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   18954篇
  免费   189篇
  国内免费   132篇
安全科学   517篇
废物处理   726篇
环保管理   2312篇
综合类   5495篇
基础理论   4004篇
环境理论   4篇
污染及防治   4446篇
评价与监测   992篇
社会与环境   686篇
灾害及防治   93篇
  2022年   140篇
  2018年   245篇
  2017年   248篇
  2016年   352篇
  2015年   276篇
  2014年   374篇
  2013年   1272篇
  2012年   449篇
  2011年   656篇
  2010年   586篇
  2009年   634篇
  2008年   677篇
  2007年   711篇
  2006年   629篇
  2005年   531篇
  2004年   563篇
  2003年   521篇
  2002年   487篇
  2001年   653篇
  2000年   437篇
  1999年   308篇
  1998年   228篇
  1997年   208篇
  1996年   217篇
  1995年   245篇
  1994年   259篇
  1993年   217篇
  1992年   237篇
  1991年   239篇
  1990年   262篇
  1989年   233篇
  1988年   190篇
  1987年   193篇
  1986年   189篇
  1985年   185篇
  1984年   206篇
  1983年   192篇
  1982年   205篇
  1981年   210篇
  1980年   172篇
  1979年   186篇
  1978年   147篇
  1974年   147篇
  1973年   146篇
  1968年   156篇
  1967年   186篇
  1966年   154篇
  1965年   149篇
  1964年   151篇
  1963年   139篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
2.
Male Baladi rabbits were acutely and sub-chronically intoxicated with cyanofenphos and profenophos. The levels of cholesterol, triglycerides, B-lipoproteins and total proteins were determined in the serum, brain, spinal cord and sciatic nerve of rabbits. Moreover, the activities of alkaline phosphatase, acid phosphatase and glutamic-pyruvic transaminase were determined in the liver of the animals. The whole studies revealed that the biochemical constituents were highly affected by the tested insecticides. Also, the liver function suffered from adverse effects of the tested insecticides.  相似文献   
3.
Codigestion of five wastes and municipal wastewater sludge was evaluated using full-scale testing. Synergistic, antagonistic, and neutral outcomes were observed depending on codigestate identity and concentration, highlighting the value of careful blending. Yeast waste resulted in notable synergism, increasing biogas production by over 50%, whereas aircraft deicing waste resulted in antagonism at high loadings and neutral outcomes at lower loadings. Restaurant waste codigestion resulted in neutral outcomes. The synergisim with yeast codigestates may have resulted from trace nutrients (i.e., iron, nickel, and cobalt) in the wastes that increased microbiological activity. Antagonist outcomes with deicing waste may have been the result of organic overload or inhibitory deicer constituents. Codigestion of wastes at the feed rates investigated was estimated to produce 0.50 ML/d of methane having an energy equivalent of 17 500 MJ/d. This was estimated to reduce net carbon dioxide emissions by 560 tonnes/y.  相似文献   
4.
Cornus stolonifera, Salix petiolaris, and Spiraea alba clones already located within the corridor of an electrical power line. To establish the efficiency of treatments, we examined the statistical differences of growth traits between species and treatments. An analysis of the effects of layering shows, after the first growth season, differences for all growth traits in only one species, Spiraea alba. After the second growth season, we observed the development of new aerial stems. Layering favors horizontal expansion of shrubs over height development. The third year after treatment, the effect of layering is reduced except for Cornus stolonifera, which continuously increases, as shown by the significant progression of the clone issued from the layer even five years after treatments. With the cutting back technique, we expected a distinct vertical growth of the shrubs at the expense of increasing the crown diameter. This technique would be best associated with the rejuvenation of clones, followed by a layering of new shoots to allow a horizontal expansion of the shrubs. Therefore, the formation of a dense shrub community by layering should be considered a valuable approach for the biological control of undesirable trees in powerline rights-of-way.  相似文献   
5.
In vitro investigations of the influence of lindane and its metabolites were performed on microsomal and mitochondrial ATPases from liver, kidney and brain of rat and mouse. The microsomal Na+-K+-ATPases in rat liver were inhibited by the tested substances. An increase of activity was observed only with 2.5 X 10(-5) M gamma-HCH. Effects on the microsomal Na+-K+-ATPase from kidney and brain of rat were also indicated. The mitochondrial enzyme in rat liver was stimulated by all the compounds tested at concentrations of 10(-4) M - 10(-2) M. The effects on mitochondrial enzymes from kidney and brain varied in dependence on the tested substances. In the microsomes and mitochondria of mouse an influence on the Na+-K+-ATPases similar to the effects on the preparations from organs of rat was evident.  相似文献   
6.
7.
8.
9.
10.
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