全文获取类型
收费全文 | 451篇 |
免费 | 16篇 |
国内免费 | 10篇 |
专业分类
安全科学 | 21篇 |
废物处理 | 18篇 |
环保管理 | 99篇 |
综合类 | 45篇 |
基础理论 | 160篇 |
环境理论 | 1篇 |
污染及防治 | 78篇 |
评价与监测 | 33篇 |
社会与环境 | 21篇 |
灾害及防治 | 1篇 |
出版年
2023年 | 4篇 |
2022年 | 4篇 |
2021年 | 5篇 |
2020年 | 3篇 |
2019年 | 7篇 |
2018年 | 11篇 |
2017年 | 11篇 |
2016年 | 17篇 |
2015年 | 15篇 |
2014年 | 15篇 |
2013年 | 31篇 |
2012年 | 23篇 |
2011年 | 34篇 |
2010年 | 22篇 |
2009年 | 21篇 |
2008年 | 28篇 |
2007年 | 38篇 |
2006年 | 28篇 |
2005年 | 11篇 |
2004年 | 18篇 |
2003年 | 13篇 |
2002年 | 10篇 |
2001年 | 12篇 |
2000年 | 5篇 |
1999年 | 9篇 |
1998年 | 8篇 |
1997年 | 5篇 |
1996年 | 7篇 |
1995年 | 3篇 |
1994年 | 6篇 |
1993年 | 4篇 |
1992年 | 4篇 |
1991年 | 6篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1986年 | 2篇 |
1985年 | 6篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 5篇 |
1980年 | 6篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有477条查询结果,搜索用时 203 毫秒
41.
42.
43.
44.
More knowledge of the proximate factors that influence parasite loads would help us understand the selective pressures faced by hosts and host-parasite evolution. Testosterone has been associated with increased parasite loads in vertebrates. Here we asked whether experimentally elevated testosterone affected ectoparasite loads in free-ranging northern fence lizards (Sceloporus undulatus hyacinthinus). Males were captured, given testosterone or sham implants, and released. In 2 consecutive years, testosterone-implanted males had significantly more ectoparasites at recapture than did controls. Additionally, ectoparasite loads were positively correlated with testosterone concentrations in unmanipulated males, and males had significantly more ectoparasites than did females. The results are consistent with an effect of testosterone on parasite loads. However, rather than elevated testosterone increasing mite loads in experimental males, it appeared that high testosterone inhibited a natural seasonal decline in mite loads. Testosterone-implanted males also lost body mass whereas controls gained mass. Among controls, those retaining the most ectoparasites over the course of the experiment experienced the smallest gains in body mass, suggesting that the mites are costly. 相似文献
45.
46.
47.
48.
49.
50.
Mahlon Craig Barber 《Ecological modelling》1978,5(2):125-135
Historic ecosystem resource flow is modeled as a retrospective discrete Markov chain to obtain the expected values and variances of compartmental residence times and numbers of intercompartmental transfers that compartmental standing crops have experienced since their latest entry into the ecosystem. The transition probabilities of the proposed retrospective Markovian model are either stationary or time inhomogeneous according to whether a steady state or non-steady state ecosystem, respectively, is analyzed. 相似文献