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   608篇
  免费   34篇
  国内免费   35篇
耳鼻咽喉   1篇
儿科学   30篇
妇产科学   4篇
基础医学   100篇
口腔科学   11篇
临床医学   96篇
内科学   142篇
皮肤病学   8篇
神经病学   14篇
特种医学   118篇
外科学   60篇
综合类   23篇
一般理论   2篇
预防医学   11篇
眼科学   3篇
药学   31篇
肿瘤学   23篇
  2023年   4篇
  2021年   8篇
  2020年   6篇
  2018年   7篇
  2017年   3篇
  2016年   7篇
  2015年   6篇
  2014年   9篇
  2013年   19篇
  2012年   32篇
  2011年   25篇
  2010年   20篇
  2009年   17篇
  2008年   19篇
  2007年   32篇
  2006年   21篇
  2005年   36篇
  2004年   17篇
  2003年   18篇
  2002年   13篇
  2001年   21篇
  2000年   20篇
  1999年   22篇
  1998年   18篇
  1997年   22篇
  1996年   28篇
  1995年   14篇
  1994年   11篇
  1993年   25篇
  1992年   3篇
  1991年   7篇
  1990年   9篇
  1989年   11篇
  1988年   16篇
  1987年   13篇
  1986年   9篇
  1985年   10篇
  1984年   11篇
  1983年   9篇
  1982年   9篇
  1981年   6篇
  1980年   5篇
  1979年   7篇
  1978年   9篇
  1977年   6篇
  1976年   6篇
  1975年   6篇
  1974年   7篇
  1973年   4篇
  1970年   5篇
排序方式: 共有677条查询结果,搜索用时 31 毫秒
31.
The increasing use of digitally formatted imaging systems requires high-quality interactive gray-scale computer raster graphics systems for the management, display, and analog film recording of digital image and alphanumeric information. These systems are a combination of computer hardware and software and implement a set of graphics protocols. This paper describes a set of interactive graphics protocols that has been developed for clinical use.  相似文献   
32.
33.
34.
A family history of certain malignancies, especially breast, ovarian, colorectal, and prostate cancers, can place persons at increased risk of developing these cancers. By constructing a pedigree that includes 3 generations, family physicians can identify patients at increased risk because of family cancer history. Persons at increased cancer risk because of family history warrant a surveillance strategy for early detection. Genetic professionals represent an important resource in assessing genetic risk and possible testing. Persons identified as being at increased risk of various cancers based on their family history should understand the surveillance plan that is recommended and the importance of maintaining a healthy lifestyle and remaining up to date on other cancer screening tests.  相似文献   
35.
36.
37.
BACKGROUND: Laboratory tests are widely used to screen children with planned surgery to detect unknown coagulation defects. This study investigates the predictive value of commonly used coagulation tests (thromboplastin time, partial thromboplastin time and thrombocyte count) compared with a standardized bleeding history. PATIENTS: In 702 patients 500 adenoidectomies and 500 tonsillectomies were done, results of laboratory evaluation and individual bleeding history were evaluated. RESULTS: 9.4 % of all laboratory tests showed abnormal results. 30.5 % of the children awaiting adenoidectomy had a suspicious bleeding history as had 22 % of patients undergoing tonsillectomy. In the clinical course of adenoidectomy no bleeding occurred. After tonsillectomy 15 children (3 %) showed moderate, 12 patients (2.4 %) severe postoperative bleeding. The positive predictive value of coagulation screening reached 6.8 % whereas history alone predicted 9.2 % of observed post tonsillectomy bleeding. CONCLUSIONS: The results of this study demonstrate the lacking effect of laboratory tests to predict postoperative bleeding complications. Taking a careful history of bleeding risks and testing only patients with suspicious history reduces the risk of bleeding more effective. Counseling about bleeding symptoms and postoperative survey of patients are additional measures which may protect the children.  相似文献   
38.
39.
40.
Activation of human Vgamma9/Vdelta2 T cells by many pathogens depends on the presence of small phosphorylated non-peptide compounds derived from the 2-C-methyl-d-erythritol 4-phosphate (MEP) pathway of isoprenoid biosynthesis. We here demonstrate that in Escherichia coli mutants deficient in lytB, an essential gene of the MEP pathway, a potent Vgamma9/Vdelta2 T-cell activator accumulates by a factor of approximately 150 compared to wild-type E. coli. The compound responsible for the strong immunogenicity of this E. coli mutant was subsequently characterized and identified as a small pyrophosphorylated metabolite, with a molecular mass of 262 Da, derived from the MEP pathway. Stimulation of human peripheral blood mononuclear cells (PBMC) with extracts prepared from the lytB-deficient E. coli mutant led to upregulation of T-cell activation markers on the surface of Vgamma9/Vdelta2 T cells as well as proliferation and expansion of Vgamma9/Vdelta2 T cells. This response was dependent on costimulatory growth factors, such as interleukin (IL)-2, IL-15 and IL-21. Significant levels of interferon-gamma (IFN-gamma) and tumour necrosis factor-alpha (TNF-alpha) were secreted in the presence of IL-2 and IL-15, but not in the presence of IL-21, demonstrating that proliferating phosphoantigen-reactive Vgamma9/Vdelta2 T cells do not necessarily produce proinflammatory cytokines.  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