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61.
Pol32 is a subunit of Saccharomyces cerevisiae DNA polymerase δ required in DNA replication and repair. To gain insight into the function of Pol32 and to determine in which
repair pathway POL32 may be involved, we extended the analysis of the pol32Δ mutant with respect to UV and methylation sensitivity, UV-induced mutagenesis; and we performed an epistasis analysis of
UV sensitivity by combining the pol32Δ with mutations in several genes for postreplication repair (RAD6 group), nucleotide excision repair (RAD3 group) and recombinational repair (RAD52 group). These studies showed that pol32Δ is deficient in UV-induced mutagenesis and place POL32 in the error-prone RAD6/REV3 pathway. We also found that the increase in the CAN1 spontaneous forward mutation of different rad mutators relies entirely or partially on a functional POL32 gene. Moreover, in a two-hybrid screen, we observed that Pol32 interacts with Srs2, a DNA helicase required for DNA replication
and mutagenesis. Simultaneous deletion of POL32 and SRS2 dramatically decreases cellular viability at 15 °C and greatly increases cellular sensitivity to hydroxyurea at the permissive
temperature. Based on these findings, we propose that POL32 defines a link between the DNA polymerase and helicase activities, and plays a role in the mutagenic bypass repair pathway.
Received: 25 May 2000 / Accepted: 3 July 2000 相似文献
62.
Local thermal unpleasantness and discomfort prediction in the vicinity of thermoneutrality 总被引:2,自引:0,他引:2
This work emphasizes a better understanding of the origin of human thermal discomfort under heterogeneous but steady environments, in subjects in the vicinity of physiological and sensory thermoneutrality. The knowledge of skin temperatures allows a psychophysiological study aiming at linking the body thermal state (local and global) to thermal sensation (perceptive and affective judgements). By using two driving simulators, 345 subjects were exposed to different thermal environments, modulated by factors such as the air distribution in the automotive cockpit or the clothing insulation (winter or summer). This work shows that consideration of the local thermal state is essential for the evaluation of thermal comfort in the case of non-uniform environments. Our experimental conditions point out that the overall sensation of discomfort is quantitative, with local unpleasantness needing to be felt for a certain number of body surfaces. A local origin is suggested for cold discomfort, in opposition to the global characteristics of warm discomfort. 相似文献
63.
Hilger C Bessot JC Hutt N Grigioni F De Blay F Pauli G Hentges F 《The Journal of allergy and clinical immunology》2005,115(3):617-622
BACKGROUND: Anaphylactic reactions caused by bites of the European pigeon tick Argas reflexus are repeatedly reported. This soft-backed tick is a parasite of wild pigeons colonizing urban buildings and houses. Occasionally the ticks can bite human beings, inducing anaphylactic reactions in sensitized patients. OBJECTIVE: Our aim was to characterize the major allergen implicated in a series of anaphylactic reactions caused by Argas bites and to produce the allergen as recombinant protein for diagnostic purposes. METHODS: Protein extracts were prepared from whole A reflexus bodies, and IgE immunoblots were performed with sera from 13 patients who had an anaphylactic reaction with pigeon tick bites. A cDNA expression library was constructed from whole ticks and screened with a polyclonal rabbit antiserum raised against the major allergen. RESULTS: The cDNA coding for the dominant allergen Arg r 1 could be isolated. It encodes a protein belonging to the lipocalin family. Allergenicity of the recombinant Arg r 1 was confirmed by immunoblot, ELISA, and intradermal skin tests. CONCLUSION: The dominant allergen of A reflexus has been isolated and the corresponding cDNA cloned. The recombinant protein, a lipocalin, was expressed in Escherichia coli and was shown to be immunoreactive in vitro and in vivo. Recombinant Arg r 1 was used as a diagnostic tool in a series of anaphylactic reactions caused by pigeon tick bites. 相似文献
64.
