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111.
112.
Sten Iwarson Lars Magnius Annika Lindholm Per Lundin 《BMJ (Clinical research ed.)》1973,1(5845):84-87
Subtyping of hepatitis B antigen (HBA) in blood donors revealed subtype ad in 56% while patients with icteric post-transfusion hepatitis from the same centre showed subtype ay in the majority of the cases (75%). Donors with subtype ad in serum were mostly asymptomatic long-term carriers of the antigen with normal liver function (83%), while 70% of donors with subtype ay in serum had signs of acute or chronic liver disease. Healthy long-term carriers of HBA seem to present little risk of transmitting hepatitis irrespective of subtype. It is, however, possible that these differences in blood donors with subtype ad and patients with post-transfusion hepatitis with subtype ay might reflect epidemiological circumstances rather than biological differences in the two viral strains. 相似文献
113.
Bo Lambert Margareta Sten Stefan Söderhäll Ulrik Ringborg Rolf Lewensohn 《Mutation research》1983,111(2):171-184
The effects of adriamycin (AM) on DNA repair replication, the frequency of sister-chromatid exchange (SCE), the rate of cell proliferation and the frequency of DNA strand breaks were studied in human cells in vitro. No repair replication was observed in lymphocytes exposed to AM in concentrations up to 10?3 moles/1. DNA repair replication induced by UV and alkylating agents was not affected by a concentration of AM that completely inhibited cell proliferation (10?6 moles/1).Fibroblasts exposed to AM at 10?4 moles/1 in the presence of hydroxyurea showed an increase of strand breaks and cross-links in DNA. When AM was added to UV-irradiated fibroblasts, there was an increase of DNA strand breaks in addition to the breaks caused by UV alone. Similar effects were observed in lymphocytes.A dose-dependent increase of SCE was observed in lymphocytes exposed to low concentrations of AM (<10?7 moles/1). At higher concentrations the increase of SCE levelled off, and cell proliferation became severely inhibited. There was no evidence of removal of SCE-inducing damage in cells exposed to AM during G0 or G1. The level of SCE induced in the third cell cycle after treatment with AM was not different from that induced during the first two cell cycles.These results suggest that the various genotoxic and cytotoxic effects of AM are caused by different types of cellular damage. Moreover, AM-induced DNA damage persists for several cell cycles in human cells in vitro and seems to be resistant to repair activity. 相似文献
114.
The mannitol cycle is an important NADPH regenerating system in Alternaria alternata. The cycle is built up of the following enzymes: mannitol 1-phosphate dehydrogenase, mannitol 1-phosphatase, mannitol dehydrogenase and hexokinase. The net reaction of one cycle turn is: NADH+NADP++ATP NAD++NADPH+ADP+Pi. The enzymes needed for an operating cycle were found in Aspergillus, Botrytis, Penicillium, Pyricularia, Trichothecium, Cladosporium and Thermomyces all genera belonging to Fungi Imperfecti. The only genus of this class lacking the cycle was Candida. No genera from the classes Basidiomycetes and Phycomycetes showed any mannitol 1-phosphate dehydrogenase or mannitol 1-phosphatase activities. The genera investigated, belonging to Ascomycetes, Gibberella, Ceratocystis and Neurospora all lacked mannitol 1-phosphate dehydrogenase. It was concluded that the mannitol cycle is an important and widespread pathway for NADH oxidation and NADP+ reduction in the organisms belonging to the class Fungi Imperfecti. 相似文献
115.
116.
Donato Di Monte Giorgio Bellomo Hjördis Thor Pierluigi Nicotera Sten Orrenius 《Archives of biochemistry and biophysics》1984,235(2):343-350
The toxicological implications of alterations in intracellular thiol homeostasis during menadione metabolism have been investigated using freshly isolated rat hepatocytes. A strict correlation between depletion of protein sulfhydryl groups and loss of cell viability was observed. Loss of protein thiols preceded cell death, and occurred more rapidly in cells with decreased levels of reduced glutathione. Depletion of protein thiols was also associated with inhibition of Ca2+ efflux from the cells and perturbation of intracellular Ca2+ homeostasis. It is proposed that the oxidative stress induced by menadione metabolism in isolated hepatocytes results in the depletion of both soluble and protein thiols, and that the latter effect is critically associated with a perturbation of Ca2+ homeostasis and loss of cell viability. 相似文献
117.
