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151.
Dipple Anthony Pigott Margaret A. Milner John A. 《Biological trace element research》1986,10(2):153-157
Since selenium has been found to exert a protective action against carcinogenesis in various systems, the mechanism where-by
sodium selenite inhibits DNA binding of the carcinogen, 7,12-dimethylbenz[a]anthracene, was investigated. It was found that
selenite preferentially reduced DNA binding occurring through ananti-dihydrodiol epoxide metabolite of this carcinogen by inhibiting the induction of an enzyme system that generates this specific
reactive metabolite. 相似文献
152.
The lysosomal enzyme binding protein (receptor protein) isolated from monkey brain was immobilised on Sepharose 4B and used
to study the binding of brain lysosomal enzymes. The immobilised protein could bind \-D-glucosaminidase, α-D-mannosidase,
α-L-fucosidase and2-D-glucuronidase. The bound enzymes could be eluted either at an acid pH of 4.5 or by mannose 6-phosphate
but not by a number of other sugars tested. Binding could be abolished by prior treatment of the lysosomal enzymes with sodium
periodate. Alkaline phosphatase treatment of the enzymes did not prevent the binding of the lysosomal enzymes to the column
but decreased their affinity, as seen by a shift in their elution profile, when a gradient elution with mannose 6-phosphate
was employed. These results suggested that an ‘uncovered’ phosphate on the carbohydrate moiety of the enzymes was not essential
for binding but can enhance the binding affinity. 相似文献
153.
Summary Cationized ferritin was injected into the circulatory system of teleosts, the sea raven and Atlantic eelpout, and into elasmobranchs, the spiny dogfish and the skate, to determine if the glomerular basement membranes (GBM) from these different groups of fishes possess anionic binding sites similar to those present in the GBM of mammals. The distribution of cationized ferritin was the same in all fishes listed. Cationized ferritin was localized only in the GBM and the mesangial matrix. The regular distribution of cationized ferritin within the laminae rarae (60 nm intervals) was taken as evidence of the presence of anionic binding sites. Cationized ferritin did not bind to the glomerular capillary endothelium, nor was any of it localized at the base of the slit diaphragms of the foot processes of the podocytes. The distribution of binding sites in the GBM of these fishes is similar to that in another teleost, the winter flounder, and in a cyclostome, the hagfish. 相似文献
154.
Kurt Kraeuchi Anna Wirz-Justice Tadaomi Morimasa Rosi Suetterlin-Willener Hans Feer 《Chronobiology international》1986,3(2):127-133
Specific binding of [3H]-imipramine in the rat suprachiasmatic nuclei, occipital cortex and caudate putamen underwent significant and replicable changes throughout 24 hr under a light-dark cycle or under constant conditions. Daily variations were also found in the medial and dorsal raphe nuclei and the lateral hypothalamus. Methamphetamine, a psychoactive drug with marked effect on circadian rhythms in physiological and hormonal parameters and adrenergic receptors, did not have any significant effect on imipramine binding rhythms in eight discrete brain regions. Thus a drug known to reduce serotoninergic neurotransmission did not change characteristics of the modulatory binding site related to serotonin uptake. 相似文献
155.
Association of spectrin with desmin intermediate filaments 总被引:5,自引:0,他引:5
The association of erythrocyte spectrin with desmin filaments was investigated using two in vitro assays. The ability of spectrin to promote the interaction of desmin filaments with membranes was investigated by electron microscopy of desmin filament-erythrocyte inside-out vesicle preparations. Desmin filaments bound to erythrocyte inside-out vesicles in a spectrin-dependent manner, demonstrating that spectrin is capable of mediating the association of desmin filaments with plasma membranes. A quantitative sedimentation assay was used to demonstrate the direct association of spectrin with desmin filaments in vitro. When increasing concentrations of spectrin were incubated with desmin filaments, spectrin cosedimented with desmin filaments in a concentration-dependent manner. At near saturation the spectrin:desmin molar ratio in the sedimented complex was 1:230. Our results suggest that, in addition to its well characterized associations with actin, spectrin functions to mediate the association of intermediate filaments with plasma membranes. It might be that nonerythrocyte spectrins share erythrocyte spectrin's ability to bind to intermediate filaments and function in nonerythroid cells to promote the interaction of intermediate filaments with actin filaments and/or the plasma membrane. 相似文献
156.
J L Markley D H Croll R Krishnamoorthi G Ortiz-Polo W M Westler W C Bogard M Laskowski 《Journal of cellular biochemistry》1986,30(4):291-309
The traditional approach of using homologous sequences to elucidate the role of specific amino acid residues in protein structure and function becomes more meaningful as the number of differences is minimized, with the limit being alteration of a single residue. For small proteins in solution, NMR spectroscopy offers a means of obtaining detailed information about each residue and its response to a given change in the protein sequence. Extraction of this information has been aided by recent progress in spectrometer technology (higher magnetic fields, more sensitive signal detection, more sophisticated computers) and experimental strategies (new NMR pulse sequences including multiple-quantum and two-dimensional NMR methods). The set of avian ovomucoid third domains, which consists of the third domain proper plus a short leader (connecting peptide) and has a maximum of 56 amino acid residues, offers an attractive system for developing experimental methods for investigating sequence-structure and structure-function relationships in proteins. Our NMR results provide examples of sequence effects on pKa' values, average conformation, and internal motion of amino acid side chains. 相似文献
157.
158.
Kinetic characterization of early intermediates in the folding of E. coli tryptophan-synthase beta 2 subunit 总被引:1,自引:0,他引:1
This report describes the use of fluorescence energy transfer between an intrinsic energy donor (tryptophan 177) and two chemically added acceptors to study intermediates in the folding of the beta 2 subunit of E. coli tryptophan-synthase. Two early folding steps are thus identified and characterized. One is very rapid (its rate constant at 12 degrees C is 0.02 sec-1) and corresponds to the folding of the N-terminal domain into a structure whose overall features approximate well those of the native domain. The second step is somewhat slower (its rate constant at 12 degrees C is 0.008 sec-1) and involves a conformational rearrangement of the N-terminal domain brought about by the interactions between the N- and C-terminal domains within a monomeric beta chain. This brings to five the number of intermediates which have been identified and ordered on the folding pathway of the dimeric beta 2 subunit. 相似文献
159.
N A Sharif N S Pilotte D R Burt 《Biochemical and biophysical research communications》1983,116(2):669-674
Receptors for thyrotropin-releasing hormone (pGlu-His-Pro-NH2, TRH) on thaw-mounted sections of rabbit spinal cord have been identified biochemically and visualized by light microscopic autoradiography. Binding of [3H] [3-Me-His2]TRH to 20 microns sections exhibited high apparent affinity and a pharmacological specificity almost identical to that previously demonstrated for spinal TRH receptors in membranes. In autoradiograms, the highest density of TRH receptors appeared in the substantia gelatinosa of the dorsal gray and around the central canal, with intermediate levels in the ventral gray. 相似文献
160.
The binding parameters of the oligomycin-sensitivity conferring protein (OSCP) in inside-out particles from beef heart mitochondria have been tested by means of two assays, the oligomycin-sensitive ATP-Pi exchange, and the oligomycin-sensitive ATP hydrolysis. The total number of OSCP binding sites in A particles was equal to 220 pmol/mg particle protein. Each mole of ATPase active site was able to bind 1.1 +/- 0.5 mol OSCP with Kd 1.7 nM. 相似文献