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   207485篇
  免费   3694篇
  国内免费   203篇
耳鼻咽喉   1477篇
儿科学   7698篇
妇产科学   3829篇
基础医学   20359篇
口腔科学   2187篇
临床医学   15407篇
内科学   37575篇
皮肤病学   1225篇
神经病学   18933篇
特种医学   9947篇
外科学   33805篇
综合类   3131篇
一般理论   14篇
预防医学   20103篇
眼科学   4072篇
药学   11810篇
  1篇
中国医学   781篇
肿瘤学   19028篇
  2023年   208篇
  2022年   306篇
  2021年   822篇
  2020年   521篇
  2019年   767篇
  2018年   22689篇
  2017年   17887篇
  2016年   20111篇
  2015年   1706篇
  2014年   1886篇
  2013年   2052篇
  2012年   9005篇
  2011年   23053篇
  2010年   19938篇
  2009年   12513篇
  2008年   21259篇
  2007年   23395篇
  2006年   2237篇
  2005年   3800篇
  2004年   4990篇
  2003年   5761篇
  2002年   3761篇
  2001年   1459篇
  2000年   1492篇
  1999年   1091篇
  1998年   531篇
  1997年   449篇
  1996年   315篇
  1995年   334篇
  1994年   288篇
  1993年   233篇
  1992年   585篇
  1991年   610篇
  1990年   595篇
  1989年   520篇
  1988年   455篇
  1987年   420篇
  1986年   382篇
  1985年   396篇
  1984年   266篇
  1983年   255篇
  1982年   177篇
  1981年   119篇
  1980年   164篇
  1979年   212篇
  1978年   111篇
  1977年   125篇
  1976年   91篇
  1974年   119篇
  1973年   85篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
A method for rapid separation and visualization of creatine phosphokinase (EC 2.7.3.2 ATP: creatine phosphotransferase) isoenzymes on cellulose acetate has been developed. The technic uses the Beckman microzone electrophoresis system, and is applicable to other cellulose acetate systems. Incubation is with a commercially available substrate solution, and the isoenzyme bands are visualized by fluorescence using a long-wavelength ultraviolet light. An intermediate migrating isoenzyme band (CPK-MB) was detected in sera of 67 of 68 patients with myocardial infarction, and was not present in patients with other disorders that might clinically be confused with myocardial infarction.  相似文献   
992.
993.

Background  

Statistics is relevant to students and practitioners in medicine and health sciences and is increasingly taught as part of the medical curriculum. However, it is common for students to dislike and under-perform in statistics. We sought to address these issues by redesigning the way that statistics is taught.  相似文献   
994.
DicomWorks is freeware software for reading and working on medical images [digital imaging and communication in medicine (DICOM)]. It was jointly developed by two research laboratories, with the feedback of more than 35,000 registered users throughout the world who provided information to guide its development. We detail their occupations (50% radiologists, 20% engineers, 9% medical physicists, 7% cardiologists, 6% neurologists, and 8% others), geographic origins, and main interests in the software. The viewer’s interface is similar to that of a picture archiving and communication system viewing station. It provides basic but efficient tools for opening DICOM images and reviewing and exporting them to teaching files or digital presentations. E-mail, FTP, or DICOM protocols are supported for transmitting images through a local network or the Internet. Thanks to its wide compatibility, a localized (15 languages) and user-friendly interface, and its opened architecture, DicomWorks helps quick development of non proprietary, low-cost image review or teleradiology solutions in developed and emerging countries.  相似文献   
995.

Background  

Interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) are expressed by microglia and infiltrating macrophages following ischemic stroke. Whereas IL-1β is primarily neurotoxic in ischemic stroke, TNF-α may have neurotoxic and/or neuroprotective effects. We investigated whether IL-1β and TNF-α are synthesized by overlapping or segregated populations of cells after ischemic stroke in mice.  相似文献   
996.
997.
Plasmids containing the inosine monophosphate dehydrogenase gene CaIMH3 from Candida albicans strain ATCC 32354 transform their host to resistance against mycophenolic acid (MPA). The transformants maintain the plasmids at a high copy number (20–40 per cell) and express the CaIMH3 gene at very high levels relative to untransformed controls. The plasmid copy number can be controlled by the concentration of MPA in the media. The transformation procedure is reproducible and the efficiency of transformation is high, up to 15,000 per microgram. Unrearranged plasmids are readily recovered by transforming total DNA from transformants back into Escherichia coli. C. albicans genes cloned into the plasmid are expressed at elevated levels relative to untransformed controls. A derivative vector containing the CaMAL2 promoter and termination sequences expresses the CaERG11 ORF at high levels and confers moderate resistance to fluconazole. These shuttle vectors should facilitate global genomics approaches in C. albicans that have been hampered by its diploid genome.  相似文献   
998.
Epstein-Barr virus (EBV)-associated smooth muscle tumor (SMT) is a recognized but uncommon disease that is found to occur in patients with immunocompromised conditions such as acquired immunodeficiency syndrome (AIDS). These tumors may be multifocal and located at unusual sites, such as the brain and liver. This report describes the case of 2 AIDS patients with EBV-associated SMT and highlights the features and outcome of this rare but potentially important tumor in human immunodeficiency virus management.  相似文献   
999.
Mutations of bone morphogenetic protein receptor type II (BMPR-II) have been associated with familial and idiopathic pulmonary arterial hypertension (PAH). BMPR-II is a member of the transforming growth factor-beta receptor superfamily. It consists of extracellular, transmembrane, and kinase domains, and a unique C-terminus with mostly unknown function. However, a number of PAH-causing mutations are predicted to truncate the C-terminus, suggesting that this domain plays an important role in the homeostasis of pulmonary vessels. In this study, we sought to elucidate the functional role of this C-terminus by seeking its interacting partners. Using yeast two-hybrid screening, we identified c-Src tyrosine kinase as a binding partner of this C-terminus. In vitro co-immunoprecipitation confirmed their interaction. Mutations truncating the C-terminus disrupted their interaction, while missense mutation within kinase domain reduced their interaction. In addition, BMPR-II and c-Src tyrosine kinase colocalized within intracellular aggregates when overexpressed in HEK293 cells. Moreover, mutations truncating the C-terminus disrupted their colocalization, whereas missense mutation within kinase domain had no effect on their colocalization. Furthermore, BMP ligand stimulation decreased c-Src-activating phosphorylation at Tyrosine 418 in pulmonary smooth muscle cells in both time- and concentration-dependent manners. Mutations that truncated the C-terminus abolished this response. Taken together, these results suggest a model in which proliferative effect of c-Src by vasoactive molecules is balanced by opposing effect of BMP signaling in basal state, and the loss of this balance due to BMPR2 mutations leads to increased c-Src activity and subsequently cell growth.  相似文献   
1000.
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