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61.
The 85-kilodalton phosphoprotein (pp85) of human herpesvirus 7 is encoded by open reading frame U14 and localizes to a tegument substructure in virion particles. 总被引:5,自引:0,他引:5 下载免费PDF全文
A family of antigenically related proteins present in cells infected with human herpesvirus 7 (HHV-7), designated phosphoprotein 85 (pp85), comprises a complex of proteins, of which the 85-kDa species is phosphorylated. pp85 is a major determinant of human response to HHV-7 infection (L. Foà-Tomasi, E. Avitabile, L. Ke, and G. Campadelli-Fiume, J. Gen. Virol. 75:2719-2727, 1994; L. Foà-Tomasi, M. P. Fiorilli, E. Avitabile, and G. Campadelli-Fiume, J. Gen. Virol. 77:511-518, 1996; J. B. Black et al., Clin. Diagn. Lab. Immunol. 3:79-83, 1996). By immunoscreening of a cDNA library from HHV-7-infected cells with monoclonal antibody (MAb) 5E1, directed to the proteins of the pp85 complex, we mapped the gene encoding pp85 to the U14 open reading frame of the HHV-7 genome. A prokaryotically expressed fusion protein containing the U14 open reading frame reacted with MAb 5E1 in an immunoblot assay. A functional role for pp85 was defined by immunoelectron microscopy studies. Immunogold labeling of cryosections of HHV-7-infected cord blood mononuclear cells at high resolution localized the reactivity of MAb 5E1 to the outer surface of the virion tegument. This finding demonstrates that pp85, the product of the U14 gene, is a component of the HHV-7 tegument and suggests that the HHV-7 tegument is not a homogeneous structure but rather is composed of substructures, including an outermost layer containing pp85. The present findings, together with previously reported properties of MAb 5E1, including its ability to react with formalin-fixed paraffin-embedded samples, make this antibody a specific tool useful for etiopathogenetic studies of HHV-7 infection in humans and provide the basis for further development of pp85 into a specific recombinant diagnostic reagent. 相似文献
62.
Assumpció Bosch Stefan Wiemann Jordi Guimerá Wilhelm Ansorge David Patterson Xavier Estivill 《Human genetics》1995,95(1):119-122
Five clones, containing polymorphic CA-repeat sequences, have been isolated from a specific human chromosome 21 phage library and have been localised to band q21 of chromosome 21 using a somatic cell hybrid panel. These highly repetitive sequences (D21S1263, D21S1264, D21S1415, D21S1417 and D21S1420) have been characterised in the CEPH reference parents and have heterozygosities ranging from 0.30 to 0.81 and an average polymorphism information content (PIC) of 0.62. The relative order of these markers, based on the somatic cell hybrid panel, is cen-D21S1417, D21S1420-D21S1263, D21S1415-D21S1264-tel. The most polymorphic marker (D21S1264) has been included in the chromosome 21 genetic map. They have also been localised in the CEPH/ Généthon YAC panel, providing a refined localisation of these polymorphic sequences. These five CA-repeat markers should provide a better characterisation of the q21 region of chromosome 21. 相似文献
63.
Molecular cloning and functional expression of bacteriophage PK1E-encoded endoneuraminidase Endo NE 总被引:10,自引:3,他引:7
Rita Gerardy-Schahn rea Bethe Thomas Brennecke † Martina Mühlenhoff Matthias Eckhardt Stefan Ziesing Friedrich Lottspeich Matthias Frosch 《Molecular microbiology》1995,16(3):441-450
Homopolymeric α-2,8-linked sialic acid (PSA) has been found as a capsular component of sepsis- and meningitis-causing bacterial pathogens, and on eukaryotic cells as a post-translational modification of the neural cell adhesion molecule (NCAM). The polysaccharide is specifically recognized and degraded by a phage-encoded enzyme, the endo-N-acetylneuraminidase E (Endo NE). Endo NE therefore has become a valuable tool in the study of bacterial pathogenesis and eukaryotic morphogenesis. In this report we describe the molecular cloning of Endo NE and the expression of a functionally active recombinant enzyme. The cloned DNA sequence (2436 bp) encodes a polypeptide of 811 amino acids, which at the 5′ end contains a totally conserved neuraminidase motif. Expressed in Escherichia coli, the enzyme migrates as a single band of approximately 74 kDa in SDS-PAGE. A central domain of 669 amino acid residues is about 90% homologous to the recently cloned Endo NF. Both phage-induced lysis of bacteria and the catalysis of PSA degradation by the recombinant enzyme are efficiently inhibited by a polyclonal antiserum raised against the intact phage particle. The C-terminal region seems to be essential to enzymatic functions, as truncation of 32 amino acids outside the homology domain completely abolishes Endo NE activity. Our data also indicate that the 38 kDa protein, previously assumed to be a subunit of the Endo NE holoenzyme, is the product of a separate gene locus and is not necessary for in vitro depolymerase activity. 相似文献
64.
