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71.
Phalloidin-induced accumulation of myosin in rat hepatocytes is caused by suppression of autolysosome formation 总被引:1,自引:0,他引:1
T Ueno S Watanabe M Hirose T Namihisa E Kominami 《European journal of biochemistry》1990,190(1):63-69
Administration of phalloidin in vivo to rats causes marked changes in the distribution of actin and myosin in hepatocytes, which accompanies reduced bile flow. We have found that in hepatocytes treated with phalloidin for 3 and 7 days, cellular myosin content increased about 1.5-fold and 4.7-fold, respectively. In addition, total cell protein content and several marker enzyme activities were also elevated by 30-120% depending on the duration of phalloidin treatment. These observations allow us to speculate that phalloidin somehow elicits inhibition of cellular protein degradation, which results in the increase of these protein levels. To examine this possibility further, we analyzed leupeptin-induced density shift of phagolysosomes. In normal liver, the injection of leupeptin/E64c caused an increase in the density of both heterolysosomes and autolysosomes, due to retarded digestion of sequestered proteins as a result of the inhibition of lysosomal cathepsins. Accumulation, in these denser autolysosomes, of lactic dehydrogenase, pyruvate kinase, aldolase, and myosin was demonstrated by enzyme assays and immunoblot analysis. In the phalloidin-treated liver, the increase in the density of autolysosomes and the accumulation of above cytoplasmic enzymes were markedly inhibited. However, phalloidin did not affect the shift in the density of heterolysosomes. From these data, we concluded that autolysosome formation was specifically hindered in phalloidin-treated rat hepatocytes, which results in the reduction of autophagic protein degradation and eventual increase in intracellular protein levels. 相似文献
72.
Kenzo Yokozeki Shigeru Yamanaka Koichi Takinami Yoshio Hirose Atsuo Tanaka Kenji Sonomoto Saburo Fukui 《Applied microbiology and biotechnology》1982,14(1):1-5
Summary Lipase from Rhizopus delemar was immobilized by entrapment with photo-crosslinkable resin prepolymers or urethane prepolymers or by binding to various types of porous silica beads. The immobilized lipase preparations thus obtained were examined for their activity in converting olive oil to an interesterified fat (cacao butter-like fat), whose oleic acid moieties at 1- and 3-positions were replaced with stearic acid moieties, in the reaction solvent n-hexane. Although all of the immobilized preparations exhibited some activity, lipase adsorbed on Celite and then entrapped with a hydrophobic photo-crosslinkable resin prepolymer showed the highest activity, about 75% of that of lipase simply adsorbed onto Celite. Entrapment markedly enhanced the operational stability of lipase.Dedicated to Professor H. Holzer, Freiburg University, on his 60th birthday (June 13, 1981) 相似文献
73.
Subcellular Localization of Sorbitol-6-phosphate Dehydrogenase in Protoplast from Apple Cotyledons 总被引:1,自引:0,他引:1
The subcellular localization of sorbitol-6-phosphate (S6P) dehydrogenasein protoplasts of apple cotyledons was examined by differentialcentrifugation and linear sucrose density gradient centrifugation(3060%, w/w). The distribution of S6P dehydrogenase activitywas 55% in the 500 x g pellet of the homogenate and 35% in thesupernatant of 105,000 x g. When the x g pellet was recentrifugedin a linear sucrose density gradient, one major peak of activitywas found at a density of 1.23. This peak coincided with themajor peak of chlorophyll and NADP+-triose-P dehydrogenase activity.When the 500 x g pellet was sonicated, the major peak of S6Pdehydrogenase activity shifted to a lighter density (d=1.18).The shifted peak also coincided with the peak of chlorophyll.The enzyme detected in the major peak of chlorophyll (d=1.23)was partially solubilized by sonic or detergent treatment, butnot by hypotonic solution. The results supported the localizationof S6P dehydrogenase in chloroplasts, and presumably their associationwith thylakoid membranes. Part of the enzyme was assumed tobe naturally present in the cytosol, too. (Received November 4, 1980; Accepted January 21, 1981) 相似文献
74.
A new type of sorbitol oxidase which converts sorbitol to glucosein the absence of NAD or NADP was found in the leaf of the apple.The partially purified enzyme consumed 1/2 mole of oxygen inconverting one mole of sorbitol to glucose (sorbitol+1/2 O2 glucose+H2O). The enzyme had its optimum activity at pH 4.0,and it had a Km value of 100 mM for sorbitol and showed a weakdependency on divalent cations. This sorbitol oxidase seemsto play an important role in the utilization of accumulatedsorbitol.
1This paper is contribution A-109, Fruit Tree Research Station (Received March 15, 1980; ) 相似文献
75.
M Kitada K Igarashi S Hirose H Kitagawa 《Biochemical and biophysical research communications》1979,87(2):388-394
Both NADPH- and ascorbic acid-dependent lipid peroxidations were inhibited by spermine, the degree of inhibition being greater with the former peroxidation. The effective concentration of spermine required for inhibition was higher when larger amounts of microsomes were used. However, the activities of NADPH-cytochrome c reductase and NADPH-peroxidase were not influenced by spermine. These results suggest that spermine inhibits lipid peroxidation by binding to phospholipids in the microsomes. 相似文献
76.
K Igarashi K Kashiwagi R Aoki M Kojima S Hirose 《Biochemical and biophysical research communications》1979,91(2):440-448
In the presence of polyamines, the fidelity of protein synthesis in a wheat germ cell-free system was increased significantly, while it was increased slightly in an cell-free system. The effective concentration of polyamines for the increase in fidelity of protein synthesis was nearly equal to that for the stimulation of protein synthesis in a wheat germ cell-free system. 相似文献
77.
K Igarashi M Tanaka K Eguchi S Hirose 《Biochemical and biophysical research communications》1978,83(1):274-280
It is shown that rat liver isoleucyl-tRNA formation in the presence of Mg2+ is inhibited by poly(G), poly(I) or ribosomes and that this inhibition is prevented by polyamines. The inhibition is found to be noncompetitive with respect to tRNA. 相似文献
78.
K Igarashi H Kumagai Y Watanabe N Toyoda S Hirose 《Biochemical and biophysical research communications》1975,67(3):1070-1077
The activities of ribonucleases (RNase HS and RNase A), which hydrolyze ribonucleic acid at linkages attached to pyrimidine nucleotides were stimulated by polyamines, while the activities of ribonucleases (RNase T1 and RNase M), which attack ribonucleic acid at linkages attached to purine nucleotides were not influenced by polyamines. In the presence of polyamines, the cleavage of C5′-O-P linkages adjacent to cytosine nucleotide was stimulated, while the cleavage of C5′-O-P linkages adjacent to uracil nucleotides was inhibited slightly. The effect of polyamines on the activities of ribonucleases occured through the binding of the polyamines to nucleic acid. 相似文献
79.
80.
Phosphorylation of mononucleotides and formation of cytidine 5''-diphosphate-choline and sugar nucleotides by respiration-deficient mutants of yeasts.
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Respiration-deficient mutants (Rho-, petite) of Saccharomyces carlsbergensis were obtained by treatment with trypaflavin (euflavine). Dried cells of these mutants phosphorylated mononucleotides to their triphosphates and further formed not only cytidine 5'-diphosphate-choline, but also sugar nucleotides, such as uridine 5'-diphosphate-glucose, guanosine 5'-diphosphate-mannose, etc. The activities were the same or slightly greater than those of the wild strain. These results showed that energy (adenosine 5'-triphosphate) necessary for phosphorylation of mononucleotides was sufficiently supplied by the glycolysis system. 相似文献