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   2596382篇
  免费   185025篇
  国内免费   7609篇
耳鼻咽喉   34372篇
儿科学   85456篇
妇产科学   71768篇
基础医学   364686篇
口腔科学   69849篇
临床医学   235210篇
内科学   517613篇
皮肤病学   62773篇
神经病学   214105篇
特种医学   100172篇
外国民族医学   736篇
外科学   387657篇
综合类   50446篇
现状与发展   5篇
一般理论   971篇
预防医学   196820篇
眼科学   56740篇
药学   188452篇
  8篇
中国医学   5374篇
肿瘤学   145803篇
  2021年   20319篇
  2019年   20911篇
  2018年   29615篇
  2017年   22770篇
  2016年   26393篇
  2015年   29706篇
  2014年   40774篇
  2013年   60824篇
  2012年   80728篇
  2011年   84987篇
  2010年   51349篇
  2009年   49470篇
  2008年   79414篇
  2007年   84264篇
  2006年   85961篇
  2005年   82174篇
  2004年   79135篇
  2003年   76433篇
  2002年   73699篇
  2001年   128560篇
  2000年   131504篇
  1999年   110659篇
  1998年   31323篇
  1997年   27979篇
  1996年   28283篇
  1995年   27429篇
  1994年   25107篇
  1993年   23456篇
  1992年   85250篇
  1991年   81649篇
  1990年   78870篇
  1989年   76157篇
  1988年   69544篇
  1987年   68081篇
  1986年   63614篇
  1985年   60564篇
  1984年   44987篇
  1983年   37981篇
  1982年   22475篇
  1981年   20002篇
  1979年   39005篇
  1978年   27456篇
  1977年   23274篇
  1976年   21520篇
  1975年   22836篇
  1974年   26819篇
  1973年   25389篇
  1972年   23776篇
  1971年   21972篇
  1970年   20202篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.

Background

Limited data exists demonstrating the efficacy of minimally invasive surgery (MIS) compared to median sternotomy (MS) for multiple valvular disease (MVD). This systematic review and meta-analysis aims to compare operative and peri-operative outcomes of MIS vs MS in MVD.

Methods

PubMed, Ovid, and Embase were searched from inception until August 2019 for randomized and observational studies comparing MIS and MS in patients with MVD. Clinical outcomes of intra- and postoperative times, reoperation for bleeding and surgical site infection were evaluated.

Results

Five observational studies comparing 340 MIS vs 414 MS patients were eligible for qualitative and quantitative review. The quality of evidence assessed using the Newcastle-Ottawa scale was good for all included studies. Meta-analysis demonstrated increased cardiopulmonary bypass time for MIS patients (weighted mean difference [WMD], 0.487; 95% confidence interval [CI], 0.365-0.608; P < .0001). Similarly, aortic cross-clamp time was longer in patients undergoing MIS (WMD, 0.632; 95% CI, 0.509-0.755; P < .0001). No differences were found in operative mortality, reoperation for bleeding, surgical site infection, or hospital stay.

Conclusions

MIS for MVD have similar short-term outcomes compared to MS. This adds value to the use of minimally invasive methods for multivalvular surgery, despite conferring longer operative times. However, the paucity in literature and learning curve associated with MIS warrants further evidence, ideally randomized control trials, to support these findings.
  相似文献   
62.
63.
64.
65.
BackgroundThe aim of this paper is to assess the current state of quality and outcomes measures being reported for hepatic resections in the recent literature.MethodsMedline and PubMed databases were searched for English language articles published between 1 January 2002 and 30 April 2013. Two examiners reviewed each article and relevant citations for appropriateness of inclusion, which excluded papers of liver donor hepatic resections, repeat hepatectomies or meta-analyses. Data were extracted and summarized by two examiners for analysis.ResultsFifty-five studies were identified with suitable reporting to assess peri-operative mortality in hepatic resections. In only 35% (19/55) of the studies was the follow-up time explicitly stated, and in 47% (26/55) of studies peri-operative mortality was limited to in-hospital or 30 days. The time period in which complications were captured was not explicitly stated in 19 out of 28 studies. The remaining studies only captured complications within 30 days of the index operation (8/28). There was a paucity of quality literature addressing truly patient-centred outcomes.ConclusionQuality outcomes after a hepatic resection are inconsistently reported in the literature. Quality outcome studies for a hepatectomy should report mortality and morbidity at a minimum of 90 days after surgery.  相似文献   
66.
67.
68.
69.
Objective: Report measured resting energy expenditure (REE) in wheelchair rugby athletes and evaluate agreement between REE and the prediction models of Chun, Cunningham, Harris-Benedict, Mifflin, Nightingale and Gorgey, and Owen.

Design: Cohort-based validation study.

Setting. Paralympic team training camp.

Participants: Fourteen internationally competitive athletes who play wheelchair rugby, 13 of whom had cervical spinal cord injuries (SCI).

Outcome Measures: A portable metabolic analyzer was used to measure REE following an overnight fast and dual-energy X-ray absorptiometry (DXA) was used to assess lean body mass for the prediction equations.

Results: REE in the current sample was 1735?±?257?kcal?×?day?1 ranging from 1324 to 2068?kcal?×?day?1 Bhambhani Y. Physiology of wheelchair racing in athletes with spinal cord injury. Sports Med 2002;32(1):2351.[Crossref], [PubMed], [Web of Science ®] [Google Scholar]. Bland–Altman analyses revealed negative mean bias but similar limits of agreement between measured REE and scores predicted by Chun, Cunningham, Mifflin, Nightingale and Gorgey, and Owen models in elite athletes who play wheelchair rugby.

Conclusion: Prediction models regressed on persons with and without SCI under-predicted REE of competitive wheelchair rugby athletes. This outcome may be explained by the higher REE/fat-free mass (FFM) ratio of current athletes compared to less active samples. Findings from the current study will help practitioners to determine nutrient intake needs on training days of varied intensity.  相似文献   
70.
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