全文获取类型
收费全文 | 4862篇 |
免费 | 41篇 |
国内免费 | 15篇 |
专业分类
安全科学 | 99篇 |
废物处理 | 323篇 |
环保管理 | 347篇 |
综合类 | 553篇 |
基础理论 | 1021篇 |
环境理论 | 7篇 |
污染及防治 | 1761篇 |
评价与监测 | 461篇 |
社会与环境 | 333篇 |
灾害及防治 | 13篇 |
出版年
2023年 | 57篇 |
2022年 | 114篇 |
2021年 | 172篇 |
2020年 | 72篇 |
2019年 | 73篇 |
2018年 | 174篇 |
2017年 | 175篇 |
2016年 | 261篇 |
2015年 | 147篇 |
2014年 | 273篇 |
2013年 | 474篇 |
2012年 | 316篇 |
2011年 | 356篇 |
2010年 | 240篇 |
2009年 | 176篇 |
2008年 | 291篇 |
2007年 | 325篇 |
2006年 | 228篇 |
2005年 | 189篇 |
2004年 | 138篇 |
2003年 | 111篇 |
2002年 | 115篇 |
2001年 | 71篇 |
2000年 | 49篇 |
1999年 | 36篇 |
1998年 | 18篇 |
1997年 | 17篇 |
1996年 | 13篇 |
1995年 | 27篇 |
1994年 | 14篇 |
1993年 | 14篇 |
1992年 | 7篇 |
1991年 | 9篇 |
1990年 | 13篇 |
1989年 | 3篇 |
1988年 | 8篇 |
1987年 | 3篇 |
1983年 | 3篇 |
1967年 | 8篇 |
1966年 | 6篇 |
1965年 | 3篇 |
1964年 | 13篇 |
1963年 | 8篇 |
1962年 | 10篇 |
1960年 | 6篇 |
1959年 | 6篇 |
1958年 | 23篇 |
1957年 | 8篇 |
1956年 | 5篇 |
1955年 | 4篇 |
排序方式: 共有4918条查询结果,搜索用时 15 毫秒
991.
Quantitative alterations in the structure of the digestive cell of Littorina littorea on exposure to cadmium 总被引:3,自引:0,他引:3
The effects of sublethal concentrations of cadmium (Cd) on the morphology of the digestive gland of the periwinkle Littorina littorea have been investigated using a planimetric procedure. Five planimetric parameters were recorded (mean epithelial thickness: MET; mean diverticular radius: MDR; mean luminal radius: MLR; MLR/MET and MET/MDR) and tested by diverse statistical methods. The results indicate that MET is depressed after long exposures at high Cd concentrations whilst MLR increases. Variations in MDR have been attributed to different conditions in the tissues surrounding digestive tubules, and are not-significant in relation to the treatment. However, certain increases might be significant due to the presence of parasites or hemocyte proliferation. The ratios MLR/MET and MET/MDR are highly sensitive, and can be expressed as statistical functions of metal concentration and exposure time. Combination of these five planimetric parameters is reliably indicative of the structural changes occurring in the digestive gland of molluscs under conditions of environmental stress. 相似文献
992.
Ortíz-Rodriguez Oscar Orlando Sonnemann Guido Villamizar-G Raquel A. 《Environment, Development and Sustainability》2022,24(3):3982-3999
Environment, Development and Sustainability - At a global level, it has been scientifically reported that the processes of water purification, management and disposal of wastewater, and solid waste... 相似文献
993.
Luis Antonio Bojórquez-Tapia Peter F. Ffolliott D. Phillip Guertin 《Environmental management》1990,14(3):317-324
The current Mexican environmental law provides the legal basis for comprehensive land-use planning. Under the law, development
of natural ecosystems must combine goals, policies, and practices towards the sustainable use of natural resources and the
protection of biological diversity. Thus, ecosystem manipulation must be able to counter fragmentation of natural ecosystems
and isolation of natural reserves, while providing for human needs. Assessment of the potential of natural ecosystems and
management impacts are required. Multiple-resource simulation is an assessment and land-use planning tool that permits managers
and decision makers to comply with the law, providing a flexible, user-oriented system that can meet the needs of managers,
conservationists, and researchers. A multiple-resource model and an example of how it can be applied to meet planning needs
is presented for discussion. 相似文献
994.
995.
996.
997.
998.
999.
1000.