全文获取类型
收费全文 | 613篇 |
免费 | 2篇 |
国内免费 | 6篇 |
专业分类
安全科学 | 4篇 |
废物处理 | 2篇 |
环保管理 | 18篇 |
综合类 | 367篇 |
基础理论 | 100篇 |
污染及防治 | 92篇 |
评价与监测 | 19篇 |
社会与环境 | 16篇 |
灾害及防治 | 3篇 |
出版年
2018年 | 9篇 |
2017年 | 9篇 |
2015年 | 9篇 |
2014年 | 8篇 |
2013年 | 22篇 |
2012年 | 11篇 |
2011年 | 13篇 |
2010年 | 17篇 |
2009年 | 15篇 |
2008年 | 15篇 |
2007年 | 18篇 |
2006年 | 10篇 |
2004年 | 7篇 |
2003年 | 8篇 |
2002年 | 11篇 |
2001年 | 11篇 |
2000年 | 7篇 |
1999年 | 19篇 |
1998年 | 6篇 |
1996年 | 7篇 |
1995年 | 6篇 |
1994年 | 6篇 |
1992年 | 6篇 |
1990年 | 6篇 |
1989年 | 7篇 |
1979年 | 7篇 |
1978年 | 7篇 |
1967年 | 6篇 |
1966年 | 8篇 |
1965年 | 7篇 |
1964年 | 8篇 |
1961年 | 9篇 |
1960年 | 6篇 |
1957年 | 6篇 |
1955年 | 7篇 |
1952年 | 6篇 |
1942年 | 6篇 |
1941年 | 9篇 |
1940年 | 9篇 |
1938年 | 6篇 |
1937年 | 12篇 |
1936年 | 10篇 |
1935年 | 9篇 |
1934年 | 11篇 |
1933年 | 7篇 |
1931年 | 7篇 |
1929年 | 8篇 |
1922年 | 6篇 |
1921年 | 7篇 |
1920年 | 5篇 |
排序方式: 共有621条查询结果,搜索用时 15 毫秒
231.
R. K. M. Jayanty J. R. Albritton Y. H. Straley D. J. von Lehmden 《Journal of the Air & Waste Management Association (1995)》2013,63(9):1198-1201
A repository of 39 and 34 gaseous organic compounds in compressed gas cylinders at PPM (5 to 700) and PPB levels (1 to 10,000) respectively has been established by EPA for use in performance audits. In this program, to ensure that the concentration of each gas standard has not changed, each standard is periodically analyzed for stability. The gas mixtures were initially analyzed once or twice by the manufacturer before shipment to Research Triangle Institute (RTI). The gas mixtures were then analyzed at RTI upon receipt from the gas manufacturer and then reanalyzed at 2, 6 and 12 months, and annually thereafter, to determine any change in concentration. An examination of the stability data shows that concentrations for all the organics tested usually varied by less than 10 percent over a period of several years. Ethylene oxide and propylene oxide and trans 1, 4-dichloro-2-butene below the 10 ppb level have been found to be unstable. Six other compounds at the PPM level (aniline, cyclohexanone, p-dichlorobenzene, ethylamine 1, 2-dibromoethylene, and formaldehyde) have been found to be unstable in compressed gas cylinders. 相似文献
232.
von Helversen O Heller KG Mayer F Nemeth A Volleth M Gombkötö P 《Die Naturwissenschaften》2001,88(5):217-223
The analysis of morphological, behavioural and genetic characters of whiskered bats revealed a new European bat species within the family Vespertilionidae. We describe the morphology, karyology, genetic similarity, ecology and distribution of Myotis alcathoe n. sp. It closely resembles Myotis mystacinus, Myotis brandtii and Myotis ikonnikovi in morphology, but all four species show clear genetic differences in two mitochondrial genes (ND1 and 12S rRNA). Myotis alcathoe n. sp. is the smallest species among the European whiskered bats and uses the highest-frequency echolocation calls of all the European Myotis species. It prefers to hunt in small valleys with deciduous trees and flowing water, which is an endangered habitat. Records from Greece and Hungary indicate a distribution range in south-eastern Europe. 相似文献
233.
Karl von Meyenn 《Die Naturwissenschaften》1982,69(12):564-573
The story of the discovery of the neutrino as is well known, has been distorted by a number of legends. The factual information now available from the Pauli Correspondence shows the neutrino so to speak, as a by-product of a much more comprehensive revision of the foundations of physics, to which end the efforts of several great theoreticians were directed in order to overcome the theoretical difficulties confronting nuclear physics at the beginning of the 1930's. The well known letter from Pauli to the “radioactive ladies and gentlemen” outlines merely the properties of a particle postulated by this theory. Had the complete theory been revealed these would have won little attention because of the inherent difficulties it still contained. Nevertheless the predicted qualities of this hypothetical particle corresponded exactly with observational data and allowed in addition the preservation of the tried and tested conservation laws. Accordingly an incomplete theory led to a fruitful development in physics. 相似文献
234.
235.
The authors identify problems of political, economic and social development in Mexico, which has now become a net oil exporter. Aspects of Mexican society are analysed - possession of resources, population growth, agricultural and industrial sectors of the economy and development policy. The political and economic components of social change and policy limitations are considered. It is clear that the severity of Mexico's development problems present serious issues for the current administration. 相似文献
236.
Gebhard von Jagow 《Die Naturwissenschaften》1979,66(11):539-546
The energy transformation systems of Halobacterium halobium, Vibrio succinogenes, chloroplasts and mitochondria are described on the basis of the chemiosmotic theory. Nature seems to utilize three quite different mechanisms for electrogenic proton transport. Structure and function of the ATP-synthetase complexes, however, seem to be quite similar in the various energy-conserving systems. 相似文献
237.
238.
239.
240.
Michael von Reinhardt 《Die Naturwissenschaften》1969,56(12):581-590