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101.
The artifactual nature of fluoride inhibition of reverse transcriptase and associated ribonuclease H
S K Srivastava E Gillerman M J Modak 《Biochemical and biophysical research communications》1981,101(1):183-188
Surprisingly, the -1 configuration of 1-0-hexadecyl-2-acetyl-glycerylphosphorylcholine showed significant activity, 3.22 × 10?9 M, when compared to the -3 enantiomer, 2.92 × 10?10 M and a racemic mixture with a value of 7.2 × 10?10 M. A methoxy substitution at the C-1 or C-2 position of octadecyl glycerylphosphorylcholine gave a derivative with high biological activity for stimulating serotonin release from rabbit platelets. A 1-0-dodecyl-2-methoxy analogue showed very low activity; also, a comparable series of 0-benzyl derivatives were inactive. Examination of 1-0-hexadecyl, 1-0-octadecyl- or 1-0-dodecyl-2-acetyl--glyceryl-3-phosphorylcholine showed that the hexadecyl compound had three times the biological activity of the octadecyl and five times that of the dodecyl. 相似文献
102.
Genomic structure, mapping, and expression analysis of the mammalian Lunatic, Manic, and Radical fringe genes 总被引:3,自引:0,他引:3
Jennifer L. Moran Stuart H. Johnston Cordelia Rauskolb Jayant Bhalerao Anne M. Bowcock Thomas F. Vogt 《Mammalian genome》1999,10(6):535-541
The three members of the mammalian fringe gene family, Manic fringe (Mfng), Radical fringe (Rfng), and Lunatic fringe (Lfng), were identified on the basis of their similarity to Drosophila fringe (fng) and their participation in the evolutionarily conserved Notch receptor signaling pathway. Fringe genes encode pioneer secretory
proteins with weak similarity to glycosyltransferases. Both expression patterns and functional studies support an important
role for Fringe genes in patterning during embryonic development and an association with cellular transformation. We have
now further characterized the expression and determined the chromosomal localization and genomic structure of the mouse Mfng, Rfng, and Lfng genes; the genomic structure and conceptual open reading frame of the human RFNG gene; and the refined chromosomal localization
of the three human fringe genes. The mouse Fringe genes are expressed in the embryo and in adult tissues. The mouse and human
Fringe family members map to three different chromosomes in regions of conserved synteny: Mfng maps to mouse Chr 15, and MFNG maps to human Chr 22q13.1 in the region of two cancer-associated loci; Lfng maps to mouse Chr 5, and LFNG maps to human Chr 7p22; Rfng maps to mouse Chr 11, and RFNG maps to human Chr 17q25 in the minimal region for a familial psoriasis susceptibility locus.
Characterization of the genomic loci of the Fringe gene family members reveals a conserved genomic organization of 8 exons.
Comparative analysis of mammalian Fringe genomic organization suggests that the first exon is evolutionarily labile and that
the Fringe genes have a genomic structure distinct from those of previously characterized glycosyltransferases.
Received: 19 February 1999 / Accepted: 22 February 1999 相似文献
103.
A procedure to measure exchange rates of fast exchanging protein amide hydrogens by time-resolved NMR spectroscopy following in situ initiation of the reaction by diluting a native protein solution into an exchanging deuterated buffer is described. The method has been used to measure exchange rates of a small set of amide hydrogens of reduced cytochrome c, maintained in a strictly anaerobic atmosphere, in the presence of an otherwise inaccessible range of guanidinium deuterochloride concentrations. The results for the measured protons indicate that hydrogen exchange in the unfolding transition region of cytochrome c reach the EX2 limit, but emphasize the difficulty in interpretation of the exchange mechanism in protein hydrogen exchange studies. Comparison of free energies of structure opening for the measured hydrogens with the global unfolding free energy monitored by far-UV CD measurements has indicated the presence of at least one partially unfolded equilibrium species of reduced cytochrome c. The results provide the first report of measurement of free energy of opening of structure to exchange in the 0–2-kcal/mol range. Proteins 32:241–247, 1998. © 1998 Wiley-Liss, Inc. 相似文献
104.
