中国北方农牧交错带人类生存环境的过去,现在和未来   总被引：1，自引：0，他引：1  

刘清泗  武羡慧 《城市地质》1996,8(1):10-18

中国北方农牧业交错带是我国生产最不稳定的地带，风、旱、冻、雪等灾害频繁出现，具有敏感而脆弱的人地关系。文章在研究了该地带人类生存环境的演化及其规律的基础上，对未来百年人类的生存环境作了预测。  相似文献   

地震前人的异常浅议     

高立保  阮修春 《山西地震》1992,(4)

叙述了地震之前一些人出现异常反应的表现形式,分析了发生异常的内在原因,认为利用人体的异常表现,探索地震预报是有意义的。  相似文献   

The Disparity Between the Level of Economic Development and Human Welfare     

Steven R. Holloway  Kavita Pandit 《The Professional geographer》1992,44(1):57-71

The lack of correspondence between traditional economic development measures, such as GNP per capita, and human welfare measures, such as the PQLI, has been well documented in the literature. We devised and analyzed an economic development-welfare disparity measure, and found considerable geographic variability, with actual levels of human welfare much less than expected in many Middle Eastern and African countries, given the level of economic development. Exploratory correlation and regression analysis revealed that inequalities in the distribution of economic power and governmental expenditures contributed to the geographic variability. More importantly, each region improved its standing on the development-welfare disparity measure when relevant factors were controlled via multivariate regression.  相似文献   

植被区面积对局地气候影响的数值研究   总被引：7，自引：0，他引：7  

罗哲贤  余晖 《干旱气象》1995,(2)

用一个三维模式实施了５个数值试验，研究了植被覆盖与裸土之间的非均一性对局地气候的影响。结果指出：存在着一个最适宜的植被区面积Ｓ＿ｃ，当Ｓ＝Ｓ＿ｃ，这种非均一性激发的上升运动最强，上升气流区的空间范围最大。  相似文献   

Large-sample hydrology: recent progress,guidelines for new datasets and grand challenges     

Nans Addor  Hong X. Do  Camila Alvarez-Garreton  Gemma Coxon  Keirnan Fowler  Pablo A. Mendoza 《水文科学杂志》2020,65(5):712-725

ABSTRACT

Large-sample hydrology (LSH) relies on data from large sets (tens to thousands) of catchments to go beyond individual case studies and derive robust conclusions on hydrological processes and models. Numerous LSH datasets have recently been released, covering a wide range of regions and relying on increasingly diverse data sources to characterize catchment behaviour. These datasets offer novel opportunities, yet they are also limited by their lack of comparability, uncertainty estimates and characterization of human impacts. This article (i) underscores the key role of LSH datasets in hydrological studies, (ii) provides a review of currently available LSH datasets, (iii) highlights current limitations of LSH datasets and (iv) proposes guidelines and coordinated actions to overcome these limitations. These guidelines and actions aim to standardize and automatize the creation of LSH datasets worldwide, and to enhance the reproducibility and comparability of hydrological studies.  相似文献   

广州信息密集服务业的空间发展及其对城市地域结构的影响   总被引：27，自引：0，他引：27  

阎小培 《地理科学》1999,19(5):405-410

采用第三产业普查资料,深入分析了改革开放以来广州信息密集服务业的发展水平,空间发展特征和原因及其对城市地域结构的影响,揭示了信息密集服务业发展与城市地域运动的关系。  相似文献   

The impact of seasonality on multi-scale feature extraction techniques     

Brian Moore  Jacob J. McKee 《International Journal of Digital Earth》2020,13(1):9-21

  相似文献   

基于抗震性态的设防标准研究   总被引：11，自引：0，他引：11       下载免费PDF全文

谢礼立  马玉宏 《地震学报》2002,24(2):200-209

以基于性态的抗震设计为出发点,并以我国为例,针对目前国内外抗震设防标准的若干问题和不足,提出了基于性态抗震设计的三环节抗震设防方法．将现有的设防内容改为确定结构的抗震设计类别、确定设计烈度或设计地震动参数、确定建筑的重要性等级３个方面,并分别在每一方面进行具体深入的研究,从而形成了一套完整的基于性态的抗震设防标准确定的原则、方法和框架,可以直接用来编制规范供抗震设计使用．   相似文献   

龙骨坡遗址第7水平层石制品新材料          下载免费PDF全文

侯亚梅  李英华  黄万波  徐自强  鲁娜 《第四纪研究》2006,26(4):555-561

文章记述并分析了20世纪90年代后期重庆巫山龙骨坡遗址出土于第7水平层的16件石制品,包括若干各具特色的工具类型,如原型手镐、原型薄刃斧、大型尖刃器、直刃砍砸器、凸刃砍砸器、长刃石刀、短刃石刀、刮削器、凿刃器等,反映出石器制作者明确的工作目标和为了达到目标所经历的一个又一个中间过程;说明了当时的人类对工具制作的具体需求和适当利用自然环境的事实。研究证据还体现了大约200万年前华南早期人类工具类型的多样性与特殊性,标志着中国早期人类在当时阶段所达到的技术发展水平。龙骨坡遗址很可能是东亚早期人类文化的一个发祥地。  相似文献   

Variation characteristics of heavy metals and nutrients in the core sediments of Taihu Lake and their pollution history   总被引：4，自引：2，他引：4  

LIU Enfeng  SHEN Ji  LIU Xingqi  ZHU Yuxin  WANG Sumin 《中国科学D辑(英文版)》2006,49(Z1)

The sedimentary environment change, trophic evolution and heavy metals pollution history of the northern Taihu Lake in the last 100 years are studied according to the sedimentary geo-chemical proxies of the core sediments, such as grain size, nutrients, heavy metals, diatom, etc. The nutrients in the sediments depended mainly on the lake internal circulation and the heavy metals were from natural geogenic sources before the 1920s, which were not influenced by human activities generally, and grain size was one of the key factors influencing heavy metals content in the sediments. The alternation of manner and strength of human activities in Taihu Lake catchment before and after the 1920s made the lake sediments coarser, and hence heavy metals and TP content decreased contrasted with that before the 1920s. TP content in sediments and water increased from the 1950s to late 1970s due to anthropogenic pollutants discharge, and the lake belonging to mesotrophic state. TN and TOC content and C/N ratio increased due to the increasing external pollutants into Taihu Lake by human activities, TP content also increased obviously in water and sediments, and the diatom association was dominated by eutrophic species since the late 1970s, indicating the eutrophication state of Taihu Lake in this period. Meanwhile the increasing in heavy metals content, such as Cu, Mn, Ni, Pb and Zn, and their proportion of valid fractions in the sediments indicates that they all result from human pollutants since the late 1970s. The heavy metals in the surface sediments have certain potential biological toxicity due to the higher SEM/AVS ratio.  相似文献