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   33414篇
  免费   361篇
  国内免费   245篇
安全科学   886篇
废物处理   1411篇
环保管理   4562篇
综合类   5477篇
基础理论   9258篇
环境理论   14篇
污染及防治   8565篇
评价与监测   2068篇
社会与环境   1553篇
灾害及防治   226篇
  2022年   219篇
  2021年   242篇
  2019年   251篇
  2018年   428篇
  2017年   431篇
  2016年   689篇
  2015年   493篇
  2014年   750篇
  2013年   2588篇
  2012年   934篇
  2011年   1330篇
  2010年   1100篇
  2009年   1082篇
  2008年   1375篇
  2007年   1410篇
  2006年   1297篇
  2005年   1065篇
  2004年   1091篇
  2003年   1037篇
  2002年   983篇
  2001年   1282篇
  2000年   916篇
  1999年   549篇
  1998年   441篇
  1997年   438篇
  1996年   453篇
  1995年   520篇
  1994年   516篇
  1993年   451篇
  1992年   468篇
  1991年   443篇
  1990年   482篇
  1989年   461篇
  1988年   403篇
  1987年   375篇
  1986年   338篇
  1985年   331篇
  1984年   400篇
  1983年   355篇
  1982年   403篇
  1981年   363篇
  1980年   297篇
  1979年   323篇
  1978年   281篇
  1977年   233篇
  1975年   229篇
  1974年   251篇
  1973年   240篇
  1972年   247篇
  1971年   215篇
排序方式: 共有10000条查询结果,搜索用时 8 毫秒
401.
402.
403.
Dimock  R. V.  Groves  K. H. 《Marine Biology》1975,33(4):301-308
Marine Biology - The combined effects of temperature and salinity on the rate of oxygen consuption by the estuarine crab Panopeus herbstii Milne-Edwards (Crustacea: Decapoda: Xanthidae) were...  相似文献   
404.
405.
In the UK for the period 1994-99, a broad range of environmental projects were given financial support through the European Agriculture Guidance and Guarantee Fund under the Objective 1 and Objective 5b programmes. This paper is concerned with the ex-post evaluation of these projects set within a Sustainable Development framework. The aim was to identify project types or characteristics that offered the greatest return on investment. A classification of six broad project types was adopted. The evaluation revealed that there were significant differences between individual projects with respect to the type and scale, and temporal and social distribution of the benefits they delivered. In particular, as well as delivering environmental and economic benefits, many projects made a significant contribution to the development of human and social capital. The paper concludes that it is possible to improve the basis for future project selection in order to maximise the returns on environmental investments in the context of sustainable development.  相似文献   
406.
The small-scale gold and diamonds mining industry is of great importance to Ghana. Since its regularization in 1989 the sector has produced and sold over 1.5 million troy ounces of gold and 8.0 million carats of diamonds. During the same period the sector also provided direct employment to over 100,000 people and improved the socioeconomic life of many individuals and communities. However, these were largely achieved at a cost to the environment in areas where mining is carried out and there is the need to develop the industry in a sustainable manner. This paper looks at the developments in the small-scale gold and diamonds mining industry in Ghana and proposes some strategies on how the concepts of sustainable development could be applied to the industry.  相似文献   
407.
408.
409.
Laboratory column experiments run for up to 13 days compared air sparging of groundwater contaminated by dissolved petroleum hydrocarbons in sterile and non-sterile aquifer sediments as well as uncontaminated sediments and groundwater. Loss of dissolved BTEX compounds in the contaminated columns was very rapid, occurring through volatilisation. The majority of the dissolved total organic carbon (TOC) persisted for much longer periods however. A direct comparison between losses from sterile and non-sterile columns suggested a negligible contribution of biodegradation to the removal of TOC. This was difficult to confirm through examination of O2 utilisation because oxidation of a small amount of reduced sulphur in the aquifer materials was the dominant sink for O2. Despite this, it was possible to conclude that less than 22% of the removal of TOC was through biodegradation during the first three days of air sparging.  相似文献   
410.
The UK National Air Quality Strategy has required local authorities to review and assess air quality in their area of jurisdiction and determine locations in their areas where concentrations of specific air quality pollutants are predicted to exceed national air quality objectives in the future. Statutory air quality management areas (AQMAs) are designated where air quality is predicted to be above specified objective concentrations by specific target dates, and statutory air quality action plans will be necessary to improve the local air quality within these areas. Over 124 local authorities in England (including London), Wales and Scotland anticipate declaring AQMAs following the conclusion of the statutory air quality review and assessment process. However, other influences are being exerted on the local air quality management process and AQMA decision-making processes. Such influences include regional and sub- regional collaborative working between local authorities and government agencies and wider political decision-making processes. Some regions of Great Britain (encompassing England (including London), Scotland and Wales) anticipate many AQMA designations, whilst other regions are not anticipating any such designations despite apparently similar air quality circumstances. Evidence for regional or sub-regional variations in the locations of anticipated AQMAs are examined through an evaluation of the outcomes of the scientific review and assessment process undertaken by local authorities declaring AQMAs, and through a local authority survey to identify influences on decision-making processes at a level above that of the local authority. Regional variation is reported in the type of pollutant causing AQMAs to be declared, in the numbers of AQMAs in regions and in the spatial distribution of AQMAs across Great Britain.  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