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991.
Ralf Dieler J. Michael Schröder 《Virchows Archiv : an international journal of pathology》1990,417(3):213-221
Summary Muscle spindles in the lower lumbrical muscles of rats were studied by transmission electron microscopy following denervation with or without reinnervation. The number and total area of elastic fibres per muscle spindle increased at 3–12 months following various experimental procedures: (1) denervation and reinnervation after a single crush lesion to the sciatic nerve; (2) reinnervation after four-fold repeated crush injuries; and (3) transection and suture of the nerve. The increased number of oxytalan and elaunin fibres, the precursors of mature elastic fibres, within these muscle spindles provided further evidence for their numerical and dimensional increase. An attachment site of elastic fibres at the spindle pole was identified at the inner cells of the outer spindle capsule. The processes of these cells embraced terminating elastic fibres tightly. Attachment of elastic fibres to intrafusal muscle fibres was less conspicuous since they were not similarly embraced but were rather indistinctly, though closely, associated with the basal lamina along longitudinal surface indentations of intrafusal muscle fibres. It is concluded from this series of experiments that muscle spindles, as dynamic mechanoreceptors, maintain their elastic properties even under pathological conditions. The increase of elastic fibres following denervation and reinnervation represents an obviously meaningful reaction that may compensate for loss of tonic properties of muscle spindles without causing stiffness. 相似文献
992.
Laccase from the white-rot fungus Trametes versicolor: cDNA cloning of lcc1 and expression in Pichia pastoris 总被引:2,自引:0,他引:2
A cDNA coding for laccase was isolated from the ligninolytic fungus Trametes versicolor by RNA-PCR. The cDNA corresponds to the gene lcc1, which encodes a laccase isoenzyme of 498 amino-acid residues preceded by a 22-residue signal peptide. The lcc1 cDNA was cloned into the vector pHIL-D2 for expression in Pichia pastoris under the control of the AOX1 promoter. Transformants were found to secrete active recombinant enzyme after induction with methanol. The use of growth
medium buffered to pH 6.0 and control of pH during cultivation were found to be important, or even necessary, for obtaining
activity in liquid cultures. The effect of exchanging the native secretion signal for the Saccharomyces cerevisiae α-factor pre-pro secretion signal was studied by cloning the portion encoding the mature enzyme into the vector pPIC9. The
activity obtained for the construct encoding the native laccase signal sequence was found to be seven-fold higher than for
the construct encoding the α-factor secretion signal. Utilisation of the P. pastoris pep4 mutant strain SMD1168 was found to provide a two-fold higher level of activity compared with P. pastoris GS115.
Received: 16 May / 8 August 1997 相似文献
993.
Particle agglutination assays for rapid detection of fibronectin, fibrinogen, and collagen receptors on Staphylococcus aureus. 总被引:4,自引:5,他引:4 下载免费PDF全文
Latex beads (0.8-micron diameter; Difco Laboratories) were coated with fibronectin, fibrinogen, collagen type I, or denatured collagen (gelatin) and evaluated in a particle agglutination assay (PAA) for the rapid detection of fibronectin, fibrinogen, or collagen binding to Staphylococcus aureus. These assays were compared with a commercial test for detecting the binding of fibrinogen and immunoglobulin G (Staphaurex). Bacterial cells (approximately 10(10) cells per ml) suspended in 0.02 M potassium phosphate buffer (pH 6.8) caused the clumping of standard fibronectin, collagen, gelatin, and fibrinogen latex suspensions within 2 min on glass slides. The test results were scored semiquantitatively from strongly positive ( ) to weakly positive (+) and negative (-) reactions. The negative PAA reactions corresponded to a median value of 11.5% relative to the binding of 125I-labeled protein to strain Cowan 1, indicating the high sensitivity of the test. The reactions with fibronectin and fibrinogen latex suspensions and with Staphaurex were optimal for cells grown on tryptic soy and brain heart infusion broth media. Blood agar was optimal for reactions with collagen and gelatin latex suspensions. Media containing high salts (mannitol salt agar and staphylococcus medium 110) enhanced the tendency of cells to autoaggregate. These assays were also clinically evaluated on 187 S. aureus isolates. The PAA reagents were stable, and the assays were highly specific, sensitive, and reproducible, thus making PAA suitable for the rapid screening of the binding of various bacterial pathogens to serum and connective-tissue proteins. 相似文献
994.
