全文获取类型
收费全文 | 735篇 |
免费 | 33篇 |
国内免费 | 6篇 |
出版年
2013年 | 12篇 |
2012年 | 10篇 |
2011年 | 19篇 |
2010年 | 15篇 |
2009年 | 24篇 |
2008年 | 22篇 |
2007年 | 25篇 |
2006年 | 13篇 |
2005年 | 11篇 |
2004年 | 17篇 |
2003年 | 11篇 |
2002年 | 6篇 |
1998年 | 17篇 |
1997年 | 10篇 |
1996年 | 14篇 |
1995年 | 12篇 |
1994年 | 16篇 |
1993年 | 8篇 |
1992年 | 7篇 |
1991年 | 14篇 |
1990年 | 10篇 |
1989年 | 13篇 |
1988年 | 12篇 |
1987年 | 10篇 |
1985年 | 10篇 |
1984年 | 12篇 |
1983年 | 7篇 |
1982年 | 13篇 |
1981年 | 7篇 |
1979年 | 17篇 |
1978年 | 10篇 |
1977年 | 14篇 |
1976年 | 7篇 |
1975年 | 16篇 |
1973年 | 6篇 |
1972年 | 19篇 |
1971年 | 9篇 |
1960年 | 6篇 |
1959年 | 18篇 |
1958年 | 31篇 |
1957年 | 23篇 |
1956年 | 29篇 |
1955年 | 22篇 |
1954年 | 21篇 |
1953年 | 11篇 |
1952年 | 12篇 |
1951年 | 15篇 |
1950年 | 11篇 |
1949年 | 19篇 |
1948年 | 6篇 |
排序方式: 共有774条查询结果,搜索用时 15 毫秒
61.
62.
63.
64.
65.
66.
67.
MANUEL ALEJANDRO RAMÍREZ JENNY PATRICIA‐ACEVEDO SILVIA PLANAS JOEL L. CARLIN STEPHAN M. FUNK W. OWEN MCMILLAN 《Molecular ecology resources》2006,6(3):813-817
We characterized nine microsatellite loci and identified an additional 60 genomic regions containing microsatellites in the red hind grouper, Epinephelus guttatus. The nine loci were highly polymorphic, and primers designed from red hind genomic DNA produced a strong amplification product in a test panel of 16 other groupers in the genera Epinephelus and Mycteroperca collected from across the world. Most of the amplified regions were homologous to the red hind locus and a well‐defined microsatellite repeat was generally evident. The nine loci, together with the 60 uncharacterized microsatellite‐containing regions, provide a powerful tool for ecological and evolutionary studies in groupers. 相似文献
68.
BRANT C. FAIRCLOTH GWEN P. KELLER C. JOSEPH NAIRN WILLIAM E. PALMER JOHN P. CARROLL PATRICIA ADAIR GOWATY 《Molecular ecology resources》2006,6(3):646-649
We describe primers and polymerase chain reaction (PCR) conditions to amplify 18 tetranucleotide microsatellite DNA loci in eastern bluebirds (Sialia sialis). The primers were tested using individuals from two study sites in Georgia and South Carolina. Among individuals from the Georgia population (n = 23), the primer pairs developed in this study yielded an average of 6.6 alleles per locus (range 2–12), an average observed heterozygosity of 0.56 (range 0.24–0.96) and an average polymorphic information content of 0.65 (range 0.3–0.86). Among individuals from the South Carolina population (n = 19), the primer pairs yielded an average of 5.8 alleles per locus (range 2–9), an average observed heterozygosity of 0.56 (range 0.05–0.86) and an average polymorphic information content of 0.63 (range 0.29–0.83). 相似文献
69.
RAQUEL VASCONCELOS ANA PERERA PHILIPPE GENIEZ D. JAMES HARRIS SALVADOR CARRANZA 《Zoological Journal of the Linnean Society》2012,164(2):328-360
Recent phylogeographical analyses using mitochondrial DNA (mtDNA) sequences indicate that the Tarentola geckos from the Cape Verde archipelago originated from a propagule that dispersed from the Canary Islands approximately 7.7 Mya and that underwent a fast evolutionary radiation. Molecular analyses carried out to date clearly show some incongruences with the current taxonomy of Tarentola from the Cape Verde Islands, with some species being paraphyletic or polyphyletic, and several independently evolving lineages needing formal taxonomic recognition. The aim of this study was to clarify the systematics of this group to unravel its taxonomy by applying an integrative approach based on information from three independent sources: mtDNA, nuclear genes, and morphology. As a result of this taxonomic revision, two novel species for the islands of S. Nicolau and Fogo are described and eight subspecies are upgraded to species level. Moreover, an identification key for the genus Tarentola from the Cape Verde archipelago is presented. This study reconciles taxonomy and phylogeny in this group, provides a better understanding of diversity patterns, new insights on evolutionary hypotheses, and supports the basic framework for the future management and conservation of this unique reptile radiation. © 2012 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 164 , 328–360. 相似文献
70.
1. Mycosporine‐like amino acids (MAAs) are ubiquitous compounds in aquatic organisms that are usually considered sunscreens that protect them from harmful ultraviolet radiation. Given that virtually all animals lack the metabolic pathways to synthesise MAAs de novo, they must acquire them either from their diet or from microorganisms living in close association. In freshwater copepods, accumulation of MAAs is stimulated by exposure to ultraviolet and/or visible radiation. 2. A 2 × 2 factorial experiment was performed to assess the contributions of dietary and microbial sources of MAAs in the freshwater copepod Boeckella antiqua. The treatments consisted of two different diets: an MAA‐free diet, including only Chlamydomonas reinhardtii, and an MAA‐rich diet, including both C. reinhardtii and Peridinium inconspicuum, crossed with two antibiotic treatments, with and without chloramphenicol. Treatment with chloramphenicol was intended to inhibit the development of bacteria associated with the copepods. 3. MAA concentration in B. antiqua was affected by the experimental conditions: (i) exposure to artificial PAR + UVR stimulated the accumulation of several MAAs (up to 62% increase in total MAA concentration with respect to the initial concentration); (ii) the presence of chloramphenicol in the culture media reduced the MAA concentration in copepods fed an MAA‐free diet; (iii) in the absence of chloramphenicol, copepods fed the MAA‐rich diet had significantly higher total MAA concentration than those fed the MAA‐deficient diet; but (iv) dietary supplementation with an MAA‐rich algae in the presence of chloramphenicol failed to significantly increase total MAA concentration. 4. Analysis of profiles from denaturing gradient gel electrophoresis (DGGE) showed that the prokaryotic community associated with the copepods was affected by chloramphenicol. Dendograms constructed from digitalised DGGE images consistently grouped the antibiotics treatments separately from the initial samples and the treatments without antibiotics. Two band positions were exclusive to treatments without antibiotics. 5. We conclude that when offered an MAA‐rich diet, B. antiqua may accumulate a proportion of MAAs from diet. However, we suspect that in the absence of an MAA‐rich dietary source (as in its natural habitat), virtually all MAAs present in B. antiqua are produced by copepod‐associated prokaryotes. 相似文献