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   25443篇
  免费   1207篇
  国内免费   83篇
耳鼻咽喉   307篇
儿科学   637篇
妇产科学   628篇
基础医学   3340篇
口腔科学   1601篇
临床医学   1865篇
内科学   6113篇
皮肤病学   514篇
神经病学   1931篇
特种医学   504篇
外科学   2867篇
综合类   121篇
一般理论   13篇
预防医学   3053篇
眼科学   386篇
药学   1712篇
中国医学   144篇
肿瘤学   997篇
  2023年   229篇
  2022年   150篇
  2021年   538篇
  2020年   337篇
  2019年   598篇
  2018年   1060篇
  2017年   631篇
  2016年   648篇
  2015年   792篇
  2014年   834篇
  2013年   1132篇
  2012年   2053篇
  2011年   2264篇
  2010年   1020篇
  2009年   686篇
  2008年   1719篇
  2007年   1825篇
  2006年   1620篇
  2005年   1569篇
  2004年   1382篇
  2003年   1279篇
  2002年   1179篇
  2001年   444篇
  2000年   493篇
  1999年   360篇
  1998年   88篇
  1997年   45篇
  1996年   43篇
  1995年   43篇
  1994年   27篇
  1993年   36篇
  1992年   220篇
  1991年   157篇
  1990年   133篇
  1989年   114篇
  1988年   97篇
  1987年   98篇
  1986年   85篇
  1985年   70篇
  1984年   54篇
  1983年   54篇
  1979年   30篇
  1975年   38篇
  1974年   50篇
  1973年   29篇
  1971年   34篇
  1970年   36篇
  1969年   32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 31 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