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   16537篇
  免费   147篇
  国内免费   91篇
安全科学   409篇
废物处理   706篇
环保管理   2057篇
综合类   2734篇
基础理论   4483篇
环境理论   4篇
污染及防治   4192篇
评价与监测   1103篇
社会与环境   991篇
灾害及防治   96篇
  2022年   135篇
  2021年   111篇
  2020年   124篇
  2019年   146篇
  2018年   204篇
  2017年   248篇
  2016年   345篇
  2015年   293篇
  2014年   474篇
  2013年   1296篇
  2012年   510篇
  2011年   740篇
  2010年   638篇
  2009年   615篇
  2008年   715篇
  2007年   755篇
  2006年   638篇
  2005年   534篇
  2004年   545篇
  2003年   548篇
  2002年   518篇
  2001年   668篇
  2000年   492篇
  1999年   263篇
  1998年   181篇
  1997年   217篇
  1996年   221篇
  1995年   247篇
  1994年   245篇
  1993年   188篇
  1992年   205篇
  1991年   193篇
  1990年   213篇
  1989年   193篇
  1988年   155篇
  1987年   170篇
  1986年   160篇
  1985年   163篇
  1984年   161篇
  1983年   152篇
  1982年   138篇
  1981年   138篇
  1980年   119篇
  1979年   130篇
  1978年   105篇
  1977年   118篇
  1975年   88篇
  1974年   93篇
  1973年   99篇
  1972年   87篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
992.
Vulnerability is a term frequently used to describe the potential threat to rural communities posed by climate variability and change. Despite growing use of the term, analytical measures of vulnerability that are useful for prioritising and evaluating policy responses are yet to evolve. Demand for research capable of prioritising adaptation responses has evolved rapidly with an increasing awareness of climate change and its potential impacts on rural communities. Research into the climate-related vulnerability of Australian rural communities is only just beginning to emerge. Current research is dominated by hazard/impact modelling, drawing on a heritage of managing the risks posed by seasonal climate variability. There is a natural tendency to use the same risk management approach to understand the emergent nature of vulnerability. In this paper, we explore the consequences for policy advice of imperfectly examining vulnerability through the lens of an impact/hazard modelling approach to risk management. In a second paper in this series, we show how hazard/impact modelling can be complemented with more holistic measures of adaptive capacity to provide quantitative insights into the vulnerability of Australian rural communities to climate variability and change.  相似文献   
993.
994.
Habitat loss is one of the greatest threats for biodiversity. In Finland, two thirds of natural mires have been drained for silviculture, which transforms open wetlands into dense forests. However, vegetation management of power line rights-of-way (ROW) maintain the drained mires as open areas. The aim of this study was to determine the effect of the power line ROW vegetation management on butterfly abundance, species richness and community structure by comparing the managed power line ROWs to unmanaged drained control sites and to natural mires. The species richness or abundance of mire butterflies did not differ between the power line ROWs and natural mires. In contrast, both species richness and abundance of butterflies was low on the unmanaged control sites. Tree canopy cover had a negative effect on mire butterflies and this is most likely related to changes in microclimate. The results indicate that the active vegetation removal in the power line ROWs maintain alternative habitats for mire butterflies; yet, the power line ROWs cannot substitute the natural mires.  相似文献   
995.
We report relatively high citrulline concentration in amniotic fluid of a citrullinemic fetus suggesting that prenatal detection of this condition could be done on this basis in conjunction with a direct or an indirect determination of argininosuccinate synthetase activity in amniotic fluid cells.  相似文献   
996.
Partial desynapsis in pearl millet   总被引:1,自引:0,他引:1  
  相似文献   
997.
Soil depletion and degradation have been increasingly recognized as important environmental issues in many parts of the world. Over the last decade a number of political and legislative measures have been introduced to encourage and enforce sustainable soil management in New Zealand. Application of the new legislation has highlighted gaps in our knowledge of soil quality and a lack of scientific methods to assess and monitor soil quality. This paper describes the legislative measures and outlines the sdentific response to the needs of regulatory agencies responsible for maintaining environmental quality. The research recommended a set of indicators to assess soil quality. Each soil quality attribute has an associated "target range" defining the acceptable value for the attribute. The paper also discusses the communication of results to end-users, including the development of a computerized assessment tool. The legislative measures and scientific response have fostered a closer relationship between the policy and science communities, leading to more well-focused research, but greater collaboration is still required.  相似文献   
998.
999.
1000.
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