全文获取类型
收费全文 | 13320篇 |
免费 | 976篇 |
国内免费 | 57篇 |
专业分类
耳鼻咽喉 | 120篇 |
儿科学 | 229篇 |
妇产科学 | 183篇 |
基础医学 | 1829篇 |
口腔科学 | 407篇 |
临床医学 | 1338篇 |
内科学 | 3156篇 |
皮肤病学 | 195篇 |
神经病学 | 1178篇 |
特种医学 | 378篇 |
外科学 | 2016篇 |
综合类 | 124篇 |
一般理论 | 13篇 |
预防医学 | 1205篇 |
眼科学 | 248篇 |
药学 | 873篇 |
中国医学 | 12篇 |
肿瘤学 | 849篇 |
出版年
2023年 | 122篇 |
2022年 | 245篇 |
2021年 | 458篇 |
2020年 | 217篇 |
2019年 | 379篇 |
2018年 | 391篇 |
2017年 | 280篇 |
2016年 | 302篇 |
2015年 | 353篇 |
2014年 | 489篇 |
2013年 | 629篇 |
2012年 | 996篇 |
2011年 | 969篇 |
2010年 | 552篇 |
2009年 | 518篇 |
2008年 | 827篇 |
2007年 | 886篇 |
2006年 | 839篇 |
2005年 | 894篇 |
2004年 | 829篇 |
2003年 | 701篇 |
2002年 | 643篇 |
2001年 | 122篇 |
2000年 | 95篇 |
1999年 | 112篇 |
1998年 | 153篇 |
1997年 | 113篇 |
1996年 | 96篇 |
1995年 | 94篇 |
1994年 | 69篇 |
1993年 | 68篇 |
1992年 | 52篇 |
1991年 | 41篇 |
1990年 | 46篇 |
1989年 | 46篇 |
1988年 | 49篇 |
1987年 | 54篇 |
1986年 | 55篇 |
1985年 | 42篇 |
1984年 | 52篇 |
1983年 | 47篇 |
1982年 | 52篇 |
1981年 | 29篇 |
1980年 | 30篇 |
1979年 | 31篇 |
1978年 | 14篇 |
1977年 | 25篇 |
1976年 | 23篇 |
1973年 | 14篇 |
1970年 | 16篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
Wojciech Szychta M.D. Ph.D. Gheorghe Cerin M.D. Ph.D. F.E.S.C. Bogdan Adrian Popa M.D. Armienti Felice M.D. Guido Lanzillo M.D. Ph.D. Marco Diena M.D. Grzegorz Opolski M.D. Ph.D. F.E.S.C. 《Echocardiography (Mount Kisco, N.Y.)》2015,32(6):1040-1043
Sinus venosus atrial septal defect (SV‐ASD) usually coexists with partial anomalous pulmonary vein connection (PAPVC). It is a difficult diagnosis in transthoracic echocardiography (TTE) due to eccentric position of defects. We present a rare case of atypical anatomical variation in PAPVC, which was never described before. Two right pulmonary veins drained into superior vena cava, which overrode SV‐ASD and interatrial septum, a third pulmonary vein into the right atrium. Complete diagnosis could not be set after TTE, nor transesophageal echocardiography, whereas angio‐CT was finally conclusive. This diagnostic approach allowed the surgical planning. 相似文献
2.
Stress Testing Versus CT Angiography in Patients With Diabetes and Suspected Coronary Artery Disease
Abhinav Sharma Adrian Coles Nishant K. Sekaran Neha J. Pagidipati Michael T. Lu Daniel B. Mark Kerry L. Lee Hussein R. Al-Khalidi Udo Hoffmann Pamela S. Douglas 《Journal of the American College of Cardiology》2019,73(8):893-902
Background
The optimal noninvasive test (NIT) for patients with diabetes and stable symptoms of coronary artery disease (CAD) is unknown.Objectives
The purpose of this study was to assess whether a diagnostic strategy based on coronary computed tomographic angiography (CTA) is superior to functional stress testing in reducing adverse cardiovascular (CV) outcomes (CV death or myocardial infarction [MI]) among symptomatic patients with diabetes.Methods
PROMISE (Prospective Multicenter Imaging Study for Evaluation of Chest Pain) was a randomized trial evaluating an initial strategy of CTA versus functional testing in stable outpatients with symptoms suggestive of CAD. The study compared CV outcomes in patients with diabetes (n = 1,908 [21%]) and without diabetes (n = 7,058 [79%]) based on their randomization to CTA or functional testing.Results
Patients with diabetes (vs. without) were similar in age (median 61 years vs. 60 years) and sex (female 54% vs. 52%) but had a greater burden of CV comorbidities. Patients with diabetes who underwent CTA had a lower risk of CV death/MI compared with functional stress testing (CTA: 1.1% [10 of 936] vs. stress testing: 2.6% [25 of 972]; adjusted hazard ratio: 0.38; 95% confidence interval: 0.18 to 0.79; p = 0.01). There was no significant difference in nondiabetic patients (CTA: 1.4% [50 of 3,564] vs. stress testing: 1.3% [45 of 3,494]; adjusted hazard ratio: 1.03; 95% confidence interval: 0.69 to 1.54; p = 0.887; interaction term for diabetes p value = 0.02).Conclusions
In diabetic patients presenting with stable chest pain, a CTA strategy resulted in fewer adverse CV outcomes than a functional testing strategy. CTA may be considered as the initial diagnostic strategy in this subgroup. (PROspective Multicenter Imaging Study for Evaluation of Chest Pain [PROMISE]; NCT01174550) 相似文献3.
