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   30719篇
  免费   356篇
  国内免费   385篇
安全科学   1049篇
废物处理   1508篇
环保管理   4040篇
综合类   4708篇
基础理论   7940篇
环境理论   10篇
污染及防治   7724篇
评价与监测   2195篇
社会与环境   2088篇
灾害及防治   198篇
  2023年   150篇
  2022年   314篇
  2021年   355篇
  2020年   213篇
  2019年   273篇
  2018年   468篇
  2017年   500篇
  2016年   772篇
  2015年   574篇
  2014年   919篇
  2013年   2547篇
  2012年   1085篇
  2011年   1444篇
  2010年   1162篇
  2009年   1193篇
  2008年   1469篇
  2007年   1393篇
  2006年   1277篇
  2005年   1108篇
  2004年   1067篇
  2003年   1016篇
  2002年   962篇
  2001年   1104篇
  2000年   782篇
  1999年   494篇
  1998年   367篇
  1997年   393篇
  1996年   406篇
  1995年   475篇
  1994年   402篇
  1993年   347篇
  1992年   379篇
  1991年   358篇
  1990年   326篇
  1989年   323篇
  1988年   295篇
  1987年   241篇
  1986年   250篇
  1985年   248篇
  1984年   267篇
  1983年   256篇
  1982年   268篇
  1981年   221篇
  1980年   165篇
  1979年   181篇
  1978年   163篇
  1977年   133篇
  1975年   138篇
  1973年   167篇
  1972年   142篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
111.
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   
112.
113.
114.

This article aims to evaluate municipal solid waste (MSW) management schemes in order to promote sustainability and eco-efficiency, core elements in global mitigation strategies in both public and private policies. A discrete event simulation (DES) approach was used to integrate the economic, environmental, and social aspects related to aseptic carton packages (ACP) in Itajuba, Brazil. The simulated scenarios consider three alternatives for disposing ACP: landfills, recycling, and incineration with energy recovery. According to our findings, incineration alternatives are preferred from an eco-efficiency perspective, given the potential greenhouse gas (GHG) emissions reductions and due to the possibility of energy recover, which reinforces the contribution of this technology to promote sustainability as largely found in the international literature. Given the context of MSW management in Brazil, this represents a significant opportunity to increase the effectiveness of mitigation strategies adopted in the country. Taking into account that this is by far the least applied technology, the authors strongly advocate that global strategies for mitigation consider different approaches to integrate carbon dioxide (CO2) emission reductions related to the entire MSW management system and its alternatives, thus advancing from a waste disposal-oriented system to a life cycle–oriented system.

  相似文献   
115.
Advanced oxidation technologies are a friendly environmental approach for the remediation of industrial wastewaters. Here, one pot synthesis of mesoporous WO_3 and WO_3-graphene oxide(GO) nanocomposites has been performed through the sol–gel method. Then, platinum(Pt) nanoparticles were deposited onto the WO_3 and WO_3-GO nanocomposite through photochemical reduction to produce mesoporous Pt/WO_3 and Pt/WO_3-GO nanocomposites. X-ray diffraction(XRD) findings exhibit a formation of monoclinic and triclinic WO_3 phases. Transmission Electron Microscope(TEM) images of Pt/WO_3-GO nanocomposites exhibited that WO_3 nanoparticles are obviously agglomerated and the particle sizes of Pt and WO_3 are ~ 10 nm and 20–50 nm, respectively. The mesoporous Pt/WO_3 and Pt/WO_3-GO nanocomposites were assessed for photocatalytic degradation of Methylene Blue(MB) as a probe molecule under visible light illumination.The findings showed that mesoporous Pt/WO_3, WO_3-GO and Pt/WO_3-GO nanocomposites exhibited much higher photocatalytic efficiencies than the pure WO_3. The photodegradation rates by mesoporous Pt/WO_3-GO nanocomposites are 3, 2 and 1.15 times greater than those by mesoporous WO_3, WO_3-GO, and Pt/WO_3, respectively. The key factors of the enhanced photocatalytic performance of Pt/WO_3-GO nanocomposites could be explained by the highly freedom electron transfer through the synergetic effect between WO_3 and GO sheets, in addition to the Pt nanoparticles that act as active sites for O2 reduction, which suppresses the electron hole pair recombination in the Pt/WO_3-GO nanocomposites.  相似文献   
116.
117.
118.
119.
120.
Diapause embryos in the neustonic copepodAnomalocera patersoni   总被引:2,自引:0,他引:2  
The neustonic copepodAnomalocera patersoni Templeton, collected from the Gulf of Naples from January to May 1988, laid subitaneous and diapause eggs that were of equal size and dark and smooth in appearance. In January and February, most eggs were subitaneous and hatched within 2 to 3 d at room temperature. Conspicuous numbers of diapause eggs were first obtained in February when several clutches contained a second egg type which did not hatch in a subitaneous manner. By March and April, most clutches contained only diapause eggs. Transmission electron microscope studies of subitaneous and diapause eggs revealed striking morphological differences. Subitaneous eggs had a thin vitelline coat covering the plasma membrane, whereas diapause eggs were enveloped by a complex four-layer structure which is assembled after spawning and which probably serves as a protective shell during dormancy. No major morphological differences were discernible in the oogenic cycle of females spawning either of the two egg types. Diapause eggs were shown to be embryos in early stages of development, and segmentation of these embryos was arrested for the entire 6-mo period of investigation. Diapause eggs hatched after 7 mo of dormancy.  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