Twenty patients with type II diabetes mellitus and hypertension (WHO stages I and II) participated in a 3-month double-blind cross-over study to evaluate the effects of clonidine (75-300 micrograms daily) on blood pressure, glycemic control and plasma lipoproteins. Already after 1 month's treatment with clonidine the systolic and diastolic blood pressures had decreased, from 168/103 to 161/98 mmHg (p less than 0.01). Fasting blood glucose and HbA1c concentrations were unaffected by 3 months' treatment. Similarly, plasma lipid and lipoprotein concentrations remained unchanged throughout the study (i.e. mean high and low density lipoprotein cholesterol concentrations were 0.89 and 3.87 mmol/l on placebo vs. 0.90 and 3.98 mmol/l on clonidine). Adverse effects were mild and tolerable, and consisted mainly of dryness of the mouth. We conclude that clonidine lowers the blood pressure in patients with type II diabetes without any adverse effects on glycemic control or plasma lipoproteins. 相似文献
995.
C Wallfelt R Larsson H Johansson J Rastad G Akerstr?m S Ljunghall E Gylfe 《Acta physiologica Scandinavica》1985,124(2):239-245
Pieces of rat parathyroid glands were used to study fluxes of 45Ca and 86Rb. The uptake of 45Ca increased with the extracellular Ca2+ concentration up to at least 5 mM. A rise of extracellular Ca2+ had dual effects on 45Ca efflux in terms of an initial stimulation and a subsequent inhibition. However, K+ depolarization neither affected the uptake nor the efflux of 45Ca indicating a lack of voltage-dependent Ca2+ channels. The depolarization obtained with exposure to Ca2+ cannot be attributed to a decreased K+ permeability, since the 86Rb concentrating ability diminished and the efflux of the isotope increased when parathyroid pieces were exposed to a raised Ca2+ concentration. A stimulation of 86Rb efflux by the Ca2+ ionophore A-23187 indicated that the parathyroid cells possess a K+ permeability activated by cytoplasmic Ca2+. It is suggested that Ca2+ fluxes through channels sensitive to activation by Ca2+ are important both for the membrane potential and the cytoplasmic Ca2+ activity. 相似文献
996.
Pierre Chatelain Patrick Robberecht Philippe De Neef Monique Deschodt-Lanckman Wolfgang König Jean Christophe 《Pflügers Archiv : European journal of physiology》1980,388(1):21-27
The exact positions of microelectrodes used to measure thePO2 in the cerebral cortex of the rat were determined by staining the tissue with Alcian Blue. The measurement sites were subsequently located under a light microscope and correlated with the capillary and cellular arrangement of the cortex. The microelectrodes used for thePO2 measurements were made of gold glass fibers; the Alcian Blue was injected hydrostatically through a micropipette attached to thePO2 microelectrode. The sites where dye had been deposited were seen under a light microscope as green blue spots about 100 m in diameter. The capillaries were visualized by silver nitrate perfusion. Differences between the localPO2 values in the neo- and the archeocortex were found. In the neocortex the meanPO2 was 31 mm Hg, capillary volume 1.6%, capillary surface area 980/mm2, capillary length 13.5/mm; whereas in the archeocortex these values where 21 mm Hg, 0.9%, 820/mm2 and 9.4/mm respectively. These data indicate a relationship between the microcirculatory transport system and the local oxygen tension and provide further evidence that the meanPO2 level tends to decrease when moving from the surface into the archeocortex.Supported by the Deutsche ForschungsgemeinschaftReported in part at the 3rd Symposium of ISOTT, Cambridge, GB, 1977; and at the 27th International Congress of Physiological Sciences, Paris, France, 1977 相似文献
997.
