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   2663篇
  免费   293篇
  国内免费   8篇
耳鼻咽喉   28篇
儿科学   71篇
妇产科学   76篇
基础医学   378篇
口腔科学   34篇
临床医学   302篇
内科学   486篇
皮肤病学   76篇
神经病学   160篇
特种医学   142篇
外国民族医学   1篇
外科学   527篇
综合类   140篇
一般理论   2篇
预防医学   179篇
眼科学   27篇
药学   197篇
中国医学   3篇
肿瘤学   135篇
  2022年   17篇
  2021年   38篇
  2020年   16篇
  2019年   28篇
  2018年   36篇
  2017年   27篇
  2016年   32篇
  2015年   44篇
  2014年   73篇
  2013年   100篇
  2012年   108篇
  2011年   83篇
  2010年   70篇
  2009年   86篇
  2008年   99篇
  2007年   125篇
  2006年   118篇
  2005年   102篇
  2004年   98篇
  2003年   77篇
  2002年   79篇
  2001年   94篇
  2000年   75篇
  1999年   84篇
  1998年   68篇
  1997年   44篇
  1996年   53篇
  1995年   39篇
  1994年   39篇
  1993年   41篇
  1992年   85篇
  1991年   75篇
  1990年   54篇
  1989年   79篇
  1988年   73篇
  1987年   50篇
  1986年   43篇
  1985年   63篇
  1984年   57篇
  1983年   39篇
  1982年   29篇
  1981年   21篇
  1980年   24篇
  1979年   28篇
  1978年   17篇
  1977年   25篇
  1976年   18篇
  1974年   21篇
  1973年   20篇
  1966年   17篇
排序方式: 共有2964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.
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   
8.
9.
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   
10.
Apolipoprotein E (apoE, protein; APOE, gene) is the major lipid-transport protein in the brain and plays an important role in modulating the outcome and regenerative processes after acute brain injury. The aim of the present study was to determine if gene transfer of the epsilon3 form of APOE improves outcome in a murine model of transient focal cerebral ischaemia. Mice received an intrastriatal injection of vehicle, a second-generation adenoviral vector containing the green fluorescent protein gene (Ad-GFP) or a vector containing the APOE epsilon3 gene (Ad-APOE) 3 days before 60 mins focal ischaemia. Green fluorescent protein expression was observed in cells throughout the striatum and subcortical white matter indicating successful gene transfer and expression. ApoE levels in the brain were significantly increased after Ad-APOE compared with Ad-GFP or vehicle treatment. Ad-APOE treatment reduced the volume of ischaemic damage by 50% compared with Ad-GFP or vehicle treatment (13+/-3 versus 29+/-4 versus 27+/-5 mm(3)). The extent of postischaemic apoE immunoreactivity was enhanced in Ad-APOE compared with Ad-GFP or vehicle treated mice. These results show the ability of APOE gene transfer to markedly improve outcome after cerebral ischaemia and suggest that modulating apoE levels may be a potential strategy in human stroke therapy.  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