全文获取类型
收费全文 | 145篇 |
免费 | 2篇 |
出版年
2016年 | 2篇 |
2015年 | 3篇 |
2014年 | 2篇 |
2012年 | 2篇 |
2010年 | 2篇 |
2009年 | 2篇 |
2008年 | 3篇 |
2005年 | 2篇 |
2003年 | 2篇 |
2001年 | 4篇 |
1999年 | 2篇 |
1998年 | 4篇 |
1997年 | 2篇 |
1989年 | 2篇 |
1986年 | 2篇 |
1977年 | 2篇 |
1960年 | 4篇 |
1959年 | 2篇 |
1957年 | 2篇 |
1956年 | 1篇 |
1955年 | 1篇 |
1953年 | 3篇 |
1952年 | 1篇 |
1947年 | 2篇 |
1945年 | 1篇 |
1940年 | 2篇 |
1939年 | 1篇 |
1938年 | 4篇 |
1937年 | 2篇 |
1936年 | 9篇 |
1935年 | 5篇 |
1934年 | 2篇 |
1933年 | 8篇 |
1932年 | 9篇 |
1931年 | 9篇 |
1930年 | 2篇 |
1929年 | 7篇 |
1927年 | 1篇 |
1926年 | 1篇 |
1924年 | 2篇 |
1923年 | 3篇 |
1922年 | 1篇 |
1920年 | 2篇 |
1919年 | 1篇 |
1918年 | 3篇 |
1916年 | 1篇 |
1914年 | 1篇 |
1910年 | 2篇 |
1909年 | 1篇 |
1907年 | 1篇 |
排序方式: 共有147条查询结果,搜索用时 46 毫秒
101.
Positive selection and the molecular evolution of a gene of male reproduction, Acp26Aa of Drosophila 总被引:4,自引:1,他引:3
The gene for a male ejaculatory protein, Acp26Aa, in four sibling species
of the Drosophila melanogaster subgroup has previously been shown to have a
nonsynonymous rate (Ka) of nucleotide substitution that is
indistinguishable from the synonymous rate (Ks). By examining this gene in
two other species of this subgroup, we found that Ka is generally large and
can sometimes be more than twice as large as Ks. This suggests that
positive selection may be operating at this locus of male reproduction.
相似文献
102.
103.
104.
105.
106.
M Moritz S Laborde SC Phang M Ahmadou M Durand A Fernandez 《African Journal of Aquatic Science》2016,41(1):99-108
African floodplains are an excellent example of coupled human–natural systems because they exhibit strong interactions among multiple social, ecological, and hydrological systems. The intra-annual and interannual variations in seasonal flooding have direct and indirect impacts on ecosystems and human lives and livelihoods. Coupled human and natural system (CHANS) is a broad conceptual framework that is used to study systems in which human and natural components interact. While there are other conceptual frameworks to study social-ecological systems, the CHANS framework offers a clear way of studying the interactions, called couplings, between human and natural systems. Core features of the framework are the following: human and natural systems are analytically separated; focus is on processes within and couplings between systems; and the goal is to build an integrative, quantitative model of the coupled system. This paper explains the conceptual framework of coupled systems, using the case study of the Logone floodplain in Cameroon. We compare the CHANS framework with other frameworks that have been used to study the same floodplain, and argue for its usefulness in the study of African floodplains. 相似文献
107.
108.
109.
110.