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   233350篇
  免费   11041篇
  国内免费   393篇
耳鼻咽喉   3047篇
儿科学   7269篇
妇产科学   4735篇
基础医学   33524篇
口腔科学   5309篇
临床医学   18414篇
内科学   51573篇
皮肤病学   6204篇
神经病学   20802篇
特种医学   6997篇
外国民族医学   101篇
外科学   28914篇
综合类   976篇
一般理论   62篇
预防医学   21208篇
眼科学   4550篇
药学   16391篇
中国医学   699篇
肿瘤学   14009篇
  2023年   1239篇
  2022年   850篇
  2021年   3432篇
  2020年   2041篇
  2019年   3871篇
  2018年   7424篇
  2017年   4873篇
  2016年   4860篇
  2015年   5436篇
  2014年   5658篇
  2013年   9159篇
  2012年   15972篇
  2011年   15916篇
  2010年   7903篇
  2009年   5885篇
  2008年   13688篇
  2007年   14663篇
  2006年   13498篇
  2005年   13359篇
  2004年   12540篇
  2003年   11440篇
  2002年   10826篇
  2001年   6108篇
  2000年   6205篇
  1999年   5512篇
  1998年   886篇
  1997年   738篇
  1996年   703篇
  1992年   3194篇
  1991年   2864篇
  1990年   2733篇
  1989年   2494篇
  1988年   2363篇
  1987年   2194篇
  1986年   2088篇
  1985年   1882篇
  1984年   1395篇
  1983年   1186篇
  1982年   668篇
  1979年   1203篇
  1978年   845篇
  1977年   795篇
  1975年   800篇
  1974年   984篇
  1973年   994篇
  1972年   935篇
  1971年   922篇
  1970年   860篇
  1969年   905篇
  1968年   787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