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   30025篇
  免费   335篇
  国内免费   251篇
安全科学   1004篇
废物处理   1464篇
环保管理   3983篇
综合类   4519篇
基础理论   7815篇
环境理论   8篇
污染及防治   7419篇
评价与监测   2156篇
社会与环境   2061篇
灾害及防治   182篇
  2023年   143篇
  2022年   266篇
  2021年   324篇
  2020年   200篇
  2019年   251篇
  2018年   447篇
  2017年   467篇
  2016年   736篇
  2015年   541篇
  2014年   865篇
  2013年   2484篇
  2012年   1031篇
  2011年   1367篇
  2010年   1114篇
  2009年   1168篇
  2008年   1423篇
  2007年   1343篇
  2006年   1224篇
  2005年   1087篇
  2004年   1048篇
  2003年   996篇
  2002年   939篇
  2001年   1094篇
  2000年   772篇
  1999年   487篇
  1998年   366篇
  1997年   385篇
  1996年   400篇
  1995年   469篇
  1994年   396篇
  1993年   347篇
  1992年   376篇
  1991年   355篇
  1990年   327篇
  1989年   324篇
  1988年   295篇
  1987年   241篇
  1986年   247篇
  1985年   247篇
  1984年   270篇
  1983年   256篇
  1982年   268篇
  1981年   223篇
  1980年   166篇
  1979年   181篇
  1978年   162篇
  1977年   135篇
  1975年   138篇
  1973年   168篇
  1972年   143篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Residues of Bromopropylate were determine in artichokes, strawberries and beans after foliar spray of acaricide at two rates. The rates used were 1 g/l formulated product (normal recommended) and 1.5 g/l. The residue levels of bromopropylate in the three crops after 14 days were lower than 0.7 ppm and did not exceed the Maximum Residual Level (MRL) recommended by FAO. In the artichokes and strawberries, the total concentration of residues decreased by 50% of the initial level after 2-3 days. Only trace levels of the bromopropylate residues (less than 0.01 ppm) were detected in the "hearts" of the artichokes. Bromopropylate residues in the green beans were also less than 0.8 ppm after the first day of foliar spraying. The kinetic of degradation occurred in two different steps. In the first step (4-6 days) the dissipation of bromopropylate was faster whereas in the second step (7-14 days) the loss of residues was much slower.  相似文献   
22.
23.
Pomonis A 《Disasters》1990,14(2):89-114
The 1988 earthquake in Armenia was the most serious seismic disaster since the 1976 earthquake in Tangshan, China. At least 25,000 people lost their lives in a tremor of moderate magnitude and the USSR suffered a loss of more than 2.5 per cent of 1988's GDP. Research at the Martin Centre on the effects of earthquakes on human lives has shown an increase in global earthquake mortality rate, despite the well known improvements in some countries. The Armenian disaster was a warning to all of us concerned with natural or man-made disasters. Areas of potential high hazard are pointed out for the sub-Caucasian region. Construction practices similar to those in Armenia are certainly found in many other parts of the world, with some regional variations, and the fast assimilation of the lessons is an important target. The structural characteristics of all the residential building types existing in the affected area are presented in terms of their seismic vulnerability. Vulnerable points are discussed with a view to low cost interventions that will drastically improve the seismic safety of new buildings.  相似文献   
24.
Ornas AH 《Disasters》1990,14(2):115-122
The most vulnerable people in Third World countries are often accused of destroying forests and fragile ecosystems and of practising destructive forms of agriculture and animal husbandry. The key to environmental sustainability, however, lies in more reliable production and food security at the local level. This article focuses on individual and household security amongst dryland herders in East Africa. The most crucial aspect of pastoral viability is the maintenance of a balance between family herd and size of household. Risk-spreading, through dependence on relatives, the borrowing of animals, redistribution through marriage etc. is a general principle of social behaviour amongst these peoples. Consideration of local-level security, furthermore, reveals the connection between ecological stress and political conflict. Only by establishing secure access to food for individuals and families can sustainable development and political security, not only at the local but also at the national and international levels, be achieved.  相似文献   
25.
26.
27.
28.
29.
30.
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