全文获取类型
收费全文 | 375篇 |
免费 | 5篇 |
国内免费 | 12篇 |
专业分类
安全科学 | 23篇 |
废物处理 | 17篇 |
环保管理 | 27篇 |
综合类 | 72篇 |
基础理论 | 85篇 |
污染及防治 | 114篇 |
评价与监测 | 32篇 |
社会与环境 | 19篇 |
灾害及防治 | 3篇 |
出版年
2023年 | 2篇 |
2022年 | 9篇 |
2021年 | 5篇 |
2020年 | 3篇 |
2019年 | 4篇 |
2018年 | 8篇 |
2017年 | 11篇 |
2016年 | 9篇 |
2015年 | 16篇 |
2014年 | 20篇 |
2013年 | 21篇 |
2012年 | 19篇 |
2011年 | 27篇 |
2010年 | 17篇 |
2009年 | 21篇 |
2008年 | 20篇 |
2007年 | 21篇 |
2006年 | 29篇 |
2005年 | 22篇 |
2004年 | 9篇 |
2003年 | 20篇 |
2002年 | 11篇 |
2001年 | 4篇 |
2000年 | 4篇 |
1999年 | 5篇 |
1998年 | 3篇 |
1997年 | 5篇 |
1995年 | 4篇 |
1994年 | 5篇 |
1990年 | 2篇 |
1987年 | 1篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1971年 | 2篇 |
1970年 | 2篇 |
1969年 | 1篇 |
1966年 | 1篇 |
1963年 | 1篇 |
1962年 | 1篇 |
1956年 | 1篇 |
1954年 | 1篇 |
1950年 | 1篇 |
1941年 | 1篇 |
1936年 | 1篇 |
排序方式: 共有392条查询结果,搜索用时 93 毫秒
361.
E. W. Backer W. Ehrfeld D. Münchmeyer H. Betz A. Heuberger S. Pongratz W. Glashauser H. J. Michel R. v. Siemens 《Die Naturwissenschaften》1982,69(11):520-523
X-ray lithography using synchrotron radiation has been applied in a multi-step process for the production of plastic moulds to be used in the fabrication of separation nozzles by electrodeposition. For characteristic dimensions of a few microns a total height of the nozzle structure of about 400 μm has been achieved. Structural details of about 0.1 μm are being reproduced across the total thickness of the polymer layer. The surface finish of metallic separation nozzles produced by electrodeposition was equivalent to the high quality of the polymer surface. The separation-nozzle systems fabricated by the described method allow an increase by a factor three of the gas pressure in separationnozzle plants as compared to the present standard. This results in considerable savings in the enrichment of 235U for nuclear power production. 相似文献
362.
Audrey Athlan Christian Braud Michel Vert 《Journal of Polymers and the Environment》1997,5(4):243-247
Oligomers of poly(3-hydroxybutyric acid) (P(3-HB)) were prepared by partial degradation of high molecular weight P(3-HB) dissolved
in 1,2-dichloroethane/water mixture in the presence of p-toluene sulfonic acid (p-TSA). The water-soluble fraction of the
resulting oligomers was extracted from the mixture with neutral sodium phosphate buffer. Capillary zone electrophoresis showed
that the aqueous extracts were composed of two series of oligomers. The first one was composed of one to seven P(3-HB) oligomers
(O(3-HB)). In contrast, the second series was composed of four oligomers characterized by the presence of a terminal C=C bond
[O’(3-HB)]. Both series of oligomers behaved differently insofar as their fate in aqueous medium was concerned. The 0(3-HB)
compounds were stable over a period of 2 months. On the other hand, the population of the O’(3-HB) oligomers varied, the proportion
of oligomers increasing with aging time. 相似文献
363.
The FAIR model: A tool to analyse environmental and costs implications of regimes of future commitments 总被引:1,自引:0,他引:1
Michel?G.?J.?den?ElzenEmail author Paul?L.?Lucas 《Environmental Modeling and Assessment》2005,10(2):115-134
This article describes the policy decision-support tool, FAIR, to assess the environmental and abatement costs implications of international regimes for differentiation of future commitments. The model links long-term climate targets and global reduction objectives with regional emission allowances and abatement costs, accounting for the Kyoto Mechanisms used. FAIR consists of three sub-models: a simple climate model, an emission-allocation model and a cost model. The article also analyses ten different rule-based emission allocation schemes for two long-term concentration stabilisation targets for greenhouse gases. This analysis shows that evaluating regimes requires not only an assessment of the initial allocation, but also of the distribution of abatement costs and the impacts from emissions trading. The Multi-Stage approach (with a gradual increase of Parties adopting emission intensity or reductions targets) and the Triptych approach (with sectoral targets for all Parties) seem to provide the best prospects for most of the Parties when compared to the other allocation schemes analysed. 相似文献
364.
