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111.
G. M. Alder B. M. Austen C. L. Bashford A. Mehlert C. A. Pasternak 《Bioscience reports》1990,10(6):509-518
Human heat shock protein (hsp) 70 and bacterial protein groEL promote leakage of calcein from liposomes induced by human serum albumin signal peptide, byS. aureus toxin or by diphtheria toxin. Hsp 70 and groEL, as well as two mycobacterial homologues hsp 71 and hsp 65, induce ion conducting pores across planar lipid bilayers at low or neutral pH. It is concluded that hsp induce pores in membranes and that this may contribute to their action within cells. 相似文献
112.
Anna L. Trifillis Myong Won Kahng 《In vitro cellular & developmental biology. Plant》1990,26(5):441-446
Summary We have developed an in vitro model of human papillary collecting duct cells isolated from cadaver kidneys using methods similar
to those we previously reported for the isolation of human proximal tubule cells. To date we have isolated papillary collecting
duct cells from 100 normal human kidneys. Papillae were dissected and digested in Cellgro containing 400 U/ml collagenase.
Cells were plated on fibronectin-coated culture flasks at a density of 104 live cells/ml in Cellgro supplemented with insulin and 10% fetal bovine serum. Confluent monolayers, which were able to withstand
600 mOsm for 8 h, were obtained within 10 to 15 d. Cells of primary isolates and first passages exhibited epithelial cell ultrastructure
including cell junctions, microvilli, and cilia. A dark-brown reaction product was observed in these cells when stained by
the immunoperoxidase method with peroxidase-labeled peanut lectin (Arachis hypogaea), which binds specifically to human distal tubule and collecting duct cells. These cells were negative for Factor-VIII (a
marker for endothelial cells) and γ-glutamyltransferase (a marker for proximal tubule cells). High activities of the glycolytic
enzyme pyruvate kinase and arginine vasopressin-stimulated cAMP production in these cells are consistent with a distal nephron
origin. The results indicate that human collecting duct cells can be isolated and cultured to provide an in vitro system to
probe pathogenetic mechanisms of potential nephrotoxins.
Part of this work was presented at a Symposium of the Center for Alternatives to Animal Testing, April 4–5, 1989, Johns Hopkins
Medical Institutions, Baltimore, MD 21205.
This work was supported in part by grants R01-AI24179, PO1-A804393 for the Public Health Service, U.S. Department of Health
and Human Services, and by a grant from the National Kidney Foundation, Baltimore, MD affiliate. 相似文献
113.
114.
E.V. Sviderskaya E. Jazrawi S.A. Baldwin C.C. Widnell C.A. Pasternak 《The Journal of membrane biology》1996,149(2):133-140
The stimulation of glucose transport in response to various types of stress has been studied. There is no relationship between
effects of stress-inducing agents on glucose transport and their effects on cellular protein synthesis. Although the effect
of stress on glucose transport appears analogous to its stimulation by insulin, cells that are slightly insulin-sensitive
in terms of glucose transport (BHK cells) show a similar degree of stimulation as highly insulin-sensitive cells (differentiated
3T3-L1 cells). External labeling of the transporter protein with a photoactivatable derivative of mannose, 2-N-4-(1-azi-2,2,2-trifluoroethyl)
benzoyl-1, 3-bis-(D-mannos-4-yloxy)-propylamine, shows that most of the increased glucose transport activity correlates with
an increase in the amount of the transporter on the cell surface. Cells subjected to K+-depletion, which inhibits endocytosis and results in an accumulation of receptors at the cell surface, show the same increase
in glucose transport as cells exposed to stress; stressed cells show no further increase in glucose transport when subjected
to K+ depletion. These results support the view (Widnell, C.C., Baldwin, S.A., Davies, A., Martin, S., Pasternak, C.A. 1990. FASEB J
4:1634–1637) that cellular stress increases glucose transport by promoting the accumulation of glucose transporter molecules
at the cell surface.
Received: 20 June 1995/Revised: 29 September 1995 相似文献
115.
Anna Jachner 《Hydrobiologia》1996,325(2):151-155
The response of bleak (Alburnus alburnus (L.)) to alarm substance (from skin extract of conspecifics) was quantified, using a video camera, in laboratory experiments across two light and one dark periods (18 hrs). In the light alarm substance induced hiding in refuges (vegetation) and formation of aggregations. There was no such reaction during darkness or during a second light period. 相似文献
116.
