全文获取类型
收费全文 | 87篇 |
免费 | 2篇 |
出版年
2015年 | 1篇 |
2010年 | 2篇 |
2009年 | 2篇 |
2008年 | 2篇 |
2007年 | 1篇 |
2005年 | 3篇 |
2003年 | 1篇 |
1997年 | 1篇 |
1995年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1989年 | 1篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1983年 | 2篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1974年 | 4篇 |
1972年 | 3篇 |
1971年 | 3篇 |
1968年 | 1篇 |
1967年 | 3篇 |
1966年 | 2篇 |
1963年 | 1篇 |
1962年 | 1篇 |
1961年 | 2篇 |
1959年 | 3篇 |
1958年 | 2篇 |
1957年 | 5篇 |
1956年 | 4篇 |
1955年 | 3篇 |
1953年 | 3篇 |
1951年 | 6篇 |
1950年 | 2篇 |
1949年 | 5篇 |
1948年 | 7篇 |
排序方式: 共有89条查询结果,搜索用时 15 毫秒
1.
Neopomacentrus filamentosus, a common damselfish on the Indo–Australian archipelago, undergoes significant shifts in size and mitochondrial genetic structure upon larval settlement and metamorphosis to juvenile stages. We characterized five polymorphic microsatellite loci in order to study temporal genetic shifts within a single generation of N. filamentosus sampled first as larval settlers then again as demersal juvenile recruits. All loci were extremely polymorphic and exhibited high levels of heterozygosity. While all loci from the larval samples conformed to Hardy – Weinberg expectations, significant heterozygote deficiencies were seen in two loci in the juvenile samples, likely due to extreme size‐selective mortality imposed post‐settlement. 相似文献
2.
3.
4.
5.
6.
Transport of glutamine into isolated pea chloroplasts 总被引:4,自引:2,他引:2
Abstract. Uptake of [14 C] glutamine into isolated pea chloroplasts has been examined by using a centrifugal filtration technique. Competition experiments showed that glutamine uptake is mediated by a dicarboxylate carrier with Km 1.10 mM and V max . 118 nmol of glutamine min−1 per mg of chlorophyll. Isolated pea chloroplasts accumulated glutamine in the sucrose-impermeable space to concentrations higher than that present in the external solution when the latter was below 0.5 mM. It is suggested that glutamine accumulation is driven by exchange (utilizing the dicarboxylate carrier) with the endogenous pool of dicarboxylates in the chloroplasts. Increasing pH stimulated glutamine uptake but inhibited that of glutamate and 2-oxoglu-tarate. The hypothesis is advanced that when molecules of different charge are exchanged across the chloroplast envelope via the dicarboxylate carrier, electroneutrality is maintained by transport of protons, and that this explains the observed effects of increasing pH. The low rates of glutamine transport coupled with the strong competition of other dicarboxylates for the carrier suggest that export in vivo from the chloroplast of nitrogen in the form of glutamine is not of major importance. 相似文献
7.
The night sky is the venue of an ancient acoustic battle between echolocating bats and their insect prey. Many tiger moths (Lepidoptera: Arctiidae) answer the attack calls of bats with a barrage of high frequency clicks. Some moth species use these clicks for acoustic aposematism and mimicry, and others for sonar jamming, however, most of the work on these defensive functions has been done on individual moth species. We here analyze the diversity of structure in tiger moth sounds from 26 spe-cies collected at three locations in North and South America. A principal components analysis of the anti-bat tiger moth sounds reveals that they vary markedly along three axes: (1) frequency, (2) duty cycle (sound production per unit time) and frequency modulation, and (3) modulation cycle (clicks produced during flexion and relaxation of the sound producing tymbal) structure. Tiger moth species appear to cluster into two distinct groups: one with low duty cycle and few clicks per modulation cycle that supports an acoustic aposematism function, and a second with high duty cycle and many clicks per modulation cycle that is con-sistent with a sonar jamming function. This is the first evidence from a community-level analysis to support multiple functions for tiger moth sounds. We also provide evidence supporting an evolutionary history for the development of these strategies. Further-more, cross-correlation and spectrogram correlation measurements failed to support a "phantom echo" mechanism underlying sonar jamming, and instead point towards echo interference. 相似文献
8.
9.
10.