首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   10990篇
  免费   651篇
  国内免费   75篇
耳鼻咽喉   55篇
儿科学   267篇
妇产科学   208篇
基础医学   1660篇
口腔科学   198篇
临床医学   838篇
内科学   2988篇
皮肤病学   94篇
神经病学   985篇
特种医学   531篇
外科学   1542篇
综合类   25篇
一般理论   4篇
预防医学   422篇
眼科学   115篇
药学   500篇
中国医学   41篇
肿瘤学   1243篇
  2024年   13篇
  2023年   61篇
  2022年   150篇
  2021年   249篇
  2020年   132篇
  2019年   203篇
  2018年   261篇
  2017年   201篇
  2016年   262篇
  2015年   269篇
  2014年   398篇
  2013年   497篇
  2012年   839篇
  2011年   854篇
  2010年   475篇
  2009年   420篇
  2008年   757篇
  2007年   779篇
  2006年   749篇
  2005年   739篇
  2004年   688篇
  2003年   697篇
  2002年   594篇
  2001年   103篇
  2000年   105篇
  1999年   111篇
  1998年   144篇
  1997年   92篇
  1996年   82篇
  1995年   80篇
  1994年   63篇
  1993年   48篇
  1992年   35篇
  1991年   65篇
  1990年   35篇
  1989年   33篇
  1988年   41篇
  1987年   27篇
  1986年   26篇
  1985年   23篇
  1984年   33篇
  1983年   27篇
  1982年   33篇
  1981年   28篇
  1980年   18篇
  1979年   13篇
  1977年   11篇
  1976年   9篇
  1974年   15篇
  1973年   13篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
111.
During recent years, a clear association between complicated courses of ulcerative colitis and the presence of cytomegalovirus (CMV) has been established. The exact pathogenic role of CMV in these patients remains unclear despite a great number of published reports. Therefore, we undertook a systematic review to appraise critically all available evidence in the literature on the role of CMV during inflammatory bowel disease. We identified and analyzed more than 30 case reports and 9 case series. Based on these results, we propose a model for viral replication during inflammation and provide recommendations for future research.  相似文献   
112.
BACKGROUND: Little is known about the morphological and functional evolution of ventricular abnormalities in Loeffler endocarditis. METHODS AND RESULTS: We describe 5 patients, including 3 with long-term echocardiographic follow-up, in whom apical obliteration due to fibro-thrombotic thickening of the endocardium showed favorable patterns of evolution. In one patient there was almost complete resolution of the obliterative process with consequently increased effective ventricular volume. In two patients formation of a flow-passage in the fibrocalcific apical 'floor' between the main medioventricular cavity and the apical chamber, leading to a 'double-chambered' left ventricle was observed. CONCLUSIONS: Medical therapy and appropriate anticoagulation, can induce favorable long-term ventricular remodeling in Loeffler endocarditis.  相似文献   
113.
Detection of high-risk subjects in acute myocardial infarction (AMI) by noninvasive means would reduce the need for intracardiac catheterization and associated complications. Liver enzymes are associated with cardiovascular disease risk. A potential predictive value for liver serum markers for the severity of stenosis in AMI was analyzed.Patients with AMI undergoing percutaneous coronary intervention (PCI; n = 437) were retrospectively evaluated. Minimal lumen diameter (MLD) and percent stenosis diameter (SD) were determined from quantitative coronary angiography. Patients were classified according to the severity of stenosis (SD ≥ 50%, n = 357; SD < 50%, n = 80). Routine heart and liver parameters were associated with SD using random forests (RF). A prediction model (M10) was developed based on parameter importance analysis in RF.Age, alkaline phosphatase (AP), aspartate aminotransferase (AST), and MLD differed significantly between SD ≥ 50 and SD < 50. Age, AST, alanine aminotransferase (ALT), and troponin correlated significantly with SD, whereas MLD correlated inversely with SD. M10 (age, BMI, AP, AST, ALT, gamma-glutamyltransferase, creatinine, troponin) reached an AUC of 69.7% (CI 63.8–75.5%, P < 0.0001).Routine liver parameters are associated with SD in AMI. A small set of noninvasively determined parameters can identify SD in AMI, and might avoid unnecessary coronary angiography in patients with low risk. The model can be accessed via http://stenosis.heiderlab.de.  相似文献   
114.
Mechanisms that underly discordant CD4+ cell/virus load (VL) responses in patients who receive highly active antiretroviral therapy (HAART) were studied in 30 human immunodeficiency virus (HIV)-positive patients, in 3 groups. Discordant responders maintained CD4+ cell levels >200/mm(3) with stable or increasing trend, despite sustained VLs of 500-5000 copies/mL, for >2 years. Treatment-success patients had CD4+ cell counts >200/mm(3) with stable or increasing trend and VLs <50 copies/mL, for >2 years. Treatment-failure patients initially responded to HAART, followed by decreasing CD4+ cell counts and increasing VLs. Interferon-gamma production to gag and noncytolytic CD8+ cell suppressive activity were greater in discordant responders. Cellular activation was greatest in patients with treatment failure. All discordant responders had non-syncytium-inducing (CCR5-tropic) viruses. Viruses from discordant responders and from patients with treatment failure had extensive resistance mutations; discordant responders had significantly lower viral replication capacities. These findings suggest that discordant responses may be related to enhanced HIV-directed immune responses, diminished cellular activation, decreased viral replication capacity, and preservation of non-syncytium-inducing virus strains.  相似文献   
115.
Introduction: Patients with schizophrenia or bipolar disorder treated with antipsychotic medication can frequently experience lack of efficacy and persistent side-effects, so much so that switching from one antipsychotic to another with a different side-effect profile has become a recommended strategy for improving the tolerability and safety of long-term antipsychotic treatment. Aripiprazole is an atypical antipsychotic with proven efficacy in schizophrenia and bipolar I disorder, with a pharmacological profile distinct from other available antipsychotics and a side-effect profile that is different from other agents in the class; these characteristics make it a possible alternative in patients requiring a change in antipsychotic treatment due to lack of efficacy or persistent side-effects.

