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991.
Roles of the Pribnow box in positive regulation of the ompC and ompF genes in Escherichia coli. 总被引:2,自引:2,他引:0
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The roles of the first base of the Pribnow box in positive regulation of the ompC and ompF genes were studied. G- and A-to-T substitutions of the first base of the ompC and ompF Pribnow boxes, respectively, resulted in a high-level functioning of the promoters in the ompR background. The level was further enhanced significantly in the ompR+ background. The effects of other substitutions were also studied. Based on these observations, the roles of the Pribnow box in the positive regulation are discussed. 相似文献
992.
T Ohtsuka M Ozawa T Okamoto M Uchida N Okamura S Ishibashi 《Journal of biochemistry》1987,101(4):897-903
Superoxide anion (O2-) production stimulated by concanavalin A (Con A) in guinea pig polymorphonuclear leukocytes (PMNL) was suppressed by addition of methyl-alpha-mannoside, a Con A inhibitor, and resumed upon readdition of Con A. The reversible change in the O2- production was assumed to reflect the change in NADPH oxidase activity measured for the 30,000 X g particulate fraction. The stimulation by Con A of the phosphorylation of 46K protein(s), as observed previously with several membrane-perturbing agents in parallel with an activation of NADPH oxidase in intact guinea pig PMNL (Okamura, N., et al. (1984) Arch. Biochem. Biophys. 228, 270-277), was also suppressed by methyl-alpha-mannoside and resumed upon readdition of Con A. Similar parallelism between the phosphorylation and NADPH oxidase activity was also observed in the case of stimulation by N-formyl-methionyl-leucyl-phenylalanine (FMLP) and phorbol 12-myristate 13-acetate (PMA), though both processes were reversible after the stimulation by FMLP but not reversible after that by PMA. Thus, such a parallelism observed in both intact PMNL and 30,000 X g particulate fraction indicates possible involvement of the protein phosphorylation in the regulation of the production of active oxygen metabolites in PMNL. 相似文献
993.
K Ozawa K Yabu-uchi K Yamanaka Y Yamashita S Nomura I Oku 《Applied and environmental microbiology》1983,45(5):1513-1518
The effect of oral administration of Streptococcus faecalis BIO-4R, an antibiotic-resistant lactic acid bacterium, on the intestinal flora of weanling piglets and cows reared on antibiotic-containing diet was investigated. Fourteen days after administration of the bacteria, the intestinal flora of the piglets was examined. Animals of the administered group had stabilized lactic flora such as bifidobacteria, streptococci, and lactobacilli, whereas most animals of control group had reduced lactic flora. On the other hand, abundant yeasts were detected from the cecum, colon, and feces of the control animals, but the levels were significantly lower in the animals given strain BIO-4R. The density of Salmonella in the intestine appeared to be reduced after the administration of strain BIO-4R. The number of BIO-4R cells was shown to be 10 times lower in the duodenum and jejunum than in the ileum, suggesting that strain BIO-4R might have grown transiently in the ileum. The similar trend toward stabilization of the lactic flora was also observed in cows after administration of BIO-4R. In addition, an antagonistic effect of the strain against yeasts and Salmonella was suggested. These findings indicate that the oral administration of strain BIO-4R is one of the useful methods whereby the potentially deleterious effect of antibiotics on the intestinal flora of farm animals may be minimized. 相似文献
994.
To determine the effects of S-Adenosyl methionine (AdoMet) on TSH receptor function and adenylate cyclase coupling, human thyroidal crude membrane fraction was pretreated with AdoMet and with S-Adenosyl homocysteine (AdoHcy), separately or in combination. 125I-TSH binding to the pretreated membrane and adenylate cyclase activity of the membrane were examined. In contrast to the reported effect of AdoMet on the decrease in GH binding to lactogenic receptor, AdoMet 0.5 mumoles/ml significantly increased the binding of TSH to the receptor by increasing the affinity of the binding, whereas it decreased the coupling of adenylate cyclase significantly. The effect of AdoMet was partially counteracted by the pretreatment of the membrane with AdoHcy. This effect of AdoMet is very similar to that of diamide previously reported. The result implies that the effect is due to an alteration in the tertiary structure of receptor protein triggered by methylation. 相似文献
995.
Zonal centrifugation has been used to isolate a fraction from bovine liver which appears to be derived from the Golgi apparatus. Morphologically, the fraction consists mainly of sacs and tubular elements. Spherical inclusions, probably lipoproteins, are occasionally seen in negative stains of this material. The preparation is biochemically unique. UDP-galactose:N-acetyl glucosamine, galactosyl transferase activity is concentrated about 40-fold in this fraction compared to the homogenate. Rotenone- or antimycin-insensitive DPNH- or TPNH- cytochrome c reductase activities are 60–80% of the level of activities found in microsomes. Purified organelles from bovine liver such as plasma membranes, rough microsomes, mitochondria and nuclei have negligible levels of galactosyl transferase. Some activity is present in smooth microsomes but at a level compatible with the possible presence of Golgi membranes in this fraction. The Golgi fraction does not contain appreciable amounts of enzymes such as ATPase, 5'-nucleotidase, glycosidase, glucose-6-phosphatase, acid phosphatase, or succinate-cytochrome c reductase. Similar fractions isolated from bovine epididymis also have very high levels of galactosyl transferase. The fraction is heavily osmicated when incubated for long periods of time at elevated temperatures, a characteristic property of Golgi membranes. 相似文献
996.
