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   27265篇
  免费   238篇
  国内免费   190篇
安全科学   706篇
废物处理   1023篇
环保管理   3368篇
综合类   6939篇
基础理论   6282篇
环境理论   9篇
污染及防治   6562篇
评价与监测   1502篇
社会与环境   1160篇
灾害及防治   142篇
  2022年   210篇
  2018年   345篇
  2017年   313篇
  2016年   486篇
  2015年   382篇
  2014年   546篇
  2013年   1911篇
  2012年   688篇
  2011年   961篇
  2010年   838篇
  2009年   961篇
  2008年   1015篇
  2007年   1032篇
  2006年   902篇
  2005年   818篇
  2004年   792篇
  2003年   775篇
  2002年   745篇
  2001年   1001篇
  2000年   703篇
  1999年   464篇
  1998年   312篇
  1997年   325篇
  1996年   330篇
  1995年   390篇
  1994年   398篇
  1993年   342篇
  1992年   333篇
  1991年   371篇
  1990年   391篇
  1989年   362篇
  1988年   280篇
  1987年   271篇
  1986年   273篇
  1985年   258篇
  1984年   283篇
  1983年   282篇
  1982年   288篇
  1981年   293篇
  1980年   242篇
  1979年   277篇
  1978年   204篇
  1977年   202篇
  1976年   186篇
  1975年   185篇
  1974年   201篇
  1973年   202篇
  1972年   189篇
  1967年   233篇
  1966年   190篇
排序方式: 共有10000条查询结果,搜索用时 8 毫秒
11.
12.
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   
13.
14.
15.
16.
17.
H. Sudo  M. Azeta 《Marine Biology》1992,113(2):211-217
Ontogenetic change of habitat depths of Nautilus pompilius in the Philippines (Tañon Strait) and Fiji is considered by comparing 18O/16O ratios in septa and cameral fluid of live-caught specimens and ambient sea-water. 18O values of cameral liquid become heavier with decreasing volume within a chamber, which may be due to isotopic fractionation during discharge across the siphuncular wall. All of the seven Philippine and Fiji specimens analyzed show a distinct change in 18O from light values in the first seven septa to heavier values in the succeeding septa. Two different isotopic temperature scales are obtained for the Fiji and Philippine populations, suggesting a differential vital effect of metabolism between them. Sightly light 18O values in Septa 1 to 7 and hatching at relatively high temperatures in aquaria both suggest that N. pompilius hatch at the shallowest depths within their inhabitable vertical range. Depths of postembryonic animals in the Philippines and Fiji waters estimated from the isotopic temperature-depth diagrams range from 120 to 160 m and from 440 to 520 m, respectively, both of which correlate well with capture records. More than several tens of small-scale 18O cycles are detected in the sequence of nacreous layers within the single septum of a submature Philippine specimen. This can be interpreted as reflecting daily vertical migration.  相似文献   
18.
Environment, Development and Sustainability - Renewable energy (RE) plays an increasingly important role in the economy of almost every country in the world. In order to examine the state of...  相似文献   
19.
20.
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