Gregory A. Moore George E. N. Kass Steven K. Duddy Geoffrey C. Farrell Juan Llopis Sten Orrenius 《Free radical research》1990,8(4):337-345
Isolated hepatocytes and the isolated perfused rat liver have been used to study the alterations of cytosolic free Ca2+ concentration ([Ca2+]i) produced by 2,5-di(tert-butyl)-l.4-benzohydroquinone (tBuBHQ), a potent inhibitor of hepatic microsomal Ca2+ sequestration (Moore. G.A., McConkey. D.J., Kass, G.E.N., OBrien, P.J. and Orrenius, S. FEBS Lett.,224, 331-336). (1987). Addition of tBuBHQ to isolated hepatocytes caused a rapid increase in [Ca2+]i which was similar in magnitude to the [Ca2+]i elevation induced by the Ca2+ mobilizing hormone, vasopressin. In contrast with vasopressin which caused a Ca2+ transient, tBuBHQ elevated [Ca2+]i to a new steady state that was maintained for up to 15-20min. When vasopressin was administered during the tBuBHQ-induced period of elevated [Ca2+]i. [Ca2+]i, rapidly returned to basal levels. Similarly, if vasopressin was administered just prior to tBuBHQ, the resultant tBuBHQ-dependent change in [Ca2+]i was transient. and not sustained. The hydroquinone mobilized the same intracellular Ca2+ pool as inositol 1,4,5-trisphosphate. but tBuBHQ did not produce any detectable inositol polyphosphate accumulation. IBuBHQ stimulated glucose release from perifused hepatocytes. mimicking the effect of vasopressin. In the perfused liver, tBuBHQ infusion produced a single, slow and prolonged release of Ca2+ into the perfusate and inhibition of subsequent vasopressin-induced Ca2+ effluxes. Inhibition of the response to vasopressin was reversed over time, and closely correlated with the extent of inhibition of both Ca2+ sequestration and (Ca2+-Mg2+)-ATPase activity in microsomes isolated from the isolated perfused liver. The present results are consistent with tBuBHQ inhibiting ATP-dependent Ca2+ sequestration by a direct effect on the endoplasmic reticular Ca2+ pump, which results in net Ca2+ release and elevation of [Ca2+]i. Furthermore. vasopressin appears to stimulate active removal of increased [Ca2+] from the hepatocyte cytosol by a mechanism which does not depend on reuptake of Ca2+ into the endoplasmic reticulum
2,5-Di(tert-butyl) -l,4-benmhydroquinone. calcium. hepatocytes. perfused liver, endoplasmic reticulum 相似文献
2,5-Di(tert-butyl) -l,4-benmhydroquinone. calcium. hepatocytes. perfused liver, endoplasmic reticulum 相似文献
118.
Maris G. N. Hartmanis Tomas Klason Sten Gatenbeck 《Applied microbiology and biotechnology》1984,20(1):66-71
Summary The pathway for uptake of acids during the solvent formation phase of an acetone-butanol fermentation by Clostridium acetobutylicum ATCC 824 was studied. 13C NMR investigations on actively metabolizing cells showed that butyrate can be taken up from the medium and quantitatively converted to butanol without accumulation of intermediates. The activities of acetate phosphotransacetylase, acetate kinase and phosphate butyryltransferase rapidly decreased to very low levels when the organism began to form solvents. This indicates that the uptake of acids does not occur via a reversal of these acid forming enzymes. No short-chain acyl-CoA synthetase activity or butyryl phosphate reducing activity could be detected. Based on our results and a critical analysis of literature data on acetone-butanol fermentations, it is suggested that an acetoacetyl-CoA: acetate (butyrate) CoA-transferase is solely responsible for uptake and activation of acetate and butyrate in C. acetobutylicum. The transferase exhibits a broad carboxylic acid specificity. The key enzyme in the uptake is acetoacetate decarboxylase, which is induced late in the fermentation and pulls the transferase reaction towards formation of acetoacetate. The major implication is that it is not feasible to obtain a batch-wise butanol fermentation without acetone formation and retention of a good yield of butanol. 相似文献
119.
The fate of ochratoxin A during incubation with contents from the four stomachs of the cow was studied. It was concluded that ochratoxin A was cleaved into the nontoxic ochratoxin α and phenylalanine by the contents from all but the abomasum. 相似文献
120.