全文获取类型
收费全文 | 41篇 |
免费 | 0篇 |
国内免费 | 1篇 |
专业分类
安全科学 | 1篇 |
环保管理 | 8篇 |
综合类 | 12篇 |
基础理论 | 5篇 |
污染及防治 | 6篇 |
社会与环境 | 10篇 |
出版年
2018年 | 1篇 |
2017年 | 2篇 |
2016年 | 1篇 |
2014年 | 1篇 |
2013年 | 4篇 |
2011年 | 2篇 |
2010年 | 1篇 |
2008年 | 3篇 |
2006年 | 2篇 |
2005年 | 2篇 |
2003年 | 2篇 |
2002年 | 1篇 |
2000年 | 2篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1993年 | 2篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1973年 | 1篇 |
1972年 | 2篇 |
1971年 | 1篇 |
1967年 | 1篇 |
1965年 | 1篇 |
1952年 | 2篇 |
排序方式: 共有42条查询结果,搜索用时 15 毫秒
41.
Emily R. A. Cramer Terje Laskemoen Fabrice Eroukhmanoff Fredrik Haas Jo S. Hermansen Jan T. Lifjeld Melissah Rowe Glenn-Peter Sætre Arild Johnsen 《Behavioral ecology and sociobiology》2014,68(7):1133-1144
Sexual selection may drive speciation, but most research focuses on pre-copulatory sexual selection, overlooking post-copulatory processes. Post-copulatory sexual selection in allopatric populations could drive divergence in post-copulatory pre-zygotic (PCPZ) phenotypes, limiting gene flow upon secondary contact. Here, we performed in vitro experiments examining one potential PCPZ barrier between two closely related passerine species, house sparrows (Passer domesticus) and Spanish sparrows (Passer hispaniolensis). In birds, crossing in the vagina may be particularly challenging for sperm, so we tested the effect of female reproductive tract fluids on sperm swimming speed and motility. If a PCPZ barrier exists at this stage of the fertilization process, heterospecific female fluids are predicted to reduce sperm swimming speed or motility relative to conspecific female fluid. We found that house sparrow female fluids affected the two species’ sperm asymmetrically, depending on the control sperm velocity and male species. Overall, however, sperm performed equally in conspecific and heterospecific female fluids, and the species had similar sperm morphology and sperm swimming performance. Low divergence in PCPZ phenotypes between species, perhaps because post-copulatory sexual selection is stabilizing or only moderately strong in these taxa, may be insufficient to cause an overall PCPZ barrier. Reinforcement may be unlikely to drive PCPZ barriers for this species pair, because relatively effective pre-copulatory barriers exist between the species, and because hybrids can be quite successful. Testing the role of PCPZ barriers in birds with more divergent PCPZ phenotypes will improve our understanding of speciation in passerines. 相似文献
42.
Model of the circulation of DDT on earth 总被引:2,自引:0,他引:2
J Cramer 《Atmospheric environment(England)》1973,7(3):241-256