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   99538篇
  免费   1249篇
  国内免费   1165篇
安全科学   3935篇
废物处理   3670篇
环保管理   15115篇
综合类   21792篇
基础理论   27712篇
环境理论   80篇
污染及防治   18877篇
评价与监测   5936篇
社会与环境   4190篇
灾害及防治   645篇
  2022年   836篇
  2021年   836篇
  2020年   669篇
  2019年   894篇
  2018年   1279篇
  2017年   1321篇
  2016年   2295篇
  2015年   1896篇
  2014年   2640篇
  2013年   9392篇
  2012年   2561篇
  2011年   3124篇
  2010年   3475篇
  2009年   3634篇
  2008年   2737篇
  2007年   2688篇
  2006年   2908篇
  2005年   2725篇
  2004年   3035篇
  2003年   2869篇
  2002年   2441篇
  2001年   2896篇
  2000年   2340篇
  1999年   1665篇
  1998年   1444篇
  1997年   1439篇
  1996年   1558篇
  1995年   1650篇
  1994年   1552篇
  1993年   1382篇
  1992年   1377篇
  1991年   1345篇
  1990年   1299篇
  1989年   1251篇
  1988年   1106篇
  1987年   1022篇
  1986年   1016篇
  1985年   1093篇
  1984年   1185篇
  1983年   1195篇
  1982年   1193篇
  1981年   1120篇
  1980年   962篇
  1979年   959篇
  1978年   843篇
  1977年   738篇
  1976年   665篇
  1974年   653篇
  1973年   673篇
  1972年   688篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
132.
133.
134.
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   
135.
136.
137.
138.
139.
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   
140.
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