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   41206篇
  免费   437篇
  国内免费   346篇
安全科学   1248篇
废物处理   1897篇
环保管理   5376篇
综合类   7305篇
基础理论   10354篇
环境理论   14篇
污染及防治   10091篇
评价与监测   2836篇
社会与环境   2650篇
灾害及防治   218篇
  2022年   339篇
  2021年   395篇
  2020年   234篇
  2019年   319篇
  2018年   581篇
  2017年   600篇
  2016年   941篇
  2015年   694篇
  2014年   1077篇
  2013年   3227篇
  2012年   1287篇
  2011年   1759篇
  2010年   1421篇
  2009年   1520篇
  2008年   1808篇
  2007年   1799篇
  2006年   1614篇
  2005年   1394篇
  2004年   1399篇
  2003年   1345篇
  2002年   1257篇
  2001年   1524篇
  2000年   1030篇
  1999年   685篇
  1998年   491篇
  1997年   534篇
  1996年   570篇
  1995年   610篇
  1994年   565篇
  1993年   499篇
  1992年   510篇
  1991年   509篇
  1990年   471篇
  1989年   454篇
  1988年   416篇
  1987年   362篇
  1986年   363篇
  1985年   362篇
  1984年   394篇
  1983年   387篇
  1982年   398篇
  1981年   343篇
  1980年   279篇
  1979年   285篇
  1978年   267篇
  1977年   232篇
  1975年   228篇
  1974年   224篇
  1973年   244篇
  1972年   216篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
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   
33.
34.
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   
35.
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   
36.
37.
38.
39.
40.
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