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   91060篇
  免费   8508篇
  国内免费   2468篇
耳鼻咽喉   673篇
儿科学   2345篇
妇产科学   700篇
基础医学   5197篇
口腔科学   544篇
临床医学   15062篇
内科学   23487篇
皮肤病学   523篇
神经病学   4816篇
特种医学   3273篇
外国民族医学   2篇
外科学   9074篇
综合类   15768篇
现状与发展   4篇
一般理论   1篇
预防医学   5178篇
眼科学   979篇
药学   7930篇
  112篇
中国医学   4906篇
肿瘤学   1462篇
  2024年   120篇
  2023年   1630篇
  2022年   2565篇
  2021年   4283篇
  2020年   4402篇
  2019年   3817篇
  2018年   3538篇
  2017年   3512篇
  2016年   3416篇
  2015年   3208篇
  2014年   6370篇
  2013年   6157篇
  2012年   4887篇
  2011年   5219篇
  2010年   4393篇
  2009年   4074篇
  2008年   4312篇
  2007年   4472篇
  2006年   3922篇
  2005年   3435篇
  2004年   2775篇
  2003年   2461篇
  2002年   2093篇
  2001年   2018篇
  2000年   1630篇
  1999年   1451篇
  1998年   1194篇
  1997年   1137篇
  1996年   977篇
  1995年   1014篇
  1994年   930篇
  1993年   749篇
  1992年   780篇
  1991年   651篇
  1990年   566篇
  1989年   466篇
  1988年   458篇
  1987年   435篇
  1986年   374篇
  1985年   369篇
  1984年   365篇
  1983年   243篇
  1982年   262篇
  1981年   182篇
  1980年   141篇
  1979年   145篇
  1978年   132篇
  1977年   70篇
  1976年   74篇
  1975年   52篇
排序方式: 共有10000条查询结果,搜索用时 187 毫秒
1.
2.
BackgroundIschemia reperfusion (I/R) play an imperative role in the expansion of cardiovascular disease. Sinomenine (SM) has been exhibited to possess antioxidant, anticancer, anti-inflammatory, antiviral and anticarcinogenic properties. The aim of the study was scrutinized the cardioprotective effect of SM against I/R injury in rat.MethodsRat were randomly divided into normal control (NC), I/R control and I/R + SM (5, 10 and 20 mg/kg), respectively. Ventricular arrhythmias, body weight and heart weight were estimated. Antioxidant, inflammatory cytokines, inflammatory mediators and plasmin system indicator were accessed.ResultsPre-treated SM group rats exhibited the reduction in the duration and incidence of ventricular fibrillation, ventricular ectopic beat (VEB) and ventricular tachycardia along with suppression of arrhythmia score during the ischemia (30 and 120 min). SM treated rats significantly (P < 0.001) altered the level of antioxidant parameters. SM treatment significantly (P < 0.001) repressed the level of creatine kinase MB (CK-MB), creatine kinase (CK) and troponin I (Tnl). SM treated rats significantly (P < 0.001) repressed the tissue factor (TF), thromboxane B2 (TXB2), plasminogen activator inhibitor 1 (PAI-1) and plasma fibrinogen (Fbg) and inflammatory cytokines and inflammatory mediators.ConclusionOur result clearly indicated that SM plays anti-arrhythmia effect in I/R injury in the rats via alteration of oxidative stress and inflammatory reaction.  相似文献   
3.
4.
BackgroundSelection of the transcatheter heart valve size for a mitral valve-in-valve procedure is based on the type and manufacturer’s labelled size. However, accurate information of surgical heart valve (SHV) size may not be available in the patient’s medical record. The purpose of this study is to establish reference data for computed tomography (CT) dimensions of commonly used mitral SHV in order to determine the manufacturer’s labelled size from a cardiac CT data set.MethodsCT datasets of 105 patients with surgical mitral bioprosthesis and available manufacturer labeled datasets were included in the analysis. CT derived valve dimensions were assessed by two observers using multiplanar reformats aligned with the basal sewing ring. A circular region of interest was used in a standardized fashion to minimize influence of image acquisition and reconstruction parameters. Interobserver variability was assessed by Bland-Altman analysis.ResultsThe CT-derived dimensions were stratified by valve size and type, and SHV properties were demonstrated for 5 common valve types. Variability of measurements was small and inter-observer limits of agreement were narrow. Stratified by SHV type, no overlap was noted for CT-derived dimensions among different SHV sizes . A reference table of CT characteristics of surgical mitral bioprosthesis types was created.ConclusionThe study provides reference CT data for determining the manufacturers’ labeled SHV size across a range of commonly used mitral SHVs. The findings will be important to help identify types of surgical mitral bioprosthesis utilizing CT characteristics for patients without SHV size documentation.  相似文献   
5.
