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   31234篇
  免费   1501篇
  国内免费   104篇
耳鼻咽喉   443篇
儿科学   831篇
妇产科学   690篇
基础医学   4000篇
口腔科学   1805篇
临床医学   2237篇
内科学   7444篇
皮肤病学   628篇
神经病学   2333篇
特种医学   675篇
外国民族医学   4篇
外科学   3933篇
综合类   167篇
一般理论   34篇
预防医学   3490篇
眼科学   454篇
药学   2079篇
中国医学   185篇
肿瘤学   1407篇
  2023年   271篇
  2022年   250篇
  2021年   767篇
  2020年   465篇
  2019年   760篇
  2018年   1204篇
  2017年   735篇
  2016年   755篇
  2015年   930篇
  2014年   1028篇
  2013年   1366篇
  2012年   2414篇
  2011年   2640篇
  2010年   1251篇
  2009年   911篇
  2008年   2041篇
  2007年   2145篇
  2006年   1905篇
  2005年   1840篇
  2004年   1617篇
  2003年   1469篇
  2002年   1367篇
  2001年   584篇
  2000年   603篇
  1999年   478篇
  1998年   139篇
  1997年   92篇
  1996年   82篇
  1995年   82篇
  1994年   61篇
  1993年   66篇
  1992年   286篇
  1991年   215篇
  1990年   194篇
  1989年   179篇
  1988年   157篇
  1987年   154篇
  1986年   126篇
  1985年   107篇
  1984年   84篇
  1983年   83篇
  1981年   46篇
  1979年   68篇
  1975年   56篇
  1974年   73篇
  1973年   48篇
  1971年   53篇
  1970年   50篇
  1969年   45篇
  1968年   54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