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   1277214篇
  免费   99893篇
  国内免费   1989篇
耳鼻咽喉   18427篇
儿科学   44367篇
妇产科学   35010篇
基础医学   182252篇
口腔科学   33587篇
临床医学   111445篇
内科学   258323篇
皮肤病学   28028篇
神经病学   100393篇
特种医学   51207篇
外国民族医学   660篇
外科学   196422篇
综合类   27053篇
现状与发展   1篇
一般理论   377篇
预防医学   95755篇
眼科学   27916篇
药学   94790篇
  2篇
中国医学   2422篇
肿瘤学   70659篇
  2018年   13139篇
  2017年   9971篇
  2016年   10903篇
  2015年   12374篇
  2014年   17178篇
  2013年   26228篇
  2012年   36034篇
  2011年   38068篇
  2010年   22814篇
  2009年   21818篇
  2008年   36653篇
  2007年   39271篇
  2006年   39523篇
  2005年   38459篇
  2004年   37604篇
  2003年   36462篇
  2002年   35812篇
  2001年   64012篇
  2000年   66510篇
  1999年   56426篇
  1998年   15137篇
  1997年   13761篇
  1996年   14203篇
  1995年   13462篇
  1994年   12769篇
  1993年   11799篇
  1992年   44565篇
  1991年   43475篇
  1990年   42232篇
  1989年   40124篇
  1988年   36912篇
  1987年   36258篇
  1986年   33632篇
  1985年   32285篇
  1984年   24148篇
  1983年   20271篇
  1982年   11727篇
  1981年   10695篇
  1980年   9520篇
  1979年   21345篇
  1978年   14828篇
  1977年   12536篇
  1976年   11700篇
  1975年   12634篇
  1974年   14673篇
  1973年   14122篇
  1972年   12946篇
  1971年   11735篇
  1970年   11057篇
  1969年   10033篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
BackgroundAlthough there are robust data about the pathophysiology and prognostic implications of left ventricular (LV) systolic dysfunction in patients with acquired heart disease, similar prognostic data about LV systolic dysfunction are sparse in the tetralogy of Fallot (TOF) population. The purpose of this study was to perform a meta-analysis of all studies that assessed the relationship between LV ejection fraction (LVEF) and cardiovascular adverse events (CAEs) defined as death, aborted sudden death, or sustained ventricular tachycardia.MethodsWe used random-effects models to calculate hazard ratios (HRs) and 95% confidence intervals (CIs).ResultsOf the 1,809 citations, 7 studies with 2,854 patients (age 28 ± 4 years) were included. During 5.6 ± 3.4 years' follow-up, there were 82 deaths, 17 aborted sudden cardiac deaths, and 56 sustained ventricular tachycardia events. Overall, CAEs occurred in 5.1% (144 patients). As a continuous variable, LVEF was a predictor of CAE (HR 1.29, 95% CI, 1.09-1.53, P = 0.001) per 5% decrease in LVEF. Similarly, LVEF < 40% was also a predictor of CAE (HR 3.22, 95% CI, 2.16-4.80, P < 0.001).ConclusionsLV systolic dysfunction was an independent predictor of CAE, and we observed a 30% increase in the risk of CAE for every 5% decrease in LVEF, and a 3-fold increase in the risk of CAE in patients with LVEF <40% compared with other patients. These findings underscore the importance of incorporating LV systolic function in clinical risk stratification of patients with TOF and the need to explore new treatment options to address this problem.  相似文献   
132.
Objective: To assess the quality of images and video clips of fetal central nervous (CNS) structures obtained by ultrasound and transmitted via tele-ultrasound from Brazil to Australia.

Methods: In this cross-sectional study, 15 normal singleton pregnant women between 20 and 26 weeks were selected. Fetal CNS structures were obtained by images and video clips. The exams were transmitted in real-time using a broadband internet and an inexpensive video streaming device. Four blinded examiners evaluated the quality of the exams using the Likert scale. We calculated the mean, standard deviation, mean difference, and p values were obtained from paired t tests.

Results: The quality of the original video clips was slightly better than that observed by the transmitted video clips; mean difference considering all observers = 0.23 points. In 47/60 comparisons (78.3%; 95% CI?=?66.4–86.9%) the quality of the video clips were judged to be the same. In 182/240 still images (75.8%; 95% CI?=?70.0–80.8%) the scores of transmitted image were considered the same as the original.

Conclusion: We demonstrated that long distance tele-ultrasound transmission of fetal CNS structures using an inexpensive video streaming device provided images of subjective good quality.  相似文献   
133.
134.
135.
136.
137.
138.
139.
140.
To determine the protective effect of aloe-emodin (AE) from high glucose induced toxicity in RIN-5F (pancreatic β-cell) cell and restoration of its function was analyzed. RIN-5F cells have been cultured in high glucose (25 mM glucose) condition, with and without AE treatment. RIN-5F cells cultured in high glucose decreased cell viability and increased ROS levels after 48 hr compared with standard medium (5.5 mM glucose). Glucotoxicity was confirmed by significantly increased ROS production, increased pro-inflammatory (IFN-γ, IL-1β,) & decreased anti-inflammatory (IL-6&IL-10) cytokine levels, increased DNA fragmentation. In addition, we found increased Bax, caspase 3, Fadd, and Fas and significantly reduced Bcl-2 expression after 48 hr. RIN-5F treated with both high glucose and AE (20 μM) decreased ROS generation and prevent RIN-5F cell from glucotoxicity. In addition, AE treated cells cultured in high glucose were transferred to standard medium, normal responsiveness to glucose was restored within 8hr and normal basal insulin release within 24 hr was achieved when compared to high glucose.  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