全文获取类型
收费全文 | 2687篇 |
免费 | 29篇 |
国内免费 | 31篇 |
专业分类
安全科学 | 68篇 |
废物处理 | 107篇 |
环保管理 | 298篇 |
综合类 | 534篇 |
基础理论 | 592篇 |
环境理论 | 1篇 |
污染及防治 | 806篇 |
评价与监测 | 165篇 |
社会与环境 | 159篇 |
灾害及防治 | 17篇 |
出版年
2023年 | 26篇 |
2022年 | 32篇 |
2021年 | 45篇 |
2020年 | 31篇 |
2019年 | 40篇 |
2018年 | 78篇 |
2017年 | 82篇 |
2016年 | 98篇 |
2015年 | 86篇 |
2014年 | 112篇 |
2013年 | 140篇 |
2012年 | 130篇 |
2011年 | 190篇 |
2010年 | 151篇 |
2009年 | 172篇 |
2008年 | 148篇 |
2007年 | 157篇 |
2006年 | 115篇 |
2005年 | 89篇 |
2004年 | 107篇 |
2003年 | 70篇 |
2002年 | 82篇 |
2001年 | 77篇 |
2000年 | 49篇 |
1999年 | 21篇 |
1998年 | 22篇 |
1997年 | 31篇 |
1996年 | 25篇 |
1995年 | 33篇 |
1994年 | 26篇 |
1993年 | 11篇 |
1992年 | 20篇 |
1991年 | 30篇 |
1990年 | 16篇 |
1989年 | 20篇 |
1988年 | 8篇 |
1985年 | 5篇 |
1984年 | 8篇 |
1982年 | 13篇 |
1981年 | 10篇 |
1980年 | 5篇 |
1979年 | 11篇 |
1970年 | 10篇 |
1968年 | 5篇 |
1967年 | 5篇 |
1966年 | 5篇 |
1965年 | 8篇 |
1964年 | 5篇 |
1960年 | 6篇 |
1956年 | 5篇 |
排序方式: 共有2747条查询结果,搜索用时 156 毫秒
1.
Regional Environmental Change - The rapid environmental changes currently underway in many dry regions of the world, and the deep uncertainty about their consequences, underscore a critical... 相似文献
2.
3.
4.
5.
Rocío Mariano-Jelicich Florencia Botto Paulina Martinetto Oscar Iribarne Marco Favero 《Marine Biology》2008,155(4):443-450
The degree of individual or gender variation when exploiting food resources is an important aspect in the study of foraging
ecology within a population. Previous information on non-breeding skimmers obtained through conventional methodologies suggested
sex-related differences in prey species. In this study, stable isotope techniques were used to investigate the intraspecific
segregation in diet and foraging habits of the Black Skimmer (Rynchops niger intercedens) at Mar Chiquita Coastal Lagoon (37°40′S, 57°22′W), Argentina. These results were compared with contemporary data on the
trophic composition obtained by conventional methodologies. Blood samples were taken from birds captured with mist-nets during
their non-breeding season. The isotopic signatures of skimmers showed a diet mainly composed of marine prey with some degree
of estuarine fish intake. When comparing diet between sexes, males showed enrichment in 15N compared to females, while no differences were observed in 13C. The use of mixing models revealed differences in the relative composition of prey in the diet of male and female skimmers.
This study highlights stable isotope analysis as a valuable tool to test inter-individual differences and sexual segregation
in trophic ecology of Black Skimmers as compared to conventional methodologies. The results show a trophic segregation in
the Black Skimmer during the non-breeding season that can be explained by differences in prey species and larger prey sizes
of male skimmers. Our findings have significant implications for conservation since any environmental change occurring at
wintering areas might have profound effects on several avian life-history traits, and could be different for males and females
due to trophic segregation. 相似文献
6.
In areas of war and armed conflict it is difficult to get trustworthy and coherent information. Civil society and human rights groups often face problems of dealing with fragmented witness reports, disinformation of war propaganda, and difficult direct access to these areas. Turkish Kurdistan was used as a case study of armed conflict to evaluate the potential use of satellite images for verification of witness reports collected by human rights groups. The Turkish army was reported to be burning forests, fields and villages as a strategy in the conflict against guerrilla uprising. This paper concludes that satellite images are useful to validate witness reports of forest fires. Even though the use of this technology for human rights groups will depend on some feasibility factors such as prices, access and expertise, the images proved to be key for analysis of spatial aspects of conflict and valuable for reconstructing a more trustworthy picture. 相似文献
7.
8.
Amphibian metamorphosis assays are used to evaluate potential effects of endocrine disrupting compounds on the thyroid hormone axis. In this study, Xenopus laevis tadpoles are kept in a solution of 0.2% thiourea (TU) to arrest and synchronise them in their development. The advantage of this synchronized amphibian metamorphosis assays is that synchronised tadpoles are available at any time to start metamorphosis experiments, and experimental groups are much more homogenous at the start of experimental exposure compared with groups selected from an untreated pool of animals. The water volume per animal was kept constant throughout the experimental period to overcome the influence of declining numbers of animals per aquarium due to metamorphosis and mortality on the density dependent development of the remaining tadpoles. Clophen A50 (a technical PCB mixture), the single congener 3,3',4,4'-tetrachlorobiphenyl (PCB 77) and apolar sediment extracts that were previously tested positive in the T-Screen, an in vitro proliferation assay for thyroid hormone disruption, were tested in the Synchronized Amphibian Metamorphosis Assay. Endpoints studied were mortality, malformations, body weight, and percentage of metamorphosed froglets at the end of the 60-day experimental period, percentage of tadpoles in different developmental stages, and developmental stage-dependent awarded penalty points. Dietary exposure to Clophen A50 (0.2-50mg/kg food) resulted in a significant increased percentage of tadpoles that did not pass metamorphosis at concentrations higher than 2mg/kg food. Time until metamorphosis in those animals that were able to metamorphose after the 60-days experimental period was significantly decreased. Dietary exposure to PCB 77, a congener that can be readily metabolised, did not result in significant effects in any exposure group (2-500 microg/kg food). Apolar sediment extracts from two of the three sites that are contaminated with a wide variety of chemicals significantly decreased the percentage of metamorphosed animals and significantly increased the number of tadpoles that remained in early and late metamorphic stages. These effects already occurred when the extracts where diluted more than 1000 times (on an organic carbon base) compared to environmental concentrations. The rank of potency was comparable to results obtained with the T-screen. This suggests the presence of thyroid hormone disrupting compounds in the aquatic environment and possible effects of such compounds on animal development in the wild. 相似文献
9.
10.