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   93202篇
  免费   1225篇
  国内免费   1132篇
安全科学   3790篇
废物处理   3443篇
环保管理   14156篇
综合类   21371篇
基础理论   26665篇
环境理论   73篇
污染及防治   16094篇
评价与监测   5593篇
社会与环境   3830篇
灾害及防治   544篇
  2022年   834篇
  2021年   819篇
  2020年   649篇
  2019年   867篇
  2018年   1176篇
  2017年   1223篇
  2016年   2223篇
  2015年   1847篇
  2014年   2607篇
  2013年   9284篇
  2012年   2277篇
  2011年   2592篇
  2010年   3337篇
  2009年   3465篇
  2008年   2175篇
  2007年   2016篇
  2006年   2430篇
  2005年   2390篇
  2004年   2707篇
  2003年   2575篇
  2002年   2095篇
  2001年   2553篇
  2000年   2112篇
  1999年   1604篇
  1998年   1396篇
  1997年   1384篇
  1996年   1498篇
  1995年   1590篇
  1994年   1508篇
  1993年   1333篇
  1992年   1344篇
  1991年   1314篇
  1990年   1270篇
  1989年   1213篇
  1988年   1072篇
  1987年   988篇
  1986年   1000篇
  1985年   1074篇
  1984年   1160篇
  1983年   1169篇
  1982年   1177篇
  1981年   1096篇
  1980年   947篇
  1979年   936篇
  1978年   820篇
  1977年   713篇
  1976年   643篇
  1974年   619篇
  1973年   646篇
  1972年   643篇
排序方式: 共有10000条查询结果,搜索用时 296 毫秒
361.
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   
362.
Environment, Development and Sustainability - This study describes the results of groundwater table variation in Thanjavur District before and after the monsoon seasons. Groundwater-level data...  相似文献   
363.
Russian Journal of Ecology - Populations at the border of ranges are considered more vulnerable than those in the center. However, some recent reviews contradict this hypothesis. We have studied...  相似文献   
364.
Russian Journal of Ecology - Abstract—We tested a hypothesis about the different abilities of alien and native plants to form arbuscular mycorrhizae. The studies were carried out in the...  相似文献   
365.
Environment, Development and Sustainability - Drying of fish at the Sagar Island (21.7269° N, 88.1096° E) is generally carried out in open sun on the seashore on plastic sheets or mat of...  相似文献   
366.
Rate-temperature responses in scyphozoan medusae and polyps   总被引:1,自引:0,他引:1  
The effects of temperature on oxygen consumption and spontaneous rhythmic activity have been investigated in various stages of the life histories of 3 species of jellyfish from the Chesapeake Bay, USA. All 3 species clearly show the ability to acclimate positively to temperature change. Thermal sensitivity of metabolism in the winter medusa Cyanea capillata fulva is fairly low at temperature intervals which are experienced in nature. Polyps of the two summer medusae, Chrysaora quinquecirrha and Aurelia aurita, show reduced metabolic sensitivity at temperatures normally accompanying high developmental activity and the onset of strobilation.  相似文献   
367.
368.
369.
370.
Reversible double water in oil in water (W/O/W) emulsions were developed to contain subsurface hydrocarbon spills during their remediation using surfactant flushing. Double emulsions were prepared by emulsifying CaCl2 solutions in canola oil, and subsequently by emulsifying the W/O emulsions in aqueous sodium alginate solutions. The formation of double emulsions was confirmed with confocal and optical microscopy. The double emulsions reversed and gelled when mixed with the surfactants sodium dodecyl sulfate (SDS) and cocamidopropyl betaine (CPB). Gels can act as ‘emulsion locks’ to prevent spreading of the hydrocarbon plume from the areas treated with surfactant flushing, as shown in sand column tests. Shear rheology was used to quantify the viscoelastic moduli increase (gelation) upon mixing the double emulsion with SDS and CPB. SDS was more effective than CPB in gelling the double emulsions. CPB and SDS could adsorb at the interface between water and model hydrocarbons (toluene and motor oil), lowering the interfacial tension and rigidifying the interface (as shown with a Langmuir trough). Bottle tests and optical microscopy showed that SDS and CPB produced W/O and O/W emulsions, with either toluene or motor oil and water. The emulsification of motor oil and toluene in water with SDS and CPB facilitated their flow through sand columns and their recovery. Toluene recovery from sand columns was quantitated using Gas-Chromatography Mass-Spectroscopy (GC-MS). The data show that SDS and CPB can be used both for surfactant flushing and to trigger the gelation of ‘emulsion locks’. Ethanol also gelled the emulsions at 100 mL/L.  相似文献   
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