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   25211篇
  免费   267篇
  国内免费   141篇
安全科学   625篇
废物处理   1113篇
环保管理   3085篇
综合类   4134篇
基础理论   6910篇
环境理论   14篇
污染及防治   6830篇
评价与监测   1642篇
社会与环境   1117篇
灾害及防治   149篇
  2022年   243篇
  2021年   268篇
  2020年   164篇
  2019年   201篇
  2018年   399篇
  2017年   432篇
  2016年   636篇
  2015年   470篇
  2014年   710篇
  2013年   1962篇
  2012年   853篇
  2011年   1123篇
  2010年   873篇
  2009年   831篇
  2008年   1106篇
  2007年   1114篇
  2006年   973篇
  2005年   825篇
  2004年   802篇
  2003年   758篇
  2002年   719篇
  2001年   830篇
  2000年   606篇
  1999年   367篇
  1998年   282篇
  1997年   295篇
  1996年   295篇
  1995年   359篇
  1994年   328篇
  1993年   290篇
  1992年   295篇
  1991年   296篇
  1990年   310篇
  1989年   292篇
  1988年   262篇
  1987年   248篇
  1986年   243篇
  1985年   212篇
  1984年   266篇
  1983年   221篇
  1982年   284篇
  1981年   227篇
  1980年   192篇
  1979年   205篇
  1978年   192篇
  1977年   156篇
  1975年   149篇
  1974年   161篇
  1973年   166篇
  1972年   156篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
The lessons of history indicate that mismanagement of natural resources and the environment often leads to potentially adverse consequences.The increasing interest in economic development,particularly in the developing countries of the world coupled with increasing population pressures and the globalization of economic activity is placing noticeable stresses on the ultimate sustainability of both human and environmental systems.Sustainable development is not a new concept.It has been an area of concern for different elements of society for some time.Yet efforts to understand the implications of sustainable development have not,until recently,been formalized.We have focused singularly on economic development and environmental quality as if they were mutually exclusive.This paper focuses on the concept of concurrency as both a conceptual framework and practicable method of understanding and implementing the ecology and economy of sustainability.  相似文献   
53.
54.
A very dry climate which prevailed during the last glacial maximum of the Pleistocene from India to the Sahara, was replaced by variable weather conditions with alternating more or less humid phases, starting from the Pleistocene-Holocene transition period and lasting up to about 3000 years ago, when present arid conditions set in. A particularly wet phase is recognized throughout the region some 5000 years ago. Phase shifts within the region and in particular changes in rain distribution patterns, are interpreted as due to shifting spheres of influence of the monsoonal circulation, of Atlantic depressions and moisture originating from the Mediterranean Sea. The condition of the Mediterranean Sea itself, which is influenced by runoff and melt waters from the European Continent and by the Nile floods, as well as by the eustatic sea-level changes, is not a good indicator of local climate conditions.  相似文献   
55.
56.
Peptide chemistry has reached a plateau on which more work is devoted to the improvement of known basic principles than to the development of really new methods. As a consequence, routine syntheses of peptides concentrate on few protecting groups and coupling procedures only. The recent progress in purification of peptides by liquid chromatography helped to promote this trend. Meanwhile, recombinant technology permits the synthesis of proteins and possibly of some lower peptides, too. It cannot compete, however, with chemical solid-phase synthesis of a newly discovered peptide with up to about 40 amino acids in speed but may take over the synthesis for large-scale production. Peptides containing modified or non-natural structures, which are often superior to the natural compounds as drugs, will remain subject of chemical synthesis, too. Present research focuses on the role of peptide and protein factors in the immune response and on structure and biological activities of neuropeptides.  相似文献   
57.
58.
59.
60.
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