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41.
Modulation of Whole-Cell Currents in Plasmodium Falciparum-Infected Human Red Blood Cells by Holding Potential and Serum 总被引:3,自引:0,他引:3
Henry M. Staines Trevor Powell J. Clive Ellory Stéphane Egée Franck Lapaix Gaëtan Decherf Serge L. Y. Thomas Christophe Duranton† Florian Lang† Stephan M. Huber† 《The Journal of physiology》2003,552(1):177-183
Recent electrophysiological studies have identified novel ion channel activity in the host plasma membrane of Plasmodium falciparum -infected human red blood cells (RBCs). However, conflicting data have been published with regard to the characteristics of induced channel activity measured in the whole-cell configuration of the patch-clamp technique. In an effort to establish the reasons for these discrepancies, we demonstrate here two factors that have been found to modulate whole-cell recordings in malaria-infected RBCs. Firstly, negative holding potentials reduced inward currents (i.e. at negative potentials), although this result was highly complex. Secondly, the addition of human serum increased outward currents (i.e. at positive potentials) by approximately 4-fold and inward currents by approximately 2-fold. These two effects may help to resolve the conflicting data in the literature, although further investigation is required to understand the underlying mechanisms and their physiological relevance in detail. 相似文献
42.
Frei K Szuhai K Lucas T Weipoltshammer K Schöfer C Ramsebner R Baumgartner WD Raap AK Bittner R Wachtler FJ Kirschhofer K 《European journal of human genetics : EJHG》2002,10(7):427-432
Mutations in the connexin 26 (Cx26) gene (GJB2) are associated with autosomal nonsyndromic sensorineural hearing loss. This study describes mutations in the Cx26 gene in cases of familial and sporadic hearing loss (HL) by gene sequencing and identifies the allelic frequency of the most common mutation leading to HL (35delG) in the population of eastern Austria. For this purpose we have developed and applied a molecular beacon based real-time mutation detection assay. Mutation frequencies in the Cx26 gene of individuals from affected families (14 out of 46) and sporadic cases (11 out of 40) were 30.4% and 27.5%, respectively. In addition to known disease related alterations, a novel mutation 262 G-->T (A88S) was also identified. 35delG accounted for almost 77% of all Cx26 mutations detected and displayed an allelic frequency in the normal hearing population of 1.7% (2 out of 120). The high prevalence of the 35delG mutation in eastern Austria would therefore allow screening of individuals and family members with Cx26 dependent deafness by a highly specific and semi-automated method. 相似文献
43.
Comparison of PCR-ELISA and galactomannan detection for the diagnosis of invasive aspergillosis 总被引:1,自引:0,他引:1
AIM: To compare PCR with galactomannan antigen detection for the diagnosis of invasive aspergillosis (IA). METHODS: We prospectively collected serial blood samples from haematological patients at risk of IA, and analysed their samples retrospectively for galactomannan (GM) antigen using the Platelia test and for aspergillus DNA using an in-house PCR-ELISA assay. Matched GM and PCR analyses were performed on 263 samples from 25 patients. Patients were classified for potential IA according to international consensus criteria, with five patients classified as positive (four proven, one probable) and 20 classified as negative (seven possible, 13 no evidence IA). RESULTS: All five patients with IA were positive by PCR with positive results in 24 of 82 samples, whereas three of five patients were positive by GM with four of 82 samples being positive. Three of 20 patients without IA were positive by PCR in 18 of 181 samples, whereas corresponding results for GM detection were one of 20 and one of 181, respectively. Adjustment of ELISA cut-off values and/or the requirement for two consecutive samples to be positive generated different results; however, lowering the positivity index (PI) for GM detection to 0.5 did not improve the sensitivity of the assay. Optimal results for PCR detection and GM were: 100% and 60% sensitivity, 85% and 95% specificity, 0.625 and 0.75 positive predictive value, and 1.0 and 0.8 negative predictive value, with a false-positive sample rate of 8 and 0.4%, positive likelihood ratio of 6.66 and 11.99 and negative likelihood ratio of 0 and 0.42, respectively. CONCLUSIONS: This PCR method is very sensitive for the diagnosis of IA but is associated with a moderate rate of false positives; the GM assay exhibited poor sensitivity but high specificity. Further evaluation of PCR assays for the diagnosis of IA and other invasive fungal infections is warranted. 相似文献
44.