S Arii S Takahashi T Uozumi M Shibagaki H Takasan K Ozawa T Tobe 《Life sciences》1983,33(25):2473-2478
The incorporation of 3H-thymidine and 3H-leucine into the hepatocytes was studied, using cultured hepatocytes prepared from normal and pancreatectomized rats. (1) In the cultured hepatocytes prepared from 80% pancreatectomized rats, the incorporation of 3H-thymidine and 3H-leucine into hepatocytes remained unchanged compared with those of sham-operated controls. In contrast, in those from totally pancreatectomized rats, the incorporation of 3H-thymidine and 3H-leucine decreased to approximately 67% and 37% respectively of sham-operated controls. However, those returned to near normal in the cultured hepatocytes from totally pancreatectomized rats treated by 0.8 IU/kg of insulin. (2) The addition of insulin (10(-4) M) to the culture medium stimulated the incorporation of 3H-thymidine into cultured hepatocytes prepared from normal rats to 148% of controls. The insulin-stimulated incorporation was inhibited by the addition of glucagon to the culture medium. The combined addition of insulin and glucagon did not synergistically act on DNA synthesis. It is suggested that the portal blood insulin in the presence of more than 20% of the pancreas is imperative for maintaining spontaneous regeneration. 相似文献
997.
Kazue Ozawa Takatoshi Fujimoto Toshio Nakatani Motokazu Asano Hidehisa Aoyama Takayoshi Tobe 《Life sciences》1982,31(7):647-653
The changes in the energy charge (ATP+0.5ADP)/ (ATP+ADP+AMP) levels of the remnant liver were studied in relation to changes in the incorporation rate of methyl-3H-thymidine into DNA, the blood ratio of acetoacetate/β-hydroxybutyrate and indocyanine green (ICG) clearance in 70% hepatectomized rabbits. The energy charge levels of the remnant liver decreased rapidly to 0.767 from 0.856 of normal, despite a marked enhancement of mitochondrial phosphorylative activity, concomitant with the fall in blood ketone body ratio, before a maximal increase of DNA synthesis after hepatectomy. Blood ketone body ratio was correlated with hepatic energy charge (r=0.696, p<0.01). After a maximal increase of DNA synthesis, hepatic energy charge levels and the blood keton body ratios increased gradually to normal levels, concomitant with a rise in ICG clearance. Energy charge levels of the remnant liver can be evaluated by the blood ketone body ratio. 相似文献
998.
Voltage clamp analysis of two inward current mechanisms in the egg cell membrane of a starfish 总被引:20,自引:13,他引:7
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Ionic mechanisms of excitation were studied in the immature egg cell membrane of a starfish, Mediaster aequalis, by analyzing membrane currents during voltage clamp. The cell membrane shows two different inward current mechanisms. One is activated at a membrane potential of -55 approximately -50 mV and the other at -7 approximately -6 mV. They are referred to as channels I and II, respectively. A similar difference is also found in the membrane potential of half inactivation. Currents of the two channels can, therefore, be separated by selective inactivation. The currents of both channels depend on Ca++ (Sr++ or Ba++) but only the current of channel I depends on Na+. The time-course of current differs significantly between the two channels when compared at the same membrane potential. The relationship between the membrane current and the concentration of the permeant ions is also different between the two channels. The result suggests that channel II is a more saturable system. The sensitivity of the current to blocking cations such as Co++ or Mg++ is substantially greater in channel II than in channel I. Currents of both channels depend on the external pH with an apparent pK of 5.6. They are insensitive to 3 muM tetrodotoxin (TTX) but are eliminated totally by 7.3 mM procaine. The properties of channel II are similar to those of the Ca channel found in various adult tissues. The properties of channel I differ, however, from those of either the typical Ca or Na channels. Although the current of the channel depends on the external Na the amplitude of the Na current decreases not only with the Na concentration but also with the Ca concentration. No selectivity is found among Li+, Na+, Rb+, and Cs+. The experimental result suggests that Na+ does not carry current but modifies the current carried by Ca in channel I. 相似文献
999.
Rapid liberation of potassium ions from brain mitochondria 总被引:2,自引:0,他引:2
1000.
Participation of Tubulin in the Stimulatory Regulation of Adenylyl Cyclase in Rat Cerebral Cortex Membranes 总被引:2,自引:0,他引:2
Shinichi Hatta Hiroki Ozawa Toshikazu Saito Hideyo Ohshika 《Journal of neurochemistry》1995,64(3):1343-1350
Abstract: This study examined effects of tubulin on the activation of adenylyl cyclase in rat cerebral cortex membranes. Tubulin, prepared from rat brain by polymerization with the hydrolysis-resistant GTP analogue 5'-guanylylimidodiphosphate (GppNHp) caused significant activation of the enzyme by ∼156% under conditions in which stimulation rather than inhibition of the enzyme was favored. Tubulin-GppNHp activated isoproterenol-sensitive adenylyl cyclase, potentiated forskolin-stimulated activity of the enzyme, and reduced agonist binding affinity for β-adrenergic receptors. When tubulin, polymerized with the hydrolysis-resistant photoaffinity GTP analogue [32 P] P 3 (4-azidoanilido)- P 1 -5'-GTP ([32 P]AAGTP), was incubated with cerebral cortex membranes, AAGTP was transferred from tubulin to Gsα as well as Giα . These results suggest that, in rat cerebral cortex membranes, the tubulin dimer participates in the stimulatory regulation of adenylyl cyclase by transferring guanine nucleotide to Gsα , as well as affecting the Gi -mediated inhibitory pathway. 相似文献