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Summary Differential increases in the numbers of pinocytotic vesicles, multivesicular bodies and total complex bodies occurred in the cytoplasm of specific photoreceptor cells in the compound eye of the crab Libinia exposed for six hours to polarized light with various e-vector orientations. These data coupled with previous results on the same species proved that the seven retinular cells in each ommatidium formed two functional groups selectively light adaptable by e-vectors oriented 90° apart. One group (Channel I, comprising Cells 1, 4 and 5) was more affected by horizontal polarization; the other (Channel II, comprising Cells 2, 3, 6 and 7) was more affected by vertical polarization.This confirmed by a quite independent technique the conclusion reached from electrophysiological experiments on the crab Cardisoma that decapod compound eyes have two orthogonal polarization analyzer channels. In addition the present data showed that both channels occur in each ommatidium as hypothesized on previous electron microscopic evidence and that the axes of maximum absoprtion in the two retinal channels were parallel to the long axes of their cells' rhabdom microvilli, horizontal in Channel I and vertical in Channel II. The latter relations in turn supported the hypothesis that the dichroism of rhodopsin was fundamental to the analyzer mechanism.This research has been supported by U. S. Air Force Grant AFOSR 1064 and NASA Grant NGR 07-004-055. The authors wish to thank Professor Joseph G. Gall for generously sharing his electron microscope facilities. 相似文献
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Summary The cytological influence of light and dark adaptation (LA and DA) on the retinular cells of the spider crab Libinia emarginata has been studied by light and electron microscopy in four adaptive states: 17 hours darkness, 5 hours darkness, 5 hours diffuse light and 17 hours diffuse light. The rhabdom's fine structure is typical of decapods but its dual overall form and position mingle certain features of both apposition and superposition compound eye types. Distal and proximal retinal pigments both showed adaptive migration, but the distal pigment cells moved over a restricted range, and DA separated the retinular cell pigment granules into two groups, perinuclear and basilar.In the rhabdom no changes in its position, dimensions or microvillus fine structure were observed with LA or DA. But at the base of the rhabdom microvilli the rate of pinocytosis was strongly affected by the eye's adaptive state, being lowest after 17 hours DA and greatest after 17 hours LA; the wall of the 0.1 microvesicles so formed, looked like the membrane of the rhabdom microvillus and they were the same size as the vesicles in multivesicular bodies and in vesicular lamellar bodies.Three categories of complex cytoplasmic particles about 1 in diameter (multivesicular bodies, vesicular lamellar bodies and purely lamellar bodies) were all increased in number by decreased DA and by increased LA; similar quantitative effects occurred in the endoplasmic reticulum and in the ribosomes.The pinocytotic vesicles and the complex cytoplasmic bodies may represent part of an intracellular system to dispose of rhabdom metabolites whose production was initiated or increased by light absorption.Cytoplasmic and perirhabdomal vacuoles mainly distal in location, were also affected by light, but inversely; their maximal extent occurred after 17 hours DA; less DA or any LA significantly decreased their presence and aggregation.The data reported are of interest not only because they correlate retinal fine structure with the metabolism of vision but also because they provide a new and specific tool for distinguishing active from inactive neurosensory cells in the optic pathway.This research was initiated with the aid of U.S. Public Health Service Grant NB-03076 and has been continued with the support of U.S. Air Force Grant AFOSR-1064. The authors wish to thank Dr. Joseph G. Gall and Dr. William R. Adams for generously sharing their electron microscopic facilities; they are also grateful to Mrs. Mabelita Campbell for her collaboration on the light microscopy. 相似文献
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Simon Folkard 《Chronobiology international》1989,6(1):55-64
This paper advocates the use of a pragmatic approach to the problem of masking in real-life situations involving an abrupt change in the timing of sleep, i.e. shiftwork and “jet-lag” situations. Although “pure” chronobiological research has pointed to the importance of taking masking effects into account, the techniques that it has provided for doing so are extremely difficult to apply in real-life situations. The approach advocated here is based on Wever's pioneering work, and involves estimating the normative endogenous and exogenous components of the circadian rhythm in body temperature. These estimates are then used to: (a) simulate the results of shiftwork studies; and (b) to “remove” the exogenous component in “jet-lag” studies to allow analysis of the estimated endogenous component. The simulated curves obtained cross-correlated extremely highly with published night-shift temperature curves, while the “removal” of the exogenous component resulted in very similar findings to those obtained in temporal isolation studies. It is concluded that this pragmatic approach to masking may prove extremely useful in interpreting the results of field studies of shiftwork and “jet-lag”. 相似文献
149.
Evidence for the presence of disulfide bridges in opioid receptors essential for ligand binding. Possible role in receptor activation 总被引:1,自引:0,他引:1
T L Gioannini Y F Liu Y H Park J M Hiller E J Simon 《Journal of molecular recognition : JMR》1989,2(1):44-48
The mobility of purified mu opioid binding protein in SDS-polyacrylamide gek electrophoresis is sensitive to the presence of reducing agents. In the presence of increasing concentrations of DTT the apparent molecular weight increases in a stepwise fashion from 53 kDa to 65 kDa. This reduction in mobility is attributed to the successive breakage of disulfide bridges, resulting in an increasingly asymmetric molecule. Treatment of cell membranes from various brain areas with reducing agents, such as DTT, produced a concentration-dependent inhibition of opioid binding. Sensitivity to DTT inhibition varied between receptor types, mu greater than delta much greater than kappa. For mu receptors, agonist binding was considerably more sensitive to DTT than antagonist binding. Inhibition by DTT is readily reversible and is unaffected by Na+ and/or Mg2+ ions. Reversibility may be partially prevented by the inclusion of a low concentration of a reducing reagent such as glutathione which does not inhibit binding but blocks reformation of disulfide bonds. Scatchard analysis of saturation data shows that DTT causes a pronounced decrease in binding affinity with little effect on receptor number. It is suggested that disulfide bonds are essential for ligand binding and that cleavage of one or more of these bonds may play a role in opioid receptor activation by agonists. 相似文献
150.
Ferritin H gene polymorphism in idiopathic hemochromatosis 总被引:1,自引:1,他引:0
Véronique David Panos Papadopoulos Jacqueline Yaouanq Martine Blayau Laurent Abel Elizabetta Zappone Muriel Perichon Jim Drysdale Jean-Yves Le Gall Marcel Simon 《Human genetics》1989,82(2):123-126
Summary We have analysed karyotypes and DNA from three patients with aniridia (congenital absence of irises) and Wilms' tumour. All three had constitutional deletions from the short arm of chromosome 11. The minimum region of overlap of the deletion involves a small region of band 11p13 presumed to contain the genetic loci responsible for both phenotypic abnormalities. Using cells from these patients, somatic cell hybrids with transformed mouse cells have been prepared. Individual subclones retaining either the deletion-11 chromosome or the normal chromosome 11, in addition to a variety of other human chromosomes, have been identified. The relative position of these breakpoints have been determined and the panel of hybrids has been used to map randomly-isolated 11p13 DNA sequences. The characterisation of these deletions has provided a useful panel of hybrids for random mapping strategies designed to identify the Wilms' and aniridia genes. 相似文献