首页 | 官方网站   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   12288篇
  免费   787篇
  国内免费   51篇
医药卫生   13126篇
  2023年   137篇
  2022年   108篇
  2021年   466篇
  2020年   320篇
  2019年   421篇
  2018年   514篇
  2017年   350篇
  2016年   379篇
  2015年   429篇
  2014年   549篇
  2013年   723篇
  2012年   1019篇
  2011年   1167篇
  2010年   566篇
  2009年   457篇
  2008年   715篇
  2007年   756篇
  2006年   640篇
  2005年   549篇
  2004年   457篇
  2003年   373篇
  2002年   355篇
  2001年   233篇
  2000年   230篇
  1999年   187篇
  1998年   51篇
  1997年   44篇
  1996年   25篇
  1995年   38篇
  1994年   39篇
  1993年   31篇
  1992年   97篇
  1991年   62篇
  1990年   72篇
  1989年   58篇
  1988年   41篇
  1987年   36篇
  1986年   35篇
  1985年   37篇
  1984年   25篇
  1983年   17篇
  1980年   17篇
  1978年   23篇
  1976年   16篇
  1975年   18篇
  1974年   17篇
  1973年   23篇
  1971年   22篇
  1970年   23篇
  1969年   26篇
排序方式: 共有10000条查询结果,搜索用时 265 毫秒
1.
2.
3.
4.
5.
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   
6.
The spatial distribution of enteroparasitosis in an indigenous village from Paraná was evaluated to identify areas of risk for these infections. A cross-sectional study (from November 2010 to June 2011) was performed using Three Faecal Test® and Kato &; Katz method and a questionnaire on housing and hygiene conditions was administered. Local geostatistical analyses were performed to determine the spatial distribution of intestinal parasitic infections. The overall prevalence of enteroparasites was 67.2?% (457/680), and the most prevalent taxa were Ascaris lumbricoides (48.8?%) and Trichuris trichiura (44.7?%). The prevalence of heavy infection by soil-transmitted helminths was 3.6?% and the families lived in houses with an average of 5.1 residents and < 2 bedrooms per household. The average number of species per individual present spatial heterogeneity with the highest values (≥0.8) in areas with high clustering of residences. The visualization of the spatial distribution of intestinal parasites in this indigenous village is an important contribution to determining health risk areas and planning decisions and services.  相似文献   
7.
8.
9.
10.
Cecal intubation is a critical aspect of effective, complete colonoscopy. Difficult colonoscopy is most often considered as one in which it is challenging or impossible to reach the cecum. It may be a common occurrence due to patient and/or endoscopist factors. Incomplete colonoscopies should be avoided, since patients in this context present an important prevalence of lesions that escape examination. The approach to successful cecal intubation should depend on characterization of the problem as redundant colon or difficult sigmoid colon. Most patients with a prior incomplete colonoscopy can be colonoscoped successfully, if careful attention is paid to technique, using a variety of scopes, colonoscopy methods and additional equipment. Sufficient time should be allotted to make the attempt.  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-23

京公网安备 11010802026262号