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   3221896篇
  免费   230963篇
  国内免费   5054篇
耳鼻咽喉   45963篇
儿科学   105463篇
妇产科学   89663篇
基础医学   470878篇
口腔科学   90331篇
临床医学   286574篇
内科学   620941篇
皮肤病学   70942篇
神经病学   254692篇
特种医学   121126篇
外国民族医学   819篇
外科学   485437篇
综合类   67189篇
现状与发展   12篇
一般理论   1096篇
预防医学   252306篇
眼科学   76010篇
药学   241735篇
  63篇
中国医学   6354篇
肿瘤学   170319篇
  2019年   25769篇
  2018年   36305篇
  2017年   26975篇
  2016年   30097篇
  2015年   34123篇
  2014年   47506篇
  2013年   71832篇
  2012年   99726篇
  2011年   106093篇
  2010年   62710篇
  2009年   58637篇
  2008年   99656篇
  2007年   106413篇
  2006年   107435篇
  2005年   104623篇
  2004年   100140篇
  2003年   96447篇
  2002年   93752篇
  2001年   141609篇
  2000年   145355篇
  1999年   122498篇
  1998年   36114篇
  1997年   31731篇
  1996年   32080篇
  1995年   30157篇
  1994年   27978篇
  1993年   26296篇
  1992年   96388篇
  1991年   94231篇
  1990年   92356篇
  1989年   89372篇
  1988年   82560篇
  1987年   81059篇
  1986年   76687篇
  1985年   73489篇
  1984年   54936篇
  1983年   46997篇
  1982年   28260篇
  1979年   51448篇
  1978年   36569篇
  1977年   30883篇
  1976年   29456篇
  1975年   32081篇
  1974年   38178篇
  1973年   36590篇
  1972年   34548篇
  1971年   32572篇
  1970年   30225篇
  1969年   28883篇
  1968年   26858篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
82.
ABSTRACT

Lacrosse has gained substantial popularity across age groups in the past few decades, but epidemiologic sex differences of lacrosse injuries in emergency settings have not been well described. We characterized and described lacrosse-related injuries presenting to United States Emergency Departments (US EDs) using data from the National Electronic Injury Surveillance System (NEISS). From 1997 to 2015, 7,587 lacrosse-related injuries were treated at US EDs (national estimate of 256,358 injuries). Males accounted for 75.5% of injuries. Average age was 16.0 ± 5.0 (range 5–71) years. Sprains/strains (25.4%), contusions/abrasions (23.9%), and fractures (18.7%) were the most common diagnoses. Females sustained a higher proportion of sprains/strains (36.0%) than males (21.9%) (p< 0.01), while males sustained a higher proportion of fractures (injury proportion ratios [IPR]; 21.3% vs. 10.8%, p< 0.01). Similar proportions of concussions were observed (IPR; 6.1% in males, 6.2% among females). Differences in injury patterns may be secondary to differences in rules and equipment between the two sports.  相似文献   
83.
Abstract

Aims

The objective was to evaluate whether sodium intake, assessed with the gold standard 24-h urinary collections, was related to long-term incidence of death, cardiovascular disease (CVD) and diabetes mellitus (DM).  相似文献   
84.
85.
Abstract

Objective: Online videos are commonly used in medical education. The aim of this review was to investigate the role of online instructional videos in teaching procedural skills to postgraduate medical learners.

Methods: This systematic narrative review was conducted according to the PRISMA guidelines. MEDLINE, Cochrane Central Register of Controlled Trials, EMBASE, ERIC and Google Scholar were searched. Full texts that applied to online videos, postgraduate medical learners and procedural skills were included without language restrictions. The methodological quality of the studies was evaluated using a validated tool. A thematic analysis of the studies was carried out using a general inductive approach.

Results: A total of 785 articles were retrieved and the full text was reviewed for 66 articles that met the inclusion and exclusion criteria of the study. Twenty papers that were relevant to the role of online videos in postgraduate medical education of procedural skills were used for this review. They were heterogenous in the outcomes collected and the evidence was of variable quality. There was strong evidence for the use of online videos for procedural skill knowledge acquisition and retention. Online videos were used for various purposes, such as supervision, assessment, postoperative debriefing, providing feedback, and promoting reflection.