Moyle GJ DeJesus E Cahn P Castillo SA Zhao H Gordon DN Craig C Scott TR;Ziagen Once-Daily in Antiretroviral Combination Therapy 《Journal of acquired immune deficiency syndromes (1999)》2005,38(4):417-425
The long intracellular half-life of abacavir (ABC) supports its once-daily use, and this would be expected to simplify treatment if ABC could be given as part of a complete once-daily regimen. A randomized double-blind clinical trial compared the efficacy and safety of 600 mg of ABC administered once daily (n = 384) versus 300 mg of ABC administered twice daily (n = 386) in combination with 300 mg of lamivudine (3TC) and 600 mg of efavirenz (EFV) administered once daily in antiretroviral-naive patients over 48 weeks. The baseline median plasma HIV-1 RNA level was 4.89 log10 copies/mL (44% with viral load >100,000 copies/mL), and the median CD4 cell count was 262 cells/mm. ABC administered once daily was non-inferior to the twice-daily regimen, with 66% and 68% of patients in these respective treatment arms achieving a confirmed plasma HIV-1 RNA level <50 copies/mL (95% confidence interval: -8.4%, 4.9%). The ABC once-daily and twice-daily regimens were similar with respect to infrequency of virologic failure (10% vs. 8%), emergence of resistance mutations, CD4 cell increases from baseline (median, 188 vs. 200 cells/mm), safety profile, and incidence of ABC-related hypersensitivity reactions (9% vs. 7%). ABC administered once daily in combination with 3TC and EFV administered once daily was non-inferior to the ABC twice-daily dosing schedule when combined with 3TC and EFV over 48 weeks. 相似文献
45.
The free radical-generating system of xanthine and xanthine oxidase is commonly used experimentally as a source of superoxide anion, which can produce oxidative stress, leading to cellular damage and death. Models of oxidative stress are important in elucidating pathologies associated with increased levels of reactive oxygen species, including stroke and neurodegenerative diseases, such as Alzheimer's and Parkinson's diseases. We therefore, examined the effect of the xanthine/xanthine oxidase system on the viability of postnatal cerebellar granule neurones obtained from 8-day old Sprague–Dawley rat pups. Xanthine (100 μM) and xanthine oxidase (0.02 U/ml) applied for 1 or 6 h reduced the viability of cells at 8 div assessed using the alamar blue assay, and induced morphological changes, such as shrinkage of the cell bodies and neurites. Heat-inactivation of xanthine oxidase resulted in complete loss of its activity. Superoxide dismutase (250 U/ml) failed to modify the damage by xanthine and xanthine oxidase, while catalase (250 U/ml) completely prevented it. When applied alone, xanthine oxidase significantly lowered cell viability, an effect that was blocked by allopurinol and catalase, but not by superoxide dismutase. The results indicate that xanthine and xanthine oxidase can produce predominantly hydrogen peroxide instead of the superoxide anion. Cerebellar granule cells in culture may also possess significant levels of endogenous xanthine. 相似文献
46.
Detection of highly pathogenic and low pathogenic avian influenza subtype H5 (Eurasian lineage) using NASBA 总被引:15,自引:0,他引:15
Nucleic acid sequence-based amplification (NASBA) is a technique that allows the rapid amplification of specific regions of nucleic acid obtained from a diverse range of sources. It is especially suitable for amplifying RNA sequences. A NASBA technique has been developed that allows the detection of avian influenza A subtype H5 from allantoic fluid harvested from inoculated chick embryos. The amplified viral RNA is detected by electrochemiluminescence. The NASBA technique described below is rapid and specific for the identification of influenza A subtype H5 viruses of the Eurasian lineage. More importantly, it can be used to distinguish highly pathogenic and low pathogenic strains of the H5 subtype. 相似文献
47.
