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Thomas Adams William S. Spielman Kenneth R. Holmes S. R. Heisey Michael M. Chen 《Annals of biomedical engineering》1985,13(3-4):237-258
The kidney, with its heterogeneous regional perfusion in the two anatomically and functionally distinct vascular beds of the
renal cortex and medulla, and with its nonuniform blood vessel geometries, presents a unique challenge for measuring intrarenal
blood flow distribution. Determining whole organ perfusion, on the other hand, is comparatively simple for the kidney, but
it provides relatively little information about the suspected dependency of renal excretory function on local perfusion rate.
Among the variety of methods proposed for gauging regional renal blood flow, some depend on measuring one or more of the tissue's
thermal properties. The most straightforward, but least reliable, involve measurements either of focal tissue temperature
alone, or of regional tissue thermal gradients. Simply using heat as a diffusible indicator, however, is unreliable as a measure
of blood flow, for many of the same reasons that using an inert gas in a dilution technique is unreliable. Recently developed
thermal analytical methods, though, hold promise for measuring local tissue blood flow with accuracy and precision. Two of
them are reviewed here. One depends on measurement of the effective thermal conductivity of a small mass of tissue by evaluating
the steady state ratio between regional unidirectional heat flux across it and the associated temperature gradient in one
vector along a segment of it through an imposed spheroidal heat field. The other depends on analyses of tissue temperature
decay subsequent to a controlled pulse of heat delivered through a small inserted thermistor bead. Both techniques use bioheat
transfer equations to deduce regional blood flow
Research by K.R. Holmes and M.M. Chen was supproted by NIH-NHLBI Grant HL27011, that by T. Adams and S.R. Heisey through the
Michigan Heart Association, and that by W.S. Spielman through a grant from the NSF (PCM 8110588) who is a recipient of NIH
Research Career Development Award HL01010. 相似文献
15.
To standardize the procedure for isolating and culturing Lyme disease spirochetes, we modified the composition of the medium generally used for this purpose (BSK-II) and developed a system for its distribution. This medium contains no gelatin or agarose, and various components are used in proportions that differ from those in BSK-II. Each of the major proteinacious components was screened by substitution in samples of the complete product. The final medium was evaluated for the capacity to grow related spirochetes including Borrelia burgdorferi N40, Guilford, and JD-1 as well as strains of Borrelia hermsii (HS-1) and of Borrelia coriaceae (CO53). Each isolate developed from inocula containing as few as one to five organisms. Doubling time of B. burgdorferi during log-phase growth at 37 degrees C was 10 to 12 h. Lyme disease spirochetes were isolated in this medium from ear punch biopsies and dermal aspirates from naturally infected mice and rabbits, from dermal biopsies from a human patient, and by sampling field-collected deer ticks (Ixodes dammini). Cultured spirochetes remained infective to mice and to ticks. The medium can be stored at -20 degrees C or lower temperatures for at least 8 months without effect on its ability to support growth of small inocula to densities exceeding 10(8) spirochetes per ml. Lyme disease spirochetes remained infective to mice after being stored at -80 degrees C in this medium for at least 8 months. We anticipate that the availability of this standardized medium (Sigma Chemical Co.), supplemented with prescreened rabbit serum, will facilitate comparison of research results between laboratories and may eventually permit definitive clinical diagnosis of Lyme disease based on demonstration of the pathogen. The standardized medium is designated BSK-H. 相似文献
16.
Accelerated transmission of Lyme disease spirochetes by partially fed vector ticks. 总被引:3,自引:3,他引:3
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To determine how rapidly Lyme disease spirochetes (Borrelia burgdorferi) can be transmitted by partially fed vector ticks (Ixodes dammini), attached nymphs were removed from their hosts at various intervals post-attachment and subsequently permitted to re-feed to repletion on noninfected mice. We confirm previous reports that ticks deposit Lyme disease spirochetes in the skin of their hosts mainly after 2 days of attachment. Those that have been removed from a host within this interval can reattach and commence feeding. Spirochete-infected nymphs that have previously been attached to a host for 1 day become infectious to other hosts within another day. Noninfected nymphs acquire infection from spirochete-infected hosts within a day of attachment and become infectious to other hosts 3 to 5 days later. Virtually all ticks transmitted infection when reattaching after first feeding for 2 days. We conclude that partially fed nymphal ticks transmit spirochetal infection more rapidly than do ticks that have never been attached to a host and that infected ticks become infectious before they molt. 相似文献
17.
