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   40469篇
  免费   348篇
  国内免费   458篇
安全科学   960篇
废物处理   2189篇
环保管理   4879篇
综合类   6166篇
基础理论   11070篇
环境理论   19篇
污染及防治   9724篇
评价与监测   3045篇
社会与环境   3044篇
灾害及防治   179篇
  2023年   143篇
  2022年   324篇
  2021年   323篇
  2020年   244篇
  2019年   288篇
  2018年   1880篇
  2017年   1844篇
  2016年   1870篇
  2015年   687篇
  2014年   911篇
  2013年   2443篇
  2012年   1523篇
  2011年   2763篇
  2010年   1907篇
  2009年   1805篇
  2008年   2355篇
  2007年   2704篇
  2006年   1279篇
  2005年   1186篇
  2004年   1041篇
  2003年   1193篇
  2002年   1110篇
  2001年   1263篇
  2000年   880篇
  1999年   524篇
  1998年   373篇
  1997年   362篇
  1996年   360篇
  1995年   428篇
  1994年   449篇
  1993年   356篇
  1992年   375篇
  1991年   353篇
  1990年   391篇
  1989年   342篇
  1988年   298篇
  1987年   279篇
  1986年   225篇
  1985年   250篇
  1984年   284篇
  1983年   266篇
  1982年   244篇
  1981年   228篇
  1980年   178篇
  1979年   194篇
  1978年   178篇
  1975年   141篇
  1974年   120篇
  1972年   136篇
  1971年   135篇
排序方式: 共有10000条查询结果,搜索用时 2 毫秒
81.
82.
83.
84.
Mitigation and adaptation synergy in forest sector   总被引:1,自引:1,他引:1  
Mitigation and adaptation are the two main strategies to address climate change. Mitigation and adaptation have been considered separately in the global negotiations as well as literature. There is a realization on the need to explore and promote synergy between mitigation and adaptation while addressing climate change. In this paper, an attempt is made to explore the synergy between mitigation and adaptation by considering forest sector, which on the one hand is projected to be adversely impacted under the projected climate change scenarios and on the other provide opportunities to mitigate climate change. Thus, the potential and need for incorporating adaptation strategies and practices in mitigation projects is presented with a few examples. Firstly, there is a need to ensure that mitigation programs or projects do not increase the vulnerability of forest ecosystems and plantations. Secondly, several adaptation practices could be incorporated into mitigation projects to reduce vulnerability. Further, many of the mitigation projects indeed reduce vulnerability and promote adaptation, for example; forest and biodiversity conservation, protected area management and sustainable forestry. Also, many adaptation options such as urban forestry, soil and water conservation and drought resistant varieties also contribute to mitigation of climate change. Thus, there is need for research and field demonstration of synergy between mitigation and adaptation, so that the cost of addressing climate change impacts can be reduced and co-benefits increased.  相似文献   
85.
86.
87.
88.
89.
Fluid Mechanics of Biological Surfaces and their Technological Application   总被引:5,自引:0,他引:5  
 A survey is given on fluid-dynamic effects caused by the structure and properties of biological surfaces. It is demonstrated that the results of investigations aiming at technological applications can also provide insights into biophysical phenomena. Techniques are described both for reducing wall shear stresses and for controlling boundary-layer separation. (a) Wall shear stress reduction was investigated experimentally for various riblet surfaces including a shark skin replica. The latter consists of 800 plastic model scales with compliant anchoring. Hairy surfaces are also considered, and surfaces in which the no-slip condition is modified. Self-cleaning surfaces such as that of lotus leaves represent an interesting option to avoid fluid-dynamic deterioration by the agglomeration of dirt. An example of technological implementation is discussed for riblets in long-range commercial aircraft. (b) Separation control is also an important issue in biology. After a few brief comments on vortex generators, the mechanism of separation control by bird feathers is described in detail. Self-activated movable flaps (=artificial bird feathers) represent a high-lift system enhancing the maximum lift of airfoils by about 20%. This is achieved without perceivable deleterious effects under cruise conditions. Finally, flight experiments on an aircraft with laminar wing and movable flaps are presented.  相似文献   
90.
Three hundred and fifty-four women who underwent midtrimester genetic amniocentesis were matched for age, parity, indication, and smoking history, with an equivalent number of women who had declined the procedure, for the purpose of comparing the neonatal respiratory status of their offspring. There was no evidence that the infants exposed to genetic amniocentesis were compromised.  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