Shilling RA Pinto JM Decker DC Schneider DH Bandukwala HS Schneider JR Camoretti-Mercado B Ober C Sperling AI 《Journal of immunology (Baltimore, Md. : 1950)》2005,175(4):2061-2065
The establishment of ICOS as an important regulator of Th2 development and effector function makes the ICOS locus an attractive candidate for Th2-mediated diseases, such as asthma and allergy. In evaluation of this candidate locus in humans, we identified 11 variants and determined that two in the putative promoter region are significantly associated with allergic sensitization and serum IgE levels. In addition, cultures of activated PBMCs from individuals homozygous for the associated polymorphisms produced increased levels of the Th2 cytokines, IL-4, IL-5, and IL-13, as well as TNF-alpha compared with controls. One of the polymorphisms, -1413G/A, demonstrated differential NF-kappaB binding in mobility shift analysis, suggesting that this polymorphism has functional consequences. Overall, these data demonstrate that ICOS is a susceptibility gene for allergic sensitization, perhaps through the promotion of Th2 differentiation. 相似文献
105.
106.
Terminal deoxynucleotidyltransferase is the only DNA polymerase that is strongly inhibited in the presence of ATP. We have labeled calf terminal deoxynucleotidyltransferase with [32P]ATP in order to identify its binding site in terminal deoxynucleotidyltransferase. The specificity of ATP cross-linking to terminal deoxynucleotidyltransferase is shown by the competitive inhibition of the overall cross-linking reaction by deoxynucleoside triphosphates, as well as the ATP analogs Ap4A and Ap5A. Tryptic peptide mapping of [32P]ATP-labeled enzyme revealed a peptide fraction that contained the majority of cross-linked ATP. The properties, chromatographic characteristics, amino acid composition, and sequence analysis of this peptide fraction were identical with those found associated with dTTP cross-linked terminal deoxynucleotidyl-transferase peptide (Pandey, V. N., and Modak, M. J. (1988a). J. Biol. Chem. 263, 3744-3751). The involvement of the same 2 cysteine residues in the crosslinking of both nucleotides further confirmed the unity of the ATP and dTTP binding domain that contains residues 224-237 in the primary amino acid sequence of calf terminal deoxynucleotidyltransferase. 相似文献
107.
108.
Ethanol-fixed lens sections were incubated with calf-thymus terminal deoxynucleotidyl transferase and 3H-dATP, and the time-course of 3H-dAMP incorporation was compared among various lens cell types by quantitative autoradiography. The data show that the proportion of cell nuclei containing DNA with single-strand breaks increases during fiber cell differentiation, and that the relative number of breaks per nucleus or unit nuclear area also increase in the same sequence. 相似文献
109.
The composition of soluble eye lens proteins from four chondropterygiian and fourteen teleostean fishes were analyzed for heterogeneity in MW and pI. Lens proteins from all the fish species studies are distributed in the pI range 4.3-9.0 with polypeptides in the range 17,500-31,000 Da. Phylogenetic trees are constructed based on the observations. 相似文献
110.
Jayant Asthana Sonia Kapoor Renu Mohan Dulal Panda 《The Journal of biological chemistry》2013,288(31):22516-22526
The post-translational modification of tubulin appears to be a highly controlled mechanism that regulates microtubule functioning. Acetylation of the ϵ-amino group of Lys-40 of α-tubulin marks stable microtubules, although the causal relationship between tubulin acetylation and microtubule stability has remained poorly understood. HDAC6, the tubulin deacetylase, plays a key role in maintaining typical distribution of acetylated microtubules in cells. Here, by using tubastatin A, an HDAC6-specific inhibitor, and siRNA-mediated depletion of HDAC6, we have explored whether tubulin acetylation has a role in regulating microtubule stability. We found that whereas both pharmacological inhibition of HDAC6 as well as its depletion enhance microtubule acetylation, only pharmacological inhibition of HDAC6 activity leads to an increase in microtubule stability against cold and nocodazole-induced depolymerizing conditions. Tubastatin A treatment suppressed the dynamics of individual microtubules in MCF-7 cells and delayed the reassembly of depolymerized microtubules. Interestingly, both the localization of HDAC6 on microtubules and the amount of HDAC6 associated with polymeric fraction of tubulin were found to increase in the tubastatin A-treated cells compared with the control cells, suggesting that the pharmacological inhibition of HDAC6 enhances the binding of HDAC6 to microtubules. The evidence presented in this study indicated that the increased binding of HDAC6, rather than the acetylation per se, causes microtubule stability. The results are in support of a hypothesis that in addition to its deacetylase function, HDAC6 might function as a MAP that regulates microtubule dynamics under certain conditions. 相似文献