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   31114篇
  免费   233篇
  国内免费   367篇
安全科学   512篇
废物处理   1706篇
环保管理   3694篇
综合类   4528篇
基础理论   8793篇
环境理论   4篇
污染及防治   7257篇
评价与监测   2486篇
社会与环境   2599篇
灾害及防治   135篇
  2022年   241篇
  2021年   198篇
  2020年   159篇
  2019年   199篇
  2018年   1702篇
  2017年   1641篇
  2016年   1624篇
  2015年   503篇
  2014年   657篇
  2013年   1796篇
  2012年   1139篇
  2011年   2229篇
  2010年   1501篇
  2009年   1411篇
  2008年   1811篇
  2007年   2160篇
  2006年   852篇
  2005年   777篇
  2004年   780篇
  2003年   785篇
  2002年   789篇
  2001年   939篇
  2000年   655篇
  1999年   347篇
  1998年   247篇
  1997年   276篇
  1996年   293篇
  1995年   344篇
  1994年   306篇
  1993年   254篇
  1992年   267篇
  1991年   252篇
  1990年   272篇
  1989年   243篇
  1988年   212篇
  1987年   226篇
  1986年   201篇
  1985年   208篇
  1984年   210篇
  1983年   198篇
  1982年   177篇
  1981年   178篇
  1980年   157篇
  1979年   169篇
  1978年   130篇
  1977年   143篇
  1975年   117篇
  1974年   116篇
  1973年   133篇
  1972年   128篇
排序方式: 共有10000条查询结果,搜索用时 281 毫秒
311.
312.
 There are numerous reports of invertebrates that are visual mimics of ants, but no formal reports of mimicry of an ant, by an ant. Two endemic Australian ants, Myrmecia fulvipes and Camponotus bendigensis are remarkably similar in colour and size; both are generally black but have red legs and golden gasters. The density and hue of the pubescence of each ant's gaster are relatively uncommon in ants, but are very rare when combined with the black forebody and red legs. The ants are similarly sized but are smaller than other species closely related to M. fulvipes. The range of C. bendigensis lies entirely within that of M. fulvipes, and both species excavate ground nests in open woodland. Finally, workers of both species are crepuscular and forage solitarily. These data suggest that the relatively benign formicine C. bendigensis is a Batesian mimic of the formidable myrmeciine M. fulvipes. Received: 9 August 1999 / Accepted in revised form: 22 December 1999  相似文献   
313.
314.
315.
316.
317.
318.
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   
319.
In 1964, Walter Rothenbuhler proposed a two-gene model to explain phenotypic variance in the remarkable behavior in which honey bee workers remove dead brood from their colonies. Rothenbuhler's model proposed that one locus controls the uncapping of brood cells containing dead pupae, while a second controls the removal of the cell contents. We show here, through molecular techniques and quantitative trait loci (QTL) linkage mapping, that the genetic basis of hygienic behavior is more complex, and that many genes are likely to contribute to the behavior. In our cross, we detected seven suggestive QTLs associated with hygienic behavior. Each detected QTL controlled only 9-15% of the observed phenotypic variance in the character.  相似文献   
320.
The possible effects of landscape structure on starling roost distribution were investigated in western France using GIS analysis at different radii (2, 4, 8 and 10 km). Composition (11 land use classes) and configuration (patch size, diversity index) of the landscapes surrounding 97 roost sites used by starlings from 1981 to 2002 and surrounding 50 random points not used as roost sites were compared. Significant results suggested that starling roosts were established preferentially in the centre of an agricultural landscape where large units of pastures and arable land predominated and where natural areas were lacking both in large patches (forests or wetland classes) and in small patches such as woods in the mixed land class. A varied farmland landscape with natural areas and small patches should be promoted to limit the starling damage in wintering regions and also to favour their reproduction in regions where it has declined.  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