PurposeTo create a nonsurgical animal model of osteoarthritis (OA) to evaluate the effects of embolotherapy during geniculate artery embolization (GAE).Materials and MethodsFluoroscopy-guided injections of 700 mg of sodium monoiodoacetate were performed into the left stifle in 6 rams. Kinematic data were collected before and after induction. At 10 weeks after induction, Subjects 1 and 4–6 underwent magnetic resonance (MR) imaging with dynamic contrast enhancement (DCE) and Subjects 1, 3, and 4–6 underwent angiography with angiographic scoring to identify regions with greatest disease severity for superselective embolization (75–250-μm microspheres). Target vessel size was measured. At 24 weeks after angiography, DCE-MR imaging, angiography, and euthanasia were performed, and bilateral stifles were harvested. Medial/lateral tibial and femoral condylar, patellar, and synovial samples were cut, preserved, decalcified, and scored using the Osteoarthritis Research Society International criteria. The stifle and synovium Whole-Organ Magnetic Resonance Imaging Score and Multicenter Osteoarthritis Study score were determined. The volume transfer constant (Ktrans) and extracellular volume fraction (ve) were calculated from DCE-MR imaging along the lateral synovial regions of interest.ResultsThe mean gross and microscopic pathological scores were elevated at 38 and 61, respectively. Mean synovitis score was elevated at 9.2. Mean pre-embolization and postembolization angiographic scores were 5 and 3.8, respectively. Mean superior, transverse, and inferior geniculate artery diameters were 3.1 mm ± 1.21, 2.0 mm ± 0.50, and 1.6 mm ± 0.41 mm, respectively. Mean pre-embolization and postembolization cartilage and synovitis scores were elevated at 35.13 and 73.3 and 5.5 and 9.2, respectively. The Ktrans/ve values of Subjects 4, 5, and 6 were elevated at 0.049/0.38, 0.074/0.53, and 0.065/0.51, respectively. Altered gait of the hind limb was observed in all subjects after induction, with reduced joint mobility. No skin necrosis or osteonecrosis was observed.ConclusionsA nonsurgical ovine animal knee OA model was created, which allowed the collection of angiographic, histopathological, MR imaging, and kinematic data to study the effects of GAE.  相似文献   
6.
7.
8.
Left ventricular noncompaction (LVNC) is a genetically heterogeneous cardiomyopathy, with familial and sporadic forms, but genetic testing only identifies a pathogenic mutation in a minority of cases. The main complications are heart failure, embolism and dysrhythmias. Herein we report a familial case of LVNC associated with a mutation in the MYH7 gene and review the literature regarding controversies in LVNC. A 50-year-old woman was referred to the cardiology clinic for palpitations. She underwent echocardiography and cardiac magnetic resonance imaging that revealed mild left ventricular systolic dysfunction and LVNC criteria. She had several episodes of non-sustained ventricular tachycardia and received an implantable cardioverter-defibrillator (ICD). Genetic testing revealed the c.1003G>C (p.Ala335Pro) mutation in the MYH7 gene. Familial screening showed clear genotype-phenotype cosegregation, which provided strong evidence for the pathogenic role of this mutation. To the best of our knowledge, this is the first report of LVNC associated with the p.Ala335Pro mutation in the MYH7 gene. This mutation has been described in hypertrophic cardiomyopathy, suggesting that the same pathogenic sarcomere mutation may be associated with different cardiomyopathies. This case also highlights the current difficulties regarding decisions on ICD implantation for primary prevention of sudden cardiac death in LVNC.  相似文献   
9.
10.
目的研究阴道顺产与剖宫产对初产妇产后早期盆底功能的影响。方法选择2020年1月至12月在阳春市人民医院产科中心分娩的120例初产妇展开研究,按照分娩方式的不同分为对照组与观察组,每组各60例。对照组为阴道顺产,观察组采用剖宫产,两组均在产后第6周进行早期盆底功能检查,并进行盆底康复治疗,比较两组的治疗效果。结果观察组的尿失禁、阴道脱垂、子宫脱垂发生率低于对照组,差异有统计学意义(P<0.05);观察组治疗后的盆底肌力分级情况优于对照组,差异有统计学意义(P<0.05);观察组治疗后的膀胱颈与耻骨联合下缘水平线间的垂直距离(BSD)高于对照组,膀胱尿道后角(RA)、膀胱颈移动度(BND)低于对照组,差异均有统计学意义(P<0.05)。结论阴道顺产对于盆底功能及盆腔结构的不良影响大于剖宫产,盆底功能障碍性疾病发生率更高,而康复治疗可有效改善阴道顺产、剖宫产初产妇的盆底功能,剖宫产初产妇的盆底功能恢复更好。  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