全文获取类型
收费全文 | 2459篇 |
免费 | 182篇 |
国内免费 | 6篇 |
专业分类
耳鼻咽喉 | 17篇 |
儿科学 | 47篇 |
妇产科学 | 31篇 |
基础医学 | 340篇 |
口腔科学 | 167篇 |
临床医学 | 167篇 |
内科学 | 506篇 |
皮肤病学 | 163篇 |
神经病学 | 140篇 |
特种医学 | 63篇 |
外科学 | 245篇 |
综合类 | 9篇 |
预防医学 | 341篇 |
眼科学 | 11篇 |
药学 | 265篇 |
中国医学 | 43篇 |
肿瘤学 | 92篇 |
出版年
2024年 | 3篇 |
2023年 | 28篇 |
2022年 | 48篇 |
2021年 | 98篇 |
2020年 | 62篇 |
2019年 | 83篇 |
2018年 | 106篇 |
2017年 | 85篇 |
2016年 | 90篇 |
2015年 | 102篇 |
2014年 | 140篇 |
2013年 | 129篇 |
2012年 | 190篇 |
2011年 | 209篇 |
2010年 | 124篇 |
2009年 | 92篇 |
2008年 | 162篇 |
2007年 | 137篇 |
2006年 | 123篇 |
2005年 | 105篇 |
2004年 | 115篇 |
2003年 | 100篇 |
2002年 | 62篇 |
2001年 | 34篇 |
2000年 | 19篇 |
1999年 | 32篇 |
1998年 | 12篇 |
1997年 | 12篇 |
1996年 | 15篇 |
1995年 | 12篇 |
1994年 | 11篇 |
1992年 | 15篇 |
1991年 | 10篇 |
1990年 | 7篇 |
1989年 | 6篇 |
1988年 | 5篇 |
1987年 | 3篇 |
1986年 | 5篇 |
1985年 | 7篇 |
1984年 | 8篇 |
1983年 | 3篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1972年 | 2篇 |
1971年 | 2篇 |
1970年 | 5篇 |
1969年 | 2篇 |
1967年 | 3篇 |
1966年 | 4篇 |
1964年 | 3篇 |
排序方式: 共有2647条查询结果,搜索用时 15 毫秒
71.
72.
73.
74.
Tostões RM Leite SB Serra M Jensen J Björquist P Carrondo MJ Brito C Alves PM 《Hepatology (Baltimore, Md.)》2012,55(4):1227-1236
Primary cultures of human hepatocyte spheroids are a promising in vitro model for long-term studies of hepatic metabolism and cytotoxicity. The lack of robust methodologies to culture cell spheroids, as well as a poor characterization of human hepatocyte spheroid architecture and liver-specific functionality, have hampered a widespread adoption of this three-dimensional culture format. In this work, an automated perfusion bioreactor was used to obtain and maintain human hepatocyte spheroids. These spheroids were cultured for 3-4 weeks in serum-free conditions, sustaining their phase I enzyme expression and permitting repeated induction during long culture times; rate of albumin and urea synthesis, as well as phase I and II drug-metabolizing enzyme gene expression and activity of spheroid hepatocyte cultures, presented reproducible profiles, despite basal interdonor variability (n = 3 donors). Immunofluorescence microscopy of human hepatocyte spheroids after 3-4 weeks of long-term culture confirmed the presence of the liver-specific markers, hepatocyte nuclear factor 4α, albumin, cytokeratin 18, and cytochrome P450 3A. Moreover, immunostaining of the atypical protein kinase C apical marker, as well as the excretion of a fluorescent dye, evidenced that these spheroids spontaneously assemble a functional bile canaliculi network, extending from the surface to the interior of the spheroids, after 3-4 weeks of culture. Conclusion: Perfusion bioreactor cultures of primary human hepatocyte spheroids maintain a liver-specific activity and architecture and are thus suitable for drug testing in a long-term, repeated-dose format. 相似文献
75.
Joyce Pinho Bezerra Ariane de Siqueira Amanda Gonçalves Pires Marcelo Rocha Marques Poliana Mendes Duarte Marta Ferreira Bastos 《Journal of periodontology》2013,84(6):839-849
Background: The aim of this study is to evaluate the effects of caffeine and/or estrogen deficiency on ligature‐induced bone loss (BL), trabecular bone area (TBA), and postextraction bone healing (BH). Methods: Rats were assigned into one of the following groups (15 each): 1) control = non‐ingestion of caffeine/sham surgery; 2) caffeine = ingestion of caffeine/sham surgery); 3) ovariectomized (OVX) = non‐ingestion of caffeine/ovariectomy; or 4) caffeine/OVX = ingestion of caffeine/ovariectomy. The rats were under caffeine administration for 65 days and/or estrogen deficiency for 51 days. On day 21 after ovariectomy, one first mandibular molar received a ligature and the contralateral tooth was not ligated. The first maxillary molars were extracted 8 days before sacrifice. BL, TBA, the positive cells for tartrate‐resistant acid phosphatase (TRAP), receptor activator of nuclear factor‐κB ligand (RANKL), and osteoprotegerin (OPG) were analyzed in the furcation area of mandibular molars. Histometric BH and gene expression of bone morphogenetic protein (BMP)‐2, BMP‐7, osteopontin, and bone sialoprotein were evaluated in alveolar sockets. Results: The caffeine group presented the greatest BL and the OVX group the highest number of TRAP‐positive (TRAP+) cells around ligated teeth (P <0.05). The control group presented higher TBA and BH than the other groups (P <0.05). All test groups presented higher RANKL/OPG+ cells than the control group around ligated/unligated teeth. The OVX and caffeine/OVX groups presented a greater number of TRAP+ cells around unligated teeth than the control group (P <0.05). There were no differences among groups for gene expression (P >0.05). Conclusions: Caffeine increased BL in ligated teeth. Caffeine and/or estrogen deficiency decreased TBA in the unligated teeth and reduced BH after tooth extraction. 相似文献
76.