Ullrich K. J. Rumrich G. Klöss S. 《Pflügers Archiv : European journal of physiology》1976,364(3):223-228
Summary Using the stop flow microperfusion technique with simultaneous capillary perfusion the rate of active Ca2+ reabsorption was evaluated by measuring the static head electrochemical potential difference as well as the permeability of the tubular wall for Ca2+ ions. Under control conditions the active Ca2+ transport was calculated to be 3.35×10–13 mol/cm·s. It declined toward zero if the ambient Na+ was replaced by choline or lithium. Parallel experiments in the golden hamster showed that active Ca2+ transport, vanished completely if active Na+ transport was blocked by ouabain (1 mM). These data indicate that the active Ca2+ reabsorption from the proximal tubule depends on the active reabsorption of Na2+ presumably via a Na+–Ca2+ countertransport at the contraluminal cell membrane. The static head electrochemical potential difference of Ca2+ is the same in late and early proximal tubules. It is also not affected by the presence of acetazolamide (10–4 M) by the absence of bicarbonate or glycodiazine buffer or by the absence or presence of phosphate (2 mM). 相似文献
998.
Lena Möbus Elke Rodriguez Inken Harder Agatha Schwarz Ulrike Wehkamp Dora Stölzl Nicole Boraczynski Sascha Gerdes Thomas Litman Andreas Kleinheinz Susanne Abraham Annice Heratizadeh Christiane Handrick Eva Haufe Jochen Schmitt Thomas Werfel Stephan Weidinger 《The Journal of allergy and clinical immunology》2021,147(5):1959-1965.e2
999.
Summary Five adenovirus 15/Hx and one Ad9/Hx strain with a common novel hemagglutinin were compared serologically and by DNA restriction analysis with six endonucleases with the related prototypes. The five Ad15/Hx strains represented five different genome types.With 1 FigureAided by grants from the Deutsche Forschungsgemeinschaft (Wi 2/21-1), Bundesministerium für Jugend, Familie und Gesundheit, and Förderverein der Deutschen Vereinigung zur Bekämpfung der Viruskrankheiten e. V., FRG. 相似文献
1000.
Role of volume-stimulated osmolyte and anion channels in volume regulation by mammalian sperm 总被引:3,自引:0,他引:3
Petrunkina AM Harrison RA Ekhlasi-Hundrieser M Töpfer-Petersen E 《Molecular human reproduction》2004,10(11):815-823
The ability to maintain cellular volume is an important general physiological function. Swelling induced by hypotonic stress results in the opening of channels, through which ions exit with accompanying water loss (regulatory volume decrease, RVD). RVD has been shown to occur in mammalian sperm, primarily through the opening of quinine-sensitive potassium channels. However, as yet, direct evidence for the participation of anion channels in sperm RVD has been lacking. The chloride channel type ClC-3 is believed to be involved in RVD in other cell types. Using electronic cell sizing for cell volume measurement, the following results were obtained. (i) The anion channel blockers 5-nitro-2-(3-phenylpropylamino)-benzoic acid (NPPB), tamoxifen and 4,4'-diisothiocyanostilbene-2,2'-disulphonic acid (DIDS) increased hypotonic swelling in concentration-dependent fashion, whereas verapamil (P-glycoprotein inhibitor) had little effect. The most potent, NPPB and DIDS, blocked RVD without affecting cell membrane integrity at effective concentrations. (ii) When gramicidin was included to dissipate Na+/K+ gradients, major secondary swelling was observed under hypotonic conditions. This secondary swelling could be reduced by NPPB, and suppressed completely by replacing chloride in the medium with sulphate, an ion which does not pass through chloride channels. It was deduced that the initial hypotonic swelling activated an anion channel through which chloride ions could then enter freely down a concentration gradient, owing to the lack of a counter-gradient of potassium. (iii) Taurine, an osmolyte often involved in RVD, does not appear to play a role in sperm RVD because lengthy preincubation with taurine did not alter sperm RVD response. Our observations provide direct evidence that a chloride channel (possibly ClC-3) is involved in the process of volume regulation in mammalian sperm. 相似文献