristics of dry warming of modern climate changing,the response of growth,output and quality of main economic crops such as cotton,flax and winter rape and characteristic crop such as vini... Based on the state of characteristics of dry warming of modern climate changing,the response of growth,output and quality of main economic crops such as cotton,flax and winter rape and characteristic crop such as vinifera and apple were discussed.The coping technology for climate changing and measurements for serving the agricultural were provided. 展开更多
关键词 northwest Dry warming Economic crop Characteristic crop Influence Coping technology
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Application of Argo Data in the Analysis of Water Masses in the Northwest Pacific Ocean 被引量:2
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作者 孙朝辉 许建平 +2 位作者 刘增宏 童明荣 朱伯康 《Marine Science Bulletin》 CAS 2008年第2期1-13,共13页
The temperature and salinity distributions, and the water mass structures in Northwest Pacific Ocean are studied using the temperature and salinity data obtained by Argo profiling floats. The T-S relation in this regi... The temperature and salinity distributions, and the water mass structures in Northwest Pacific Ocean are studied using the temperature and salinity data obtained by Argo profiling floats. The T-S relation in this region indicates there exist 8 water masses, they are the North Pacific Tropical Surface Water (NPTSW), North P, acific Subsurface Water (NPSSW), North Pacific Intermediate Water (NPIW), North Pacific Subtropical Water (NPSTW), North Pacific Deep Water (NPDW) and Equatorial Surface Water (ESW), and the South Pacific Subsurface Water (SPSSW) and South Pacific Intermediate Water (SPIW). 展开更多
关键词 Argo profiling float T-S relation water mass analysis the northwest Pacific Ocean
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Investigation of Heavy Metal Contents in Traditional Chinese Herbal Medicine Peristrophe roxburghiana Collected from Northwest of Guangxi 被引量:2
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作者 刘旭辉 李容 +2 位作者 郭俊 罗志勇 覃勇荣 《Agricultural Science & Technology》 CAS 2016年第12期2751-2756,2762,共7页
Objective] This study was conducted to evaluate the product quality and safety of Peristrophe roxburghiana_ col ected from different places in Hechi City, northwest of Gunagxi, so as to provide basic data for further ... Objective] This study was conducted to evaluate the product quality and safety of Peristrophe roxburghiana_ col ected from different places in Hechi City, northwest of Gunagxi, so as to provide basic data for further development and uti-lization of the characteristic plant resource P. roxburghiana. [Method] Contents of 9 kinds of heavy metals including Cd, Mn, Pb, Zn and Cu in the herb were deter-mined by the method of wet digestion-flame atomic absorption spectrophotometry and atomic fluorescence spectrometry, respectively. [Results] Heavy metal contents of Cd, Mn, Pb, Fe, Cu, Zn, As, Hg and Se were 1.62-17.25, 8.93-142.53, 4.37-18.43, 103.7-242.81, 2.55-5.35, 85.40-146.30, 0.07-0.54, 0.00-0.08 and 0.00-0.47 mg/kg, respectively. According to the national food safety standards and Green Trade Standards of lmporting &amp; Exporting Medicinal plants &amp; Preparations, the heavy metal contents of the P. roxburghiana_samples col ected from different coun-ties in Hechi City exceeded standards or at the critical values. Among which, Cd, Pb and Zn contents of the samples are seriously higher than the standards. [Con-clusion] Therefore, the impact of soil heavy metal pol ution on the safety of edible plants in the northwest of Guangxi should be highly concerned. 展开更多
关键词 northwest of Guangxi Traditional Chinese herbal medicine Peristro-pheroxburghiana Product quality and safety Heavy metal content
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Middle Jurassic Sporo-pollen Assemblages in Northern Turpan Depression, Xinjiang, Northwest China 被引量:2
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作者 尹凤娟 张子福 《Acta Botanica Sinica》 CSCD 2002年第4期488-495,共8页
