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   28097篇
  免费   1329篇
  国内免费   134篇
耳鼻咽喉   332篇
儿科学   701篇
妇产科学   660篇
基础医学   3560篇
口腔科学   1745篇
临床医学   2087篇
内科学   6665篇
皮肤病学   564篇
神经病学   2061篇
特种医学   734篇
外科学   3481篇
综合类   160篇
一般理论   34篇
预防医学   3186篇
眼科学   412篇
药学   1846篇
中国医学   169篇
肿瘤学   1163篇
  2023年   243篇
  2022年   225篇
  2021年   683篇
  2020年   412篇
  2019年   682篇
  2018年   1124篇
  2017年   672篇
  2016年   693篇
  2015年   849篇
  2014年   949篇
  2013年   1253篇
  2012年   2219篇
  2011年   2408篇
  2010年   1151篇
  2009年   842篇
  2008年   1847篇
  2007年   1950篇
  2006年   1730篇
  2005年   1677篇
  2004年   1466篇
  2003年   1348篇
  2002年   1248篇
  2001年   482篇
  2000年   523篇
  1999年   401篇
  1998年   161篇
  1997年   104篇
  1996年   93篇
  1995年   80篇
  1994年   60篇
  1993年   79篇
  1992年   236篇
  1991年   176篇
  1990年   151篇
  1989年   148篇
  1988年   124篇
  1987年   123篇
  1986年   98篇
  1985年   92篇
  1984年   72篇
  1983年   72篇
  1982年   35篇
  1981年   38篇
  1980年   41篇
  1979年   33篇
  1975年   42篇
  1974年   52篇
  1971年   35篇
  1970年   36篇
  1968年   38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