Areas covered: A panel of Italian experts in psychiatry met to discuss the appropriateness of current strategies for the switch to aripiprazole in patients with schizophrenia or bipolar disorder once a clinician has decided to adopt this choice and also to propose alternate strategies where required. The strategies for the switch to aripiprazole presented in this position paper consider various scenarios encountered in clinical practice, highlight the importance of tapering the prior antipsychotic based on its pharmacological characteristics and provide detailed guidance throughout the entire switching process. Literature searches were conducted using the PubMed database and the search strategy (aripiprazole and switching); additional references were added from the reference lists of the papers obtained and also from the authors’ knowledge of the topic.

Expert opinion: Few studies have addressed the indications for antipsychotic switching and the best practical strategies to achieve the desired goal in the clinical practice setting. Studies on antipsychotic switching should clarify why, when and how a switch should be done. The results should standardize the reasons for switching an antipsychotic, assess the optimal time to switch and evaluate the best ways to switch. Both clinical and pharmacological factors should be considered when a patient needs to switch antipsychotics, and specific guidelines for antipsychotic switching that address all these factors are needed.  相似文献   

116.
117.

Purpose

The aim of the present study was to evaluate the efficacy of an oral formulation of Δ9-tetrahydrocannabinol (ECP002A) in patients with progressive multiple sclerosis (MS).

Methods

This accelerated proof-of-concept study consisted of 2 phases: a crossover challenge (dose-finding) phase and a 4-week, parallel, randomized, placebo-controlled treatment phase. Twenty-four patients with progressive MS and moderate spasticity were enrolled. During the treatment phase, biomarkers for efficacy and secondary pharmacodynamic effects were measured at baseline and after 2 and 4 weeks of treatment. Serum samples were collected to determine pharmacokinetic properties and perform population modeling. Safety and tolerability profiles were assessed based on adverse events and safety measurements.

Findings

Pain was significantly reduced when measured directly after administration of ECP002A in the clinic but not when measured in a daily diary. A similar pattern was observed in subjective muscle spasticity. Other clinical outcomes were not significantly different between active treatment and placebo. Cognitive testing indicated that there was no decline in cognition after 2 or 4 weeks of treatment attributable to ECP002A compared with placebo.ImplicationsThis study specifically underlines the added value of thorough investigation of pharmacokinetic and pharmacodynamic associations in the target population. Despite the complex interplay of psychoactive effects and analgesia, the current oral formulation of Δ9-tetrahydrocannabinol may play a role in the treatment of spasticity and pain associated with MS because it was well tolerated and had a stable pharmacokinetic profile.  相似文献   
118.
The long-term changes of liver stiffness (LS) in patients who achieve viral clearance after direct-acting anti-HCV therapy remain undefined. We conducted a multicentre prospective study to investigate this aspect. Patients with HCV infection treated with DAAs were enrolled from six Italian centres; they underwent clinical, biochemical, ultrasound and transient elastography evaluations before treatment (T0), 12 weeks (SVR12) and 24 months (T24) after the end of therapy. Among the 516 consecutive patients enrolled, 301 had cirrhosis. LS significantly decreased from T0 to SVR (14.3 vs 11.1 kPa, p = .002), with a progressive reduction until T24 (8.7 kPa, p < .001). However, only patients with steatosis and those who developed HCC did not experience a late improvement in LS. Multivariate analysis of baseline and follow-up variables identified steatosis as the only independent predictor of failure of LS improvement (OR 1.802, p = .013). ROC curve analysis of the association of LS with the risk of developing HCC showed that SVR12 ≥14.0 kPa had the highest accuracy (sensitivity 82%, specificity 99%; AUC: 0.774). Multivariate analysis revealed that LS was the only variable independently associated with an increased risk of developing HCC (OR 6.470, p = .035). Achieving an SVR was associated with a progressive, long-term decline of LS, suggesting a late improvement in liver fibrosis, besides the resolution of inflammation. Fatty liver and the development of HCC interfered with late reduction of LS. Patients with an LS ≥14 kPa at 12 weeks after the end of treatment were at higher risk for developing HCC.  相似文献   
119.
120.
Summary Erythrocyte deformability measured as filtration index is clearly diminished in diabetics, thus possibly contributing to diabetes-associated microvascular complications. Moreover, the erythrocyte sorbitol level in IDD is clearly higher than that of non-diabetics, suggesting an alteration in the polyol pathway as possible determinant of diabetes-associated complications. Following this line of research, intracellular sorbitol as well as glucose, inositol, galactitol, mannitol and 2,3-diphosphoglycerate have been studied in 21 diabetics and in 14 controls matched for age and sex. In addition to confirming the high levels of intraerythrocytic glucose and sorbitol in diabetic subjects, statistically significant correlations have been demonstrated between sorbitol and filtration index, between plasma glucose, intracellular glucose level and glycosylated hemoglobin, suggesting a relationship between metabolic control and hemorheologic alterations in diabetes.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号