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   2223篇
  免费   143篇
  国内免费   26篇
耳鼻咽喉   5篇
儿科学   72篇
妇产科学   38篇
基础医学   274篇
口腔科学   13篇
临床医学   182篇
内科学   350篇
皮肤病学   42篇
神经病学   234篇
特种医学   120篇
外科学   253篇
综合类   24篇
一般理论   1篇
预防医学   273篇
眼科学   5篇
药学   269篇
肿瘤学   237篇
  2023年   11篇
  2022年   16篇
  2021年   44篇
  2020年   36篇
  2019年   31篇
  2018年   36篇
  2017年   40篇
  2016年   37篇
  2015年   48篇
  2014年   52篇
  2013年   92篇
  2012年   112篇
  2011年   106篇
  2010年   76篇
  2009年   61篇
  2008年   84篇
  2007年   127篇
  2006年   85篇
  2005年   89篇
  2004年   81篇
  2003年   87篇
  2002年   75篇
  2001年   71篇
  2000年   77篇
  1999年   59篇
  1998年   35篇
  1997年   47篇
  1996年   42篇
  1995年   35篇
  1994年   25篇
  1993年   21篇
  1992年   47篇
  1991年   53篇
  1990年   47篇
  1989年   54篇
  1988年   49篇
  1987年   41篇
  1986年   55篇
  1985年   29篇
  1984年   13篇
  1983年   28篇
  1982年   17篇
  1979年   11篇
  1977年   14篇
  1976年   10篇
  1974年   7篇
  1972年   9篇
  1970年   9篇
  1969年   11篇
  1968年   6篇
排序方式: 共有2392条查询结果,搜索用时 13 毫秒
41.
42.
Background: There is an increasing tendency towards minimally invasive valve surgery and various surgical techniques have been proposed to realise this goal. The aim of the present study was to describe our current surgical technique and clinical experience with respect to an endoscopic technique that allows the surgeon to perform an operation through a series of small intercostal ports.

Methods: After a learning experience with thoracoscopic left internal mammary to left anterior descending coronary artery bypass surgery, we adopted the endocardiopulmonary bypass technique to perform mitral valve surgery. The technique requires exclusive use of video-assisted surgery and control by transoesophageal echocardiography (TEE). Surgery requires long instruments and extra-corporeal knot tying. Between February 1997 and November 2001, 259 patients were operated on. Mitral valve repair was performed in 190 of them. One patient had a redo procedure using this approach to correct a paravalvular leak, but all other procedures were primary interventions.

Results: In all patients, surgery was performed using a 2 inch working port and two additional half-inch trocar-ports. Five patients required a conversion to median sternotomy: three because of inadequate size of the femoral vessels and two because of intraoperative aortic dissection. Hospital mortality included two patients, and seven patients required late reoperation (four of these were as a result of endocarditis).

Conclusions: Endoscopic mitral valve surgery is demanding, but feasible. Once the appropriate skills are acquired, both patient and surgeon can enjoy the benefits of this exciting new technique.  相似文献   

43.
44.
45.

Aims/hypothesis

The appearance of autoantibodies (Abs) before diabetes onset has mainly been studied in young children. However, most patients develop type 1 diabetes after the age of 15?years. In first-degree relatives aged under 40?years, we investigated the frequency of seroconversion to (persistent) Ab positivity, progression to diabetes and baseline characteristics of seroconverters according to age.

Methods

Abs against insulin (IAA), glutamate decarboxylase (GADA), insulinoma-associated protein 2 (IA-2A) and zinc transporter 8 (ZnT8A) were measured during follow-up of 7,170 first-degree relatives.

Results

We identified 379 (5.3%) relatives with positivity for IAA, GADA, IA-2A and/or ZnT8A (Ab+) at first sampling and 224 (3.1%) at a later time point. Most seroconversions occurred after the age of 10?years (63%). During follow-up, Abs persisted more often in relatives initially Ab+ (76%) than in seroconverters (53%; p?Conclusions/interpretation Seroconversion to (persistent) Ab+ occurs regardless of age. Although the progression rate to diabetes is higher under age 10?years, later seroconverters (up to age 40?years) have similar characteristics when compared with age-matched initially Ab+ relatives and generate an important minority of prediabetic relatives, warranting their identification and, eventually, enrolment in prevention trials.  相似文献   
46.
Taurine is involved in numerous biological processes. However, taurine plasma level decreases in response to pathological conditions, suggesting an increased need. Knowledge on human taurine metabolism is scarce and only described by arterial-venous differences across a single organ. Here we present taurine organ fluxes using arterial-venous concentration differences combined with blood flow measurements across the 3 major organ systems involved in human taurine metabolism in patients undergoing hepatic surgery. In these patients, we collected blood from an arterial line, portal vein, hepatic vein, and renal vein, and determined blood flow of the hepatic artery, portal vein, and renal vein using Doppler ultrasound. Plasma taurine was determined by high-performance liquid chromatography, and net organ fluxes and fractional extraction rates were calculated. Seventeen patients were studied. No differences were found between taurine concentrations in arterial, portal venous, hepatic venous, and renal venous plasma. The only significant finding was a release of taurine by the portally drained viscera (P = .04). Our data show a net release of taurine by the gut. This probably is explained by the enterohepatic cycle of taurine. Future studies on human taurine metabolism are required to determine whether taurine is an essential aminosulfonic acid during pathological conditions and whether it should therefore be supplemented.  相似文献   
47.
48.
In wound care research, available high‐level evidence according to the evidence pyramid is rare, and is threatened by a poor study design and reporting. Without comprehensive and transparent reporting, readers will not be able to assess the strengths and limitations of the research performed. Randomized clinical trials (RCTs) are universally acknowledged as the study design of choice for comparing treatment effects. To give high‐level evidence the appreciation it deserves in wound care, we propose a step‐by‐step reporting standard for comprehensive and transparent reporting of RCTs in wound care. Critical reporting issues (e.g., wound care terminology, blinding, predefined outcome measures, and a priori sample size calculation) and wound‐specific barriers (e.g., large diversity of etiologies and comorbidities of patients with wounds) that may prevent uniform implementation of reporting standards in wound care research are addressed in this article. The proposed reporting standards can be used as guidance for authors who write their RCT, as well as for peer reviewers of journals. Endorsement and application of these reporting standards may help achieve a higher standard of evidence and allow meta‐analysis of reported wound care data. The ultimate goal is to help wound care professionals make better decisions for their patients in clinical practice.  相似文献   
49.
BackgroundCystic fibrosis (CF) can be a devastating disease. Disorders in essential fatty acid state are increasingly reported and various supplementation trials have been performed in an attempt to improve outcomes. However, the mechanisms leading to these disturbances remain elusive.We wanted to investigate the role of the diseased CF lung on fatty acid profiles.MethodsWe compared fatty acid profiles in patients with CF after lung transplantation (n = 11) to age-matched healthy controls and homozygous F508del patients (n = 22 each).ResultsCompared to healthy controls, in patients with CF, there are decreased levels of docosahexaenoic, linoleic and arachidonic acid and increased levels of mead acid. In patients that underwent a lung transplantation, levels of docosahexaenoic, linoleic and arachidonic acid were normal. Mead acid did not decrease significantly.ConclusionsThe diseased CFTR deficient lung is a major determinant in the disturbed fatty acid profile in CF.  相似文献   
50.
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