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1.
Sisinthy Shivaji 《Bioscience reports》1988,8(6):609-618
Proteins present in the seminal plasma of mammals are known to influence functions associated with ejaculated spermatozoa such as motility, capacitation, acrosome reaction and fertilising ability. The proteins isolated and characterised so far influence only one of the above functions of spermatozoa. Seminalplasmin, a protein isolated from the seminal plasma of bull is exceptional in that it influences many of the above spermatozoal functions. It is also a potent antimicrobial protein and capable of lysing microbial and mammalian cells. The physiological function of seminalplasmin as nature's own antifertility agent is discussed. 相似文献
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Changes in the cell surface of vaginal epithelial cells were studied by scanning microscopy and fluorescence spectroscopy. Microvilli which are prominent features of the vaginal epithelial cells in proestrus and diestrus are replaced by sheet-like structures in the estrus phase. Surface morphology of vaginal epithelial cells of estradiol primed rat resembles the vaginal cells from estrus phase rats whereas vaginal cells from control rats resembles the diestrus phase. Measurement of the fluidity of the membranes indicated that the vaginal epithelial cell membrane of estrus rats is more fluid compared to proestrus and diestrus. Similarly, estradiol primed immature rat vaginal epithelial cell membrane was observed to be more fluid than the corresponding control. 相似文献
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Phosphorylation of lipopolysaccharides in the Antarctic psychrotroph Pseudomonas syringae: a possible role in temperature adaptation. 下载免费PDF全文
Phosphorylation of lipopolysaccharide (LPS) from a psychrotrophic bacterium, Pseudomonas syringae, from Antarctica was studied by using sucrose gradient-separated membrane fractions. The bacterium was found to possess an LPS kinase which could phosphorylate more LPS postsynthetically at higher temperatures. The phosphorylation was low at a lower temperature and was also found to occur in vivo. After phosphorylation of LPS in vitro, it was found that the major part of the radioactivity (> 85%) was associated with the core oligosaccharide region of the LPS. The phosphate groups of this region are probably involved in the binding of metal ions, which could be removed by EDTA. The cells grown at the lower temperature probably contained fewer divalent cations because of the smaller amount of phosphate and thereby were more sensitive to EDTA. The cells were also more sensitive to cationic antibiotics at the lower temperature. A possible role of this differential phosphorylation of LPS in modulating the function of the outer membrane as a permeability barrier in the psychrotroph is discussed. 相似文献
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The psychrotrophic, dimorphic yeast Candida humicola, isolated from Antarctic soil, secretes an acidic protease into the medium. The secretion of this protease by C. humicola was found to be dependent on the composition of the medium. In YPD or yeast nitrogen base medium containing either amino acids or ammonium sulfate as the nitrogen source, the activity of the protease in the medium was low (basal level). However, when yeast nitrogen base medium was depleted of amino acids or ammonium sulfate and supplemented with proteins, the activity of the enzyme increased. The secretion of the enzyme was greater during exponential growth at low temperatures than during growth at higher temperatures. The purified protease had a molecular mass of 36,000 Da and was inhibited by pepstatin, iodoacetamide, and sodium dodecyl sulfate. Despite the prevalent cold temperatures in Antarctica, this extracellular protease of the psychrotrophic yeast C. humicola was active at temperatures ranging from 0 to 45 degrees C, with an optimum activity at 37 degrees C. 相似文献
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S Shivaji 《FEBS letters》1986,196(2):255-258
The binding of seminalplasmin, a protein secreted by the accessory sex glands of bull, to the plasma and outer acrosomal membrane of bovine spermatozoa was studied using three different fluorescent probes. 8-Anilino-1-naphthalenesulfonate fluorescence, pyrene excimer fluorescence and diphenylhexatriene fluorescence polarisation studies indicate that seminalplasmin binds to the spermatozoal membranes, and leads to an increase in the fluidity of both the plasma and the acrosomal membranes. Calcium was found to have no influence on the interaction of seminalplasmin with the spermatozoal membranes. These results suggest that protein(s) present in the seminal plasma could interact with spermatozoal membranes and increase their fluidity. 相似文献
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Kotakonda Arunasri Mohammed Adil Katari Venu Charan Chatterjee Suvro Seerapu Himabindu Reddy Sisinthy Shivaji 《PloS one》2013,8(3)
This study demonstrates the effects of simulated microgravity on E. coli K 12 MG1655 grown on LB medium supplemented with glycerol. Global gene expression analysis indicated that the expressions of hundred genes were significantly altered in simulated microgravity conditions compared to that of normal gravity conditions. Under these conditions genes coding for adaptation to stress are up regulated (sufE and ssrA) and simultaneously genes coding for membrane transporters (ompC, exbB, actP, mgtA, cysW and nikB) and carbohydrate catabolic processes (ldcC, ptsA, rhaD and rhaS) are down regulated. The enhanced growth in simulated gravity conditions may be because of the adequate supply of energy/reducing equivalents and up regulation of genes involved in DNA replication (srmB) and repression of the genes encoding for nucleoside metabolism (dfp, pyrD and spoT). In addition, E. coli cultured in LB medium supplemented with glycerol (so as to protect the cells from freezing temperatures) do not exhibit multiple stress responses that are normally observed when cells are exposed to microgravity in LB medium without glycerol. 相似文献