Eighty-one species of fossil spores and pollen assigned to 52 genera are found from the Middle Jurassic Xishanyao, Sanjianfang and Qiketai Formations of boreholes Le 1, Mi 1, Shan 1 and Dun 1 in the northern Turpan De... Eighty-one species of fossil spores and pollen assigned to 52 genera are found from the Middle Jurassic Xishanyao, Sanjianfang and Qiketai Formations of boreholes Le 1, Mi 1, Shan 1 and Dun 1 in the northern Turpan Depression, Xinjiang, northwest China. Three assemblages have been proposed as: Cyathidites-Psophosphaera-Cycadopites assemblage, Cyathidites-Quadraceculina-Classopollis assemblage and Cyathidites-Callialasporites-Classopollis assemblage obtained from the Xishanyao Formation, the Sanjianfang Formation and Qiketai Formation respectively. Based on the sporo-pollen assemblage features and con-elation, their geological ages are regarded as of Middle Jurassic, probably Aalenian to Bathonian. The results of the study indicate that the vegetation of early Middle Jurassic in this region consisted mainly of Gymnospermae of Ginkgoaceae of Cycadales, Podocarpaceae, Pinaceae and Pteridophyta of Cyatheacene, Osmundaceae, Lycopodiaceae and Dicksoniaceae, etc. They reflect a warm-moist subtropic climate. To the middle-late Middle Jurassic, Cheirolepidaceae was dominant in the vegetation, which indicates that the climate was in the trend of becoming dry. 展开更多
关键词 spore and pollen climate Middle Jurassic northwest China
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Quantitative data about active tectonics and possible locations of strong earthquakes in the future in the northwestern Beijing 被引量:19
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作者 冉勇康 陈立春 徐锡伟 《地震学报》 CSCD 北大核心 2001年第5期502-513,共12页
Deterministic, probabilistic and composite-grading methods are used to get the possible locations of strong earth-quakes in the future in Norwest Beijing and its vicinity based on the quantitative data and their accur... Deterministic, probabilistic and composite-grading methods are used to get the possible locations of strong earth-quakes in the future in Norwest Beijing and its vicinity based on the quantitative data and their accuracy about active tectonics in the research area and by ordering, some questions in the results are also discussed. It shows that the most dangerous fault segments for strong earthquakes in the future include: segments B and A of the southern boundary fault of the Yangyuan basin, the southern boundary fault of the Xuanhua basin, the east segment of the southern Huaian fault and the east segment of the northern YanggaoTianzhen fault. The most dangerous area is YangyuanShenjing basin, the second one is TianzhenHuaianXuanhua basin and the third dangerous areas are WanquanZhangjiakou and northeast of Yuxian to southwest of Fanshan. 展开更多
关键词 北京 活动构造定量资料 综合方法 强震地点 确定性方法 概率方法
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Theory and Application of Emergy Analysis in Arid Region in Northwest China
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作者 石惠春 孙宏山 +7 位作者 何爱红 王科明 柏玉芬 艾静文 马丽娟 张红喜 段正虎 肖洪浪 《Meteorological and Environmental Research》 CAS 2010年第6期1-5,8,共6页
Through summarizing the research status of emergy analysis at home and abroad,the basic connotation and judgment standard of emergy and indices were introduced in detail. Considering the characteristics of emergy anal... Through summarizing the research status of emergy analysis at home and abroad,the basic connotation and judgment standard of emergy and indices were introduced in detail. Considering the characteristics of emergy analysis applied to the specific geographic scope in arid region in Northwest China,the problems which should be paid attention to and the corresponding suggestions as well as counter measures were put forward. Finally,trends in the further study of emergy analysis were forecasted. 展开更多
关键词 EMERGY Emergy analysis Emergy indices northwest China China
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Analysis on Ecological Risk in Northwest China
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作者 刘引鸽 《Agricultural Science & Technology》 CAS 2014年第12期2230-2235,共6页
Based on scenario analysis method, assuming different economic develop- ment policies, and AHP method, the ecological indicators and risk prediction models were established. The trends of ecological risk in the northw... Based on scenario analysis method, assuming different economic develop- ment policies, and AHP method, the ecological indicators and risk prediction models were established. The trends of ecological risk in the northwest region were ana- lyzed. The results showed that: in the northwest, the potential ecological risks of the population economy, water resources, and land resources and natural disasters still existed. However, the environment and respond to ecological risks were decreasing. Therefore, a regional balanced development measures had been taken to curb the western trend of ecological deterioration. So that socio-economic development, re- sources, environment, and economy were expected to a virtuous cycle, and the eco- logical risks would be reduced. This study provides the basis for land and water use planning and environmental protection of government decision-making and management. 展开更多
