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61.
Michael D.Guiver Dae-Sik Kim Gilles P.Robertson Yu Seung Kim Bryan S.Pivovar 《复旦学报(自然科学版)》2007,46(5)
1 Results Hydrocarbon PEM materials are being widely studied as replacements for Nafion-type perfluorinated polymeric materials to reduce cost and improve performance such as operating temperature and methanol crossover in the DMFC application. Among some of the important property considerations required are thermal and chemical stability, low dimensional swelling, low methanol permeability in the case of DMFC and high proton conductivity. Careful structural design can reduce the effect of swelling as... 相似文献
62.
Novel putative receptor tyrosine kinase encoded by the melanoma-inducing Tu locus in Xiphophorus 总被引:12,自引:0,他引:12
J Wittbrodt D Adam B Malitschek W M?ueler F Raulf A Telling S M Robertson M Schartl 《Nature》1989,341(6241):415-421
Malignant melanoma in Xiphophorus fish hybrids is caused by the activity of a dominant oncogene Tu. By combining genetic and molecular approaches, we have isolated the melanoma oncogene. We show that its level of expression correlates with the degree of malignancy of the tumour. The corresponding proto-oncogene is developmentally regulated. The Tu gene codes for a novel receptor tyrosine kinase which is closely related to the receptor for epidermal growth factor. 相似文献
63.
64.
The elongation factors EF-Tu and EF-G interact with ribosomes during protein synthesis: EF-Tu presents incoming aminoacyl transfer RNA to the programmed ribosome as an EF-Tu-GTP-tRNA ternary complex and EF-G promotes translocation of peptidyl-tRNA and its associated messenger RNA from the A to the P site after peptidyl transfer. Both events are accompanied by ribosome-dependent GTP hydrolysis. Here we use chemical probes to investigate the possible interaction of these factors with ribosomal RNA in E. coli ribosomes. We observe EF-G-dependent footprints in vitro and in vivo around position 1,067 in domain II of 23S rRNA, and in the loop around position 2,660 in domain VI.EF-Tu gives an overlapping footprint in vitro at positions 2,655 and 2,661, but shows no effect at position 1,067. The 1,067 region is the site of interaction of the antibiotic thiostrepton, which prevents formation of the EF-G-GTP-ribosome complex and is a site for interaction with the GTPase-related protein L11 (ref. 3). The universally conserved loop in the 2,660 region is the site of attack by the RNA-directed cytotoxins alpha-sarcin and ricin, whose effects abolish translation and include the loss of elongation factor-dependent functions in eukaryotic ribosomes. 相似文献
65.
Bacteriophage coat protein as repressor 总被引:9,自引:0,他引:9
66.
The surround response mechanism in on-center X-cells in cat retina was found to be bimodally distributed and weak or nonexistent in the receptive field middle. An on-inhibition measure was used to assess surround mechanism gain. 相似文献
67.
The adaptation field of the surround mechanism of X and Y retinal ganglion cells in the cat was assessed with variable size, unmodulated adapting spots. Both an on-inhibition measure and an off-discharge measure of surround gain was used. Results suggest that the surround mechanism in Y-cells is strongest in the receptive field middle but weak or nonexistent in the middle of X-cell receptive fields. 相似文献
68.
69.
Germ-line transmission of genes introduced into cultured pluripotential cells by retroviral vector 总被引:62,自引:0,他引:62
Embryonic stem cells isolated directly from mouse embryos can be cultured for long periods in vitro and subsequently repopulate the germ line in chimaeric mice. During the culture period these embryonic cells are accessible for experimental genetic manipulation. Here we report the use of retroviral vectors to introduce exogenous DNA sequences into a stem-cell line and show that these modified cells contribute extensively to the somatic and germ-cell lineages in chimaeric mice. Compared with current methods for manipulation of the mouse genome, this approach has the advantage that powerful somatic-cell genetic techniques can be used to modify and to select cells with germ-line potential, allowing the derivation of transgenic strains with pre-determined genetic changes. We have by this means inserted many proviral vector sequences that provide new chromosomal molecular markers for linkage studies in the mouse and that also may cause insertional mutations. 相似文献
70.
Alastair S. Robertson Elizabeth Smythe Kathryn R. Ayscough 《Cellular and molecular life sciences : CMLS》2009,66(13):2049-2065
Endocytosis is a fundamental eukaryotic process required for remodelling plasma-membrane lipids and protein to ensure appropriate
membrane composition. Increasing evidence from a number of cell types reveals that actin plays an active, and often essential,
role at key endocytic stages. Much of our current mechanistic understanding of the endocytic process has come from studies
in budding yeast and has been facilitated by yeast’s genetic amenability and by technological advances in live cell imaging.
While endocytosis in metazoans is likely to be subject to a greater array of regulatory signals, recent reports indicate that
spatiotemporal aspects of vesicle formation requiring actin are likely to be conserved across eukaryotic evolution. In this
review we focus on the ‘modular’ model of endocytosis in yeast before highlighting comparisons with other cell types. Our
discussion is limited to endocytosis involving clathrin as other types of endocytosis have not been demonstrated in yeast. 相似文献