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   302篇
  免费   1篇
  国内免费   2篇
安全科学   1篇
废物处理   5篇
环保管理   25篇
综合类   144篇
基础理论   49篇
污染及防治   63篇
评价与监测   15篇
社会与环境   3篇
  2016年   4篇
  2014年   3篇
  2013年   6篇
  2012年   5篇
  2011年   5篇
  2010年   9篇
  2009年   12篇
  2008年   5篇
  2007年   7篇
  2006年   12篇
  2005年   14篇
  2004年   3篇
  2003年   5篇
  2002年   5篇
  2001年   3篇
  2000年   3篇
  1999年   9篇
  1998年   4篇
  1997年   6篇
  1996年   9篇
  1995年   7篇
  1994年   9篇
  1993年   6篇
  1991年   4篇
  1990年   3篇
  1989年   3篇
  1985年   4篇
  1984年   4篇
  1981年   3篇
  1980年   3篇
  1979年   3篇
  1970年   4篇
  1967年   3篇
  1966年   3篇
  1965年   5篇
  1962年   6篇
  1961年   7篇
  1960年   8篇
  1959年   8篇
  1958年   5篇
  1957年   5篇
  1956年   8篇
  1955年   6篇
  1954年   5篇
  1953年   7篇
  1951年   4篇
  1947年   3篇
  1941年   3篇
  1934年   2篇
  1931年   2篇
排序方式: 共有305条查询结果,搜索用时 0 毫秒
71.
72.

Goal and Scope

Which impact does the use of non-energetic abiotic resources (ores, minerals, etc.) have in life cycles of energy systems based on biogenic and fossil fuels? Is this kind of resource use less or more environmentally harmful than the utilisation of energetic abiotic resources (mineral oil, natural gas, etc.) in the same life cycles? This paper aims at answering these questions. In Part 1, a methodology is presented and applied to the life cycles of selected energy systems. Part 2 presents and discusses the results.

Method

This study looks at the complete life cycles of selected energy systems. The methodology used bases on the state-of-the-art of life cycle assessment (LCA) methodology. For the assessment of energetic abiotic resource use, a widely recognised method can be used. For the assessment of non-energetic abiotic resource use, no overall recognised methodological approach exists. That is why for this aspect two different methods are exemplarily applied and compared with each other.

Results and Conclusion

Results will be presented and discussed in Part 2.

Recommendation and Perspective

Recommendation and conclusions will be derived from study results in Part 2.  相似文献   
73.
Our objective was to determine if ground foraging passerines in a woodland surrounding a trap and skeet range were subject to lead poisoning. Lead availability to birds was determined by shot counts and soil and earthworm analysis. Avian exposure to lead was identified by measuring free-erythrocyte protoporphyrin levels in blood and lead in tissues of three passerine species. Results showed that most shot were found in the top 3 cm of soil. Lead measurements ranged from 110 to 27,000 ppm (dry wt) in soil and were 660 and 840 ppm in earthworms. Sparrows held in an aviary at the range (p=0.02) and free-flying juncos (p=0.0005) mist-netted at the range displayed significantly higher protoporphyrin levels than those at an uncontaminated site. Sparrow and cowbird carcasses from the aviary carried 37 and 39 ppm lead (dry wt), respectively, whereas a junco liver contained 9.3 ppm lead.  相似文献   
74.
The abundances of rarer trace elements in paddy (rice) soils of Sri Lanka   总被引:1,自引:0,他引:1  
Concentrations of Ti, Ga, As, Sc, Zr, Sn, Hf, Th, U and Y have been determined for 70 paddy soils from 14 villages, selected throughout Sri Lanka by means of ICP-MS. The mean elemental contents of all paddy soil samples were 6120 Ti, 14.1 Ga, 0.84 As, 7.26 Sc, 129 Zr, 2.27 Sn, 3.64 Hf, 12.71 Th, 1.53 U, and 13.35 Y (all data in microg/g). Paddy soils were classified into groups based on morphology and climate. Higher contents of Th and U were found in the wet zone lowland soils whereas the higher Ti contents were observed in dry zone soils. Arsenic, Zr and Hf contents were comparatively similar in all regions. Factor analysis was used to identify the relationships between the contents of elements.  相似文献   
75.
Biological dehalogenation and halogenation reactions   总被引:5,自引:0,他引:5  
A large number of halogenated compounds is produced by chemical synthesis. Some of these compounds are very toxic and cause enormous problems to human health and to the environment. Investigations on the degradation of halocompounds by microorganisms have led to the detection of various dehalogenating enzymes catalyzing the removal of halogen atoms under aerobic and anaerobic conditions involving different mechanisms. On the other hand, more than 3500 halocompounds are known to be produced biologically, some of them in great amounts. Until 1997, only haloperoxidases were thought to be responsible for incorporation of halogen atoms into organic compounds. However, recent investigations into the biosynthesis of halogenated metabolites by bacteria have shown that a novel type of halogenating enzymes, FADH(2)-dependent halogenases, are involved in biosyntheses of halogenated metabolites. In every gene cluster coding for the biosynthesis of a halogenated metabolite, isolated so far, one or several genes for FADH(2)-dependent halogenases have been identified.  相似文献   
76.
77.
A long-term sampling method for PCDF/D in emissions from combustion facilities is presented. The sampling of PCDF/D was performed over a four week period. The results are compared to results of four one-week measurements.  相似文献   
78.
This paper analyzes the effect of introducing a fuel tax in some countries, but not all, when the world fuel market is monopolistic. Based on the observation that price discrimination becomes possible in these circumstances, it is shown that the fuel price in countries not levying the tax may increase, in contrast to common views.  相似文献   
79.
Chapter 36 from the Agenda 21 which was held at the Conference for the Environment and Development in 1992 provides suggestions for ?promoting education, public awareness and training“ and important contributions for continuing developments in the universities. The goals which have been mentioned here can only be realized on a long-term basis. A work group at the University in Furtwangen has concentrated on the adaptation of this theme since 1991. After five years, it is now possible to draw a provisional balance: The disciplines of the environment, technology, law and ecology are bound together through a reformed course of studies in the field of process engineering. The certification based upon the EC eco-auditing ordinance offers new prospects for increasing the integration of environmental aspects on a broad basis into the routine university life. The establishment of a regional environmental center provides a possibility for the exchange of knowledge as a joint venture.  相似文献   
80.
Solid waste residues from municipal solid waste incinerator flue gas cleaning systems basically consists of Al, Ca-silicates and metal oxides. At lower concentrations, environmentally harmful compounds such as alkali halide salts, heavy metals and traces of organic pollutants, e.g. PCDD, PCDF and PCB, are also present. For the reuse of the valuable materials (Al, Ca and metal oxides), an effective treatment technique for destroying the organic contaminants and separating the anorganic toxins from the non-toxic components has to be applied, which can only be achieved through thermal processing. Detailed investigations on vitrified electrostatic precipitator ash from municipal solid waste incinerator plants have shown promising results in regard to the mass balances, the chemical composition and the quality of the glass phase obtained.  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