Analysis of the spontaneous in vitro anti-HIV-1 antibody secretion by peripheral blood mononuclear cells in HIV-1 infection. 总被引:5,自引:2,他引:5 下载免费PDF全文
J P Vendrell M Segondy J Ducos J Reynes M F Huguet J C Nicolas A Serre 《Clinical and experimental immunology》1991,83(2):197-202
We studied the spontaneous in vitro secretion of anti-HIV-1 antibodies by peripheral blood mononuclear cells (PBMC) from HIV-1-infected patients. Specific antibody production was detected in supernatants of PBMC cultures using an ELISA; HIV-1 specificity was confirmed by antigen adsorption and Western blotting. This antibody secretion was found to be an active phenomenon and was not due to a release of plasma antibodies passively adsorbed onto the cell membranes. In all positive supernatants, anti-HIV-1-secreted antibodies were directed against env-encoded antigens and many supernatants also contained antibodies to pol- and gag-encoded antigens. PBMC from all HIV-1-infected patients tested (140 adults and 18 infants) secreted anti-HIV-1 antibodies. This production was found during all the clinical stages of HIV-1 infection. Our results suggest that this spontaneous HIV-1-specific antibody secretion represents a marker of HIV-1 infection. Detection of these antibodies could be a valuable tool for early confirmation of HIV-1 infection in neonates born to HIV-1-seropositive mothers. 相似文献
65.
Dr. D. A. Poulain C. J. Lebrun J. D. Vincent 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1981,42(3-4):260-268
Summary In order to see whether septal neurones are connected to the hypothalamic neurones secreting vasopressin or oxytocin, neurones in different regions of the septum were recorded during electrical stimulation of the supraoptic nucleus. The position of the stimulating electrode within the latter was verified using lactating rats in which milk ejections could be induced by a train of electrical pulses applied to the nucleus. The responses of septal neurones to single pulse stimulation were then analysed by post-stimulus time histograms.In the septum ipsilateral to the site of stimulation, 42% of the neurones were antidromically invaded, 20% were orthodromically excited and 21% were inhibited following supraoptic stimulation. In the contralateral septum, 2% of the cells tested were antidromically invaded, 3% were excited and 16% inhibited. In the medial septum, 14% of the neurones were orthodromically excited, and 48% were inhibited.These results provide electrophysiological evidence for direct connections between septal neurones and the ipsilateral supraoptic nucleus of the hypothalamus, and give further support to the hypothesis of a septal influence on the activity of vasopressin- or oxytocin-releasing cells in the magnocellular system.Supported by grants I.N.S.E.R.M. CRL 79.5.372.6 相似文献
66.
Montano SM Sanchez JL Laguna-Torres A Cuchi P Avila MM Weissenbacher M Serra M Viñoles J Russi JC Aguayo N Galeano AH Gianella A Andrade R Arredondo A Ramirez E Acosta ME Alava A Montoya O Guevara A Manrique H Sanchez JL Lama JR de la Hoz F Sanchez GI Ayala C Pacheco ME Carrion G Chauca G Perez JJ Negrete M Russell KL Bautista CT Olson JG Watts DM Birx DL Carr JK;South American HIV Molecular Surveillance Working Group 《Journal of acquired immune deficiency syndromes (1999)》2005,40(1):57-64
HIV cross-sectional studies were conducted among high-risk populations in 9 countries of South America. Enzyme-linked immunosorbent assay screening and Western blot confirmatory testing were performed, and env heteroduplex mobility assay genotyping and DNA sequencing were performed on a subset of HIV-positive subjects. HIV prevalences were highest among men who have sex with men (MSM; 2.0%-27.8%) and were found to be associated with multiple partners, noninjection drug use (non-IDU), and sexually transmitted infections (STIs). By comparison, much lower prevalences were noted among female commercial sex workers (FCSWs; 0%-6.3%) and were associated mainly with a prior IDU and STI history. Env subtype B predominated among MSM throughout the region (more than 90% of strains), whereas env subtype F predominated among FCSWs in Argentina and male commercial sex workers in Uruguay (more than 50% of strains). A renewed effort in controlling STIs, especially among MSM groups, could significantly lessen the impact of the HIV epidemic in South America. 相似文献
67.
68.
