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   25047篇
  免费   2972篇
  国内免费   588篇
耳鼻咽喉   90篇
儿科学   462篇
妇产科学   1238篇
基础医学   1374篇
口腔科学   500篇
临床医学   7624篇
内科学   3577篇
皮肤病学   300篇
神经病学   888篇
特种医学   1523篇
外国民族医学   6篇
外科学   2837篇
综合类   4006篇
现状与发展   3篇
预防医学   1114篇
眼科学   532篇
药学   1074篇
  47篇
中国医学   240篇
肿瘤学   1172篇
  2024年   64篇
  2023年   512篇
  2022年   835篇
  2021年   1168篇
  2020年   1477篇
  2019年   1275篇
  2018年   1240篇
  2017年   1257篇
  2016年   1231篇
  2015年   1237篇
  2014年   2079篇
  2013年   1916篇
  2012年   1415篇
  2011年   1517篇
  2010年   1180篇
  2009年   1092篇
  2008年   1138篇
  2007年   1168篇
  2006年   955篇
  2005年   776篇
  2004年   651篇
  2003年   630篇
  2002年   495篇
  2001年   420篇
  2000年   328篇
  1999年   326篇
  1998年   269篇
  1997年   278篇
  1996年   232篇
  1995年   187篇
  1994年   177篇
  1993年   149篇
  1992年   132篇
  1991年   113篇
  1990年   91篇
  1989年   76篇
  1988年   71篇
  1987年   52篇
  1986年   68篇
  1985年   89篇
  1984年   67篇
  1983年   23篇
  1982年   46篇
  1981年   28篇
  1980年   28篇
  1979年   23篇
  1978年   12篇
  1977年   5篇
  1976年   3篇
  1974年   3篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
23.
24.
25.
Stellate ganglion (SG) modification has been investigated for arrhythmia treatment. In this study, transesophageal SG imaging and intervention were explored using a homemade 30F integrated focused ultrasonic catheter in healthy mongrel canines in vivo. Anatomic details of SGs were ultrasonically imaged and evaluated. SG had a heterogeneous echoic structure and characteristic profiles sketched by hyper-echoic outlines in an ultrasonogram. Left SGs in the experimental group were successfully ablated through the esophagus under ultrasonic guidance provided by the catheter itself. Two weeks after the ablation, the QT and QTc of the experimental group decreased compared with those of the sham group and at baseline (both p values < 0.001). Histologic examination revealed that left SGs were destroyed. No major complications were observed. This approach may be further explored as a method for ganglia remodeling evaluation and as a strategy of ganglia modification for arrhythmia and for other diseases.  相似文献   
26.
Invasive coronary plaque imaging such as intravascular ultrasound and optical coherence tomography has been widely used to observe culprit or non-culprit coronary atherosclerosis, as well as optimize stent sizing, apposition and deployment. Coronary computed tomographic angiography (CTA) is non-invasively available to assess coronary artery disease (CAD) and has become an appropriate strategy to evaluate patients with suspected CAD. Given recent technologies, semi-automated plaque software is available to identify coronary plaque stenosis, volume and characteristics and potentially allows to be used for the assessment of more details of plaque information, progression and future risk as a surrogate tool of the invasive imaging modalities. This review article aims to focus on various evidence in coronary plaque imaging by coronary CTA and describes how accurate coronary CTA can classify coronary atherosclerosis.  相似文献   
27.
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   
28.
29.
BackgroundPre-operative carbohydrate (CHO) drinks have shown some benefits peri-operatively and have been incorporated into many Enhanced Recovery after Surgery (ERAS) programmes. We assessed the gastric emptying of pre-operative CHO drinks prior to elective caesarean delivery using ultrasonography.MethodsAfter a standard overnight fast, non-labouring pregnant women awaiting elective caesarean delivery underwent a standardised gastric ultrasound assessment at baseline and then every 20 min for 2 h after consuming 400 mL of a CHO drink. The gastric emptying was determined at each time-point both qualitatively and quantitatively. The primary outcome was the time taken for participants to return to a qualitative fasted Perlas grade of 0 or 1.ResultsThe gastric emptying of 40 participants was analysed. At baseline, all patients had a qualitative grade of either 0 or 1. All patients had returned to either grade 0 or 1 by 100 min. At 120 min the antral right lateral decubitus (RLD) cross-sectional area (CSA) was 8.03 cm2 (95th percentile; 95% CI 7.4 to 8.3 cm2) and gastric volume per kg was 1.57 mL/kg (95th percentile; 95% CI 1.4 to 2.2). At 120 min there was no statistically significant difference from baseline for the RLD CSA (P=0.38) or gastric volume per kg (P=0.27).ConclusionsThe gastric emptying of this cohort of pregnant women suggests that 400 mL of a CHO drink can be safely consumed up to two hours before elective surgery. This study can help inform future peri-operative fasting guidelines for pregnant patients.  相似文献   
30.
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