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P P Mortimer 《BMJ (Clinical research ed.)》1987,294(6587):1602-1605
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The effect of added monoacylglycerols on the removal from plasma of chylomicron-like emulsions injected intravenously in rats 总被引:1,自引:0,他引:1
B C Mortimer W J Simmonds C A Joll R V Stick T G Redgrave 《Biochimica et biophysica acta》1989,1002(3):359-364
Lipid emulsions were prepared with compositions similar to the triacylglycerol-rich plasma lipoproteins, but also incorporating added small amounts of monoacylglycerols. Control emulsions without monoacylglycerol were metabolized similarly to natural chylomicrons or very-low-density lipoproteins when injected intravenously in rats. The emulsion triacylglycerols and cholesteryl esters were both removed rapidly from the bloodstream, with the removal rates of triacylglycerols faster than those of cholesteryl esters. Much of the removed cholesteryl ester was found in the liver, but only a small fraction of the triacylglycerol, consistent with hepatic uptake of the triacylglycerol-depleted remnants of the injected emulsion. Emulsions incorporating added monooleoylglycerol or stearic acid were metabolized similarly. Added 1- or 2-monostearoylglycerol had no effect on triacylglycerol removal from plasma, but the removal rate of cholesteryl esters was decreased and less cholesteryl ester was found in the liver. These effects are similar to those recently described when emulsions and chylomicrons contained triacylglycerols with a saturated acyl chain at the glycerol 2-position, suggesting that saturated monoacylglycerol produced by the action of lipoprotein lipase may cause triacylglycerol-depleted remnant particles to remain in the plasma instead of being rapidly taken up by the liver. 相似文献
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Lipid emulsions were prepared with a similar size and lipid composition to natural lymph chylomicrons, but in which the surface phospholipid was either egg phosphatidylcholine, dioleoyl-, dimyristoyl-, dipalmitoyl- or 1-palmitoyl-2-oleoylphosphatidylcholine (EYPC, DOPC, DMPC, DPPC or POPC). When injected into the bloodstream of conscious rats, the emulsions containing EYPC or POPC were metabolized similarly to natural chylomicrons, consistent with rapid lipoprotein lipase-mediated hydrolysis of triacylglycerols, followed by hepatic uptake of the remnants derived from the emulsions. Phospholipids from the injected emulsions were removed more slowly and became associated with the high-density lipoprotein fractions of the plasma. Emulsions containing DPPC were metabolized differently. Triacylglycerols disappeared very slowly from plasma, indicating lack of hydrolysis by lipoprotein lipase, and phospholipid radioactivity did not transfer to high-density lipoprotein. With emulsions containing DMPC, the plasma removal rates for emulsion triacylglycerols and cholesteryl esters were fast, but phospholipid radioactivity failed to transfer to the high-density lipoprotein fractions of plasma. With DOPC emulsions, clearances were slower than EYPC or POPC emulsions, but transfer to high-density lipoproteins was efficient. Therefore, an unsaturated chain at the glycerol 2-position was necessary for rapid hydrolysis by lipoprotein lipase and for efficient transfer of phospholipids to high-density lipoproteins. With an unsaturated chain at the glycerol 2-position, a saturated chain at the glycerol 1-position optimized the rate of remnant removal from the plasma. 相似文献
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We have constructed a genealogy of strain S288C, from which many of the mutant and segregant strains currently used in studies on the genetics and molecular biology of Saccharomyces cerevisiae have been derived. We have determined that its six progenitor strains were EM93, EM126, NRRL YB-210 and the three baking strains Yeast Foam, FLD and LK. We have estimated that approximately 88% of the gene pool of S288C is contributed by strain EM93. The principal ancestral genotypes were those of segregant strains EM93-1C and EM93-3B, initially distributed by C. C. Lindegren to several laboratories. We have analyzed an isolate of a lyophilized culture of strain EM93 and determined its genotype as MATa/MATα SUC2/SUC2 GAL2/gal2 MAL/MAL mel/mel CUP1/cup1 FLO1/flo1. Strain EM93 is therefore the probable origin of genes SUC2, gal2, CUP1 and flo1 of S288C. We give details of the current availability of several of the progenitor strains and propose that this genealogy should be of assistance in elucidating the origins of several types of genetic and molecular heterogeneities in Saccharomyces. 相似文献
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A Mapping Method for SACCHAROMYCES CEREVISIAE Using rad52-Induced Chromosome Loss 总被引:3,自引:2,他引:1 下载免费PDF全文
Saccharomyces cerevisiae diploids homozygous for the rad52-1 mutation have previously been shown to lose chromosomes mitotically. Spontaneous events and events following low levels of X-ray or methyl methanesulfonate treatment result in monosomic diploids, whereas higher levels of treatment result in near haploidization. This rad52-1-dependent chromosome loss has been used to develop a new mapping method which can be used to assign a previously unmapped gene to a chromosome. Chromosome loss mapping can be done in either of two ways: if a diploid, homozygous for rad52-1 but heterozygous for a variety of other recessive markers, is constructed with an unmapped recessive mutation in coupling with known chromosomal markers, chromosome loss will result in the coordinate expression of the mutation and other recessive markers on the same chromosome; if, however, the diploid is constructed with the unmapped mutation in repulsion to chromosomal markers, then even haploidization will never result in the coordinate expression of the unmapped mutation and other markers on the same homologous chromosome pair--This mapping method and subsequent tetrad analyses have been used to locate hom6 on chromosome X, ade4 on chromosome XIII and cdc31 on chromosome XV and to demonstrate that met5, previously assigned to chromosome V, actually maps to chromosome X; the met- marker on chromosome V has been shown to be met6. GAL80 and SUP5, previously assigned to an unmapped fragment, have now been mapped to the right arm of chromosome XIII. 相似文献
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STUDIES IN EXPERIMENTAL EOSINOPHILIA : VI. Uptake of Immune Complexes by Eosinophils 总被引:11,自引:1,他引:10 下载免费PDF全文
Mortimer Litt 《The Journal of cell biology》1964,23(2):355-361
A method is described whereby immune complexes may be visualized in a single cell. Bovine serum albumin labeled with a red-fluorescing dye was joined to a rabbit antiserum labeled with a green-fluorescing dye to yield an immune complex which fluoresced yellow when illuminated by ultraviolet light. Such yellow-fluorescing immune complexes were injected into the peritoneal cavity of guinea pigs, and the peritoneal exudates were examined subsequently. Yellow fluorescent particles were seen in eosinophils obtained from guinea pigs sensitized to hemocyanin and from normal animals. Eosinophils of the blood and of the bone marrow could also take up the complexes in vitro. Neither antigen nor antibody alone was taken up by eosinophils, nor was a mixture of labeled antigen and labeled normal globulin. Similar observations were made with human blood eosinophils. These experiments suggest that eosinophils act as part of the defense against the pathogenic effects of certain immune complexes. 相似文献