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   52596篇
  免费   542篇
  国内免费   497篇
安全科学   1632篇
废物处理   2432篇
环保管理   6843篇
综合类   7917篇
基础理论   13957篇
环境理论   16篇
污染及防治   13357篇
评价与监测   3777篇
社会与环境   3355篇
灾害及防治   349篇
  2022年   483篇
  2021年   515篇
  2020年   348篇
  2019年   430篇
  2018年   770篇
  2017年   809篇
  2016年   1261篇
  2015年   934篇
  2014年   1412篇
  2013年   4359篇
  2012年   1739篇
  2011年   2320篇
  2010年   1966篇
  2009年   1988篇
  2008年   2325篇
  2007年   2383篇
  2006年   2118篇
  2005年   1817篇
  2004年   1770篇
  2003年   1707篇
  2002年   1631篇
  2001年   2060篇
  2000年   1449篇
  1999年   908篇
  1998年   657篇
  1997年   678篇
  1996年   721篇
  1995年   787篇
  1994年   697篇
  1993年   614篇
  1992年   640篇
  1991年   604篇
  1990年   596篇
  1989年   594篇
  1988年   528篇
  1987年   457篇
  1986年   436篇
  1985年   445篇
  1984年   480篇
  1983年   464篇
  1982年   489篇
  1981年   414篇
  1980年   336篇
  1979年   385篇
  1978年   323篇
  1977年   296篇
  1976年   251篇
  1975年   264篇
  1973年   299篇
  1972年   254篇
排序方式: 共有10000条查询结果,搜索用时 475 毫秒
761.
762.
763.
764.
765.
766.
767.
768.
769.
Unemployment effects of climate policy   总被引:1,自引:0,他引:1  
This paper models the unemployment effects of restrictions on greenhouse gas emissions, embodying two of the most significant types of short-term economic imperfections that generate unemployment: sectoral rigidities in labor mobility and sectoral rigidities in wage adjustments. A labor policy is also analyzed that would reduce the direct negative economic effects of the emissions restrictions.The politics of limiting greenhouse gas emissions are often dominated by relatively short-term considerations. Yet the current economic modeling of emissions limitations does not embody economic features that are likely to be particularly important in the short term, in particular, the politically sensitive unemployment rate. Moreover, only a few of these studies also consider policies that would offset the negative direct economic effects of emissions restrictions. For plausible estimates of the parameters, the model shows that, with the labor market imperfections, if there were no offsetting policies, the reductions in GNP in the U.S. in the first 10 years after emissions restrictions were imposed would be as much as 4%. However, if there were two policies, instead of just one: a counteracting labor market policy, as well as the emissions restrictions, the negative direct economic effects could be completely eliminated.  相似文献   
770.
An interdisciplinary approach based on high-resolution physical stratigraphy, biostratigraphy, organic matter analysis and clay mineralogy has been applied to the mixed siliciclastic/carbonate Kimmeridgian/Tithonian deposits of the Boulonnais (north-western France). These rocks are the age-equivalents of some of the offshore marine source rocks of the North Sea and were deposited in an overall storm-dominated homoclinal ramp setting which may represent one of the most shore-proximal sediments of this age cropping out in north-western Europe. Comparison with data from the Yorkshire, Dorset, Lorraine and Aquitaine areas allows the discrimination of three major transgressive-regressive sediment packages with disconformities of interregional extent: (1) from the Baylei Zone to top Eudoxus Zone; (2) from the Autissiodorensis Zone to base Scitulus Zone; (3) from the upper Scitulus Zone to the Pectinatus Zone. The lower two regionally correlative disconformities correspond to the sequence boundaries at the top of the Eudoxus Zone and the top of the Autissiodorensis Zone, formed by high-frequency relative sea-level variations during the periods of maximum transgression of the platform. The latter disconformity (the P1 nodule bed) reflects a major tectonically induced reorganization of the north-west European intrashelf sedimentary basin, characterized by a shift in both the location of the main depocentre and the sources of sediment production.  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