青藏高原腹地现代植物δ~(13)C空间分异反映的环境信息     

王谋  李勇  张玉修  李亚林  黄润秋 《地球科学进展》2004,(Z1)

对研究区植被碳同位素组成进行分析,该区高山嵩草样δ~(13)C值在-25.63‰～-27.95‰之间,平均值-26.63‰;高寒草原区混合样δ~(13)C值于-26.29‰～-27.73‰之间,平均-27.04‰。高山嵩草样总体呈现由南东往北西方向正偏趋势,与高原夏季风运移方向一致(r=0.44603,n=29,p<0.05);研究区北部高寒草原区混合植物样则更明显的指示了研究区由南向北干旱化的趋势(r=0.8112,n=5,p<0.1)。现代植物碳同位素组成是特定环境影响的结果,在研究区内的变化趋势,则被认为是主要受降水环境影响的结果。成规律展布的区域降水条件与地理位置耦合,建立高原腹地地表植物碳同位素组成与其地理位置的相关。同时通过对该区碳同位素组成的研究反映控制植被生长发育的环境信息。  相似文献   

城市规划区中的转角直线定线方法     

奚毓敏 《现代测绘》2003,26(2):15-17,27

本文介绍如何解决城市规划区域内转角无法定立或转角前后互不通视地段的定线工作，该方法是在间接定线方法基础上采用解析法计算出直线桩及转角桩的放样元素来解决定线工作。提高了平断面图的施测精度，满足了规划部门的要求，取到了较好的经济效益，大大地加快了线路的定线工作。  相似文献   

Gold deposits in the Xiaoqinling–Xiong'ershan region, Qinling Mountains, central China   总被引：27，自引：0，他引：27  

Jingwen Mao  Richard J. Goldfarb  Zhengwei Zhang  Wenyi Xu  Yumin Qiu  Jun Deng 《Mineralium Deposita》2002,37(3-4):306-325

  相似文献   

Paleozoic–early Mesozoic gold deposits of the Xinjiang Autonomous Region, northwestern China   总被引：12，自引：0，他引：12  

Zongyao Rui  Richard J. Goldfarb  Yumin Qiu  Taihe Zhou  Renyi Chen  Franco Pirajno  Grace Yun 《Mineralium Deposita》2002,37(3-4):393-418

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分布式多级道路网的最优路径服务应用系统设计     

陈玉敏  龚健雅  姚明 《武汉大学学报(信息科学版)》2008,33(4):384-387

详细研究了分布式多级道路网的最优路径服务应用系统的设计思想、数据集成方式、服务端和客户端的制定,以及工作流程的表达等,提出一套较为完善的设计方案.从应用实例分析可知,多级道路网的最优路径服务系统是可行的,且路径分析效率较高,能够切实解决大区域道路网路径分析服务的集成与应用问题.  相似文献   

SOMATOM PLUS型CT故障分析及排除     

牟文斌  张振荣 《CT理论与应用研究》1999,8(1):9-11

环形伪影是ＣＴ设备中多见的伪影响之一,本文根据ＳＯＭＡＴＯＭＰＬＵＳＣＴ上环形伪影的直径,伪影的宽度伪影的位置和伪影出现的时间为依据,并结合ＰＬＵＳ机型ＤＡＳ系统部分的具体结构,判断故障所发生的部位和原因,并且验证了所作的判断,消除了故障。  相似文献   

Future hydro-meteorological drought of the Johor River Basin,Malaysia, based on CORDEX-SEA projections     

Mou Leong Tan  Liew Juneng  Fredolin T. Tangang  Ngai Weng Chan  Sheau Tieh Ngai 《水文科学杂志》2019,64(8):921-933