Gray PA Duwors E Villeneuve M Boyd S Legg D 《Environmental monitoring and assessment》2003,86(1-2):129-147
In recognition of the many values that people ascribe to nature, federal, provincial, and territorial agencies worked inpartnership to complete the 'Survey on the Importance of Natureto Canadians' (SINC) in 1981, 1987, 1991, and 1996. Between 1981 and 1996, more than 80% of Canadians 15 years of age and older engaged in one or more nature-related activities. This paper describes the evolution of this cooperative monitoring program, defines a classification system as a context for the values examined by the SINC, highlights trends of some nature-related recreational activities measured by the survey, and comments onthe importance of this information to Canadians. 相似文献
365.
Jean-François Fruget Michel Centofanti Jean-Michel Olivier 《Environmental management》1998,22(1):129-144
/ The part of the Doubs River between Montbeliard and Dole (France), i.e., downstream from the confluence with the Allan River, will be affected by the Rhine- Rhone connection project. In order to improve the understanding of the Doubs ichthyofauna, aquatic environments of the Doubs were sampled by electrofishing. Fish diversity and the presence of some rheophilic species demonstrated the good ecological quality of some stretches of the Doubs. This quality was due to alternating areas with very diversified aquatic environments (riffles, islands and side-arms, backwaters) and a considerable range of flow velocities. The differences in the structure of the fish communities of the different types of aquatic environments were more qualitative (fish species) than quantitative (number of species and number of fish). However, the mean number of fish was statistically lower in the canals (Freycinet canal and channelized part of the Allan River) than in the main course and in the backwaters. The natural parts of the Doubs (unnavigable reaches) showed the most diversified environmental structure and had the most rheophilic fish communities. Thus, the rheophilic species were well represented, but they proved also the most vulnerable to river regulation. However, the most abundant fishes throughout the Doubs River were generalists with no special requirements for food sources or spawning substrate.KEY WORDS: Fish communities; Regulation; Restoration; Floodplain; Large ship canal; Doubs River 相似文献
366.
367.
368.
Xiang Li Yingying Liu Athanasia C. Tzika Qian Zhu Karine Van Doninck Michel C. Milinkovitch 《Marine Biology》2011,158(8):1791-1804
The existence of three distinct populations is widely accepted for the finless porpoise (Neophocaena phocaenoides) in Chinese waters: the Yellow Sea, Yangtze River, and South China Sea populations. Here, we use nine species-specific microsatellite
loci, the complete mitochondrial DNA control region (912 bp), and the complete mitochondrial cytochrome b gene (1,140 bp)
to further investigate potential population stratification in the Yellow Sea using 147 finless porpoise samples from the Bohai
Sea and adjacent northern Yellow Sea, two regions that were largely underrepresented in previous genetic studies. Our F-statistics analyses confirm the previously described three populations, but further demonstrate significant genetic differentiation
between the [Bohai + northern Yellow] Sea and the southern Yellow Sea. On the other hand, median-joining network analyses
do not exhibit well-differentiated haplotype groups among different geographic populations, suggesting the existence of shared
ancestral haplotypes. Levels of microsatellite diversity are moderate to high (mean H
E = 0.794) among the 147 [Bohai + northern Yellow] Sea finless porpoises and no recent bottleneck was detected, whereas mtDNA
control region and cytochrome b gene diversity is low to moderate. The microsatellite genotypic and mtDNA haplotypic data
also confirm the presence of mother-calf pairs in single-net bycatch cases. The results presented here highlight the necessity
to treat the [Bohai + northern Yellow] Sea population (highly impacted by anthropogenic threats) as a separate Management
Unit. 相似文献
369.
Small societies of totipotent individuals are good systems in which to study the costs and benefits of group living that are central to the origin and maintenance of eusociality. For instance, in eusocial halictid bees, some females remain in their natal nest to help rear the next brood. Why do helpers stay in the nest? Do they really help, and if yes, is their contribution large enough to voluntarily forfeit direct reproduction? Here, we estimate the impact of helpers on colony survival and productivity in the sweat bee Halictus scabiosae. The number of helpers was positively associated with colony survival and productivity. Colonies from which we experimentally removed one helper produced significantly fewer offspring. However, the effect of helper removal was very small, on average. From the removal experiment, we estimated that one helper increased colony productivity by 0.72 additional offspring in colonies with one to three helpers, while the increase was smaller and not statistically significant in larger colonies. We conclude that helpers do actually help in this primitively eusocial bee, particularly in small colonies. However, the resulting increase in colony productivity is low, which suggests that helpers may be constrained in their role or may attempt to reproduce. 相似文献
370.
André L. F. Cançado Cibele Q. da-Silva Michel F. da Silva 《Environmental and Ecological Statistics》2014,21(4):627-650
The scan statistic is widely used in spatial cluster detection applications of inhomogeneous Poisson processes. However, real data may present substantial departure from the underlying Poisson process. One of the possible departures has to do with zero excess. Some studies point out that when applied to data with excess zeros, the spatial scan statistic may produce biased inferences. In this work, we develop a closed-form scan statistic for cluster detection of spatial zero-inflated count data. We apply our methodology to simulated and real data. Our simulations revealed that the Scan-Poisson statistic steadily deteriorates as the number of zeros increases, producing biased inferences. On the other hand, our proposed Scan-ZIP and Scan-ZIP+EM statistics are, most of the time, either superior or comparable to the Scan-Poisson statistic. 相似文献