首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   215篇
  免费   2篇
废物处理   7篇
环保管理   12篇
综合类   70篇
基础理论   54篇
污染及防治   50篇
评价与监测   11篇
社会与环境   12篇
灾害及防治   1篇
  2023年   2篇
  2022年   2篇
  2021年   2篇
  2020年   2篇
  2018年   4篇
  2017年   4篇
  2015年   4篇
  2014年   6篇
  2013年   8篇
  2012年   8篇
  2011年   16篇
  2010年   6篇
  2009年   3篇
  2008年   5篇
  2007年   14篇
  2006年   8篇
  2005年   10篇
  2004年   3篇
  2003年   4篇
  2002年   2篇
  2001年   6篇
  2000年   6篇
  1999年   3篇
  1997年   3篇
  1996年   4篇
  1995年   7篇
  1994年   5篇
  1993年   2篇
  1992年   3篇
  1990年   3篇
  1989年   4篇
  1985年   6篇
  1982年   2篇
  1981年   3篇
  1979年   2篇
  1973年   2篇
  1964年   3篇
  1963年   4篇
  1961年   2篇
  1960年   4篇
  1958年   2篇
  1957年   2篇
  1956年   3篇
  1950年   1篇
  1934年   1篇
  1933年   1篇
  1931年   2篇
  1927年   2篇
  1925年   1篇
  1924年   1篇
排序方式: 共有217条查询结果,搜索用时 0 毫秒
151.
The accumulation of natural and artificial radionuclides in humans and domestic animals is of interest in estimating effective doses of exposed humans and to decide whether animal products can be used for nutrition of the population. In this paper we present an investigation of the (137)Cs- and (40)K-activity levels of the ribs and sternum of a "mountain pasture" cow, born in a highly contaminated region of Styria, Austria, at the time of the radioactive fallout following the Chernobyl accident. This is the first systematic investigation of the variation in activity levels of a contaminated animal. The International Commission on Radiological Protection (ICRP) assumes that cesium and potassium are homogenously distributed throughout the whole body of an organism. However, the presented results show that there is a non-uniform distribution of (137)Cs and (40)K in different skeletal bones and their adherent tissues of a dairy cattle. We found that activity concentrations of (137)Cs and (40)K varied up to a factor 2.5 in different components of the ribs. The minimum values of (137)Cs and (40)K in the ribs were 29.9 and 21Bqkg(-1) fresh mass for trabecular bone in the vertebral half of asternal ribs, and the maximum values 332 and 132Bqkg(-1) fresh mass for a mixed sample composed of a cartilaginous tissue layer and parts of the perichondrium, both originating from asternal costal cartilages, respectively.  相似文献   
152.
153.
154.
The determination and assessment of mixtures of different and complex indoor pollutants is difficult. This investigation was performed in order to determine the effects of pollutants closely bound to household-dust. The approach ist not the determination of single compounds but of all pollutants (sum parameter). For this reason a new method was developed with which househould dust samples are introduced in the Microtox®-Text System to quantify the effect of pollutants. Some of the methods tested revealed good results, however, further research and investigations on the basis of the data already obtained are necessary.  相似文献   
155.
156.
157.
In many European mountain regions, natural forest regrowth on abandoned agricultural land and the related consequences for the environment are issues of increasing concern. We developed a spatial statistical model based on multiple geophysical and socio-economic variables to investigate the pattern of natural forest regrowth in the Swiss mountain area between the 1980s and 1990s. Results show that forest regrowth occurred primarily in areas with low temperature sum, intermediate steepness and soil stoniness as well as close to forest edges and relatively close to roads. Model results suggest that regions with weak labor markets are favored in terms of land abandonment and forest regrowth. We could not find an effect of population change on land abandonment and forest regrowth. Therefore, we conclude that decision makers should consider non-linearities in the pattern of forest regrowth and the fact that labor markets have an effect on land abandonment and forest regrowth when designing measures to prevent agricultural land abandonment and natural forest regrowth in the Swiss mountains.  相似文献   
158.
159.
160.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号