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   26488篇
  免费   232篇
  国内免费   366篇
安全科学   511篇
废物处理   1206篇
环保管理   3207篇
综合类   4081篇
基础理论   7562篇
环境理论   4篇
污染及防治   6139篇
评价与监测   1872篇
社会与环境   2369篇
灾害及防治   135篇
  2022年   239篇
  2021年   198篇
  2020年   159篇
  2019年   196篇
  2018年   783篇
  2017年   785篇
  2016年   874篇
  2015年   435篇
  2014年   647篇
  2013年   1790篇
  2012年   884篇
  2011年   1613篇
  2010年   1197篇
  2009年   1245篇
  2008年   1508篇
  2007年   1733篇
  2006年   847篇
  2005年   816篇
  2004年   774篇
  2003年   811篇
  2002年   819篇
  2001年   937篇
  2000年   654篇
  1999年   347篇
  1998年   254篇
  1997年   276篇
  1996年   293篇
  1995年   341篇
  1994年   306篇
  1993年   251篇
  1992年   265篇
  1991年   250篇
  1990年   271篇
  1989年   243篇
  1988年   212篇
  1987年   225篇
  1986年   200篇
  1985年   208篇
  1984年   208篇
  1983年   191篇
  1982年   176篇
  1981年   176篇
  1980年   157篇
  1979年   168篇
  1978年   130篇
  1977年   143篇
  1975年   117篇
  1974年   116篇
  1973年   133篇
  1972年   128篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
41.
42.
A site contaminated by mercury serves as an example for evaluating the environmental medicine aspects of mercury emissions on individuals living in the surroundings. Based on defined, conventional scenarios, estimations of internal exposure were made for seven different age groups and with regard to such contact media as soil, air and food. Using human monitoring methods, an attempt was made to compare the epidemiological results. The site-specific and pathway-specific estimation of exposure is based on a multitude of various samples as well as on measurements of concentrations in the compartments relevant for intake. As based upon rigid guideline values, both these calculations and the epidemiological investigations reveal a slight increase in the mercury exposure.  相似文献   
43.
The effect of industrial air pollution on natural small mammal populations has been studied in the northern taiga subzone of the boreal forest zone. The results of long-term monitoring have been used to demonstrate the possibility of predicting changes in the main population and community characteristics of the animal species studied as dependent on the degree of anthropogenic impact.  相似文献   
44.
45.
46.
47.
48.
In the diurnal lepidopteran fauna of the northern taiga subzone in the western Russian Plain, the species inhabiting primary biotopic complexes typical of this subzone currently account for slightly more than 60% of the total species richness and abundance. A large part of the fauna is represented by the species of more southern origin, whose expansion to the northern taiga was caused by anthropogenic transformation of landscapes between the 12th and 20th centuries and recent climate warming.  相似文献   
49.
Although many conventional physical remediation methods are viewed as proven, they often only relocate wastes to other sites or into the air. How do the emerging biological and chemical in situ methods perform in the same applications? This article reviews their results (much of it in the laboratory) as well as their promise of more complete neutralization of hazardous wastes, lower capital costs, and longer-duration cleanup processes. The optimal method may be a combination of chemical and biological in situ techniques with physical pump-and-treat methods.  相似文献   
50.
Three monoclonal antibodies (MAbs) against trophoblast (GB17, GB21, and GB25) and flow cytometry were used to sort trophoblast-like cells (TLCs) from peripheral blood of pregnant women. Sorted TLCs were processed for electron microscopy and fetal DNA amplification of the Y-specific sequences from mothers carrying male fetuses. At the ultra-structural level, most of the nucleated cells had the morphology of leucocytes, suggesting maternal contaminants, and we did not find the characteristic features of the free inter-villous trophoblast cells. Nevertheless, polymerase chain reaction (PCR) analysis showed an amplification of Y-specific sequences in two out of three samples of sorted TLCs. These results suggest that besides the maternal leucocytes, sufficient trophoblast nucleated fetal cells can be obtained using cell enrichment by sorting. This sensitive method holds promise for non-invasive prenatal diagnosis of fetal sex and if sufficient Y(positive) nuclei are found, for the diagnosis of selected numerical chromosome abnormalities.  相似文献   
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