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   91032篇
  免费   1216篇
  国内免费   1086篇
安全科学   3751篇
废物处理   3319篇
环保管理   14056篇
综合类   21117篇
基础理论   26398篇
环境理论   73篇
污染及防治   15052篇
评价与监测   5438篇
社会与环境   3576篇
灾害及防治   554篇
  2022年   800篇
  2021年   792篇
  2020年   647篇
  2019年   859篇
  2018年   1118篇
  2017年   1160篇
  2016年   2156篇
  2015年   1833篇
  2014年   2566篇
  2013年   9228篇
  2012年   2205篇
  2011年   2467篇
  2010年   3266篇
  2009年   3394篇
  2008年   2025篇
  2007年   1868篇
  2006年   2299篇
  2005年   2283篇
  2004年   2581篇
  2003年   2423篇
  2002年   2002篇
  2001年   2300篇
  2000年   2020篇
  1999年   1498篇
  1998年   1369篇
  1997年   1361篇
  1996年   1490篇
  1995年   1587篇
  1994年   1475篇
  1993年   1342篇
  1992年   1322篇
  1991年   1295篇
  1990年   1250篇
  1989年   1225篇
  1988年   1059篇
  1987年   990篇
  1986年   991篇
  1985年   1071篇
  1984年   1165篇
  1983年   1171篇
  1982年   1176篇
  1981年   1106篇
  1980年   944篇
  1979年   933篇
  1978年   827篇
  1977年   717篇
  1976年   651篇
  1975年   626篇
  1973年   658篇
  1972年   655篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
121.
122.
123.
124.
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   
125.
126.
127.
128.
129.
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   
130.
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   
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