Robert S. Crissman Li Zheng Nicolas L. Chiaia Robert W. Rhoades 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1996,110(1):47-54
Neonatal transection of the infraorbital nerve (ION; the trigeminal, V, branch that supplies the mystacial vibrissae follicles) results in an upregulation of galanin in the central arbors of primary afferent axons. The present study was undertaken to evaluate the synaptic organization of these galanin-positive primary afferents and compare it with that of normal neurobiotin/biocytin-labeled primary afferent axons from animals of the same age. Examination of 1200 neurobiotin/biocytin-labeled profiles in V nucleus principalis (PrV) of rats killed on postnatal day (P-) 7 indicated that 23.3% (n=279) of these profiles made synaptic contacts: 87.4% were axodendritic, 8.9% were axoaxonic, 2.8% were axosomatic, and 0.7% were axospinous. Evaluation of 1200 galanin-positive profiles in PrV from rats that sustained transection of the ION on P-0 and were killed on P-7 indicated that only 64 (5.3%) of these profiles made synaptic contacts (P<0.05 compared with the intact animals). Of the galanin-positive profiles that did make synapses in PrV, 81.2% (n=52) were axodendritic and 18.8% (n=12) were axoaxonic. These results indicate that galanin released by damaged ION primary afferents in PrV is likely to affect the activity of second-order V neurons by a paracrine action rather than by acting at specific synapses. 相似文献
69.
Sequence analysis of cDNAs for the human and bovine ATP synthase β subunit: mitochondrial DNA genes sustain seventeen times more mutations 总被引:19,自引:0,他引:19
Douglas C. Wallace Jianhong Ye S. Nicolas Neckelmann Gurparkash Singh Keith A. Webster Barry D. Greenberg 《Current genetics》1987,12(2):81-90
We have cloned and sequenced human and bovine cDNAs for the subunit of the ATP synthase (ATP-synß), a nuclear DNA (nDNA) encoded oxidative phosphorylation (OXPHOS) gene. The two cDNAs were found to share 99% amino acid homology and 94% nucleotide homology. The evolutionary rate of ATPsynß was then compared with that of two mitochondrial DNA (mtDNA) ATP synthase genes (ATPase 6 and 8), seven other mtDNA OXPHOS genes, and a number of nuclear genes. The synonymous substitution rate for ATPsynß proved to be 1.9 × 10–9 substitutions per site per year (substitutions × site–1 × year–1) (SSY). This is less than 1/2 that of the average nDNA gene, 1/12 the rate of ATPase 6 and 8, and 1/17 the rate of the average mtDNA gene. The synonymous and replacement substitution rates were used to calculate a new parameter, the selective constraint ratio. This revealed that even the most variable mtDNA protein was more constrained than the average nDNA protein. Thus, the high substitution mutation rate and strong selective constraints of mammalian mtDNA proteins suggest that mtDNA mutations may result in a disproportionately large number of human hereditary diseases of OXPHOS. 相似文献
70.
When the local field potential of a cortical network displays coherent fast oscillations ( approximately 40-Hz gamma or approximately 200-Hz sharp-wave ripples), the spike trains of constituent neurons are typically irregular and sparse. The dichotomy between rhythmic local field and stochastic spike trains presents a challenge to the theory of brain rhythms in the framework of coupled oscillators. Previous studies have shown that when noise is large and recurrent inhibition is strong, a coherent network rhythm can be generated while single neurons fire intermittently at low rates compared to the frequency of the oscillation. However, these studies used too simplified synaptic kinetics to allow quantitative predictions of the population rhythmic frequency. Here we show how to derive quantitatively the coherent oscillation frequency for a randomly connected network of leaky integrate-and-fire neurons with realistic synaptic parameters. In a noise-dominated interneuronal network, the oscillation frequency depends much more on the shortest synaptic time constants (delay and rise time) than on the longer synaptic decay time, and approximately 200-Hz frequency can be realized with synaptic time constants taken from slice data. In a network composed of both interneurons and excitatory cells, the rhythmogenesis is a compromise between two scenarios: the fast purely interneuronal mechanism, and the slower feedback mechanism (relying on the excitatory-inhibitory loop). The properties of the rhythm are determined essentially by the ratio of time scales of excitatory and inhibitory currents and by the balance between the mean recurrent excitation and inhibition. Faster excitation than inhibition, or a higher excitation/inhibition ratio, favors the feedback loop and a much slower oscillation (typically in the gamma range). 相似文献