Nitrogenase activity of ‘membrane-free’ extracts, produced from nitrogenstarved Rhodospirillum rubrum to which 4 mM NH+4 had been added is only about 10% of the activity in the control. The activity could be restored to 80% by including the membrane component, earlier found to activate R. rubrum nitrogenase, in the reaction mixture. The relation between this ‘switch-off/switch-on’ effect and the function of the membrane component is discussed.Hydrogen production catalyzed by R. rubrum nitrogenase is also dependent on activation by the membrane component. Hydrogen production is inhibited by acetylene but the degree of inhibition is dependent on the nitrogenase component ratio. The strongest inhibition is achieved at low MoFe protein/Fe protein ratios. The values are 4–5 at the component ratios giving the highest activity and increase at high MoFe protein/Fe protein ratios. CO inhibits acetylene reduction but has no effect on the hydrogen production. 相似文献
65.
Knut Pettersson Stefan Nilsson 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1980,137(2):131-138
Summary Ventral (VAP) and dorsal (DAP) aortic blood pressure, heart rate (HR) and cardiac output (
) were recorded simultaneously in unanaesthetized Atlantic cod, and the effects of vasoactive drugs on the cardio-vascular parameters studied. Mean resting values for the parameters were VAP=4,39 kPa, DAP=2,49 kPa, HR=41 beats/min, and
= 29,1 ml/min×kg. Adrenaline constricted the systemic vasculature, dilated the branchial vasculature and caused a decrease of HR and
due to a cholinergic reflex. After atropine pre-treatment this reflex was abolished, and the effect of adrenaline on blood pressure enhanced. A small decrease in
persisted after atropine, presumably reflecting the effect of an increased end-systolic afterload.Phenylephrine produced a weak increase in systemic vascular resistance, while isoprenaline lowered both systemic and branchial vascular resistance. The effect of isoprenaline is probably mediated by beta adrenoceptors in both vascular beds, since propranolol antagonizes the effect.Acetylcholine in low doses produces a drop in
without affecting HR, while higher doses also stop the heart. There is no significant change in either branchial and systemic vascular resistance after acetylcholine.Abbreviations
VAP
mean ventral aortic blood pressure
-
DAP
mean dorsal aortic blood pressure
-
TBPD
trans-branchial blood pressure drop
-
HR
heart rate
-
SV
stroke volume
-
cardiac output (ventral aortic blood flow)
-
VR
g
branchial vascular resistance
-
VR
s
systemic vascular resistance 相似文献
66.
Sympathetic nervous control of blood flow in the gills of the Atlantic cod,Gadus morhua 总被引:1,自引:1,他引:0
Stefan Nilsson Knut Pettersson 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1981,144(2):157-163
Summary The effects of sympathetic nerve stimulation, adrenaline and isoprenaline on the inflow pressure and efferent arterial and venous flow rates were studied in a cod gill preparation perfused at constant flow rate.The dominant effect of adrenaline was a reduced inflow pressure, accompanied by an increase in arterial flow and a decrease in venous flow. Isoprenaline also decreased the inflow pressure, but the changes in both outflow rates were small or absent.Sympathetic nerve stimulation gave arterial and venous flow changes comparable to the adrenaline effects, but the inflow pressure increased during nerve stimulation. Propranolol has little effect on the nerve responses, but phentolamine abolished or reversed the increase in inflow pressure, and also decreased or abolished the changes in outflow rates.The possible sites of action of the sympathetic fibres, and the distribution of adrenoceptors in the effector tissue is discussed. It is concluded that the main effect of sympathetic nerve stimulation is -adrenoceptor mediated, involving constriction of the arterio-venous pathway. The-adrenoceptor mediated control of total branchial vascular resistance may largely depend on circulating catecholamines. 相似文献
67.
