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   16539篇
  免费   1072篇
  国内免费   69篇
耳鼻咽喉   220篇
儿科学   250篇
妇产科学   288篇
基础医学   2486篇
口腔科学   1061篇
临床医学   1548篇
内科学   3955篇
皮肤病学   396篇
神经病学   1260篇
特种医学   476篇
外国民族医学   1篇
外科学   2156篇
综合类   42篇
一般理论   8篇
预防医学   1377篇
眼科学   160篇
药学   1194篇
中国医学   152篇
肿瘤学   650篇
  2023年   195篇
  2022年   358篇
  2021年   737篇
  2020年   453篇
  2019年   609篇
  2018年   748篇
  2017年   468篇
  2016年   535篇
  2015年   621篇
  2014年   806篇
  2013年   1014篇
  2012年   1419篇
  2011年   1506篇
  2010年   785篇
  2009年   609篇
  2008年   942篇
  2007年   918篇
  2006年   806篇
  2005年   707篇
  2004年   587篇
  2003年   487篇
  2002年   472篇
  2001年   249篇
  2000年   246篇
  1999年   212篇
  1998年   64篇
  1997年   61篇
  1996年   32篇
  1995年   42篇
  1994年   42篇
  1993年   34篇
  1992年   111篇
  1991年   79篇
  1990年   93篇
  1989年   73篇
  1988年   51篇
  1987年   47篇
  1986年   45篇
  1985年   52篇
  1984年   32篇
  1983年   19篇
  1979年   20篇
  1978年   23篇
  1976年   17篇
  1975年   19篇
  1974年   17篇
  1973年   22篇
  1971年   22篇
  1970年   19篇
  1969年   18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.
Melatonin receptors play important roles in the regulation of circadian and seasonal rhythms, sleep, retinal functions, the immune system, depression, and type 2 diabetes development. Melatonin receptors are approved drug targets for insomnia, non‐24‐hour sleep‐wake disorders, and major depressive disorders. In mammals, two melatonin receptors (MTRs) exist, MT1 and MT2, belonging to the G protein‐coupled receptor (GPCR) superfamily. Similar to most other GPCRs, reliable antibodies recognizing melatonin receptors proved to be difficult to obtain. Here, we describe the development of the first monoclonal antibodies (mABs) for mouse MT1 and MT2. Purified antibodies were extensively characterized for specific reactivity with mouse, rat, and human MT1 and MT2 by Western blot, immunoprecipitation, immunofluorescence, and proximity ligation assay. Several mABs were specific for either mouse MT1 or MT2. None of the mABs cross‐reacted with rat MTRs, and some were able to react with human MTRs. The specificity of the selected mABs was validated by immunofluorescence microscopy in three established locations (retina, suprachiasmatic nuclei, pituitary gland) for MTR expression in mice using MTR‐KO mice as control. MT2 expression was not detected in mouse insulinoma MIN6 cells or pancreatic beta‐cells. Collectively, we report the first monoclonal antibodies recognizing recombinant and native mouse melatonin receptors that will be valuable tools for future studies.  相似文献   
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.
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   
8.
9.
10.
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