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   6006篇
  免费   43篇
  国内免费   30篇
安全科学   159篇
废物处理   308篇
环保管理   505篇
综合类   906篇
基础理论   1459篇
环境理论   1篇
污染及防治   1522篇
评价与监测   448篇
社会与环境   734篇
灾害及防治   37篇
  2023年   50篇
  2022年   94篇
  2021年   72篇
  2020年   38篇
  2019年   55篇
  2018年   97篇
  2017年   114篇
  2016年   135篇
  2015年   87篇
  2014年   159篇
  2013年   477篇
  2012年   187篇
  2011年   270篇
  2010年   245篇
  2009年   239篇
  2008年   273篇
  2007年   273篇
  2006年   266篇
  2005年   224篇
  2004年   196篇
  2003年   225篇
  2002年   190篇
  2001年   259篇
  2000年   171篇
  1999年   105篇
  1998年   50篇
  1997年   63篇
  1996年   56篇
  1995年   62篇
  1994年   67篇
  1993年   66篇
  1992年   61篇
  1991年   66篇
  1990年   66篇
  1989年   55篇
  1988年   58篇
  1987年   56篇
  1986年   58篇
  1985年   44篇
  1984年   51篇
  1983年   49篇
  1982年   50篇
  1981年   31篇
  1980年   30篇
  1979年   33篇
  1978年   30篇
  1977年   30篇
  1974年   32篇
  1973年   30篇
  1972年   30篇
排序方式: 共有6079条查询结果,搜索用时 15 毫秒
621.
Osmoregulation by the European glass prawn Palaemon elegans Rathke, 1837 was impaired at low temperature (2°C) and high salinities (full strength sea water 35 PSU). Under these conditions, small individuals showed stronger osmoregulatory ability than larger individuals. This observation could partially explain differences in winter migrations off the UK coast where mainly large P. elegans go offshore, leaving smaller individuals in high shore rock pools, a finding consistent with winter experiments in situ.  相似文献   
622.
Radioecological conditions have been estimated in Lake Chervyanoe located on the central axis of the Eastern Ural Radioactive Trace (EURT) about 100–110 km northeast of the Mayak Production Association. Data on the 90Sr and 137Cs contents in the main components of the lake, the distribution of these radionuclides over the profile of bottom sediments, and their amounts in the lake are presented. The experimental data have been used to construct mathematical models for estimating changes in the radionuclide concentrations and amounts in the water and bottom sediments of the lake over a long period after the nuclear accident, as well as the tritium content of the lake water in different periods of time.  相似文献   
623.
 Liquid phase hydrocarbon oxidation is one of the principal routes towards industrial organic chemicals. However, low product selectivity and associated by-product formation are major problems in several oxidation processes. As a result of the increasingly stringent environmental regulations, the development of oxidation catalysts has been a major challenge in the last decade. An overview of novel selective and clean oxidation catalysts and processes is presented. Received: 27 July 1998 / Accepted: 8 September 1998  相似文献   
624.
The structural-temporal organization of a murine rodent community in the taiga has been studied near Lake Teletskoe, Mountain Altai. The results show that the long-term dynamics of indices characterizing community diversity depend mainly on changes in the structure of dominance rather than on the population dynamics of species. The distribution of species in the factor space corresponds to their preference for certain biotopes, from dry to relatively moist. An analysis of relationships within the rodent community has revealed the synchronous dynamics of species abundance and antiphase pattern of changes in the structural indices of dominant species.  相似文献   
625.
Ultrasonographic features suggestive of esophageal atresia with or without tracheo-esophageal fistula (EA/TEF) are only in a small minority of fetuses with EA/TEF (<10%) identifiable on prenatal scans. The prenatal diagnosis of EA/TEF relies in principle, on two nonspecific signs: polyhydramnios and absent or small stomach bubble. Polyhydramnios is associated with a wide range of fetal abnormalities, but most commonly it pursues a benign course. Similarly the sonographic absence of a stomach bubble may point to a variety of fetal anomalies. The combination of polyhydramnios and absent stomach bubble in two small series offers a modest positive predictive value of 44 and 56% respectively. Prenatal scanning for EA/TEF identifies a larger proportion of fetuses with Edwards syndrome; there is also a higher proportion of isolated EA in comparison to postnatal studies. Current ultrasound technology does not allow for a definite diagnosis of EA/TEF and therefore, counseling of parents should be guarded. Postnatal diagnosis of EA is confirmed by the failure to pass a firm nasogastric tube into the stomach; on chest X-ray, the tube is seen curling in the upper esophageal pouch. Corrective surgery for EA/TEF is well established and survival rates of over 90% can be expected. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   
626.
627.
628.
629.
630.
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