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   90655篇
  免费   1221篇
  国内免费   1099篇
安全科学   3746篇
废物处理   3320篇
环保管理   13938篇
综合类   21050篇
基础理论   26245篇
环境理论   71篇
污染及防治   14988篇
评价与监测   5454篇
社会与环境   3616篇
灾害及防治   547篇
  2022年   795篇
  2021年   803篇
  2020年   646篇
  2019年   861篇
  2018年   1128篇
  2017年   1153篇
  2016年   2167篇
  2015年   1828篇
  2014年   2587篇
  2013年   9244篇
  2012年   2216篇
  2011年   2458篇
  2010年   3246篇
  2009年   3401篇
  2008年   2035篇
  2007年   1878篇
  2006年   2310篇
  2005年   2278篇
  2004年   2601篇
  2003年   2430篇
  2002年   1980篇
  2001年   2287篇
  2000年   2023篇
  1999年   1495篇
  1998年   1363篇
  1997年   1352篇
  1996年   1480篇
  1995年   1573篇
  1994年   1459篇
  1993年   1326篇
  1992年   1305篇
  1991年   1283篇
  1990年   1226篇
  1989年   1198篇
  1988年   1042篇
  1987年   985篇
  1986年   988篇
  1985年   1061篇
  1984年   1162篇
  1983年   1167篇
  1982年   1170篇
  1981年   1100篇
  1980年   942篇
  1979年   932篇
  1978年   819篇
  1977年   721篇
  1976年   643篇
  1975年   604篇
  1973年   638篇
  1972年   640篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
131.
132.
133.
The towed undulating vehicle (TUV), named SARAGO, was used for two fine-scale surveys between the Italian and the Sardinian coasts during the Astraea 2 cruise (6-7 and 26-27 September 1995), studying the deep chlorophyll maximum distribution. SARAGO sections identify a sub-surface doming with higher chlorophyll a and primary production concentrations in the upwelling area of a cyclonic gyre region, detected by sea-surface temperature images. In the first section, the cyclone presents a double doming, in density and salinity, with shallower and concentrated patches of chlorophyll a for about 2 miles. Twenty days later, the second section shows that the gyre changes shape and extension, showing a single doming with higher primary production and chlorophyll a concentrations, distributed over a large area of about 40 nautical miles. SARAGO allows analysis of this high-variability phenomenon (cyclonic gyre) and allows concentrated patches (2 nm) to be identified, thus proving the importance of TUVs in the study of mesoscale processes.  相似文献   
134.
135.
136.
137.
138.
Protected areas in developing countries play a vital role in promoting the ideal of sustainable development.But 'people-park'conflicts are commonplace,threatening the future of these areas and the long term well-being of local communities. Surprisingly, little attention has been given to applying lessons learned in conflict studies to people-parkconflicts. In contrast to traditional adversarialresponses, negotiated approaches offer considerable potential for transforming people-park conflicts into mutually beneficial relationships.Experiencesin the Richtersveldregion of South Africa demonstrate the cardinal role negotiation can play in addressing key issues underlying people-park conflicts.  相似文献   
139.
Risk homeostasis theory postulates that people accept a specific level (target level) of risk in a given activity in return for benefits accruing from that activity. It follows that, if people expect a great deal from the future, the less likely they are to jeopardise it by taking risks in respect of their health and safety. One effective method for reducing target level of risk are incentives, and the available literature contains ample evidence of the effectiveness of incentives programmes in accident prevention. As incentives essentially imply an enhanced quality of life in the future, the question arises as to how expectations of the future may be related to health and safety habits. In order to explore the relationship between perceived value of the future and health and safety habits, an analysis of the psychological literature on individual differences in future time orientation/perspective is presented. Four factors are identified: (1) clear ideation of the future, (2) active planning for the future, (3) time pressure, and (4) optimistic expectations about events outside one's own control. It is hypothesised that factors (1) and (2) are associated with positive health and safety habits, while factors (3) and (4) may characterise individuals with relatively high target levels of physical risk. Research questions and procedures for the study of these relationships are discussed.  相似文献   
140.
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