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   419937篇
  免费   13121篇
  国内免费   557篇
耳鼻咽喉   4335篇
儿科学   14235篇
妇产科学   8077篇
基础医学   51935篇
口腔科学   7073篇
临床医学   31703篇
内科学   85721篇
皮肤病学   7094篇
神经病学   38267篇
特种医学   16299篇
外国民族医学   109篇
外科学   59883篇
综合类   3293篇
一般理论   66篇
预防医学   39484篇
眼科学   7446篇
药学   26517篇
中国医学   1359篇
肿瘤学   30719篇
  2023年   1347篇
  2022年   1130篇
  2021年   4024篇
  2020年   2387篇
  2019年   4399篇
  2018年   28756篇
  2017年   21619篇
  2016年   23793篇
  2015年   6810篇
  2014年   7150篇
  2013年   10824篇
  2012年   23922篇
  2011年   37301篇
  2010年   26716篇
  2009年   17779篇
  2008年   33418篇
  2007年   36525篇
  2006年   15206篇
  2005年   16727篇
  2004年   16937篇
  2003年   16733篇
  2002年   14169篇
  2001年   6629篇
  2000年   6807篇
  1999年   5921篇
  1998年   1357篇
  1997年   1170篇
  1996年   981篇
  1995年   900篇
  1992年   3358篇
  1991年   3054篇
  1990年   2961篇
  1989年   2652篇
  1988年   2505篇
  1987年   2299篇
  1986年   2186篇
  1985年   1968篇
  1984年   1470篇
  1983年   1261篇
  1979年   1247篇
  1978年   884篇
  1977年   822篇
  1975年   835篇
  1974年   1026篇
  1973年   1019篇
  1972年   958篇
  1971年   941篇
  1970年   898篇
  1969年   941篇
  1968年   826篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
5.
6.
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   
7.
8.
9.
10.

Background and aims

Since accelerated atherosclerosis has been reported in systemic lupus erythematosus (SLE), predictive biomarkers of cardiovascular disease (CVD) are needed. Among non-traditional risk factors, bone mineral density (BMD) has been related to CVD. However, its role in SLE remains controversial. This study aims to analyze the associations of subclinical atherosclerosis with traditional and non-traditional CV risk factors.

Methods and results

In a cross-sectional study, atherosclerosis burden was compared between 112 female SLE patients and 31 controls. Plaque number and carotid intima-media wall thickness (cIMT) were assessed by ultrasonography. In a retrospective study, BMD determinations obtained 5-years before the ultrasonography assessment were analyzed in a subgroup of 62 patients. Plaque frequency was increased in SLE, even in patients without CV events or carotid wall thickening. cIMT was increased in patients with CVD, positively correlated with body mass index (BMI). Interestingly, a paradoxical effect of BMI on carotid parameters was observed. Whereas underweight patients (BMI < 20) showed increased prevalence of carotid plaques with low cIMT, those with BMI > 30 showed higher cIMT and plaque burden. Overweight patients (25 < BMI<30) exhibited both elevated cIMT and plaque number. BMI was an independent predictor of BMD. In our retrospective study, patients with either clinical or subclinical CVD exhibited lower BMD levels than their CV-free counterparts. A low lumbar spine BMD independently predicted CVD development after adjusting for confounders.

Conclusion

SLE was associated with a higher subclinical atherosclerosis burden, a bimodal effect being observed for BMI. Decreased BMD can be a CV risk biomarker in SLE.  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