关键词 Ecological Risk Scenario Analysis TREND northwest
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Research on Purification Effect of Jian Lake Zizania latifolia Wetland Lakefront Zone in Northwest of Yunnan Plateau on Nitrogen and Phosphorus of Agricultural Non-point Source 被引量:2
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作者 李卫东 刘云根 +2 位作者 田昆 梁启斌 刘惠芳 《Agricultural Science & Technology》 CAS 2010年第7期109-112,150,共5页
As the main external pollution source of lake,nitrogen and phosphorus from agricultural non-point source make a great contribution to the lake eutrophication pollution.Wetland lakefront zone which plays a key role in ... As the main external pollution source of lake,nitrogen and phosphorus from agricultural non-point source make a great contribution to the lake eutrophication pollution.Wetland lakefront zone which plays a key role in externally agricultural non-point source pollution is considered as the biggest barrier for controlling external pollution.In this research,the Jian lake plateau Zizania latifolia wetland lakefront zone was selected for agricultural non-point source pollutions control with the systematic field research,and the lakefront zone was approved to have an effective purification effect on nitrogen and phosphorus from Jinlong River; the theoretical mechanism of lakefront zone removing nutrient was also investigated.Z.latifolia wetland lakefront zone could remove nitrogen and phosphorus from Jinlong River and the removal ratio can reach 55.8-62.52% and 59.47-69.81% respectively.So,we can indicate that the Jian Lake plateau Z.latifolia wetland lakefront zone had a good effect on controlling agricultural non-point source pollution and protecting the environment. 展开更多
关键词 Plateau wetland in northwest of Yunnan Zizania latifolia lakefront zone Agricultural non-point source pollutions Purification effect
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Variations of oceanic fronts and their influence on the fishing grounds of Ommastrephes bartramii in the Northwest Pacific 被引量:12
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作者 CHEN Xinjun TIAN Siquan GUAN Wenjian 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2014年第4期45-54,共10页
Two predominant currents, the warm Kuroshio Current and the cold Oyashio Current, meet in the North- west Pacific Ocean. The dynamics of physical oceanographic structures in this region, including frontal zones and me... Two predominant currents, the warm Kuroshio Current and the cold Oyashio Current, meet in the North- west Pacific Ocean. The dynamics of physical oceanographic structures in this region, including frontal zones and meandering eddies, result in a highly productive habitat that serves as a favorable feeding ground for various commercially important species. Neon flying squid, Ommastrephes bartramii, is an im- portant oceanic squid, which is widely distributed in the North Pacific Ocean. Based on the catch data col- lected by Chinese squid jigging fleets and relevant environmental data, including sea surface temperature (SST) and fronts (represented by gradients of SST and thermocline) during 1998-2009, the variations of oceanic fronts and their influence on the fishing grounds of O. bartramii were evaluated, and the differ- ences in distribution of fishing grounds of O. bartramii in 2000 and 2002 were compared by describing the differences in vertical temperature between 0-300 m. It was found that the preferred horizontal tem- perature gradient of SST for O. bartramii tended to be centered at 0.01-0.02~C/nm, which attracted nearly 80% of the total fishing effort, and the preferred horizontal temperature gradients at the 50 m and 105 m layers were mainly located at 0.01-0.03~C/nm, which accounted for more than 70% of the total fishing effort during August-October. The preferred vertical temperature gradient within the 0-50 m layer for O. bartramii tended to be centered at 0.15-0.25~C/m during August and September and at 0.10-0.15~C/m in October, implying that the mixed surface layer was distributed at depths of 0-50 m. It was concluded that the vertical temperature gradient was more important than the horizontal temperature gradient in playing a role in forming the fishing ground. The results improved our understanding of the spatial dynamics of the 0. bartramii fishery. 展开更多
关键词 Ommastrephe bartramii fishing ground ocean front interannual variation northwest Pacific
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