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Annie Conter Dominique Dupouy Christine Delteil Hubert Planel 《Archives of microbiology》1986,144(3):286-290
Previous results from this laboratory have shown that very low chronic doses of gamma radiation can stimulate proliferation of the Cyanobacterium Synechococcus lividus. This modification of cell proliferation occurred during the first doubling. In this paper, we have compared the metabolism of cells cultivated in a normal environment or under chronic irradiation. Incubation of the cells in a new medium induced a high superoxide dismutase (EC 1.15.1.1, SOD) activity at the 18th hour and a degradation of phycocyanin, thus demonstrating that cells were submitted to a photooxidative stress. This increase in superoxide dismutase activity was followed by concomittant peaks of glutathione reductase (EC 1.6.4.2, GR) and glucose-6-phosphate dehydrogenase (EC 1.1.1.49, G6P-DH) at the 24th hour. Irradiated cultures at a dose of 53.5 mGray/year show an earlier and higher peak of SOD, GR, and G6P-DH. In a second stage, cultures showed an earlier onset of photosynthesis under irradiation, as evidenced by an increase in pigment content and an enhancement of glyceraldehyde-3-phosphate dehydrogenase (EC 1.2.1.13, GAP-DH). These results show that the radiostimulation is related to the activation of enzymes protecting against peroxides that were induced under oxidative circumstances and to the activation of a glucose catabolism via the oxidative pentose phosphate pathway.Abbreviations mGy
milli-Gray
- SOD
superoxide dismutase
- G6P-DH
glucose-6-phosphate dehydrogenase
- GAP-DH
glycer-aldehyde-3-phosphate dehydrogenase
- GSSG
oxidized glutathione 相似文献
55.
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Klaus Hallermayer Christine Harmening Herbert Merz Bernd Hamprecht 《Journal of neurochemistry》1983,41(6):1761-1765
The benozomorphan derivative (-)-2-[2-(p-bromoacetamidophenyl)ethyl]-5,9 alpha-dimethyl-2'-hydroxy-6,7-benzomorphan (BAB), capable of reacting with nucleophilic groups, acts on neuroblastoma X glioma hybrid cells as a potent, irreversible opiate agonist. Its potency in inhibiting the increase in cellular cyclic AMP, evoked by prostaglandin E1, is comparable to that of Leu-enkephalin. This also applies to its capacity to compete with [3H]D-Ala2-Met-enkephalinamide ([3H]DAEA) in binding on cell membrane preparations. The comparatively lower potency of (-)-2-[2-(p-acetamidophenyl)-ethyl]-5,9 alpha-dimethly-2'-hydroxy-5,7-benzomorphan (AB), which differs from BAB in the substitution of the bromoacetamido group by an acetamido group, is of the same order of magnitude as that of morphine. The covalent interaction of BAB with the opiate receptors is deduced from the observations that (1) it is not possible to wash away this compound from the receptors, (2) the potency of BAB in inhibiting the specific binding of [3H]DAEA increases with prolonged preincubation time, and (3) AB behaves as a reversible agonist. 相似文献
57.
Christine Jolicoeur Josette Noël Léa Brakier-Gingras 《Biochemical and biophysical research communications》1983,115(1):153-158
Polysomes from the skeletal muscle of normal and dystrophic hamsters were dissociated into ribosomal subunits by treatment with puromycin and the subunits from both strains were reassociated in all possible combinations. When their protein synthesis activity was assayed in a poly(U)-directed cell-free system at a low magnesium concentration, the reassociated ribosomes from dystrophic hamsters were less active than the ribosomes from control animals. The ribosomal defect is a property of the 60S subunit and is due to a ribosomal component rather than to abnormal binding of a non-ribosomal protein. 相似文献
58.
Ribonucleic Acid Synthesis During the Differentiation of Sporangia in the Water Mold Achlya 总被引:6,自引:2,他引:4 下载免费PDF全文
The role of ribonucleic acid (RNA) synthesis in the development of sporangia in the saprolegniaceous mold Achlya was studied. Methods were developed for growing and treating large populations of mycelia so that the hyphal tips would differentiate into sporangia with considerable synchrony. Under the starvation conditions imposed for the differentiation of sporangia, net RNA, deoxyribonucleic acid (DNA), and protein synthesis ceased. However, incorporation of radioactive precursors into RNA continued at a high rate throughout the period of differentiation, showing that the enzymatic mechanism for RNA synthesis was still in an active state. Actinomycin D inhibited the differentiation of sporangia and the incorporation of labeled precursors into RNA. The level of actinomycin used did not inhibit the normal outgrowth and branching of the mycelia that occurred during differentiation. Thus, DNA-dependent RNA synthesis was required for the differentiation of sporangia. Sucrose gradient analysis of newly synthesized RNA showed that only the ribosomal and soluble fractions of RNA were labeled during vegetative growth. During the differentiation of sporangia, ribosomal and soluble RNA fractions were also labeled, and, in addition, a heterodisperse fraction of labeled RNA which was heavier than ribosomal RNA appeared; this fraction was not evident in the newly synthesized RNA from vegetative mycelia. 相似文献
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Philip S. Rudland Christine M. Hughes Sharon A. Ferns Michael J. Warburton 《In vitro cellular & developmental biology. Plant》1989,25(1):23-36
Summary Parenchymal organoidal structures that were obtained from collagenase digestion of reduction mammoplasty specimens of apparently
normal human breasts have been grown in short-term primary cultures, either on plastic or on floating gels of polymerized
rat-tail collagen. Three morphologically distinct major cell types are readily observed in both systems: cuboidal cells, which
occupy apical positions on collagen gels; larger, epithelioid, or basal cells on gels; and elongated cells which penetrate
into the gel. In addition, a fourth cell type, that of a large, flat cell, is observed less readily by phase contrast microscopy
on the surface of cultures grown on plastic. Immunofluorescent and immunocytochemical staining of cultures on plastic or histologic
sections of cultures on gels have been undertaken with antisera and other histochemical reagents that stain the different
parenchymal cell types in vivo. Thus antisera to epithelial membrane antigen(s), monoclonal antibodies (MABs) to the defatted
mammary milk fat globule membrane, peanut lectin, and keratin MAB LE61, which preferentially stain the epithelial cells of
ducts in vivo, also stain the cuboidal/apical cells in vitro. The large, flat cells are stained intensely by the first three
reagents but not by the last one. Antisera to collagen IV, laminin, fibronectin, actin, keratin MAB LP34, MABs to the common
acute lymphoblastic leukemia antigen, and MAB LICR-LON-23.10, which showed enhanced staining for the ductal myoepithelial
cells in vivo, also stain the epithelioid/elongated cells in vitro. However, the effect of the last four reagents is reduced
considerably in most elongated cells, and MAB LP34 stains the large, flat cells intensely. Heterogeneous cells of intermediate
morphologies and staining patterns between the cuboidal/flat cells and large epithelioid cells have also been identified.
The results suggest that the cuboidal cells and large, flat cells are related to mammary epithelial cells, whereas the large
epithelioid/elongated cells have some characteristics of myoepithelial cells, and that intermediate forms may exist in culture
between the two parenchymal cell types.
This work was supported in part by the Ludwig Institute for Cancer Research and the Cancer and Polio Research Fund. Dr. M.
J. Warburton is supported by the Cancer Research Campaign. 相似文献