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   547篇
  免费   3篇
  国内免费   5篇
安全科学   1篇
废物处理   10篇
环保管理   25篇
综合类   301篇
基础理论   87篇
污染及防治   97篇
评价与监测   21篇
社会与环境   12篇
灾害及防治   1篇
  2018年   5篇
  2017年   8篇
  2016年   11篇
  2015年   8篇
  2013年   17篇
  2012年   8篇
  2011年   21篇
  2010年   13篇
  2009年   15篇
  2008年   20篇
  2007年   18篇
  2006年   6篇
  2005年   13篇
  2004年   14篇
  2003年   15篇
  2002年   12篇
  2001年   7篇
  1999年   12篇
  1998年   14篇
  1997年   7篇
  1996年   6篇
  1995年   7篇
  1994年   6篇
  1993年   5篇
  1975年   5篇
  1973年   6篇
  1972年   5篇
  1970年   8篇
  1967年   8篇
  1966年   4篇
  1965年   11篇
  1964年   4篇
  1963年   13篇
  1962年   10篇
  1961年   9篇
  1960年   10篇
  1959年   13篇
  1958年   9篇
  1957年   7篇
  1956年   9篇
  1955年   7篇
  1954年   5篇
  1953年   6篇
  1952年   5篇
  1951年   4篇
  1938年   4篇
  1930年   4篇
  1926年   6篇
  1914年   6篇
  1913年   10篇
排序方式: 共有555条查询结果,搜索用时 546 毫秒
351.
352.
353.
354.
355.
This paper discusses the discrepancy of attitude and behaviour in an environmental protection from the point of view of philosophy. Coming from the classical thesis of moral philosophy, that someone who infringes the ‘good’ has no secure knowledge, it examines how ethical arguments can contribute to get such a knowledge. The result of this study is that the logical power of persuasion alone is not able to acquire such a knowledge; and in order to obtain practical efficiency, ethical arguments should converse to emotional stratifications of personality. Based on the examination of positive feelings for nature, the paper discusses how this can happen.  相似文献   
356.
Efforts to reduce the energy needs to heat or cool dwellings have the potential to create new health hazards. Increases in indoor levels of radon and its progeny from the reduction in air exchange rates add a substantial radioactive burden to the general population. Other indoor pollutants reaching critical concentrations in homes with low air exchange rates are CO and NO2 from unvented combustion in gas stoves and heaters, tobacco smoke, and asbestos fibers. In addition, insulation materials and certain types of furniture may contribute the toxicant formaldehyde diffusing from foam injected walls or chipboard. Risk estimations using linear dose-response relationships show risk factors per kWh saved which are orders of magnitude greater than for a kWh produced by large power plants using coal, oil, gas, or uranium.  相似文献   
357.
ABSTRACT: Pesticide runoff from dormant sprayed orchards is a major water quality problem in California's Central Valley. During the past several years, diazinon levels in the Sacramento and San Joaquin Rivers have exceeded water quality criteria for aquatic organisms. Orchard water management, via post‐application irrigation, and infiltration enhancement, through the use of a vegetative ground cover, are management practices that are believed to reduce pesticide loading to surface waters. Field experiments were conducted in Davis, California, to measure the effectiveness of these management practices in reducing the toxicity of storm water runoff. Treatments using a vegetative ground cover significantly reduced peak concentrations and cumulative pesticide mass in runoff for first flush experiments compared with bare soil treatments. Post‐application irrigation was found to be an effective means of reducing peak concentrations and cumulative mass in runoff from bare soil treatments, but showed no significant effect on vegetated treatments.  相似文献   
358.
On April 23, 1988, approximately 9,500 barrels (400,000 gallons) of San Joaquin Valley crude oil leaked from an aboveground storage tank at Shell Oil Company's Martinez Manufacturing Complex in Martinez, California and entered Suisun Bay, an important recreation area. This article describes the remediation techniques Shell used to protect and clean up the Bay's oiled marshes, sloughs, rocky shores, marinas, and sandy beaches, and discusses the main methods of oil spill response, site-specific factors that must be considered in choosing remediation techniques, the interaction between Shell and government agencies, and the costs associated with the spill. The cleanup's total cost was approximately $8.3 million, which did not include private claims and claims handling costs; Shell also signed a separate consent decree for $19.75 million with the state of California and the federal government. This spill and its aftermath emphasize the need for preparation that facilitates response actions, improves the chances for cooperation between responsible parties and government agencies, minimizes the time needed for remediation, lowers cleanup costs, and limits natural resource damage claims and penalties.  相似文献   
359.
Summary. The first identification of a sex pheromone of a pine sawfly (Hymenoptera, Diprionidae) dates back almost thirty years. Since then, female-produced pheromones of over twenty diprionid species have been investigated by solvent extraction followed by separation and identification. However, no study has shown what the females actually release. Collection of airborne compounds using absorbtion on charcoal filter as well as solid phase microextraction (SPME) followed by analysis employing gas chromatography combined with mass spectrometry (GC-MS), revealed an unusual system in Diprion pini, in which the pheromone precursor alcohol, 3,7-dimethyl-2-tridecanol, is released together with acetic, propionic, butyric and isobutyric acids. The corresponding acetate, propionate and butyrate esters of 3,7-dimethyl-2-tridecanol were also found in the samples. All esters were electrophysiologically active, and the propionate and isobutyrate were attractive in trapping experiments. Based on these and earlier reported results, it seems that at least in part of its range, the pheromone response of D. pini is not very specific with regard to the functional group, as long as this is an ester.  相似文献   
360.
B. Werner 《Marine Biology》1973,18(3):212-217
New observations on the complete life cycle of Tripedalia cystophora Conant have revealed that—because of the radialsymmetrically constructed body of the polyp and its complete metamorphosis into one medusa—the “Cubozoa” are unique in their development, systematics and evolution. the same is true for the sexual biology of their medusae. It has long been known that the female T. cystophora are larviparous; fertilized eggs develop within the gastral pockets into free-swimming planulae. How do spermatozoa approach the eggs inside the female? In laboratory cultures, young medusae could be raised to maturity. Rearing experiments and observations yielded surprising results, revealing a situation which is new for Cnidaria. In T. cystophora, ripe medusae of both sexes can be identified easily by the different colour and structure of the gonads. In the gonads of the ripe male, numerous spermatozoa are joined to form spermatozeugmata of a simple type. Numerous spermatozeugmata form big globular bodies (spermatophores), which develop in small grooves on the inside surface of the stomach. The spermatophores are transferred directly from the male to the female during successive steps of special mating behaviour. The observations confirm that Cubomedusae have reached the peak of medusan specialization.  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