全文获取类型
收费全文 | 150篇 |
免费 | 2篇 |
出版年
2016年 | 2篇 |
2015年 | 3篇 |
2014年 | 2篇 |
2013年 | 2篇 |
2010年 | 2篇 |
2009年 | 2篇 |
2008年 | 3篇 |
2005年 | 4篇 |
2003年 | 2篇 |
2001年 | 3篇 |
1999年 | 2篇 |
1998年 | 4篇 |
1997年 | 2篇 |
1989年 | 3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152条查询结果,搜索用时 15 毫秒
101.
J. F. G. Wheeler D.SC F.L.S. F. A. Brown Jun. Ph.D. 《Zoological Journal of the Linnean Society》1936,39(267):413-428
Observations from the jetty of the Biological Station, Bermuda, of the appearance of Anchistioides antiguensis (Schmitt) at the surface over a short period in 1934 and eight months in 1935 are recorded, and show definite periodicity sometimes of sufficient intensity to merit the term swarming.
The periodicity coincides with the two weeks of the lunar cycle when the moon wanes from the last quarter to the first quarter of the new cycle. It appears to consist of two maximum appearances separated by an interval of some days.
Direct lunar influence, sex and the reproductive period, the surface-temperature, wind and weather, and the state of the tide are shown to have no connexion with swarming.
An explanation is suggested based on the feeding habits and depending on the periodic activity of the worms that form the food. The double maximum of the swarming period is shown to represent two stages of growth. 相似文献
The periodicity coincides with the two weeks of the lunar cycle when the moon wanes from the last quarter to the first quarter of the new cycle. It appears to consist of two maximum appearances separated by an interval of some days.
Direct lunar influence, sex and the reproductive period, the surface-temperature, wind and weather, and the state of the tide are shown to have no connexion with swarming.
An explanation is suggested based on the feeding habits and depending on the periodic activity of the worms that form the food. The double maximum of the swarming period is shown to represent two stages of growth. 相似文献
102.
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
103.
104.
绿黄色光二极管(LED)附加在塑胶杯和胶片捕捉器可增加捕捉实验室和温室中昆虫的数量。附加有530nm绿黄色LED的塑胶杯捕捉器比没有附加的捕捉到更多的Trialeurodes vaporariorum(Westwood)和Bemisia tabaci(Gennadius)B生态型。在温室中昆虫笼以四季豆和棉花试验,附加有530nm绿黄色LED的黄色胶片(YC)和透明塑胶片(CS)分别缩写为LED—YC和LED—CS)比每一种没有附加的捕捉器捕捉到更多的T.vaporariorum,B.tabaci B生态型,Ahis gossypii(Glover)和Bradysia coprophila(Lintner)成虫。绿黄色LED—YC在温室中有用为监测和控制的潜在性。 相似文献
105.
106.
107.
108.
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
109.
110.