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31.
Because of their specificity and sensitivity, monoclonal antibodies are powerful tools in studies of protein structure and function. Therefore, we raised monoclonal antibodies against alpha A-crystallin and identified the antigenic determinant for two of these antibodies. Applying limited-digestion methods, we show that the region spanning residues 158-168 of alpha A-crystallin contains the epitope for the two monoclonal antibodies. These monoclonals were then used to study the occurrence in the lenses of different vertebrates of the elongated alpha Ains-crystallin chain, a product of alternative splicing. It appears that the mutational event resulting in the alternative splicing pattern of the alpha A-crystallin gene took place at least 70 million years ago. This alternative splicing phenomenon has been maintained in rodents and some other, unrelated mammals, but disappeared again in most mammalian lineages.  相似文献   
32.
Heterochromatin staining pattern of quail-chicken hybrid lymphocytes   总被引:1,自引:0,他引:1  
Feulgen-Rossenbeck staining of lymphoid cells of quail-chicken hybrids in histologic sections revealed a pattern of heterochromatin arrangement distinguishable from that of either parental type. During interphase, hybrid lymphocytes exhibited combined characteristics of both the parental quail and the parental chicken. Hybrid heterochromatin was arranged in a large central mass as in the quail and in fairly evenly distributed small chromacenters around the periphery of the nucleus similar to the arrangement in the chicken. It is suggested that this pattern of staining can be used as a marker for hybrid cells in studies of genetic interactions.  相似文献   
33.
Peroxisomes are massively induced when methylotrophic yeasts are cultured on methanol as the sole carbon and energy source. An analysis of the protein composition of the peroxisomal membrane and the generation of probes against two peroxisomal membrane proteins (PMPs) have been undertaken. Peroxisomes from Candida boidinii were obtained from sucrose gradients as previously described or from a novel one-step purification of the organelle on a Percoll gradient. The protein composition of the membranes from these two preparations was virtually identical. About 10 proteins comprise nearly all of its protein mass. The most prominent proteins have molecular masses of 120, 100, 47, 31-32 (a triplet), and 20 kDa; significant amounts of alcohol oxidase and dihydroxyacetone synthase, the two abundant matrix proteins, also remain associated with the membrane. Glycosylation of the membrane proteins could not be detected. Exposure of the membrane to chaotropes shows that PMPs 100 and 20 are the most easily removable, whereas PMP 47 appears to be the most tightly associated. Mice were injected with peroxisomal membrane, and hybridoma lines were isolated that produced antibody against PMP 20, PMP 47, and dihydroxyacetone synthase. Indirect immunofluorescence with these monoclonal antibodies confirmed that all three proteins are localized to the peroxisomal cluster. Immunoblotting experiments demonstrated that peroxisomal membrane as well as matrix proteins are induced by methanol.  相似文献   
34.
Microtubules are prominent cellular components of the mechanosensory and chemosensory sensilla associated with the insect cuticle, and a range of hypotheses have been proposed to account for their role in sensory transduction. Chemical agents such as colchicine and vinblastine, which dissociate microtubules, also interfere with transduction in these sensilla, and this has been attributed to their anti-microtubule activity. We have now examined the dynamic properties of sensory transduction in the mechanosensitive neuron of the cockroach femoral tactile spine, after the application of colchicine, vinblastine and lumicolchicine. Concurrently we have examined the ultrastructure of the same sensory ending by transmission electron microscopy. All of the drugs reduced the mechanical sensitivity o the receptor. Colchicine and vinblastine achieved this reduction without altering the dynamic properties of the receptor but lumicolchicine changed the dynamic response, and increased the relative sensitivity to rapid movements. Conduction velocity, another measure of neuronal function, which relies upon ionic currents flowing through the membrane, was reduced by all three drugs. The effects of the drugs upon the ultrastructure of the sensory ending were also disparate. In the case of colchicine there was complete dissociation of microtubules in the tubular body and distal dendrite before a total loss of mechanical sensitivity. Vinblastine was less effective in dissociating microtubules, although more effective in the reduction of mechanical sensitivity. With lumicolchicine the dominant morphological effect was a severe disruption of the dendritic membrane. We conclude from these experiments that microtubules are not essential in the transduction of mechanical stimuli by cuticular receptors and that the effects of these drugs upon mechanosensitivity are not directly related to their dissociation of the microtubules in the tubular body, but are more likely to arise from actions upon the cell membrane. These actions could include effects upon tubulin in the membrane or upon other membrane components.  相似文献   
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Hematein-free hematoxylin (HFH) was prepared by a modification of the procedure of Palmer and Lillie (Histochemie, 5: 44-54, 1965). Fifty mg of HFH were dissolved in 5 mg of ethylene glycol and then 45 nil of an aqueous solution of 2.25 gm KAl(SO4)2. 12H2O and 5.445 mg KIO3 were added. Since this amount of KIO3 would be sufficient to oxidize 25 mg of HFH to hematein we have termed this half-oxidized hematoxylin (HOH). The peak absorbance (560 nm) of this purple solution remained constant for at least a week. With omission of the KIO3 the solution was colorless. A curve was constructed by plotting absorbance against concentration of hematein in HOH at various dilutions. For analyses of hematein content of commercial hematoxylins 50 mg of sample and 100 mg of hydroquinone were dissolved in 5 ml of ethylene glycol and then 45 ml of a 5% solution of KAl(SO4)2. 12H2O were added. The addition of the hydroquinone stabilized the absorbance for about 5 min. The hematein content could then be calculated by comparing the observed absorbance with the standard curve. Eleven samples of hematoxylin certified by the Biological Stain Commission had hematein concentrations varying from 0.01 to 0.43%. For analyses of the available hematein content of commercial hemateins, 50 mg of sample were dissolved in 10 ml of ethylene glycol, then 45 ml of water and 45 ml of 5% KAI(SO4)2. 12H2O added. The hematein content could then be calculated by comparing the observed absorbance with the standard curve. In 9 samples of hematein from 4 different sources the active hematein content varied from 19 to 97%.  相似文献   
39.
Preparative isolation of phosphatidyl serine from brain   总被引:3,自引:0,他引:3  
  相似文献   
40.
Leucine aminopeptidase in extracts of swine muscle   总被引:4,自引:1,他引:3       下载免费PDF全文
1. Leucine aminopeptidase (EC 3.4.1.1) has been demonstrated in swine muscle at a level of activity one-fifth that of the swine kidney. 2. The enzyme has been purified 110-fold by precipitation with ammonium sulphate, heat treatment and chromatography on Sephadex G-100. 3. The enzyme is heat-stable, but is rapidly inactivated below pH7. It requires Mg(2+) or Mn(2+) for activity. The Michaelis constant for leucine amide with Mg(2+)-activated enzyme is 5.0x10(-3)m. 4. Muscle leucine aminopeptidase is very similar to the kidney enzyme.  相似文献   
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