68.
Cartilage proteoglycan aggregates. Electronmicroscopic studies of native and fragmented molecules 下载免费PDF全文
1. Proteoglycan aggregates from bovine nasal cartilage were studied by using electron microscopy of proteoglycan/cytochrome c monolayers. 2. The aggregates contained a variably long central filament of hyaluronic acid with an average length of 1037nm. The proteoglycan monomers attached to the hyaluronic acid appeared as side chain filaments varying in length (averaging 249nm). They were distributed along the central filament at an average distance of about 36nm. 3. Chondroitin sulphate side chains were removed from the proteoglycan monomers of the aggregates by partial chondroitinase digestion. The molecules obtained had the same general appearance as intact aggregates. 4. Proteoglycan aggregates were treated with trypsin and the largest fragment, which contains the hyaluronic acid, link protein and hyaluronic acid-binding region, was recovered and studied with electron microscopy. Filaments that lacked the side chain extensions and had the same length as the central filament in the intact aggregate were observed. 5. Hyaluronic acid isolated after papain digestion of cartilage extracts gave filaments with similar length and size distribution as observed for the central filament both in the intact aggregate and in the trypsin digests. 6. Umbilical-cord hyaluronic acid was also studied and gave electron micrographs similar to those described for hyaluronic acid from cartilage. However, the length of the filament was somewhat shorter. 7. The electron micrographs of both intact and selectively degraded proteoglycans corroborate the current model of cartilage proteoglycan structure. 相似文献
69.
Stefan Berking 《Development genes and evolution》1977,181(3):215-225
Summary From crude extracts ofHydra tissue a substance has been purified which prevents or retards the asexual reproduction by budding. The molecular weight is in the range of 300 to 1000 daltons. Inhibition of bud formation can be observed with concentrations equivalent to the extract from one hydra per 4 ml, that is, to a more than 10,000-fold dilution of the initial crude extract of a hydra. The purified inhibitor is active at a concentration of less than 10–8 M.Most of the inhibitor present inHydra is bound to cells. Within the cells the substance is mainly bound to particulate structures which sediment at 10,000 g. Its concentration is highest in the hypostomal region and decreases in the direction of the tentacles and peduncle. A second, lower, peak has been found in the basal disc. Treatment of the animals with a toxic agent (nitrogen mustard) which depletes the animal of interstitial cells, nematocytes and nematoblasts excludes the possibility that the inhibitor is present to any great extent in these cells. In conjunction with cell separation experiments by centrifugation of fixed cells in suspension, these results indicate that nerve cells are the most likely sites of storage of the inhibiting substance, although epithelial cells are not excluded as sources for the inhibitor. 相似文献
70.
Summary Buds originate inHydra attenuata at a position 1/3 of the body length from the basal disc. The position with respect to the vertical axes is determined first and the position of the bud on the circumference of this budding region is specified later.Bud formation in hydra is reversibly prevented by pre-treatment with an inhibitor purified from hydra tissue (Berking, 1977). Some hours after the end of the treatment with the inhibitor, bud formation is resumed. From the starting or restarting point of development after the inhibitory treatment to the visible beginning of bud formation, 4 intermediary stages were distinguished on the basis of different responses to a second treatment with inhibitor. The pre0treatment is followed immediately by a period of maximal sensitivity to the inhibitor, which varies in length. At the conclusion of this phase the time interval required for the visible appearance of buds is fixed (12 h). In this and the following phase another application of inhibitor can cancel the entire preparatory process from the pre-treatment onwards. A transition to near complete resistance to inhibitor is the basis for defining a third phase. In a fourth phase, immediately before the evagination of the bud starts, the proesence of the inhibitor will again hinder the development. Upon removal of the inhibitor the suppressed buds will appear. 相似文献