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排序方式: 共有596条查询结果,搜索用时 218 毫秒
591.
Alisha Kellner Michael Taylor Tuhina Banerjee Christopher B.T. Britt Ken Teter 《Cellular microbiology》2019,21(10)
Cholera toxin (Ctx) is an AB‐type protein toxin that acts as an adenosine diphosphate (ADP)‐ribosyltransferase to disrupt intracellular signalling in the target cell. It moves by vesicle carriers from the cell surface to the endoplasmic reticulum (ER) of an intoxicated cell. The catalytic CtxA1 subunit then dissociates from the rest of the toxin, unfolds, and activates the ER‐associated degradation system for export to the cytosol. Translocation occurs through an unusual ratchet mechanism in which the cytosolic chaperone Hsp90 couples CtxA1 refolding with CtxA1 extraction from the ER. Here, we report that Hsp90 recognises two peptide sequences from CtxA1: an N‐terminal RPPDEI sequence (residues 11–16) and an LDIAPA sequence in the C‐terminal region (residues 153–158) of the 192 amino acid protein. Peptides containing either sequence effectively blocked Hsp90 binding to full‐length CtxA1. Both sequences were necessary for the ER‐to‐cytosol export of CtxA1. Mutagenesis studies further demonstrated that the RPP residues in the RPPDEI motif are required for CtxA1 translocation to the cytosol. The LDIAPA sequence is unique to CtxA1, but we identified an RPPDEI‐like motif at the N‐ or C‐termini of the A chains from four other ER‐translocating toxins that act as ADP‐ribosyltransferases: pertussis toxin, Escherichia coli heat‐labile toxin, Pseudomonas aeruginosa exotoxin A, and Salmonella enterica serovar Typhimurium ADP‐ribosylating toxin. Hsp90 plays a functional role in the intoxication process for most, if not all, of these toxins. Our work has established a defined RPPDEI binding motif for Hsp90 that is required for the ER‐to‐cytosol export of CtxA1 and possibly other toxin A chains as well. 相似文献
592.
A G Britt C L Cotton B H Kellett I H Pitman J A Trask 《Australian journal of biological sciences》1985,38(2):165-174
Light-microscopic examination of frozen sections of skin taken from the dorsal thoraco-lumbar region of Australian Merino sheep in winter revealed that the thickness of the epidermis plus a sudanophilic layer was 24.9 micron in the interfollicular region. The uncornified epidermis (10.9 micron) was separated from the sudanophilic layer (14.0 micron) by a thin stratum corneum. It was concluded that the bulk of the sudanophilic layer was emulsified sebum in which was embedded a disorganized collection of desquamated cornified cells. Although large variances were observed in the thickness of the uncornified epidermis and of the sudanophilic layers between sheep and both within the between blocks of tissue obtained from individual sheep, there were no strong seasonal effects on either epidermal structure or layer thickness over a 12-month period. These results suggest that the Australian Merino differs from Finnish Landrace X Dorset Horn ewes, which are reported to possess, at least in winter, a thicker uncornified epidermis and a thicker stratum corneum that could be divided into two zones and was uniformly permeated by lipid. 相似文献
593.
Frank E. Zachos Dusko Cirovic Julia Kirschning Marthe Otto Günther B. Hartl Britt Petersen Ann-Christin Honnen 《Biochemical genetics》2009,47(3-4):241-250
We analyzed 121 golden jackals (Canis aureus) from six sample sites in Serbia with regard to genetic variability and differentiation as revealed by mitochondrial control region sequences and eight nuclear microsatellite loci. There was no variation at all in the mtDNA sequences, and nuclear variability was very low (average observed and expected heterozygosity of 0.29 and 0.34, respectively). This is in line with the considerable recent range expansion of this species in the Balkans and indicates a strong founder effect in the recently established Serbian population. We did not find evidence of differentiation between the northeastern jackals and those from the plain of Srem or those in between. F-statistics and Bayesian Structure analyses, however, were indicative of a low degree of overall differentiation in the Serbian population. A vagrant Austrian jackal that was also analyzed was genetically indistinguishable from its Serbian conspecifics. 相似文献
594.
Marie-Thérese Cerceau-Larrival Siwert Nilsson Anne Cauneau-Pigot Britt Berggren Lise Derouet Anne-Marie Verhille 《Grana》2013,52(2):532-545
Pollen material of the two anemophilous plants of known allergic significance Dactylis glomerata (Poaceae) and Betula verrucosa (Betulaceae) was collected at several places (in Sweden and France) and exposed to natural or experimental conditions. This material was analyzed with Electron Probe X Microanalysis (EPMA) (System ORTEC 5000) attached to a Scanning Electron Microscope (Jeol JMS 35), or with EDAX, a 10000 X-Ray Analyser, Link System, connected to a SEM-microscope (Jeol JSM 820). It is clear that the environment has an effect on such a co-inductor or adjuvant of allergenicity as K. The possible presence of pollutant inorganic (mineral) particles on the pollen grain surface may play a role in the allergenic activity. Pollen, consequently, may be used as sensitive biological indicators of atmospheric pollution. 相似文献
595.
596.
Although exposure to stressors is known to increase disease susceptibility and accelerate ageing, evidence is accumulating that these effects can span more than one generation. Stressors experienced by parents have been reported to negatively influence the longevity of their offspring and even grand offspring. The mechanisms underlying these long-term, cross-generational effects are still poorly understood, but we argue here that telomere dynamics are likely to play an important role. In this review, we begin by surveying the current connections between stress and telomere dynamics. We then lay out the evidence that exposure to stressors in the parental generation influences telomere dynamics in offspring and potentially subsequent generations. We focus on evidence in mammalian and avian studies and highlight several promising areas where our understanding is incomplete and future investigations are critically needed. Understanding the mechanisms that link stress exposure across generations requires interdisciplinary studies and is essential to both the biomedical community seeking to understand how early adversity impacts health span and evolutionary ecologists interested in how changing environmental conditions are likely to influence age-structured population dynamics. 相似文献