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   91725篇
  免费   1229篇
  国内免费   1115篇
安全科学   3761篇
废物处理   3308篇
环保管理   14065篇
综合类   21142篇
基础理论   26380篇
环境理论   73篇
污染及防治   15276篇
评价与监测   5496篇
社会与环境   4012篇
灾害及防治   556篇
  2022年   809篇
  2021年   814篇
  2020年   654篇
  2019年   876篇
  2018年   1180篇
  2017年   1229篇
  2016年   2192篇
  2015年   1838篇
  2014年   2597篇
  2013年   9259篇
  2012年   2231篇
  2011年   2530篇
  2010年   3307篇
  2009年   3431篇
  2008年   2119篇
  2007年   2000篇
  2006年   2341篇
  2005年   2323篇
  2004年   2654篇
  2003年   2436篇
  2002年   1987篇
  2001年   2350篇
  2000年   2031篇
  1999年   1503篇
  1998年   1375篇
  1997年   1362篇
  1996年   1484篇
  1995年   1590篇
  1994年   1484篇
  1993年   1334篇
  1992年   1337篇
  1991年   1303篇
  1990年   1254篇
  1989年   1202篇
  1988年   1057篇
  1987年   985篇
  1986年   992篇
  1985年   1065篇
  1984年   1157篇
  1983年   1170篇
  1982年   1177篇
  1981年   1100篇
  1980年   945篇
  1979年   928篇
  1978年   826篇
  1977年   721篇
  1976年   641篇
  1975年   614篇
  1973年   644篇
  1972年   649篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
The past two decades have witnessed an increase in the exploration for, and development of, mineral resources at Arctic latitudes. Such effort has resulted in the commencement of production at a number of different localities in close proximity to the ocean. Since proximity to a source of transportation for the conveyance of concentrates to the market is a primary requirement governing the economic decisions for the mine to proceed, it is logical that ore deposits near a coastline are primary targets for development.

Closely tied to coastal mining developments is the need to dispose of tailings and waste rock in the most economical manner. Prior to the advent of heightened public awareness and environmental concern, and the enactment of pollution legislation, disposal practices were largely based upon convenience. Currently, however, proposed disposal and operating practices receive closer scrutiny, with a view to providing adequate protection for aquatic resources and habitat. This paper summarizes some of the features of three Arctic mines, wastes from which enter the marine environment, and compares the disposal practices used at each to measures of environmental change as indicated by metal concentrations in various media.  相似文献   
53.
The occurrence and impact of psychological contract violations were studied among graduate management alumni (N = 128) who were surveyed twice, once at graduation (immediately following recruitment) and then two years later. Psychological contracts, reciprocal obligations in employment developed during and after recruitment, were reported by a majority of respondents (54.8 per cent) as having been violated by their employers. The impact of violations are examined using both quantitative and qualitative data. Occurrence of violations correlated positively with turnover and negatively with trust, satisfaction and intentions to remain.  相似文献   
54.
55.
56.
57.
58.
Early non-invasive fetal sexing is widely available over the Internet, leading to concerns about its possible use for sex selection. The aim of this review is to summarise the results of surveys describing lay attitudes towards sex selection for non-medical reasons to help address or inform such concerns. A search of electronic databases and key journals was supplemented by an Internet search and citation-tracking. Twenty-one quantitative studies were identified. Most were conducted in the US, with five recent studies in the UK and Germany. Most studies found that, overall, people were not in favour of sex selection. However, this varied from 94 to 18%. People may hold more negative attitudes when the method of sex selection is specified, particularly if this involves termination of pregnancy (TOP). Attitudes towards the general availability of sex selection are less negative than those towards personal use. Attitudes were consistently negative in German surveys. Little is known of such attitudes outside the US, the UK and Germany, and how such attitudes may change as new sex selection technologies become available. Studies of use of early non-invasive fetal sexing for sex selection for non-medical reasons are needed to assess the extent to which concerns about usage are justified and to assist in debates on how these might be most appropriately addressed. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   
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