Teixeira R Monteiro P Marques G Pego JM Louren?o M Tavares C Reboredo A Monteiro S Gon?alves F Ferreira MJ Freitas M Ribeiro G Providência LA 《Revista portuguesa de cardiologia》2012,31(9):545-554
IntroductionInhibition of platelet aggregation appears two hours after the first dose of clopidogrel, becomes significant after the second dose, and progresses to a steady-state value of 55% by day seven. Low response to clopidogrel has been associated with increased risk of stent thrombosis and ischemic events, particularly in the context of stable heart disease treated by percutaneous coronary intervention.ObjectiveTo stratify medium-term prognosis of an acute coronary syndrome (ACS) population by platelet aggregation.MethodsWe performed a prospective longitudinal study of 70 patients admitted for an ACS between May and August 2009. Platelet function was assessed by ADP-induced platelet aggregation using a commercially available kit (Multiplate® analyzer) at discharge. The primary endpoint was a combined outcome of mortality, non-fatal myocardial infarction, or unstable angina, with a median follow-up of 136.0 (79.0–188.0) days.ResultsThe median value of platelet aggregation was 16.0 U (11.0–22.5 U) with a maximum of 41.0 U and a minimum of 4.0 U (normal value according to the manufacturer: 53–122 U). After ROC curve analysis with respect to the combined endpoint (AUC 0.72), we concluded that a value of 18.5 U conferred a sensitivity of 75.0% and a specificity of 68% to that result. We therefore created two groups based on that level: group A – platelet aggregation <18.5 U, n = 44; and group B – platelet aggregation ≥18.5 U, n = 26. The groups were similar with respect to demographic data (age 60.5 [49.0–65.0] vs. 62.0 [49.0–65.0] years, p = 0.21), previous cardiovascular history, and admission diagnosis. There were no associations between left ventricular ejection fraction, GRACE risk score, or length of hospital stay and platelet aggregation. The groups were also similar with respect to antiplatelet, anticoagulant, proton pump inhibitor (63.6 vs. 46.2%, p = 0.15) and statin therapy. The variability in platelets and hemoglobin was also similar between groups. Combined event-free survival was higher in group A (96.0 vs. 76.7%, log-rank p < 0.01). Platelet aggregation higher than 18.5 U was an independent predictor of the combined event (HR 6.75, 95% CI 1.38–32.90, p = 0.02).ConclusionIn our ACS population platelet aggregation at discharge was a predictor of medium-term prognosis. 相似文献
77.
MD Bastos S Santos A Souza B Finkmoore O Bispo T Barreto I Cardoso I Bispo F Bastos D Pereira L Riley E Carvalho 《BMC infectious diseases》2012,12(1):199
ABSTRACT: BACKGROUND: HTLV-1 is associated with increased susceptibility to Mycobacterium tuberculosis infection and severity of tuberculosis. Although previous studies have shown that HTLV-1 infected individuals have a low frequency of positive tuberculin skin test (TST) and decreasing in lymphoproliferative responses compared to HTLV-1 uninfected persons, these studies were not performed in individuals with history of tuberculosis or evidence of M. tuberculosis infection. Therefore the reasons why HTLV-1 infection increases susceptibility to infection and severity of tuberculosis are not understood.The aim of this study was to evaluate how HTLV-1 may influence the clinical, bacteriologic and immunologic presentation of tuberculosis. METHODS: The study prospectively enrolled and followed 13 new cases of tuberculosis associated with HTLV-1 (cases) and 25 patients with tuberculosis without HTLV-1 infection (controls). Clinical findings, bacterial load in the sputum, x-rays, immunological response and death were compared in the two groups. RESULTS: There were no differences in the demographic, clinical and TST response between the two study groups. IFN-gamma and TNF-alpha production was higher in unstimulated cultures of mononuclear cells of case than in control patients (p < 0.01). While there was no difference in IFN-gamma production in PPD stimulated cultures, TNF-alpha levels were lower in cases than in controls (p = 0.01). There was no difference in the bacterial load among the groups but sputum smear microscopy results became negative faster in cases than in controls. Death only occurred in two co-infected patients. CONCLUSION: While the increased susceptibility for tuberculosis infection in HTLV-1 infected subjects may be related to impairment in TNF-alpha production, the severity of tuberculosis in co-infected patients may be due to the enhancement of the Th1 inflammatory response, rather than in their decreased ability to control bacterial growth. 相似文献
78.
Vilares-Morgado Rodrigo Madeira Carolina Falcão Manuel Godinho Gonçalo Ribeiro Margarida Beato João Pedrosa Ana Catarina Brandão Elisete Falcão-Reis Fernando Carneiro Ângela 《Albrecht von Graefes Archiv fur klinische und experimentelle Ophthalmologie》2021,259(9):2583-2595
Graefe's Archive for Clinical and Experimental Ophthalmology - To identify predictive factors for RPE tear remodelling and its correlation with functional and morphological outcomes.... 相似文献
79.
80.
Kleyton Bastos Luis Antonio Lucarelli Elizabeth De Francesco-Daher Roberto Pecoits Filho Carlos Henríquez Beatriz Espinoza Ignacio Villanueva Emma Schwedt Ruben Schiavelli Ricardo Correa-Rotter 《International urology and nephrology》2013,45(5):1355-1364