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   92458篇
  免费   1235篇
  国内免费   1130篇
安全科学   3749篇
废物处理   3381篇
环保管理   14122篇
综合类   21197篇
基础理论   26677篇
环境理论   78篇
污染及防治   15513篇
评价与监测   5596篇
社会与环境   3939篇
灾害及防治   571篇
  2022年   824篇
  2021年   845篇
  2020年   666篇
  2019年   881篇
  2018年   1220篇
  2017年   1240篇
  2016年   2237篇
  2015年   1860篇
  2014年   2602篇
  2013年   9313篇
  2012年   2281篇
  2011年   2615篇
  2010年   3345篇
  2009年   3447篇
  2008年   2133篇
  2007年   2026篇
  2006年   2406篇
  2005年   2339篇
  2004年   2649篇
  2003年   2497篇
  2002年   2065篇
  2001年   2420篇
  2000年   2077篇
  1999年   1543篇
  1998年   1388篇
  1997年   1365篇
  1996年   1501篇
  1995年   1582篇
  1994年   1487篇
  1993年   1338篇
  1992年   1337篇
  1991年   1298篇
  1990年   1248篇
  1989年   1220篇
  1988年   1064篇
  1987年   993篇
  1986年   995篇
  1985年   1063篇
  1984年   1160篇
  1983年   1169篇
  1982年   1181篇
  1981年   1098篇
  1980年   944篇
  1979年   928篇
  1978年   824篇
  1977年   720篇
  1976年   639篇
  1974年   605篇
  1973年   634篇
  1972年   632篇
排序方式: 共有10000条查询结果,搜索用时 913 毫秒
181.
182.
183.
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   
184.
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   
185.
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   
186.
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   
187.
188.
189.
190.
The typical parameters of acid precipitation are evaluated in the forest of Vallombrosa (Tuscan Appennines) during the dry period 1988-89. Individual rain events (dry and wet deposition) were sampled in a clearing of the forest and below the canopy of an evergreen tree as well as a deciduous broadleaf tree.

In atmospheric precipitation the pH values usually vary around 4.4, with neutralization in the hot season due to calcareous material from distant sources. Relatively large concentrations of Pb and Cd are found in rain, but only in a small amount in canopy leachate. Aluminium, manganese and iron are more significantly washed off than Pb and Cd.  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