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   38273篇
  免费   4622篇
  国内免费   26642篇
安全科学   1960篇
废物处理   1635篇
环保管理   4714篇
综合类   33067篇
基础理论   9793篇
环境理论   10篇
污染及防治   12339篇
评价与监测   3497篇
社会与环境   2104篇
灾害及防治   418篇
  2023年   146篇
  2022年   267篇
  2021年   333篇
  2020年   794篇
  2019年   2095篇
  2018年   2454篇
  2017年   2451篇
  2016年   2470篇
  2015年   2714篇
  2014年   3673篇
  2013年   5432篇
  2012年   3863篇
  2011年   3711篇
  2010年   3284篇
  2009年   3281篇
  2008年   3195篇
  2007年   3140篇
  2006年   2480篇
  2005年   2052篇
  2004年   1908篇
  2003年   1664篇
  2002年   1490篇
  2001年   1659篇
  2000年   1421篇
  1999年   1053篇
  1998年   808篇
  1997年   803篇
  1996年   850篇
  1995年   866篇
  1994年   652篇
  1993年   538篇
  1992年   646篇
  1991年   619篇
  1990年   559篇
  1989年   522篇
  1988年   437篇
  1987年   314篇
  1986年   322篇
  1985年   305篇
  1984年   324篇
  1983年   293篇
  1982年   317篇
  1981年   259篇
  1980年   169篇
  1979年   185篇
  1978年   167篇
  1977年   137篇
  1975年   140篇
  1973年   167篇
  1972年   145篇
排序方式: 共有10000条查询结果,搜索用时 375 毫秒
11.
12.
Journal of Material Cycles and Waste Management - The present research work focused on fabricating Biodegradable Plate (BD plate) composed of rice husk ash, bagasse and corn starch which is...  相似文献   
13.
Quantitative methods have been applied to the study of floristic structure and diversity in Samarskaya Luka. The results show that Samarskaya Luka is a floristically heterogeneous area in which six elementary floras can be distinguished. This area has been assessed as a floristically autonomous formation, and its floristic representativeness was estimated.  相似文献   
14.
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   
15.
16.
17.
18.
19.
20.
This paper presents the technical aspects of a new methodology for assessing the susceptibility of society to drought. The methodology consists of a combination of inference modelling and fuzzy logic applications. Four steps are followed: (1) model input variables are selected—these variables reflect the main factors influencing susceptibility in a social group, population or region, (2) fuzzification—the uncertainties of the input variables are made explicit by representing them as ‘fuzzy membership functions’, (3) inference modelling—the input variables are used to construct a model made up of linguistic rules, and (4) defuzzification—results from the model in linguistic form are translated into numerical form, also through the use of fuzzy membership functions. The disadvantages and advantages of this methodology became apparent when it was applied to the assessment of susceptibility from three disciplinary perspectives: Disadvantages include the difficulty in validating results and the subjectivity involved with specifying fuzzy membership functions and the rules of the inference model. Advantages of the methodology are its transparency, because all model assumptions have to be made explicit in the form of inference rules; its flexibility, in that informal and expert knowledge can be incorporated through ‘fuzzy membership functions’ and through the rules in the inference model; and its versatility, since numerical data can be converted to linguistic statements and vice versa through the procedures of ‘fuzzification’ and ‘defuzzification’.  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