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Michael Bach Graham E. Holder 《Documenta ophthalmologica. Advances in ophthalmology》1996,92(3):193-202
The pattern electroretinogram was recorded to checkerboard stimuli with a wide range of check sizes and two stimulus field
sizes. Check sizes ranged from 0.25° to 7° (field size, 16°×14°) and 0.25° to 15° (field size, 32°×27°) in 14 and seven subjects,
respectively. Reversal rate was 4.5/s. For minimal intrusion of blink artifacts the interrupted stimulation technique was
employed. The P50 and N95 components of the pattern electroretinogram were evaluated separately. With both stimulus field
sizes amplitude of P50 and N95 was maximal between 0.75° and 1°. With smaller check sizes the amplitude dropped monotonically.
With larger check sizes field size played a role: with the 16°×14° field, P50 gradually dropped to 89% from 1° to 7°, which
was paralleled by N95 only up to 7°, where N95 dropped to 81% (p<0.05). With the 32°×27° field, there was no significant difference in size dependency between P50 and N95 for large checks,
both components staying constant from 1° to 15° We conclude that there is only minor large-check attenuation of the pattern
electroretinogram, especially with a large field. The apparent field-size dependency may explain previous discrepancies in
the literature. 相似文献
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The role of growth factors and cytokines in the impaired healing of chronic leg ulcers remains uncertain. The aim of this study was to determine whether changes in the amount and location of cytokines and growth factors may be associated with impaired healing in chronic leg ulcers. Biopsies from leg ulcers of 21 patients and from normal skin of nine healthy volunteers were examined immunohistochemically for selected growth factors and cytokines. Greater staining intensity was found in keratinocytes at the edges of ulcers compared to normal skin, or skin adjacent to the ulcers. Staining at the ulcer edge was more intense in nonhealing ulcers for only vascular endothelial growth factor and platelet-derived growth factor, whereas staining in the adjacent skin was more intense for all factors in the nonhealing phase. For all factors staining was cytoplasmic, suggesting production in these areas. This study shows up-regulation of the production of cytokines and growth factors in keratinocytes of chronic leg ulcers that is greater when the ulcers are nonhealing. 相似文献
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M J Blackman I T Ling S C Nicholls A A Holder 《Molecular and biochemical parasitology》1991,49(1):29-33
The amino-terminal sequence has been obtained for 2 fragments of the Plasmodium falciparum T9/94 merozoite surface protein precursor (PfMSP1) and these have been compared with the sequence predicted from the gene. These data define the position of these fragments in the precursor and indicate that the C-terminal sequence which is carried into the red cell during invasion consists of 2 epidermal growth factor (EGF)-like domains. A homologous cleavage sequence and domain structure can be identified in the MSP1 molecules of other malarial species. In addition the results suggest that the smaller fragment is not N-glycosylated. 相似文献
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The proteolytic environment in which Candida albicans exists strongly affects its virulence. To determine whether virulence might be related to C. albicans growth in different proteolytic environments, we measured renal fungal load in burned mice and found significantly greater Candida census in kidneys from mice that were challenged with a high proteinase-generating parent C. albicans (MY 1044) versus those that were challenged with its low proteinase-generating mutant (MY 1049). In vitro, MY 1044 cells grew faster than MY 1049 cells in media that contained sera from burned mice as the only nitrogen source. Augmentation of media with proteinase or a mixture of amino acids increased growth of MY 1049 cells, whereas augmentation with proteinase inhibitor decreased MY 1044 growth. In conclusion, in vitro growth of both the mutant and its parent strain was affected by the proteolytic environment in which they existed; thus, virulence differences for MY 1044 and MY 1049 could be due in part to growth differences between these two strains in different proteolytic environments. These results were combined with existing observations, and we proposed a theory for the pathogenesis of C. albicans in burns. 相似文献
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C L Holder H C Thompson A B Gosnell P H Siitonen W A Korfmacher C E Cerniglia D W Miller D A Casciano W Slikker 《Journal of analytical toxicology》1987,11(3):113-121
Elimination and metabolic profiles of doxylamine and its nonconjugated metabolites were determined after the oral administration of [14C]-doxylamine succinate (13.3 mg/kg and 133 mg/kg doses) to male and female Fischer 344 rats. Total urine and fecal recovery of the administered dose was greater than 90% regardless of sex or dose. The cumulative urinary and fecal elimination of these nonconjugated doxylamine metabolites at the 13.3 mg dose was 44.4 +/- 4.4% and 36.0 +/- 5.8% of the total recovered dose for male and female rats, respectively. The cumulative urinary and fecal elimination of the doxylamine nonconjugated metabolites at the 133 mg/kg dose was 38.7 +/- 2.7% and 41.4 +/- 1.0% of the total recovered dose for male and female rats, respectively. In order to determine the contribution of mammalian and bacterial enzymes in the overall metabolism and excretion patterns for doxylamine, two in vitro techniques were investigated. Incubation of [14C]-doxylamine succinate with human and rat intestinal microflora indicated that anaerobic bacteria were not capable of effecting the degradation of [14C]-doxylamine succinate. However, the incubation of [14C]-doxylamine succinate with isolated rat hepatocytes generated several metabolites similar to those observed in vivo. The nonconjugated doxylamine metabolites isolated and identified include: doxylamine N-oxide, desmethyldoxylamine, didesmethyldoxylamine and ring-hydroxylated products of doxylamine and desmethyldoxylamine. The studies demonstrate the role of hepatic metabolism in the elimination of doxylamine succinate in the rat. 相似文献
9.
K Hunter M Maden D Summerbell U Eriksson N Holder 《Proceedings of the National Academy of Sciences of the United States of America》1991,88(9):3666-3670
There is increasing evidence that retinoic acid (RA), a vitamin A metabolite, plays a role in the development of the nervous system. Here we specifically test this notion by examining the effect of RA on neurite outgrowth from explanted segments of the axolotl spinal cord. We show that there is a threshold concentration in the region of 0.1-1 nM above which neurite outgrowth is stimulated 4-5 fold. Retinol, by contrast, only stimulated the migration of glial cells from the explants. Using HPLC we demonstrate that RA and retinol are present endogenously in the axolotl spinal cord. In addition, we have identified by immunocytochemistry with antipeptide antibodies the cells of the spinal cord that contain the binding proteins for RA (cellular RA-binding protein; CRABP) and retinol (cellular retinol-binding protein; CRBP). CRABP is found in the axons and CRBP is found in the ependyma and glial cells. These results provide strong evidence for a role for RA in the developing nervous system, and we propose a specific hypothesis involving CRBP, CRABP, retinol, and RA in the control of axon outgrowth in the spinal cord. 相似文献
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