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ANDRZEJ KAIM ROBERT G. JENKINS ANDERS WARÉN 《Zoological Journal of the Linnean Society》2008,154(3):421-436
A fauna of provannid and provannid‐like shells is described from Upper Cretaceous seep carbonates in Hokkaido, Japan. We describe two new provannid species, Provanna tappuensis sp. nov. and Desbruyeresia kanajirisawensis sp. nov. , with preserved protoconchs of unquestionable provannid type with decollate apex. This material confirms the occurrence of Provannidae as early as the Middle Cenomanian. We also describe Hokkaidoconcha gen. nov. and a new family Hokkaidoconchidae fam. nov. , with two named species, H. hikidai sp. nov. and H. tanabei sp. nov . Hokkaidoconchidae are possibly related to the Provannidae, judging from a similar, but not decollate larval shell, although the juvenile teleoconch whorls differ in being of a general cerithimorph appearance and the details of the aperture are unknown. Furthermore, we review the published fossil record of Provannidae and Abyssochrysidae, and we consider that in those older than the Eocene, there is no evidence preserved that unequivocally supports a position there. The Jurassic Acanthostrophia acanthica from Italy seems to be the oldest known record of Abyssochrysidae, and the most reliable occurrence of the family, older than from the Miocene. Other fossil, pre‐Miocene species that have been classified in the Abyssochryssidae are provisionally referred to Hokkaidoconchidae. © 2008 The Linnean Society of London, Zoological Journal of the Linnean Society, 2008, 154 , 421–436. 相似文献
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Divergent natural selection is often thought to be the principal factor driving phenotypic differentiation between populations. We studied two ecotypes of the aquatic isopod Asellus aquaticus which have diverged in parallel in several Swedish lakes. In these lakes, isopods from reed belts along the shores colonized new stonewort stands in the centre of the lakes and rapid phenotypic changes in size and pigmentation followed after colonization. We investigated if selection was likely to be responsible for these observed phenotypic changes using indirect inferences of selection (FST–QST analysis). Average QST for seven quantitative traits were higher than the average FST between ecotypes for putatively neutral markers (AFLPs). This suggests that divergent natural selection has played an important role during this rapid diversification. In contrast, the average QST between the different reed ecotype populations was not significantly different from the mean FST. Genetic drift could therefore not be excluded as an explanation for the minor differences between allopatric populations inhabiting the same source habitat. We complemented this traditional FST–QST approach by comparing the FST distributions across all loci (n = 67–71) with the QST for each of the seven traits. This analysis revealed that pigmentation traits had diverged to a greater extent and at higher evolutionary rates than size‐related morphological traits. In conclusion, this extended and detailed type of FST–QST analysis provides a powerful method to infer adaptive phenotypic divergence between populations. However, indirect inferences about the operation of divergent selection should be analyzed on a per‐trait basis and complemented with detailed ecological information. 相似文献
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ANDERS G. FINSTAD TORBJØRN FORSETH BROR JONSSON EDWIGE BELLIER TRYGVE HESTHAGEN ARNE J. JENSEN DAG O. HESSEN ANDERS FOLDVIK 《Global Change Biology》2011,17(4):1703-1711
We tested the importance of thermal adaptations and energy efficiency in relation to the geographical distribution of two competing freshwater salmonid fish species. Presence–absence data for Arctic char and brown trout were obtained from 1502 Norwegian lakes embracing both temperature and productivity gradients. The distributions were contrasted with laboratory‐derived temperature scaling models for food consumption, growth and energy efficiency. Thermal performances of the two species were almost identical. However, Arctic char exhibited double the growth efficiency (per unit of food) and appear to have out‐competed brown trout from cold, low‐productivity lakes, perhaps by scramble competition. Brown trout, for which previous reports have shown to be aggressive and dominant, have likely excluded the more energy‐efficient Arctic char from relatively warm, productive lakes, perhaps by contest competition. Competitive interaction changing in outcome with lake productivity, rather than thermal performance, is likely a major determinant of the range distribution of the two species. Our study highlights the need for more focus on choice of relevant ecophysiological traits in ecological climate impact studies and species distribution modelling. 相似文献
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ANDERS N. NILSSON 《Systematic Entomology》1992,17(2):155-179
Abstract. The thirteen species of Agabus Leach, 1817, of the Afrotropical Region are revised and classified into four species groups: the dibasic ambulator -group endemic to Ethiopia, ragazzii -group with five species in Ethiopia, raffrayi -group with five species in East and South Africa, and A.discicollis Ancey, 1882, endemic to Ethiopia, is placed in the Nearctic cordatus -group. Agabus perssoni sp.n. and Agabus galamensis sp.n. are described from the highlands of Ethiopia. Agabus ruwenzoricus Guignot, 1936, stat.n. is given specific rank. Agabus ferrugatus Régimbart, 1905, is synonymized with Agabus ragazzii Régimbart, 1887, and Agabus limbicollis Régimbart, 1905, is synonymized with Agabus raffrayi Sharp, 1882, syn.n. Lectotypes are designated for the following nominal species: Agabus discicollis Ancey, 1882, Agabus raffrayi Sharp, 1882, Agabus limbicollis Régimbart, 1905, Agabus pallidus Omer-Cooper, 1931, Agabus ruwenzoricus Guignot, 1936, Agabus sjostedti Régimbart, 1908, Agabus dytiscoides Régimbart, 1908, Agabus ragazzii Régimbart, 1887, Agabus ferrugatus Régimbart, 1905, and Gaurodytes abessinicus Zimmermann, 1928. Reconstructed phylogenies are presented for the raffrayi -and ragazzii -groups. The following adaptations to tropicoalpine habitats are suggested: (1) body and especially pronotum narrow, (2) head broad anteriorly, (3) hindwing small, and (4) hind leg long and slender. Biogeography and evolution of the studied species are discussed. Four different invasions of Holarctic lineages to the East African mountains are suggested. Recurrent periods of cold and dry climate are considered the chief driving force in the evolution of high altitude super specialists. 相似文献
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