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   18669篇
  免费   213篇
  国内免费   153篇
安全科学   491篇
废物处理   765篇
环保管理   2372篇
综合类   3027篇
基础理论   5108篇
环境理论   13篇
污染及防治   4781篇
评价与监测   1240篇
社会与环境   1099篇
灾害及防治   139篇
  2022年   141篇
  2021年   142篇
  2020年   117篇
  2019年   133篇
  2018年   267篇
  2017年   301篇
  2016年   401篇
  2015年   343篇
  2014年   539篇
  2013年   1433篇
  2012年   636篇
  2011年   876篇
  2010年   747篇
  2009年   738篇
  2008年   838篇
  2007年   912篇
  2006年   782篇
  2005年   657篇
  2004年   621篇
  2003年   605篇
  2002年   600篇
  2001年   710篇
  2000年   530篇
  1999年   301篇
  1998年   221篇
  1997年   265篇
  1996年   248篇
  1995年   286篇
  1994年   281篇
  1993年   209篇
  1992年   225篇
  1991年   205篇
  1990年   226篇
  1989年   197篇
  1988年   165篇
  1987年   175篇
  1986年   172篇
  1985年   172篇
  1984年   167篇
  1983年   161篇
  1982年   142篇
  1981年   136篇
  1980年   133篇
  1979年   143篇
  1978年   113篇
  1977年   122篇
  1975年   90篇
  1974年   94篇
  1973年   101篇
  1972年   92篇
排序方式: 共有10000条查询结果,搜索用时 203 毫秒
21.
As part of a programme to characterize floating anthropogenic debris in the aquatic environment, the US Environmental Protection Agency (EPA) conducted 18 field surveys in the harbours of major metropolitan cities of the east, west, and Gulf coasts of the United States and the Mid-Atlantic Bight. the surveys were designed to provide information on the types, relative amounts, and distributions of aquatic debris in different geographic regions of the United States. Neuston nets (0.33 mm mesh) were used to collect surface debris during outgoing tides on two or three consecutive days in selected areas of each city. After each net tow, the debris, which ranged in size from small resin pellets to large plastic sheeting pieces, was identified, categorized, and counted. the data are being used to qualitatively characterize aquatic debris in coastal metropolitan areas, to examine potential regional variations, and to tentatively identify potential sources.  相似文献   
22.
23.
This paper examines how political risk taking is necessary for gains in sustainability. It provides a personal perspective covering some of the key turning points in Australia (and some global examples) to demonstrate how policy innovation in sustainability will always require political leaders to go out on a limb and then in hindsight the policy will be seen as obvious and normal. The key components of sustainability (vision, interdisciplinary, geographical and sectoral synergies) are used to illustrate stories of tree climbing. Some deeper levels of sustainability applied to thinking, creativity, belonging and spirituality are then used as the framework for illustrating the significance of political risk taking for sustainability.  相似文献   
24.
Single cell polymerase chain reaction (PCR) for preimplantation genetic diagnosis (PGD) requires high efficiency and accuracy. Allele dropout (ADO), the random amplification failure of one of the two parental alleles, remains the most significant problem in PCR-based PGD testing since it can result in serious misdiagnosis for compound heterozygous or autosomal dominant conditions. A number of different strategies (including the use of lysis buffers to break down the cell and make the DNA accessible) have been employed to combat ADO with varying degrees of success, yet there is still no consensus among PGD centres over which lysis buffer should be used (ESHRE PGD Consortium, 1999 ). To address this issue, PCR amplification of three genes (CFTR, LAMA3 and PKP1) at different chromosomal loci was investigated. Single lymphocytes from individuals heterozygous for mutations within each of the three genes were collected and lysed in either alkaline lysis buffer (ALB) or proteinase K/SDS lysis buffer (PK). PCR amplification efficiencies were comparable between alkaline lysis and proteinase K lysis for PCR products spanning each of the three mutated loci (ΔF508 in CFTR 90% vs 88%; R650X in LAMA3 82% vs 78%; and Y71X in PKP1 91% vs 87%). While there was no appreciable difference between ADO rates between the two lysis buffers for the LAMA3 PCR product (25% vs 26%), there were significant differences in ADO rates between ALB and PK for the CFTR PCR product (0% vs 23%) and the PKP1 PCR product (8% vs 56%). Based on these results, we are currently using ALB in preference to PK/SDS buffer for the lysis of cells in clinical PGD. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   
25.
26.
Progress in the greening of UK local government has been hampered by uncertainty about the relationship between resource use and environmental protection. Ecological modernizationmay offer the most appropriateparadigm to reconcile economic, social and environmentalinterpretationsof sustainability. The transition from corporate to strategic environmental management currently being attempted by some 'green' authorities can be construed as an attempt to promote ecological modernization in the form of institutional learning. Fife Council in Scotland provides an interesting case study. Progress with corporate environmental management has become bound up with a radical devolution of decision making. Efforts to link the authority's Sustainable Development Policy to a Local Agenda 21 programme have been initiated with the piloting of sustainability indicators.  相似文献   
27.
28.
29.
30.
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