Conclusion: Online videos are a valuable educational tool especially for procedural skill knowledge acquisition and retention. Future research needs to be carried out on the appropriate use of platforms in disseminating and using online videos, identifying the factors surrounding the learners, video characteristics, and data protection.  相似文献   
86.
ABSTRACT

Background

Dynamic lycra splints are proposed to modify hypertonicity due to their characteristics – neutral warmth, circumferential pressure, and creating a low-intensity prolonged stretch on hypertonic muscles – to contribute to increased sensory awareness of the involved limb.  相似文献   
87.
Abstract

Objectives: Overlapping decreases in extrastriatal dopamine D2/D3-receptor availability and glucose metabolism have been reported in subjects with schizophrenia. It remains unknown whether these findings are physiologically related or coincidental.

Methods: To ascertain this, we used two consecutive 18F-fluorodeoxyglucose and 18F-fallypride positron emission tomography scans in 19 healthy and 25 unmedicated schizophrenia subjects. Matrices of correlations between 18F-fluorodeoxyglucose uptake and 18F-fallypride binding in voxels at the same xyz location and AFNI-generated regions of interest were evaluated in both diagnostic groups.

Results: 18F-fluorodeoxyglucose uptake and 18F-fallypride binding potential were predominantly positively correlated across the striatal and extrastriatal grey matter in both healthy and schizophrenia subjects. In comparison to healthy subjects, significantly weaker correlations in subjects with schizophrenia were confirmed in the right cingulate gyrus and thalamus, including the mediodorsal, lateral dorsal, anterior, and midline nuclei. Schizophrenia subjects showed decreased D2/D3-receptor availability in the hypothalamus, mamillary bodies, thalamus and several thalamic nuclei, and increased glucose uptake in three lobules of the cerebellar vermis.

Conclusions: Dopaminergic system may be involved in modulation of grey matter metabolism and neurometabolic coupling in both healthy human brain and psychopathology. Hyperdopaminergic state in untreated schizophrenia may at least partly account for the corresponding decreases in grey matter metabolism.  相似文献   
88.
89.
ObjectiveTo evaluate the outcomes after septal myectomy in patients with obstructive hypertrophic cardiomyopathy according to atrial fibrillation and surgical ablation of atrial fibrillation.MethodsWe reviewed patients with obstructive hypertrophic cardiomyopathy who underwent septal myectomy at the Mayo Clinic from 2001 to 2016. History of atrial fibrillation was obtained from patient histories and electrocardiograms. All-cause mortality was the primary end point.ResultsA total of 2023 patients underwent septal myectomy, of whom 394 (19.5%) had at least 1 episode of atrial fibrillation preoperatively. Among patients with atrial fibrillation, 76 (19.3%) had only 1 known episode, 278 (70.6%) had recurrent paroxysmal atrial fibrillation, and 40 (10.2%) had persistent atrial fibrillation. Surgical ablation was performed in 190 patients at the time of septal myectomy, including 148 with pulmonary vein isolation and 42 with the classic maze procedure. Among all patients, operative mortality was 0.4%, and there were no early deaths in patients undergoing surgical ablation. Over a median follow-up of 5.6 years, patients with preoperative atrial fibrillation had increased mortality (hazard ratio, 1.36; 95% confidence interval, 0.97-1.91; P = .070) after multivariable adjustment for comorbidities. When considering the impact of atrial fibrillation with or without surgical treatment, the adjusted hazard ratio for mortality in patients undergoing ablation compared with no ablation was 0.93 (95% confidence interval, 0.52-1.69; P = .824).ConclusionsAtrial fibrillation is present preoperatively in one-fifth of patients with obstructive hypertrophic cardiomyopathy undergoing myectomy and showed a trend toward higher all-cause mortality. Survival of patients undergoing septal myectomy with preoperative atrial fibrillation was similar between those who did and did not receive concomitant surgical ablation.  相似文献   
90.
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