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   2548篇
  免费   294篇
  国内免费   47篇
耳鼻咽喉   28篇
儿科学   53篇
妇产科学   75篇
基础医学   368篇
口腔科学   29篇
临床医学   337篇
内科学   443篇
皮肤病学   82篇
神经病学   157篇
特种医学   211篇
外国民族医学   1篇
外科学   473篇
综合类   89篇
一般理论   2篇
预防医学   172篇
眼科学   19篇
药学   219篇
中国医学   3篇
肿瘤学   128篇
  2021年   33篇
  2019年   28篇
  2018年   31篇
  2017年   23篇
  2016年   27篇
  2015年   39篇
  2014年   66篇
  2013年   93篇
  2012年   102篇
  2011年   78篇
  2010年   57篇
  2009年   61篇
  2008年   97篇
  2007年   141篇
  2006年   90篇
  2005年   101篇
  2004年   90篇
  2003年   77篇
  2002年   75篇
  2001年   87篇
  2000年   76篇
  1999年   86篇
  1998年   53篇
  1997年   44篇
  1996年   40篇
  1995年   47篇
  1994年   41篇
  1993年   41篇
  1992年   98篇
  1991年   77篇
  1990年   64篇
  1989年   88篇
  1988年   68篇
  1987年   50篇
  1986年   49篇
  1985年   60篇
  1984年   54篇
  1983年   43篇
  1982年   33篇
  1981年   26篇
  1980年   28篇
  1979年   31篇
  1978年   24篇
  1977年   36篇
  1976年   22篇
  1975年   13篇
  1974年   21篇
  1973年   20篇
  1968年   14篇
  1966年   17篇
排序方式: 共有2889条查询结果,搜索用时 15 毫秒
1.
2.
Microvascular thrombosis is a prominent feature in cardiac delayed xenograft rejection (DXR). We investigated the impact of warfarin or low-molecular-weight heparin (LMWH) anti-coagulation on xenograft function using a heterotopic pig-to-primate model. Donor hearts were from CD46 transgenic pigs and baboon immunosuppression included tacrolimus, sirolimus, anti-CD20 and TPC, an alpha-galactosyl-polyethylene glycol conjugate. Three groups of animals were studied. Group 1 (n = 9) was treated with warfarin, Group 2 (n = 13) with LMWH and Group 3, received no anti-coagulant drugs. The median duration of xenograft function was 20 days (range 3-62 days), 18 days (range 5-109 days) and 15 days (range 4-53 days) in Groups 1 to 3 respectively. Anti-coagulation achieved the targeted international normalized prothrombin ratio (INR) and anti-factor Xa levels consistent with effective in vivo therapy yet, no significant impact on median xenograft function was observed. At rejection, a similar histology of thrombosis and ischemia was apparent in each group and the levels of fibrin deposition and platelet thrombi in rejected tissue was the same. Anti-coagulation with warfarin or LMWH did not have a significant impact on the onset of DXR and microvascular thrombosis. However, a role for specific anti-coagulant strategies to achieve long-term xenograft function cannot be excluded.  相似文献   
3.
4.
5.
The aim of this article is to provide clinicians and researchers a comprehensive overview of the development and functions of gesture in childhood and in select populations with developmental language impairments. Of significance is the growing body of evidence that gesture enhances, not hinders, language development. In both normal and impaired populations, gesture and language development parallel each other and share underlying symbolic abilities. Gesture serves several functions, including those of communication, compensation, and transition to spoken language. In clinical practice, gesture may play a valuable role in diagnosis, prognosis, goal selection, and intervention for children with language impairments. Where available, supporting evidence is presented. Needs for additional research on gesture are also highlighted.  相似文献   
6.
7.
8.
The presence of human papilloma virus (HPV) has recently been demonstrated in colon tumors, but the incidence of HPV infection in normal colon mucosa or in benign or malignant neoplasms of the mucosa is unknown. We studied both neoplastic and normal human colon tissue for the presence of HPV antigen using immunohistochemical techniques. Ninety colon specimens were studied. Three consecutive series of normal colon mucosa (N = 30), single benign tubulovillous adenomas (N = 30), and invasive carcinomas (N = 30) were selected and confirmed histologically. Formalin-fixed paraffin-embedded samples of each tissue were prepared using immunohistochemical techniques and resultant slides were read blindly and graded simply as positive or negative for HPV antigen. The presence of HPV antigen varied dramatically between groups, with 97% of the invasive carcinomas, 60% of the benign tubulovillous adenomas, and 23% of the normal mucosa positive for HPV antigen. Groups were statistically significant using chi 2 analysis (P less than 0.001). We conclude that an association exists between the human colon neoplasia and the presence of HPV antigen. This may suggest an etiologic role of the virus in colon cancer.  相似文献   
9.
10.
Today "safe sex" means protection from both unintended pregnancy and sexually transmitted disease and human immunodeficiency virus. These parallel complications of sexual activity have serious biologic and clinical sequelae that should be considered at the time of contraceptive selection. In addition, there is ongoing debate regarding potential interactions between antibiotic intervention and contraceptive steroids. This article assesses the impact of hormonal contraception, spermicides, barrier methods, intrauterine devices, and douching on the pathogenesis of sexually transmitted disease and the human immunodeficiency virus infection. It discusses the direct and indirect effects of contraception methods on clinical physiology and host immune responses while also considering the possible consequences on maternal and infant health if pregnancy results from the use of ineffective contraception. Counseling and care for both family planning and infectious disease protection must be provided to all sexually active individuals. (Ann J OBSTET GVNECOL 1993;168:2033-41.)  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