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   87428篇
  免费   1441篇
  国内免费   2012篇
安全科学   3919篇
废物处理   3144篇
环保管理   13420篇
综合类   22525篇
基础理论   25891篇
环境理论   72篇
污染及防治   12739篇
评价与监测   5234篇
社会与环境   3342篇
灾害及防治   595篇
  2022年   917篇
  2021年   920篇
  2020年   783篇
  2019年   975篇
  2018年   1168篇
  2017年   1194篇
  2016年   2211篇
  2015年   1985篇
  2014年   2767篇
  2013年   9478篇
  2012年   2185篇
  2011年   2223篇
  2010年   3340篇
  2009年   3450篇
  2008年   1653篇
  2007年   1482篇
  2006年   1982篇
  2005年   2021篇
  2004年   2354篇
  2003年   2175篇
  2002年   1711篇
  2001年   1986篇
  2000年   1849篇
  1999年   1452篇
  1998年   1396篇
  1997年   1360篇
  1996年   1471篇
  1995年   1566篇
  1994年   1458篇
  1993年   1309篇
  1992年   1284篇
  1991年   1260篇
  1990年   1199篇
  1989年   1173篇
  1988年   1011篇
  1987年   952篇
  1986年   983篇
  1985年   1047篇
  1984年   1141篇
  1983年   1158篇
  1982年   1168篇
  1981年   1088篇
  1980年   932篇
  1979年   902篇
  1978年   812篇
  1977年   705篇
  1976年   629篇
  1975年   589篇
  1973年   611篇
  1972年   615篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
171.
Four introduced and one aboriginal species of the genus Pinus L. have been studied in the middle taiga subzone of southern Karelia. Significant interspecific differences in the dates of onset, cessation, and peak of the growth of shoots and needles have been revealed. It has been shown that their annual increment depends on the rate of growth, rather than on its duration. The dynamics of shoot and needle growth in introduced and aboriginal species, though largely similar, differ in some respects. These differences reflect species-specific responses to hydrothermal conditions in a certain growing season.  相似文献   
172.
173.
174.
175.
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   
176.
Effluent from dyeing and finishing processes is an important source of water pollution. The effectiveness of bentonite, kaolinite and sediment from a local deposit in removing methylene blue as a cationic dye from aqueous solutions has been investigated. The adsorption equilibrium (isotherm) has been determined according to Freundlich and Langmuir equations. The optimum amount is 0.5 g for all adsorbents, and the optimum pH ranges are 2-8 for bentonite and 2-6 for kaolinite and sediment. With respect to kinetic modelling, the adsorption of methylene blue on various adsorbents was fitted to a second-order equation. Also, the thermodynamic parameters were determined. The negative free energy values indicate the feasibility of the process and spontaneous nature of adsorption. The positive ΔH° values indicate the endothermic nature of the process. Thus, Egyptian clay minerals and sediments have a great tendency to remove the dye from solutions.  相似文献   
177.
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   
178.
Garden black ants,Lasius niger L., in a laboratory colony, attacked three species of live ladybirds found near their nest, killing the smaller two species. A second colony was offered artificial diets containing crushed ladybirds of two species, and the ants' choice of feeding site noted. Both the diets were aversive compared to control, but that containing 7spot,Coccinella septempunctata L., was more aversive than the diet containing 2spot,Adalia bipunctata L. The implications of this lesser protection for 2spots in terms of the chemical defence of the species are discussed.  相似文献   
179.
180.
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