Butomus umbellatus L. is a plant species typical of littoral communities of river and stream shores. It can form continuous stands in shallow reservoirs with fluctuating water level. Their expansion is promoted by: (a) intensive vegetative reproduction of plants, (b) crowded sprouting from rhizome fragments on emerged pond bottom, (c) shallow water layer in the year following summer drainage. Expansion of B. umbellatus depends on ploidy level: two cytotypes were found in the Czech and Slovak Republics, differing in their reproductive ability. Seed production of triploids is strongly limited (they are self-incompatible within clones), while diploids can be fully fertile. Nevertheless, even in diploids, the efficiency of seed reproduction under natural conditions is low. Triploids spread by intensive vegetative reproduction, which is decisive for clonal growth of populations and their regeneration after scraping of bottom surface. During seasonal development, maximum of aboveground biomass is produced in early summer, while underground biomass increases till autumn. Growth of the plants is limited by cutting before maximum underground biomass is attained, or by duck grazing. 相似文献
117.
Further studies on theisfA mutation responsible for anti-SOS and antimutagenic activities inEscherichia coli are described. We have previously shown that theisfA mutation inhibits mutagenesis and other SOS-dependent phenomena, possibly by interfering with RecA coprotease activity. TheisfA mutation has now been demonstrated also to suppress mutator activity inE. coli recA730 andrecA730 lexA51(Def) strains that constitutively express RecA coprotease activity. We further show that the antimutator activity of theisfA mutation is related to inhibition of RecA coprotease-dependent processing of UmuD. Expression of UmuD' from plasmid pGW2122 efficiently restores UV-induced mutagenesis in therecA730 isfA strain and partially restores its mutator activity. On the other hand, overproduction of UmuD'C proteins from pGW2123 plasmid markedly enhances UV sensitivity with no restoration of mutability. 相似文献
118.
Marcella Carcupino Anna Maria Fausto Maria Luisa Bernardino Ortega Marzio Zapparoli Massimo Mazzini 《Zoomorphology》1996,116(3):103-110
Spermatophore development and ultrastructure of the mature sperm of Craterostigmus tasmanianus were studied using light and electron microscopy. In C. tasmanianus, as in the Scolopendromorpha, the spermatophore develops within the vas deferens. The latter consists of three parts, each
with a different morphology. The first may be involved in guiding the sperm to roll up into typical ring-like structures,
while the other two, which show an evident secretory activity, secrete the acellular wall of the spermatophores. The ultrastructure
of mature spermatozoa showed that a very close similarity exists between Craterostigmomorpha and Lithobiomorpha, especially
regarding the organization of the connecting piece. Based on this similarity, we consider the Craterostigmomorpha together
with the Scolopendromorpha, Geophilomorpha and Lithobiomorpha (=Pleurostigmophora) to be the sister group of the Scutigeromorpha.
Accepted: 2 June 1996 相似文献
119.
In this report we investigate the inhibition of membrane conductivity, due to the murine polyomavirus infection in permissive cells in culture. We define experimental conditions to have reproducible results and demonstrate that the intensity of the effects on the cell membrane, depends upon the virus titer used in the infection. Finally, the virus dependent effects disappear if the infection is performed in the presence of a drug that inhibits polymavirus DNA replication. 相似文献
120.
Selenium,zinc, and thyroid hormones in healthy subjects 总被引:3,自引:0,他引:3
Oliviero Olivieri Domenico Girelli Anna Maria Stanzial Luigi Rossi Antonella Bassi Roberto Corrocher 《Biological trace element research》1996,51(1):31-41
Iodothyronine 5′ deiodinase, which is mainly responsible for peripheral T3 production, has recently been demonstrated to be a selenium (Se)-containing enzyme. The structure of nuclear thyroid hormone
receptors contains Zinc (Zn) ions, crucial for the functional properties of the protein. In the elderly, reduced peripheral
conversion of T4 to T3 with a lower T3/T4 ratio and overt hypothyroidism are frequently observed. We measured serum Se and RBC GSH-Px (as indices of Se status), circulating
and RBC Zinc (as indices of Zn status), thyroid hormones and TSH in 109 healthy euthyroid subjects (52 women, 57 men), carefully
selected to avoid abnormally low thyroid hormone levels induced by acute or chronic diseases or calorie restriction. The subjects
were subdivided into three age groups. To avoid under- or malnutrition conditions, dietary records were obtained for a sample
of 24 subjects, randomly selected and representative of the whole population for age and sex. Low T3/T4 ratios and reduced Se and RBC GSH-Px activity were observed only in the older group. A highly significant linear correlation
between the T3/T4 ratio and indices of Se status was observed in the older group of subjects (r=0.54;p<0.002, for Se;r=0.50;p<0.002, for RBC GSH-Px). Indices of Zn status did not correlate with thyroid hormones, but RBC Zn was decreased in older as
compared with younger subjects. We concluded that reduced peripheral T4 conversion is related to impaired Se status in the elderly. 相似文献