Water scarcity issues in the Johor River Basin (JRB) could affect the populations of Malaysia and Singapore. This study provides an overview of future hydro-meteorological droughts using climate projections from an ensemble of four Coordinated Regional Climate Downscaling Experiments – Southeast Asia (CORDEX-SEA) domain outputs under the Representative Concentration Pathway (RCP) 4.5 and 8.5 scenarios for the 2021–2050 and 2071–2100 periods. The climate projections were bias corrected using the quantile mapping approach before being incorporated into the Soil and Water Assessment Tool (SWAT) hydrological model. The Standardized Precipitation Index (SPI) and Standardized Streamflow Index (SSI) were used to examine the meteorological and hydrological droughts, respectively. Overall, future annual precipitation, streamflow, and maximum and minimum temperatures are projected to change by about ?44.2 to 24.3%, ?88.7 to 42.2%, 0.8 to 3.7ºC and 0.7 to 4.7ºC, respectively. The results show that the JRB is likely to receive more frequent meteorological droughts in the future.  相似文献   

唐山大地震震害分布研究   总被引：4，自引：0，他引：4  

苏幼坡  张玉敏 《地震工程与工程振动》2006,26(3):18-21

利用唐山大地震后对7772个自然村的实际震害调查数据,研究了唐山地震灾区的主要震害及其与地震烈度的关系、人员死亡率与建筑物倒塌率的地域分布,揭示出唐山大地震震害的实际状况与分布规律。探讨了研究成果的实用性。  相似文献   

东南极普里兹湾陆架区大型底栖动物群落结构     

刘坤  林和山  何雪宝  黄雅琴  李众  林俊辉  牟剑锋  张舒怡  王建军  孙军 《海洋学报(英文版)》2020,39(2):38-48

To explore the spatial pattern of macrobenthic communities and their response to environmental factors in the Prydz Bay,samples were collected using a 0.25-m2 box corer at 10 stations from November 2012 to April 2013.A total of 50 species of macrobenthos belonging to 8 phyla and 33 families were identified,of which polychaetes(e.g.,Maldane sarsi)and sponges(e.g.,Halichondria sp.and Leucosolenia sp.)were the most prominent groups.The macrobenthos in study area were categorized into five functional groups based on the feeding type,and the detritivorous group represented by polychaetes showed the highest average abundance,while the planktophagous group represented by sponges showed the highest average biomass.Macrobenthos abundance(0–592 ind./m2)and biomass(0–1155.5 g/m2)in the Prydz Bay were relatively lower than those of other Antarctic shelf soft-bottom waters,although the compositions of the dominant species and functional feeding groups were similar.The results of the Spearman rank correlation analysis indicated that the average biomass of the macrobenthos and the biomass of the planktophagous group in the study area were negatively correlated with the water depth,sediment grain size and silt percentage.However,these variables were clearly not strong determinants of macrobenthos assemblage structure.Many factors not measured in the study,e.g.,sediment organic matter and iceberg interference,have probably influenced the spatial distribution of macrobenthic community structure in the Prydz Bay.  相似文献   

平潭岛东北部近岸海域大型污损生物群落结构特征     

刘坤  林和山  李众  何雪宝  黄雅琴  林俊辉  牟剑锋  张舒怡  马丽  全俊杰  王建军  孙军 《海洋学报》2020,42(6):70-82

于2017年6月至2018年5月在平潭岛东北部近岸海域开展污损生物生态研究,探讨了该海域大型污损生物的群落结构特点及演替趋势。周年模拟挂板试验结果显示,该海域大型污损生物隶属13门92种,以广分布暖水种为主,其中主要优势种为营固着生活的网纹藤壶(Amphibalanus reticulatus)、大室别藻苔虫(Biflustra grandicella)、三角藤壶(Balanus trigonus)和中胚花筒螅(Ectopleura crocea),以及自由生活的廉形叶钩虾(Jassa falcata)和齿掌细身钩虾(Maeropsis serratipalma)等。虽然该海域全年均有生物附着,但附着强度的季节性差异显著,附着盛期为6月至8月(生物量介于7 326.0～12 970.0 g/m2之间,以湿质量计),12月至次年2月(生物量介于39.5～1 580.5 g/m2之间)为附着淡季,而且污损生物摄食类型以悬浮物食者为主。温度和盐度是影响污损生物附着和分布的主要环境因素,水体透明度、水动力条件、地表径流和养殖等人类活动对污损生物的分布也有重要影响。  相似文献