全文获取类型
收费全文 | 4691篇 |
免费 | 96篇 |
国内免费 | 73篇 |
专业分类
安全科学 | 213篇 |
废物处理 | 233篇 |
环保管理 | 1260篇 |
综合类 | 394篇 |
基础理论 | 1067篇 |
环境理论 | 5篇 |
污染及防治 | 1140篇 |
评价与监测 | 330篇 |
社会与环境 | 170篇 |
灾害及防治 | 48篇 |
出版年
2023年 | 21篇 |
2022年 | 20篇 |
2021年 | 47篇 |
2020年 | 29篇 |
2019年 | 59篇 |
2018年 | 70篇 |
2017年 | 88篇 |
2016年 | 109篇 |
2015年 | 109篇 |
2014年 | 104篇 |
2013年 | 538篇 |
2012年 | 176篇 |
2011年 | 246篇 |
2010年 | 189篇 |
2009年 | 187篇 |
2008年 | 254篇 |
2007年 | 257篇 |
2006年 | 232篇 |
2005年 | 161篇 |
2004年 | 182篇 |
2003年 | 189篇 |
2002年 | 166篇 |
2001年 | 78篇 |
2000年 | 105篇 |
1999年 | 96篇 |
1998年 | 73篇 |
1997年 | 64篇 |
1996年 | 72篇 |
1995年 | 71篇 |
1994年 | 61篇 |
1993年 | 65篇 |
1992年 | 72篇 |
1991年 | 43篇 |
1990年 | 51篇 |
1989年 | 42篇 |
1988年 | 32篇 |
1987年 | 38篇 |
1986年 | 44篇 |
1985年 | 40篇 |
1984年 | 44篇 |
1983年 | 49篇 |
1982年 | 38篇 |
1981年 | 54篇 |
1980年 | 44篇 |
1979年 | 22篇 |
1978年 | 24篇 |
1977年 | 17篇 |
1976年 | 12篇 |
1975年 | 14篇 |
1971年 | 13篇 |
排序方式: 共有4860条查询结果,搜索用时 62 毫秒
551.
Miscanthus for Renewable Energy Generation: European Union Experience and Projections for Illinois 总被引:1,自引:0,他引:1
Heaton Emily A. Long Stephen P. Voigt Thomas B. Jones Michael B. Clifton-Brown John 《Mitigation and Adaptation Strategies for Global Change》2004,9(4):433-451
Mitigation and Adaptation Strategies for Global Change - 相似文献
552.
John Simpson 《黑龙江环境通报》2004,24(13):1081-1091
553.
554.
555.
Summary We collected pregnant female Peromyscus leucopus from natural populations during the summer of 1987 and 1988 and allowed these females to give birth to their field-conceived young in the laboratory. Blood samples were taken by suborbital puncture and phenotypes of five genetic loci (Esterase-1, trasferrin, hemoglobin, albumin and 6-phosphogluconate dehydrogenase) were studied using horizontal starch-gel electrophoresis to detect multiple paternity in single litters. Only esterase-1 was found to be highly polymorphic, with four alleles in samples of both years. One litter out of 29 in 1987 and 6 litters out of 32 in 1988 contained three different paternal alleles and served as direct evidence of multiple paternity in the field. The proportion of females engaging in multiple matings in natural populations of P. leucopus, assuming that all males were involved in every multiple mating, is 25%–100% (mean 68%). Because it is unlikely that all males are involved in every multiple mating, the actual proportion of females engaging in multiple matings should be greater.
Offprint requests to: X. Xia at his Canadian address 相似文献
556.
557.
The measurement properties of the Rizzo, House and Lirtzman (1970) role conflict and role ambiguity scales have been debated in the research literature for several years. The criticisms are that the scales do not measure separate constructs and are contaminated by method variance. However, some researchers have presented evidence supporting the scales' continued use as independent measures. We attempted to clarify the running debate by re-examining these issues and presenting additional data, which focused on the item level of analysis. Using confirmatory factor analyses and item statistics, we show discriminant validity for the role conflict and ambiguity scales across three diverse samples of workers. We also contend that the evidence for method bias is not as strong as previously argued. 相似文献
558.
John M. Ratcliffe Hanumanthan Raghuram Ganapathy Marimuthu James H. Fullard M. Brock Fenton 《Behavioral ecology and sociobiology》2005,58(2):157-164
The literature suggests that in familiar laboratory settings, Indian false vampire bats (Megaderma lyra, family Megadermatidae) locate terrestrial prey with and without emitting echolocation calls in the dark and cease echolocating when simulated moonlit conditions presumably allow the use of vision. More recent laboratory-based research suggests that M. lyra uses echolocation throughout attacks but at emission rates much lower than those of other gleaning bats. We present data from wild-caught bats hunting for and capturing prey in unfamiliar conditions mimicking natural situations. By varying light level and substrate complexity we demonstrated that hunting M. lyra always emit echolocation calls and that emission patterns are the same regardless of light/substrate condition and similar to those of other wild-caught gleaning bats. Therefore, echoic information appears necessary for this species when hunting in unfamiliar situations, while, in the context of past research, echolocation may be supplanted by vision, spatial memory or both in familiar spaces.Communicated by T. Czeschlik 相似文献
559.
560.