4.
Multivariate survival data are frequently encountered in biomedical applications in the form of clustered failures (or recurrent events data). A popular way of analyzing such data is by using shared frailty models, which assume that the proportional hazards assumption holds conditional on an unobserved cluster-specific random effect. Such models are often incorporated in more complicated joint models in survival analysis. If the random effect distribution has finite expectation, then the conditional proportional hazards assumption does not carry over to the marginal models. It has been shown that, for univariate data, this makes it impossible to distinguish between the presence of unobserved heterogeneity (eg, due to missing covariates) and marginal nonproportional hazards. We show that time-dependent covariate effects may falsely appear as evidence in favor of a frailty model also in the case of clustered failures or recurrent events data, when the cluster size or number of recurrent events is small. When true unobserved heterogeneity is present, the presence of nonproportional hazards leads to overestimating the frailty effect. We show that this phenomenon is somewhat mitigated as the cluster size grows. We carry out a simulation study to assess the behavior of test statistics and estimators for frailty models in such contexts. The gamma, inverse Gaussian, and positive stable shared frailty models are contrasted using a novel software implementation for estimating semiparametric shared frailty models. Two main questions are addressed in the contexts of clustered failures and recurrent events: whether covariates with a time-dependent effect may appear as indication of unobserved heterogeneity and whether the additional presence of unobserved heterogeneity can be detected in this case. Finally, the practical implications are illustrated in a real-world data analysis example. 相似文献
5.
While once considered as incurable systemic disease, treatment options for liver metastases have increased over the last 30 years and safety has improved dramatically, such that for a selected group of patients the hope of cure can now be offered with radical treatment, and low morbidity interventions can be offered which prolong survival, even in patients with more widely disseminated disease. Advances have been made in selection and surgical technique for liver resection and several adjuncts to resection now exist in the form of portal vein embolization, thermal ablation and targeted drug or radiotherapy delivery options. A natural consequence of these developments has been the delivery of services within fewer specialist units, with the result that later complications of therapy may present to local hospitals, rather than directly to the specialist centres. This article will describe the current common liver-directed therapies and outline the presentation and management of their complications. 相似文献
6.
7.
There are an estimated 200 million users of an illicit drug in the world today. In addition, an estimated 40 million people are infected with the human immunodeficiency virus (HIV) and an estimated 180 million people are infected with the hepatitis C virus (HCV). Both the use of an illicit drug and the co-occurrence of infections are associated with a multitude of medical and health consequences including hormonal and metabolic disorders. Thus, the National Institute on Drug Abuse (NIDA), a part of the National Institutes of Health (NIH) hosted a workshop on hormonal and metabolic disorders of HIV among substance abusers. A number of clinicians and scientists participated and discussed a wide range of issues concerning hormones, nutrition and metabolic complications in HIV and substance abuse. Their observations and the recommendations they made for future research are presented in these proceedings. The readers are encouraged to contact the NIH staff (JK, FV) for technical guidance and programmatic priorities on the subject and directly contact the individual authors for collaborations. 相似文献
8.
9.
Katherine A Hillman Tanya M Johnson Paul J D Winyard Geoffrey Burnstock Robert J Unwin Adrian S Woolf 《Experimental nephrology》2002,10(1):34-42
BACKGROUND: Purinergic receptors are cell-surface molecules that bind extracellular nucleotides, notably ATP. The P2X family includes seven nonselective ion channels with one member, P2X(7), implicated in cytolytic pore formation and cell death. MATERIALS AND METHODS: We sought P2X(7) expression in mouse nephrogenesis and cpk/cpk renal cyst growth, conditions in which both proliferation and apoptosis are prominent. RESULTS: P2X(7) immunolocalized to condensed metanephric mesenchyme: both proliferation and apoptosis were detected in this compartment, assessed by proliferating cell nuclear antigen expression and propidium iodide-stained pyknotic nuclei respectively. Later in nephrogenesis, P2X(7) was detected in collecting ducts, a pattern persisting to maturity. A mesenchymal to epithelial shift of P2X(7) expression was also documented in ureter development. In cpk/cpk kidneys, P2X(7)-expressing collecting duct cysts dominated histology from two weeks until four weeks after birth, when animals die from uremia. In polycystic kidneys pyknotic nuclei were rarely identified in P2X(7)-expressing epithelia, but were detected between cysts, consistent with a non-apoptotic role for P2X(7) in cyst enlargement. CONCLUSION: P2X(7) is expressed during normal nephrogenesis and in a model of congenital polycystic kidney disease. Further experiments are necessary to define possible functions of P2X(7) in these settings. 相似文献
10.