Paul S. Miller Marco Beato Robert J. Harvey Trevor G. Smart 《The Journal of physiology》2005,566(3):657-670
Glycine receptors exhibit a biphasic sensitivity profile in response to Zn2+ -mediated modulation, with low Zn2+ concentrations potentiating (< 10 μ m ), and higher Zn2+ concentrations inhibiting submaximal responses to glycine. Here, a substantial 30-fold increase in sensitivity to Zn2+ -mediated inhibition was apparent for the homomeric glycine receptor (GlyR) α1 subunit compared to either GlyR α2 or α3 subtypes. Swapping the divergent histidine (H107) residue in GlyR α1, which together with the conserved H109 forms part of an intersubunit Zn2+ -binding site, for the equivalent asparagine residue present in GlyR α2 and α3, reversed this phenotype. Co-expression of heteromeric GlyR α1 or α2 with the ancillary β subunit yielded receptors that maintained their distinctive sensitivities to Zn2+ inhibition. However, GlyR α2β heteromers were consistently 2-fold more sensitive to inhibition compared to the GlyR α2 homomer. Comparative studies to elucidate the specific residue in the β subunit responsible for this differential sensitivity revealed instead threonine 133 in the α1 subunit as a new vital component for Zn2+ -mediated inhibition. Further studies on heteromeric receptors demonstrated that a mutated β subunit could indeed affect Zn2+ -mediated inhibition but only from one side of the intersubunit Zn2+ -binding site, equivalent to the GlyR α1 H107 face. This strongly suggests that the α subunit is responsible for Zn2+ -mediated inhibition and that this is effectively transduced, asymmetrically, from the side of the Zn2+ -binding site where H109 and T133 are located. 相似文献
48.
Therapeutic Effect of Doxycycline in Experimental Subclinical Canine Monocytic Ehrlichiosis: Evaluation of a 6-Week Course 总被引:4,自引:1,他引:4 下载免费PDF全文
Shimon Harrus Trevor Waner Itzhak Aizenberg Hylton Bark 《Journal of clinical microbiology》1998,36(7):2140-2142
The efficacy of doxycycline treatment (10 mg/kg of body weight every 24 h for 42 days) in eliminating Ehrlichia canis from four subclinically infected dogs was evaluated. One dog remained PCR positive, suggesting that 6 weeks of doxycycline treatment may not be sufficient to clear E. canis parasites from all subclinically infected dogs. Serology (indirect immunofluorescent antibody assay) was shown to be unreliable in assessing recovery from the carrier state, as anti-E. canis antibodies persisted after elimination of the parasite. Our findings suggest that an increase in the platelet count may be an important indicator for dogs that recover from subclinical ehrlichiosis. 相似文献
49.
Shimon Harrus Trevor Waner Itzhak Aizenberg Janet E. Foley Amy M. Poland Hylton Bark 《Journal of clinical microbiology》1998,36(1):73-76
In order to determine whether dogs in the subclinical phase of canine monocytic ehrlichiosis (CME) are carriers of Ehrlichia canis and to determine the significance of persistent indirect immunofluorescent anti-E. canis antibody titers during this phase, PCR was performed with blood, bone marrow, and splenic aspirates collected 34 months postinoculation from six clinically healthy beagle dogs experimentally infected with E. canis. At least one of the three samples (spleen, bone marrow, and blood) from four of the six dogs was PCR positive. The spleens of all four of these dogs were PCR positive, and the bone marrow and blood of two of the four dogs were PCR positive. Indirect immunofluorescent-antibody titers increased progressively during the first 5 months postinfection, remained high for an additional period of more than 11 months, and declined thereafter, suggesting that the dogs were recovering from the disease. Five of the dogs remained seropositive 34 months postinfection. The data obtained in this study demonstrate for the first time that clinically healthy dogs in the subclinical phase of CME are carriers of the rickettsia. It was shown that dogs can harbor E. canis for years without developing the chronic clinical disease and that dogs can eliminate the parasite and recover from CME without medical treatment. Our findings suggest that the spleen is the organ most likely to harbor E. canis parasites during the subclinical phase and the last organ to accommodate the parasite before elimination. It was concluded that PCR of DNA extracted from splenic aspirates is a reliable method for determining the carrier state of CME. 相似文献
50.