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   34806篇
  免费   367篇
  国内免费   273篇
安全科学   977篇
废物处理   1452篇
环保管理   4799篇
综合类   5353篇
基础理论   9561篇
环境理论   14篇
污染及防治   9347篇
评价与监测   2179篇
社会与环境   1520篇
灾害及防治   244篇
  2022年   224篇
  2021年   267篇
  2019年   249篇
  2018年   425篇
  2017年   448篇
  2016年   735篇
  2015年   576篇
  2014年   868篇
  2013年   2834篇
  2012年   1047篇
  2011年   1430篇
  2010年   1153篇
  2009年   1238篇
  2008年   1471篇
  2007年   1576篇
  2006年   1388篇
  2005年   1157篇
  2004年   1168篇
  2003年   1106篇
  2002年   1074篇
  2001年   1347篇
  2000年   1008篇
  1999年   569篇
  1998年   445篇
  1997年   449篇
  1996年   491篇
  1995年   525篇
  1994年   503篇
  1993年   460篇
  1992年   432篇
  1991年   419篇
  1990年   447篇
  1989年   418篇
  1988年   390篇
  1987年   369篇
  1986年   330篇
  1985年   314篇
  1984年   383篇
  1983年   344篇
  1982年   390篇
  1981年   360篇
  1980年   297篇
  1979年   321篇
  1978年   262篇
  1977年   231篇
  1976年   209篇
  1975年   213篇
  1974年   210篇
  1973年   224篇
  1972年   230篇
排序方式: 共有10000条查询结果,搜索用时 694 毫秒
701.
Although oil spill cleanup requirements have existed in the United States for years, recent increases in oil imports and marine transportation of petroleum products as well as growing environmental concern have exposed a new industry, the Oil Spill Cleanup Industry. This paper explores some of the microeconomic aspects of this industry which has come under increased scrutiny by the general public, big business, and the federal government.In addition to a brief history and definition, several basic questions about the economic viability of the oil spill cleanup industry are raised and explored, and the impact on the industry of cleanup from government sources is examined, both from the perspective of present operations and from apparent future increases in federal participation. The primary dilemma facing the industry, that of providing continued and immediate supply while confronted with stochastic demand, is discussed. The effects of the large spill on the industry both in terms of revenue and ability to meet cleanup requirements is also considered.Information for the paper is drawn from past and continuing involvement in the U.S. Coast Guard's Marine Environmental Protection Program by both authors. The statistical evidence presented here was compiled through personal interviews and from two computerized Coast Guard information systems; PIRS (the Pollution Incident Reporting System), and SKIM (the Spill Cleanup Equipment Inventory System).  相似文献   
702.
703.
Cuny FC 《Disasters》1980,4(1):112-112
  相似文献   
704.
705.
706.
Two techniques are presented for estimation of natural animal populations, both of which may incorporate the effect of pollutants on populations. Both techniques assume specific underlying population dynamics which may not be applicable to certain species or ecosystems. However, both techniques allow for testing the hypothesis that the population dynamics specified is applicable. The techniques are used to criticize two recent empirical investigations of fisheries.  相似文献   
707.
In a recent issue of this Journal, Sandler and Smith developed an analysis from which they concluded that discounting is Pareto inefficient in an intertemporal context. This comment questions the validity of that conclusion and demonstrates the essential role played by the discount rate in achieving intertemporal Pareto efficiency within a market economy.  相似文献   
708.
709.
Melville CP 《Disasters》1983,7(2):107-117
The disastrous floods of July 1934 in Tabriz are examined in the context of the history of floodinginthe city, which is crossed by a dry stream bed liable to sudden Inundation by mountain torrents from the southeast. Few details of past events have survived, suggesting that relatively little significance has been attached to them. Typically, flood dykes were inadequately maintained. This neglect, combined with a radical alteration in urban topography after 1925, when broad straight avenues were constructed through the old heart of the city, led to serious losses from flooding twice in 1929 and again in 1934. Enhanced perception of the flood risk finally found expression in the adoption of large scale engineering measures to mitigate future events, including strengthening protective dykes and widening the river channel through the city. These works have reduced vulnerability to flooding from river overflow. No long-term detrimental Impact of the 1934 flood has been observed. Some of the physical and social parameters that have influenced the vulnerability of Tabrizinthe past continue to be present both there and elsewhere in Iran, and they may be characteristic also of other regions with comparable natural environments or in a similar stage of socio-economic development.  相似文献   
710.
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