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   15691篇
  免费   158篇
  国内免费   126篇
安全科学   388篇
废物处理   670篇
环保管理   1811篇
综合类   2582篇
基础理论   4329篇
环境理论   4篇
污染及防治   4068篇
评价与监测   1066篇
社会与环境   964篇
灾害及防治   93篇
  2022年   126篇
  2021年   108篇
  2020年   101篇
  2019年   107篇
  2018年   199篇
  2017年   234篇
  2016年   328篇
  2015年   269篇
  2014年   459篇
  2013年   1210篇
  2012年   495篇
  2011年   703篇
  2010年   615篇
  2009年   586篇
  2008年   676篇
  2007年   722篇
  2006年   595篇
  2005年   520篇
  2004年   531篇
  2003年   513篇
  2002年   498篇
  2001年   651篇
  2000年   477篇
  1999年   256篇
  1998年   175篇
  1997年   208篇
  1996年   206篇
  1995年   238篇
  1994年   235篇
  1993年   182篇
  1992年   200篇
  1991年   184篇
  1990年   203篇
  1989年   187篇
  1988年   154篇
  1987年   165篇
  1986年   154篇
  1985年   161篇
  1984年   149篇
  1983年   143篇
  1982年   126篇
  1981年   121篇
  1980年   115篇
  1979年   126篇
  1978年   101篇
  1977年   114篇
  1975年   87篇
  1974年   87篇
  1973年   96篇
  1972年   86篇
排序方式: 共有10000条查询结果,搜索用时 593 毫秒
141.
The paper focuses upon the organization of a federal state-funded pollution prevention project in the Styrian industry. The project includes 13 companies from the textile, pulp and paper, machine building, wood working and printed circuit board manufacturing industries, covering most of the sectors and sizes in the Styrian industry. It started in January 1994 and will last for one year. It will demonstrate the possibilities of pollution prevention and the need for further research work. This project will make use of the methods and tools that were refined in the Austrian Prepare project. As a first step, a systematic balance of all the inputs and outputs of a company is made, after which the weak points and inefficiencies of material and energy use are identified and the options for improvements, both economical and ecological, are defined. Consequently, modifications in products and production lead to a situation with less waste and emissions. The preliminary lessons from these projects are presented: as a rule, the utilities (consumption of process materials and water, cleaning, energy, preparatory and finishing steps) are treated as black boxes and usually represent a considerable optimization potential. In these areas especially there is usually a lack of information and coordination as well as a need for a systematic and comprehensive approach. Leadership in the company and creative consultants are needed for starting lasting successful pollution prevention projects.  相似文献   
142.
The 57-MW high-flux reactor of the Institute Max von Laue-Paul Langevin at Grenoble serves as a central neutron-beam facility for laboratories and research institutes in the three member countries, the United Kingdom, France, and the Federal Republic of Germany. The heavy-water-moderated and -cooled reactor is equipped with hot, thermal, and cold moderators, providing neutrons with high intensity over an unusual wide range of energies (wavelengths) extending from some 0.1 meV (30 Å) up to some 500 meV (0.4 Å). An extensive system of neutron guides with different curvatures permits the transport of neutrons over distances ranging up to 140 m with minimal intensity losses for neutrons in the useful wavelength band. The transmitted beams, in addition, exhibit very low background contamination by fast and epithermal neutrons, and γ-radiation. A large variety of high-resolution neutron spectrometers provide unique opportunities in fields such as nuclear physics, crystallography, solid-state physics, chemistry, metallurgy, and biology.  相似文献   
143.
The distribution of actinomycetes in oil contaminated sandy loam ultisols of the Niger Delta region of Nigeria was studied to aid in understanding the effect of hydrocarbons on indigenous microbial population in tropical soils. The average total counts of actinomycetes in all the oil samples analysed was 103 cfu/g. Higher counts of actinomycetes were observed during the dry season than during the wet season. The counts of hydrocarbonoclastic actinomycetes correlated positively with the total count of actinomycetes.The actinomycetes were generally restricted to the top soil(0-10 cm soil depth) although a seemingly deeper(down to 40 cm soil depth) distribution was noticed in the dry season. The isolates included oil degrading species of Actinoplanes, Norcadia,Streptomyces and Streptosporangium. Their high oil utilization ability indicates their positive potential and role in the bioremediation of oil-spilled soils.  相似文献   
144.
145.
146.
147.
148.
149.
150.
Seleniummetabolisminanimalsandhumans¥P.D.Whanger(DepartmentofAgriculturalChemistry,OregonUniversity,Oregon97331-7301,USA)Abst...  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