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   17457篇
  免费   145篇
  国内免费   114篇
安全科学   410篇
废物处理   660篇
环保管理   1937篇
综合类   5351篇
基础理论   3625篇
环境理论   4篇
污染及防治   4158篇
评价与监测   883篇
社会与环境   625篇
灾害及防治   63篇
  2018年   207篇
  2017年   192篇
  2016年   291篇
  2015年   220篇
  2014年   321篇
  2013年   1178篇
  2012年   377篇
  2011年   524篇
  2010年   497篇
  2009年   564篇
  2008年   580篇
  2007年   612篇
  2006年   537篇
  2005年   471篇
  2004年   510篇
  2003年   462篇
  2002年   441篇
  2001年   621篇
  2000年   418篇
  1999年   285篇
  1998年   206篇
  1997年   197篇
  1996年   197篇
  1995年   235篇
  1994年   242篇
  1993年   207篇
  1992年   226篇
  1991年   232篇
  1990年   255篇
  1989年   229篇
  1988年   184篇
  1987年   181篇
  1986年   183篇
  1985年   180篇
  1984年   201篇
  1983年   193篇
  1982年   198篇
  1981年   209篇
  1980年   169篇
  1979年   181篇
  1978年   147篇
  1977年   141篇
  1974年   147篇
  1973年   147篇
  1968年   156篇
  1967年   184篇
  1966年   154篇
  1965年   148篇
  1964年   151篇
  1963年   139篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
121.
122.
123.
124.
Twelve second-trimester fetuses with cystic hygroma underwent fetal blood sampling for rapid karyotyping, haematologic evaluation, and blood gas analysis. An abnormal karyotype was found in seven cases: monosomy X in five, trisomy 21 in one, and trisomy 13 in the other. Eight often fetuses undergoing blood gas analysis showed hypoxaemia, five of which were growth-retarded. Nine pregnancies were terminated. Of the remaining three, only one fetus survived the perinatal period.  相似文献   
125.
Several genera and species of plant-parasitic nematodes cause losses in grain yield in cereals; some are of relatively minor importance (e.g. Anguina tritici (Steinbuch) Chitwood, the cause of “ear cockle” in wheat), while others such as the cereal cyst nematode (CCN) (Heterodera avenae Woll.) have a wide geographic distribution, infest extensive areas, and may cause losses valued at millions of dollars. Some of these nematodes are difficult to control because the measures that might be used are uneconomic to apply or are impractical. The control of CCN, however, can be achieved, and several successful strategies have been developed in parts of Europe and in Australia. The various measures available to Australian cereal growers include: crop rotation, resistant cultivars, manipulation of sowing dates, use of nematicides, and reduced cultivation. The selection of an appropriate management strategy for the control of CCN is influenced by factors such as: climate, cereal species grown, yield potential, rotations practised and the availability of alternative crops, pathotype present, farm size, availability of resistant cultivars, nematicides registered, and the availability of suitable equipment for their application.  相似文献   
126.
127.
128.
129.
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   
130.
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