The tallest sand dune worldwide is located in the Badain Jaran Desert(BJD),China,and has been standing for thousands of years.Previous studies have conducted limited physical exploration and excavation on the formatio...The tallest sand dune worldwide is located in the Badain Jaran Desert(BJD),China,and has been standing for thousands of years.Previous studies have conducted limited physical exploration and excavation on the formation of sand dunes and have proposed three viewpoints,that is,bedrock control,wind dominance,and groundwater maintenance with no unified conclusion.Therefore,this study analyzed the underlying bedding structure of sand dunes in the BJD.Although the bedrock of sand dunes is uplifted and wind controls the shape of dunes,the main cause of dune formation is groundwater that maintains the deposition of calcareous sandstone and accumulation of aeolian sand.According to water transport model and vapor transports in the unsaturated zone of sand dunes,capillary water transport height is limited with film water constituting the main form of water in dunes.Chemical properties and temperature of groundwater showed that aquifers in different basins receive relatively independent recharge from deep sources in the crater.Result of dune formation mechanism is of considerable importance in understanding groundwater circulation and provides a new perspective on water management in arid desert areas.展开更多
目的:探讨中青年人群急性心肌梗死发病的主要危险因素。方法:在中国知网、维普、万方、CBM、PubMed、Embase、Web of Science、the Cochrane Library等数据库中,检索从建库至2023年2月,中青年人群急性心肌梗死危险因素的病例对照研究和...目的:探讨中青年人群急性心肌梗死发病的主要危险因素。方法:在中国知网、维普、万方、CBM、PubMed、Embase、Web of Science、the Cochrane Library等数据库中,检索从建库至2023年2月,中青年人群急性心肌梗死危险因素的病例对照研究和队列研究。采用纽卡斯卡-渥太华量表(NOS)对文献进行质量评价,应用Stata 14.0软件进行Meta分析。结果:本研究纳入15篇文献,病例组患者2961例,对照组患者57604例,共7项危险因素。Meta分析结果显示,男性(OR=4.79,95%CI:3.28~6.99)、合并高血压(OR=2.77,95%CI:2.07~3.70)、合并糖尿病(OR=2.65,95%CI:1.89~3.71)、早发冠心病家族史(OR=3.66,95%CI:2.51~5.32)、吸烟(OR=2.29,95%CI:1.92~2.73)、合并高脂血症(OR=1.87,95%CI:1.67~2.10)、睡眠不足(OR=1.97,95%CI:1.57~2.47)为中青年人群发生急性心肌梗死的危险因素(P<0.05)。结论:男性、合并高血压、合并糖尿病、早发冠心病家族史、吸烟、高脂血症及睡眠不足均为中青年人群发生急性心肌梗死的危险因素。展开更多
目的通过科学知识图谱分析中药百合的研究热点及趋势。方法检索2000年1月1日-2021年12月31日中国知识资源总库(CNKI)、万方数据知识服务平台(万方数据)、Web of Science(WOS)数据库、PubMed中药百合相关的中英文文献,应用Coocation9.9、...目的通过科学知识图谱分析中药百合的研究热点及趋势。方法检索2000年1月1日-2021年12月31日中国知识资源总库(CNKI)、万方数据知识服务平台(万方数据)、Web of Science(WOS)数据库、PubMed中药百合相关的中英文文献,应用Coocation9.9、VOSviewer、CiteSpace文献计量软件绘制百合相关研究的发文量、作者、合作机构、关键词聚类的科学知识图谱。结果共纳入文献1137篇,其中中文文献1011篇、英文文献126篇。中药百合相关研究在国际上呈增长趋势,国内呈现波动式增长。国家之间、国内各省份间与国际作者间合作交流不强。国内形成了以蔡宝昌、周日宝、刘永琦为代表的大型研究团队。关键词共现与聚类分析中发现,国内研究更加多样化涉及到临床应用、复方研究、化学成分、质量评价、药理作用及百合多糖等各方面。结论百合相关临床研究,百合多糖、生物碱,抑郁症相关研究是近年中药百合相关研究持续的研究热点及研究趋势。展开更多
基金This work was funded by the National Natural Science Foundation of China(61771183).
文摘The tallest sand dune worldwide is located in the Badain Jaran Desert(BJD),China,and has been standing for thousands of years.Previous studies have conducted limited physical exploration and excavation on the formation of sand dunes and have proposed three viewpoints,that is,bedrock control,wind dominance,and groundwater maintenance with no unified conclusion.Therefore,this study analyzed the underlying bedding structure of sand dunes in the BJD.Although the bedrock of sand dunes is uplifted and wind controls the shape of dunes,the main cause of dune formation is groundwater that maintains the deposition of calcareous sandstone and accumulation of aeolian sand.According to water transport model and vapor transports in the unsaturated zone of sand dunes,capillary water transport height is limited with film water constituting the main form of water in dunes.Chemical properties and temperature of groundwater showed that aquifers in different basins receive relatively independent recharge from deep sources in the crater.Result of dune formation mechanism is of considerable importance in understanding groundwater circulation and provides a new perspective on water management in arid desert areas.
文摘目的通过科学知识图谱分析中药百合的研究热点及趋势。方法检索2000年1月1日-2021年12月31日中国知识资源总库(CNKI)、万方数据知识服务平台(万方数据)、Web of Science(WOS)数据库、PubMed中药百合相关的中英文文献,应用Coocation9.9、VOSviewer、CiteSpace文献计量软件绘制百合相关研究的发文量、作者、合作机构、关键词聚类的科学知识图谱。结果共纳入文献1137篇,其中中文文献1011篇、英文文献126篇。中药百合相关研究在国际上呈增长趋势,国内呈现波动式增长。国家之间、国内各省份间与国际作者间合作交流不强。国内形成了以蔡宝昌、周日宝、刘永琦为代表的大型研究团队。关键词共现与聚类分析中发现,国内研究更加多样化涉及到临床应用、复方研究、化学成分、质量评价、药理作用及百合多糖等各方面。结论百合相关临床研究,百合多糖、生物碱,抑郁症相关研究是近年中药百合相关研究持续的研究热点及研究趋势。
