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   16816篇
  免费   172篇
  国内免费   153篇
安全科学   403篇
废物处理   500篇
环保管理   2101篇
综合类   4861篇
基础理论   3773篇
环境理论   10篇
污染及防治   4097篇
评价与监测   809篇
社会与环境   507篇
灾害及防治   80篇
  2018年   192篇
  2017年   189篇
  2016年   261篇
  2015年   220篇
  2014年   292篇
  2013年   1131篇
  2012年   429篇
  2011年   522篇
  2010年   418篇
  2009年   517篇
  2008年   583篇
  2007年   632篇
  2006年   542篇
  2005年   423篇
  2004年   431篇
  2003年   489篇
  2002年   401篇
  2001年   539篇
  2000年   398篇
  1999年   289篇
  1998年   207篇
  1997年   198篇
  1996年   210篇
  1995年   223篇
  1994年   245篇
  1993年   205篇
  1992年   207篇
  1991年   208篇
  1990年   241篇
  1989年   221篇
  1988年   190篇
  1987年   176篇
  1986年   164篇
  1985年   189篇
  1984年   163篇
  1983年   170篇
  1982年   179篇
  1981年   176篇
  1980年   170篇
  1979年   172篇
  1978年   163篇
  1977年   146篇
  1976年   151篇
  1974年   151篇
  1973年   147篇
  1972年   138篇
  1967年   159篇
  1966年   131篇
  1965年   135篇
  1963年   129篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
2.
Energy efficiency is often stated to be the most cost-effective measure for satisfying our energy demand with minimal environmental damage. However, the potential energy savings attainable in 'the real world' are frequently overestimated, as is shown in an industrial case study of the glass industry. Nevertheless, there are significant energy savings to be realized, and the role of new technologies in this is important. However, the key to the effective use of new technology for improved energy efficiency is good management and. for best effect, it must be integrated into the normal resource management activities of a company.  相似文献   
3.
4.
5.
6.
7.
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   
8.
9.
Childhood-onset spinal muscular atrophy (SMA) is one of the most common neurodegenerative genetic disorders. SMN1 is the SMA-determining gene deleted or mutated in the majority of SMA cases. There is no effective cure or treatment for this disease yet. Thus, the availability of prenatal testing is important. Here we report prenatal prediction for 68 fetuses in 63 Turkish SMA families using direct deletion analysis of the SMN1 gene by restriction digestion. The genotype of the index case was known in 40 families (Group A) but unknown in the remaining 23 families (Group B). A total of ten fetuses were predicted to be affected. Eight of these fetuses were derived from Group A and two of these fetuses were from Group B families. Two fetuses from the same family in Group A had the SMNhyb1 gene in addition to homozygous deletion of the NAIP gene. One fetus from Group A was homozygously deleted for only exon 8 of the SMN2 gene, and further analysis showed the presence of both the SMN1 and SMNhyb1 genes but not the SMN2 gene. In addition, one carrier with a homozygous deletion of only exon 8 of the SMN1 gene was detected to have a SMNhyb2 gene, which was also found in the fetus. To our knowledge, these are the first prenatal cases with SMNhyb genes. Follow-up studies demonstrated that the prenatal predictions and the phenotype of the fetuses correlated well in 33 type I pregnancies demonstrating that a careful molecular analysis of the SMN genes is very useful in predicting the phenotype of the fetus in families at risk for SMA. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   
10.
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