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61.
Professor Bertrand Kerebel Marie-Thérèse Le Cabellec Guy Daculsi Lise-Marie Kerebel 《Cell and tissue research》1978,187(1):135-146
Summary TEM, SEM and X-ray diffraction analysis demonstrate the heterogeneity of the dentinal tissue of Anarhichas lupus, a vascular osteodentine. The disordered aspect of collagen fibres, incompletely mineralized (the periodical striation being still visible), explains the scattered distribution of crystallites since they are responsible for their arrangement. The low degree of mineralization revealed by the visible collagen striation is confirmed by X-ray diffraction analysis (the crystallinity of vascular osteodentine being much lower than that of the peripheral dental tissue) as well as by high resolution TEM, since no lattice planes could be observed. Osteodentine, supporting bone and proper bone have in common a mineral phase, more or less organized, different from the apatite system.The authors thank Mireille Cottrel-Gengoux for her technical assistance 相似文献
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Summary Fox and Woese (1975a) have shown that a model of 5S RNA secondary structure similar to the one originally derived forChlorella 5S RNA can be generalized with relatively minor variations to all sequenced 5S RNA molecules, i.e. that corresponding base paired regions can be formed at approximately the same positions. We present experimental data in favour of this hypothesis and show that the points at which ribonucleases T1, T2 and pancreatic ribonuclease cleave six different 5S RNA molecules under mild conditions (high ionic strength, low temperature, low RNAase concentration) nearly always fall in the proposed single-stranded regions. We conclude that this model is a good approximation to the conformation of 5S RNA in solution. 相似文献
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In 234 copulations, male and female behavioural patterns were collected, especially the vocal pattern for the female. Moreover
quantitative structural analysis was performed on 38 of these female copulatory vocalizations. A multifactorial analysis,
ANAFAC, was performed to seek relations between (1) utterance of female copulatory call and male and female copulatory behaviour
and (2) these patterns and the great variability of female calls. Utterance of female copulatory vocalizations is essentially
due to the female’s own copulatory behaviour in periods of intense sexual activity. Long female calls are related to male
ejaculation, and those “rich” in harmonics are related to visual and tactile communicatory signals exchanged by the male and
the female during a mount. This analysis strongly confirms the tied bond between quality of a call and internal state of the
emitter. Long calls, rich in harmonics, may serve as signals maintaining or strengthening the possibly temporary preferential
relation between male and sexually receptive female. 相似文献
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Helmut Bertrand Frank E. Nargang Richard A. Collins Cheryl A. Zagozeski 《Molecular & general genetics : MGG》1977,153(3):247-257
Summary We have isolated twenty-six nuclear, singlegene cytochrome-deficient mutants of Neurospora crassa as an initial step toward the study of the structural components and regulatory mechanisms involved in the biogenesis of the mitochondrial cytochrome system. These mutants, together with two previously described mutants, cyt-1 and cyt-2, have been classified into six distinct groups on the basis of cytochrome phenotype: a) cytochrome aa
3
deficiency (due to mutations affecting loci designated cya); b) cytochrome b deficiency (cyb-1 locus); c) cytochrome b deficiency with a partial deficiency of cytochrome aa
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(cyb-2 locus); d) deficiency of both cytochromes aa
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and b (cyt loci); e) deficiency of both cytochromes aa
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and c (cyt-2 locus); and f) partial deficiency of cytochromes aa
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and c (cyt-12 locus).Four of seven mutations affecting cya loci have been mapped and are located on linkage groups I, II, V, and VI. It is not yet known whether these genes code for structural components of cytochrome oxidase or have a regulatory function that affects synthesis or assembly of the enzyme. The cyb-1 and cyb-2 genes are located on linkage groups V and VI, respectively, and appear to code for regulatory elements that control the biogenesis of cytochromes b and aa
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. The positions of the cyt mutations that cause a simultaneous deficiency of cytochromes aa
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and b are dispersed throughout the genome, except for two gene clusters on the left arm of linkage group I. Some of these mutants may be deficient in mitochondrial protein synthesis. Two mutations, cyt-2 and cyt-12, are located on linkage groups VI and II, respectively, and appear to affect genes that code for components of a regulatory system that controls the biogenesis of cytochromes aa
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and c. 相似文献
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