首页 | 官方网站   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   22815篇
  免费   109篇
  国内免费   93篇
环境安全   23017篇
  2022年   107篇
  2021年   103篇
  2020年   81篇
  2019年   97篇
  2018年   1709篇
  2017年   1597篇
  2016年   1466篇
  2015年   321篇
  2014年   287篇
  2013年   909篇
  2012年   850篇
  2011年   1930篇
  2010年   1213篇
  2009年   1155篇
  2008年   1517篇
  2007年   1921篇
  2006年   472篇
  2005年   519篇
  2004年   399篇
  2003年   508篇
  2002年   534篇
  2001年   500篇
  2000年   365篇
  1999年   225篇
  1998年   160篇
  1997年   163篇
  1996年   172篇
  1995年   201篇
  1994年   196篇
  1993年   160篇
  1992年   136篇
  1991年   171篇
  1990年   168篇
  1989年   160篇
  1988年   118篇
  1987年   116篇
  1986年   118篇
  1985年   93篇
  1984年   131篇
  1983年   120篇
  1982年   122篇
  1981年   114篇
  1980年   98篇
  1979年   116篇
  1978年   74篇
  1977年   76篇
  1975年   77篇
  1973年   74篇
  1972年   66篇
  1967年   66篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
Mitigation and adaptation synergy in forest sector   总被引:1,自引:1,他引:1  
Mitigation and adaptation are the two main strategies to address climate change. Mitigation and adaptation have been considered separately in the global negotiations as well as literature. There is a realization on the need to explore and promote synergy between mitigation and adaptation while addressing climate change. In this paper, an attempt is made to explore the synergy between mitigation and adaptation by considering forest sector, which on the one hand is projected to be adversely impacted under the projected climate change scenarios and on the other provide opportunities to mitigate climate change. Thus, the potential and need for incorporating adaptation strategies and practices in mitigation projects is presented with a few examples. Firstly, there is a need to ensure that mitigation programs or projects do not increase the vulnerability of forest ecosystems and plantations. Secondly, several adaptation practices could be incorporated into mitigation projects to reduce vulnerability. Further, many of the mitigation projects indeed reduce vulnerability and promote adaptation, for example; forest and biodiversity conservation, protected area management and sustainable forestry. Also, many adaptation options such as urban forestry, soil and water conservation and drought resistant varieties also contribute to mitigation of climate change. Thus, there is need for research and field demonstration of synergy between mitigation and adaptation, so that the cost of addressing climate change impacts can be reduced and co-benefits increased.  相似文献   
33.
34.
35.
36.
The impact of prenatal sonographic diagnosis of oesophageal and gastrointestinal obstructions has been analysed over a 10-year period. Three groups of patients were evaluated. The first group consisted of 46 newborns with abnormal prenatal sonogratns, 41 of which were confirmed to have intestinal obstruction postnatally. The second group consisted of 17 neonates with normal prenatal sonograms who had intestinal obstruction postnatally. The third group included 56 newborns who did not undergo a prenatal sonogram but who had intestinal obstruction confirmed at surgery. Polyhydramnios without the appearance of a stomach on ultrasound was diagnostic of pure oesophageal atresia. Polyhydramnios with intestinal dilation was diagnostic of intestinal obstruction. Although surgery was performed earlier in the infants diagnosed prenatally with ultrasound, mortality was no less than in the group that did not undergo a prenatal sonogram, probably because of the high incidence of associated anomalies.  相似文献   
37.
38.
39.
40.
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-23

京公网安备 11010802026262号