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Historical mitochondrial introgression causes differences between a species' mitochondrial gene genealogy and its nuclear gene genealogy, making tree-based species delineation ambiguous. Using sequence data from one mitochondrial gene (cytochrome b ) and three nuclear genes (introns), we examined the evolutionary history of four high elevation Tibetan megophryid frog species, Scutiger boulengeri , Scutiger glandulatus , Scutiger mammatus and Scutiger tuberculatus . The three nuclear genes shared a similar history but the mitochondrial gene tree suggested a drastically different evolutionary scenario. The conflicts between them were explained by multiple episodes of mitochondrial introgression events via historical interspecific hybridization. 'Foreign' mitochondrial genomes might have been fixed in populations and extended through a large portion of the species' distribution. Some hybridization events were probably as old as 10 Myr, while others were recent. An F1 hybrid was also identified. Historical hybridization events among the four species appeared to be persistent and were not restricted to the period of Pleistocene glaciation, as in several other well-studied cases. Furthermore, hybridization involved several species and occurred in multiple directions, and there was no indication of one mitochondrial genome being superior to others. In addition, incomplete lineage sorting resulting from budding speciation may have also explained some discrepancies between the mitochondrial DNA and nuclear gene trees. Combining all evidences, the former ' Scutiger mammatus ' appeared to be two species, including a new species. With the availability of a wide range of highly variable nuclear gene markers, we recommend using a combination of mitochondrial gene and multiple nuclear genes to reveal a complete species history. 相似文献
763.
åKE HOLM 《Zoologica scripta》1979,8(1-4):255-278
On the basis of the results of an analysis primarily of the morphology of the male palps and palpal organs the delimitation of the erigonine genera Pelecopsis Simon and Trichopterna Kulczyński and the phylogenetic relationships between European and East African species of these genera are discussed. For the East African species Pelecopsis convexa (Holm), and P. bacelarae (di Caporiacco), together with two undescribed species from Nigeria, the new genus Locketia is established. Pelecopsis humiliceps sp.n. and P. albifrons sp.n., both from Kenya, are described and P. tenera (Holm, 1962), preocc. P. tenera (Schenkel, 1927), is replaced by P. tenuipalpis nom.n. Viewpoints are presented on evolutionary trends and phylogeny of European and East African Pelecopsis species. 相似文献
764.
A new scanilepiform, Beishanichthys brevicaudalis gen. et sp. nov. , is named and described based on fossils from the Lower Triassic lake deposits exposed in Beishan area, Gansu Province, China. The discovery documents a new record of this group, which is significantly older than other known scanilepiforms from China, and is slightly younger than Evenkia from the Lowest Triassic of Central Siberia. Although the Beishan beds were previously interpreted as Late Permian in age, based on megaplant fossils, this new discovery supports the reinterpretation of the deposits as Early Triassic in age, based on vertebrate fossils from the same locality and horizon. Phylogenetic analysis was conducted to resolve the relationships of Scanilepiformes with other actinopterygian clades, and the inter‐relationships within Scanilepiformes. Contrary to previous thought that scanilepiforms are closely related to the Amiidae, the phylogenetic results of this study recognize the Scanilepiformes as stem‐group neopterygians. Relationships of the Scanilepiformes and Australosomus with other neopterygians remain unresolved. With a characteristic long‐based dorsal fin, scanilepiforms represent a small group that emerged in Early Triassic freshwater environments, inhabited Eurasia and North America during the Middle–Late Triassic, briefly invaded the marine environment by the Late Triassic in Europe, and became extinct at the end of Triassic. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011, 161 , 595–612. 相似文献
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Pheromone deactivation catalyzed by receptor molecules: a quantitative kinetic model 总被引:9,自引:5,他引:4
A quantitative model of pheromone-receptor interaction and pheromone
deactivation, the supposed rate-limiting processes underlying the receptor
potential kinetics, is worked out for the moth Antheraea polyphemus. In
this model, the pheromone interacts with the receptor molecule while bound
to the reduced form of the pheromone binding protein. The receptor
molecules--besides their receptor function-- catalyze the observed shift of
the pheromone-binding protein from the reduced to the oxidized form
(Ziegelberger, G., Eur. J. Biochem., 232, 706-711, 1995), which deactivates
the pheromone bound to pheromone binding protein. With the following
parameters, the model fits morphological, radiometric, electrophysiological
and biochemical data: a maximum estimate of 1.7 x 10(7) receptor
molecules/cell (with 40,000 units/micron 2 of receptor cell membrane), rate
constants k1 = 0.2/(s.microM) for the association, k2 = 10/s for the
dissociation of the ternary complex of binding protein, pheromone and
receptor, and k3 = 10/s for the deactivation via the redox shift. With
these parameters, the duration of elementary receptor potentials elicited
by single pheromone molecules (approximately 50 ms) reflects the lifetime
of the ternary complex, tau = 1/(k2 + k3). The receptor occupancy produced
by the model for threshold stimuli fits the sensitivity of the receptor
cell to single pheromone molecules.
相似文献
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