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   26029篇
  免费   1228篇
  国内免费   90篇
耳鼻咽喉   307篇
儿科学   654篇
妇产科学   637篇
基础医学   3389篇
口腔科学   1675篇
临床医学   1944篇
内科学   6265篇
皮肤病学   521篇
神经病学   1958篇
特种医学   534篇
外科学   2926篇
综合类   128篇
一般理论   13篇
预防医学   3098篇
眼科学   388篇
药学   1740篇
中国医学   161篇
肿瘤学   1009篇
  2023年   229篇
  2022年   202篇
  2021年   599篇
  2020年   372篇
  2019年   628篇
  2018年   1065篇
  2017年   634篇
  2016年   654篇
  2015年   800篇
  2014年   860篇
  2013年   1153篇
  2012年   2061篇
  2011年   2286篇
  2010年   1050篇
  2009年   729篇
  2008年   1736篇
  2007年   1831篇
  2006年   1629篇
  2005年   1576篇
  2004年   1390篇
  2003年   1283篇
  2002年   1180篇
  2001年   447篇
  2000年   500篇
  1999年   372篇
  1998年   99篇
  1997年   57篇
  1996年   57篇
  1995年   53篇
  1994年   43篇
  1993年   46篇
  1992年   221篇
  1991年   159篇
  1990年   135篇
  1989年   119篇
  1988年   108篇
  1987年   104篇
  1986年   90篇
  1985年   80篇
  1984年   59篇
  1983年   62篇
  1979年   30篇
  1975年   40篇
  1974年   51篇
  1973年   31篇
  1971年   39篇
  1970年   36篇
  1969年   34篇
  1968年   38篇
  1967年   28篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
1.
2.
3.
4.
5.
6.
Matrix metalloproteinase-11 (MMP11) is an enzyme with proteolytic activity against matrix and nonmatrix proteins. Although most MMPs are secreted as inactive proenzymes and are later activated extracellularly, MMP11 is activated intracellularly by furin within the constitutive secretory pathway. It is a key factor in physiological tissue remodeling and its alteration may play an important role in the progression of epithelial malignancies and other diseases. TCGA colon and colorectal adenocarcinoma data showed that upregulation of MMP11 expression correlates with tumorigenesis and malignancy. Here, we provide evidence that a germline variant in the MMP11 gene (NM_005940: c.232C>T; p.(Pro78Ser)), identified by whole exome sequencing, can increase the tumorigenic properties of colorectal cancer (CRC) cells. P78S is located in the prodomain region, which is responsible for blocking MMP11's protease activity. This variant was detected in the proband and all the cancer-affected family members analyzed, while it was not detected in healthy relatives. In silico analyses predict that P78S could have an impact on the activation of the enzyme. Furthermore, our in vitro analyses show that the expression of P78S in HCT116 cells increases tumor cell invasion and proliferation. In summary, our results show that this variant could modify the structure of the MMP11 prodomain, producing a premature or uncontrolled activation of the enzyme that may contribute to an early CRC onset in these patients. The study of this gene in other CRC cases will provide further information about its role in CRC development, which might improve patient treatment in the future.  相似文献   
7.
8.
9.
10.
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   
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