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   42108篇
  免费   424篇
  国内免费   584篇
安全科学   1267篇
废物处理   1896篇
环保管理   5032篇
综合类   7847篇
基础理论   10686篇
环境理论   24篇
污染及防治   10836篇
评价与监测   2916篇
社会与环境   2362篇
灾害及防治   250篇
  2022年   421篇
  2021年   415篇
  2020年   306篇
  2019年   378篇
  2018年   668篇
  2017年   667篇
  2016年   988篇
  2015年   781篇
  2014年   1205篇
  2013年   3196篇
  2012年   1428篇
  2011年   1935篇
  2010年   1571篇
  2009年   1639篇
  2008年   1895篇
  2007年   1955篇
  2006年   1697篇
  2005年   1473篇
  2004年   1360篇
  2003年   1422篇
  2002年   1299篇
  2001年   1672篇
  2000年   1128篇
  1999年   709篇
  1998年   479篇
  1997年   493篇
  1996年   494篇
  1995年   575篇
  1994年   590篇
  1993年   446篇
  1992年   490篇
  1991年   478篇
  1990年   511篇
  1989年   462篇
  1988年   421篇
  1987年   342篇
  1986年   323篇
  1985年   344篇
  1984年   363篇
  1983年   349篇
  1982年   339篇
  1981年   320篇
  1980年   253篇
  1979年   273篇
  1978年   264篇
  1976年   193篇
  1975年   200篇
  1974年   204篇
  1972年   201篇
  1971年   200篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
11.
12.
13.
14.
Biomethane production through biogas upgrading is a promising renewable energy for some industries which could be part of the equilibrium needed with fossil fuels consumption to achieve a sustainable society. This paper presents a comprehensive list of biogas upgrading technologies focused on carbon dioxide removal as well as recent advances reported by researcher with wide expertise in this topic. Additionally, an extensive costs–performance comparison among the technologies studied is discussed. Among the different alternatives, chemical scrubbing stood out to achieve high biomethane purities while cryogenic technologies proved to be effective against methane losses. Regarding the different costs, water scrubbing and membrane separation seem to be the most affordable techniques.  相似文献   
15.
16.
Catastrophic disasters like earthquake and flood cause widespread destruction and financial devastation. This has brought disaster management into limelight making it a burgeoning academic research field. The remarkable rise of ICT (Information and Communication Technology) has instigated the scientific world to incorporate these technologies in disaster management. This study presents scientometric analysis to identify the status quo of research on the management of various disasters and role of ICT in it. This paper uses bibliographic data retrieved from Scopus for the observation period from 2011 to 2018. We provide extensive insights into growth of publications, citation pattern and their connectedness with other subject disciplines. Furthermore, we identify most productive and influential countries, institutes and journals. Our study analyses co-occurrence of keywords using Visualization of Similarities (VOS) Viewer. This structured overview will enhance the understanding of this field leading to more focussed and purposeful research.  相似文献   
17.
Introduced and cryptogenic species in Port Phillip Bay, Victoria, Australia   总被引:4,自引:0,他引:4  
Port Phillip Bay (PPB) is a large (1,930 km2), temperate embayment in southern Victoria, Australia. Extensive bay-wide surveys of PPB have occurred since 1840. In 1995/1996 the Commonwealth Scientific and Industrial Research Organization (CSIRO) Centre for Research on Introduced Marine Pests (CRIMP) undertook an intensive evaluation of the region with the aims of developing a comprehensive species list of native and introduced biota and contrasting previous bay-wide assessments with a current field survey in order to detect new incursions and discern alterations to native communities. Two methods were used to meet these aims: a re-evaluation of regional museum collections and published research in PPB to identify and determine the timing of introductions; and field surveys for benthic (infauna, epifauna and encrusting) organisms between September 1995 to March 1996. One hundred and sixty introduced (99) and cryptogenic (61) species were identified representing over 13% of the recorded species of PPB. As expected, the majority of these are concentrated around the shipping ports of Geelong and Melbourne. Invasions within PPB appear to be increasing, possibly due to an increase in modern shipping traffic and an increase in aquaculture (historically associated with incidental introductions); however the records of extensive biological surveys suggest that this may, in part, be an artefact of sampling effort. In contrast to Northern Hemisphere studies, PPB (and Southern Hemisphere introductions in general) have significantly different suites of successfully invading taxa. PPB is presented as one of the most invaded marine ecosystems in the Southern Hemisphere.Communicated by M.S. Johnson, Crawley  相似文献   
18.
19.
Elevated concentrations of arsenic, nickel, and molybdenum in aquatic systems around northern Saskatchewan uranium mines are an environmental concern. Early life stage fathead minnows were used to assess toxicity from several aquatic systems near the Key Lake and Rabbit Lake uranium operations. Hatching success of fish embryos exposed to waters receiving contaminants associated with uranium ore milling was reduced by 32-61% relative to controls. Mortality differed in two lakes receiving mill effluents because of opposing factors influencing metal toxicity (i.e. low pH and high hardness). In one mill receiving water (Fox Lake), larval mortality was 0%, whereas mortality was 85% in water collected from a downstream location (Unknown Lake). Fish embryos exposed to open-pit dewatering effluent receiving waters, or water from a flooded open pit (i.e. pit waters), hatched 26-39% earlier than those exposed to reference or control water. The combination of low water hardness and elevated nickel concentrations in pit waters contributed to the early hatching. Egg hatchability and hatching time were more sensitive indicators of toxicity than 'standard' endpoints, like larval mortality and growth. Current regulatory emphasis on single contaminants and standard toxicological endpoints should be re-evaluated in light of the complex interaction among confounding variables such as pH, hardness. conductivity, and multi-metal mixtures.  相似文献   
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