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   1341176篇
  免费   102752篇
  国内免费   4262篇
耳鼻咽喉   16898篇
儿科学   43786篇
妇产科学   36537篇
基础医学   199053篇
口腔科学   36075篇
临床医学   130343篇
内科学   259410篇
皮肤病学   26467篇
神经病学   112388篇
特种医学   48484篇
外国民族医学   368篇
外科学   185392篇
综合类   28907篇
现状与发展   1篇
一般理论   480篇
预防医学   115059篇
眼科学   29246篇
药学   99358篇
  6篇
中国医学   3171篇
肿瘤学   76761篇
  2021年   11014篇
  2019年   11748篇
  2018年   16451篇
  2017年   12388篇
  2016年   13352篇
  2015年   15335篇
  2014年   20987篇
  2013年   32339篇
  2012年   44661篇
  2011年   47328篇
  2010年   27381篇
  2009年   25211篇
  2008年   43166篇
  2007年   45530篇
  2006年   45614篇
  2005年   44094篇
  2004年   42034篇
  2003年   39910篇
  2002年   38738篇
  2001年   61026篇
  2000年   62708篇
  1999年   52445篇
  1998年   14694篇
  1997年   13373篇
  1996年   13198篇
  1995年   12534篇
  1994年   11696篇
  1993年   11003篇
  1992年   41700篇
  1991年   40878篇
  1990年   39561篇
  1989年   37470篇
  1988年   34691篇
  1987年   33799篇
  1986年   32239篇
  1985年   30751篇
  1984年   23134篇
  1983年   19690篇
  1982年   11826篇
  1979年   20891篇
  1978年   14906篇
  1977年   12123篇
  1976年   11943篇
  1975年   12174篇
  1974年   14871篇
  1973年   14528篇
  1972年   13396篇
  1971年   12456篇
  1970年   11534篇
  1969年   10446篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
911.
912.
This study evaluates the potential for endothelial seeding of a collagen-impregnated Dacron graft with or without surface modifiers (fibronectin, heparin) to attach and retain these cells during flow. Human umbilical endothelial cells were harvested, cultured, labeled with Indium111-oxine and seeded onto 30 mm X 4 mm diameter grafts. Six graft surfaces were studied: 1) a collagen-impregnated Dacron graft, HemashieldR (C); 2) C + fibronectin (C + F); 3) C + heparin (C + H); 4) C + F + H; 5) HytrelR + F (Hyt + F); and 6) Hyt + F + H. Radioactive loss determined the percentage attachment and then percentage retention of labeled inoculum after a one-hour in vitro perfusion. Scanning electron and light microscopy demonstrated the endothelium on the graft surface following perfusion. Fibronectin-coated grafts had a significantly higher percentage attachment than those without fibronectin (ANOVA, P less than 0.05). However, the percentage retention following perfusion was similar for all Dacron grafts and statistically inferior to the HytrelR grafts studied (ANOVA, P less than 0.05). SEM evaluation of the C + F + H graft surface was qualitatively the most impressive Dacron surface for seeding, yet was inferior to the HytrelR graft. We conclude that fibronectin benefits the initial attachment of endothelium to collagen-coated Dacron rivaling the HytrelR surface. Fibronectin does not improve percentage retention of the HemashieldR surface during perfusion, therefore, some of its initial benefit is lost.  相似文献   
913.
The authors report their experience of anterolateral bilateral approach of cervical spine. They underline the advantages and inconvenience of this route and discuss the indications.  相似文献   
914.
915.
Cancer risk after evaluation for infertility   总被引:3,自引:0,他引:3  
To evaluate cancer risk by various causes of infertility, the authors conducted a retrospective cohort study among 2,335 women evaluated for infertility at the Mayo Clinic between 1935 and 1964. Most cancers occurred at expected frequencies, with the exception of cancers of the thyroid (standardized incidence ratio (SIR) = 2.6) and other endocrine glands (SIR = 6.7), although analyses were based on small numbers. Patients with progesterone deficiencies (31 per cent of the study subjects) had a 20 per cent higher cancer risk than did those with other causes of infertility, with excesses deriving primarily from cancers of the lung, cervix, ovary, and thyroid and from melanoma. Breast cancer risk, however, was not elevated in either patients with progesterone deficiencies (SIR = 0.9) or patients with other causes of infertility (SIR = 1.0). Examination of other parameters of infertility, including age at evaluation, type of infertility (primary vs. secondary), and years of attempted conception, showed no elevated risks of breast cancer in any subgroup. These results fail to support previous studies that have linked progesterone deficiencies among infertile women to elevated breast cancer risk. However, the data suggest a possible involvement of a progesterone deficiency in the etiology of other cancers, particularly thyroid cancer and melanoma.  相似文献   
916.
917.
918.
A general overview of the literature concerning the development of diabetic neuropathic arthropathy is discussed. A case report is presented dealing with spontaneous fractures of the lesser metatarsal in a patient with an amputated hallux and peripheral neuropathy secondary to diabetes mellitus.  相似文献   
919.
920.
The anti-granulocyte activity of serum from patients with B-cell chronic lymphocytic leukaemia (CLL) and other lymphoproliferative disorders was investigated. Granulocyte-binding IgG was measured in 34 patients with CLL, 13 patients with hairy cell leukaemia, one patient with prolymphocytic leukaemia, two patients with Sézary cell leukaemia, and seven patients with chronic T-cell lymphocytosis who had a predominance of circulating large granular lymphocytes. Anti-granulocyte activity was absent in CLL and its variants, but present in the majority of granulocytopenic patients with chronic T-cell lymphocytosis. In one of these patients, granulocytopenia was associated with complement-activating IgG granulocyte antibody. Thus, antibody-mediated granulocyte injury appears to be an unusual occurrence in chronic lymphocytic leukaemia, but is a frequent complication of chronic T-cell lymphocytosis.  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