Seasonal activity of immature Ixodes dammini (Acari: Ixodidae) 总被引:2,自引:0,他引:2
18.
Glycoproteins present in human follicular fluid that inhibit the zona- binding capacity of spermatozoa 总被引:1,自引:0,他引:1
Previous studies have suggested that human follicular fluid contains
factors that reduce the zona-binding capacity of spermatozoa. The present
study provides further evidence of the existence of such factors. Using the
hemizona binding assay (HZA), we have shown that the inhibitory effect of
human follicular fluid on the zona-binding capacity of spermatozoa is
concentration-dependent, an inhibitory effect being detected when the
concentration of human follicular fluid was > or = 10%. A 1%
concentration of human follicular fluid did not possess this inhibitory
activity. Heating human follicular fluid at 56 degrees C for 30 min did not
affect its inhibitory properties; treatment with proteinase-K abolished
such inhibition. Human follicular fluid was fractionated sequentially by
concanavalin-A affinity chromatography, Mono Q ion-exchange chromatography
and Superose-12 gel filtration. The zona binding inhibitory activity
resided in the fraction which bound to the lectin and Mono Q column and
contained molecules with native molecular weights of 32 and 192 kDa. Sodium
dodecyl sulphate-polyacrylamide gel electrophoresis analysis suggested that
the 192 kDa glycoprotein was a tetramer, while the 32 kDa glycoprotein
remained as a single molecular species under denaturing conditions. We
conclude that two glycoproteins were responsible for the zona binding
inhibitory activity of human follicular fluid. The physiological role of
these factors remains unclear.
相似文献
19.
Randomized trial of cognitive behavior therapy versus supportive psychotherapy for HIV-related peripheral neuropathic pain 总被引:1,自引:0,他引:1
The feasibility and acceptability of cognitive behavior therapy for HIV-related peripheral neuropathic pain was examined and the potential efficacy of the intervention was compared with that of supportive psychotherapy in reducing pain, pain-related interference with functioning, and distress. Sixty-one patients were randomly assigned to receive six weekly sessions of cognitive behavior therapy or supportive psychotherapy. Thirty-three subjects completed the protocol. Both groups showed significant reductions in pain. The cognitive behavior group improved in most domains of pain-related functional interference and distress; the supportive psychotherapy group showed fewer gains. The high dropout rate suggests that psychotherapeutic treatments for HIV-related pain may have limited feasibility and acceptability. 相似文献
20.
Franz-Rainer Matuschka Peter Fischer Mirjam Heiler Sigurd Blümcke Andrew Spielman 《Parasitology research》1992,78(8):695-698
To more closely define the risk of infection by the agent of Lyme disease in Europe, we determined whether spirochetal prevalence increases throughout the development of theIxodes ricinus vector tick. Of all ticks that could be flagged from vegetation,I. ricinus were by far the most abundant. Spirochetal infection rates in the adult stage of this tick (15%) are no higher than those in nymphs (18%) but greatly exceed those in larvae (0.7%). This tick therefore appears to attain infection mainly from the host of its larval stage, generally feeds on hosts that are noncompetent as reservoirs in its nymphal stage, and rarely inherits infection. Risk of human infection mainly derives from contact with the nymphal stage of the vector tick because the larva is rarely infected and the adult is large enough to be noticed and promptly removed.This work was supported in part by grant AI 19693 from the National Institute of Allergy and Infectious Disease and by grants from the city of Berlin 相似文献