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   44103篇
  免费   460篇
  国内免费   408篇
安全科学   1403篇
废物处理   2116篇
环保管理   5760篇
综合类   6413篇
基础理论   11541篇
环境理论   12篇
污染及防治   11272篇
评价与监测   3254篇
社会与环境   2919篇
灾害及防治   281篇
  2023年   201篇
  2022年   410篇
  2021年   461篇
  2020年   288篇
  2019年   370篇
  2018年   663篇
  2017年   687篇
  2016年   1096篇
  2015年   780篇
  2014年   1203篇
  2013年   3692篇
  2012年   1477篇
  2011年   1941篇
  2010年   1639篇
  2009年   1686篇
  2008年   1993篇
  2007年   2026篇
  2006年   1796篇
  2005年   1574篇
  2004年   1538篇
  2003年   1478篇
  2002年   1385篇
  2001年   1730篇
  2000年   1213篇
  1999年   779篇
  1998年   569篇
  1997年   567篇
  1996年   621篇
  1995年   653篇
  1994年   574篇
  1993年   515篇
  1992年   534篇
  1991年   501篇
  1990年   475篇
  1989年   487篇
  1988年   445篇
  1987年   360篇
  1986年   331篇
  1985年   342篇
  1984年   390篇
  1983年   372篇
  1982年   415篇
  1981年   331篇
  1980年   259篇
  1979年   298篇
  1978年   257篇
  1977年   213篇
  1976年   200篇
  1975年   203篇
  1973年   233篇
排序方式: 共有10000条查询结果,搜索用时 706 毫秒
621.
622.
623.
624.
625.
626.
627.
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   
628.
XII Ecdysone Workshop July 22–26, 1996 Barcelona, Spain  相似文献   
629.
Anticardiolipin antibodies were measured in 60 pregnant women with acute parvovirus B19 infection. Test results for eight (13.3 per cent) women were positive for anticardiolipin antibody. Six of these eight women became negative later, yielding a prevalence of anticardiolipin antibodies of 3.3 per cent (2/60) 6 months after acute parvovirus B19 infection. Anticardiolipin antibody positivity was not associated with an increased risk of abortion, fetal death, or maternal complications. This study suggests that there is an elevated frequency of anticardiolipin antibodies in pregnant women with acute parvovirus B19, probably representing an epiphenomenon. However, this is not associated with an adverse maternal or perinatal outcome.  相似文献   
630.
A fetus with multiple structural defects was seen at prenatal ultrasound examination. After termination of the pregnancy a bilateral cleft lip, alveolus, and palate; micrognathia; and webbed joints were seen. Fetal tissues showed indications of infection, intranuclear inclusion bodies, chronic stress, haemolysis, arterial wall damage, and profuse haemorrhage. Parvovirus B19 DNA was detected in fetal tissues by dot hybridization after polymerase chain reaction. The possibility of parvovirus B19 infection leading to congenital malformations is 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