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   735篇
  免费   42篇
  国内免费   7篇
耳鼻咽喉   1篇
儿科学   33篇
妇产科学   6篇
基础医学   65篇
口腔科学   37篇
临床医学   63篇
内科学   158篇
皮肤病学   20篇
神经病学   16篇
特种医学   134篇
外科学   68篇
综合类   77篇
预防医学   22篇
药学   47篇
  1篇
肿瘤学   36篇
  2021年   3篇
  2019年   5篇
  2018年   11篇
  2017年   7篇
  2016年   12篇
  2015年   15篇
  2014年   18篇
  2013年   15篇
  2012年   15篇
  2011年   10篇
  2010年   20篇
  2009年   28篇
  2008年   15篇
  2007年   16篇
  2006年   33篇
  2005年   11篇
  2004年   14篇
  2003年   15篇
  2002年   9篇
  2001年   14篇
  2000年   8篇
  1999年   9篇
  1998年   31篇
  1997年   50篇
  1996年   46篇
  1995年   33篇
  1994年   33篇
  1993年   36篇
  1992年   23篇
  1991年   16篇
  1990年   18篇
  1989年   16篇
  1988年   19篇
  1987年   9篇
  1986年   8篇
  1985年   9篇
  1984年   9篇
  1983年   11篇
  1982年   16篇
  1981年   14篇
  1980年   12篇
  1979年   7篇
  1978年   9篇
  1977年   6篇
  1976年   17篇
  1975年   10篇
  1973年   3篇
  1972年   4篇
  1969年   2篇
  1968年   3篇
排序方式: 共有784条查询结果,搜索用时 0 毫秒
101.
102.
A technique for simultaneous bilateral biplane arteriography of the abdomen, pelvis, and lower extremities is described. The biplane views provided clinically significant information in approximately 40% of cases.  相似文献   
103.
The specificity of T-cell helper factor in man   总被引:7,自引:3,他引:4       下载免费PDF全文
Supernates of human T cells stimulated with TT antigen contain a factor that induces mitogenesis and immunoglobulin synthesis in autologous as well as allogeneic B cells. A fraction of the IgG produced has specificity against TT. The T-cell-derived LMF-TT eluted after albumin on Sephadex G 200 and did not contain immunoglobulin heavy chain determinants. LMF-TT was active on B cells from TT immune as well as TT- nonimmune individuals but in the latter instance the IgG secreted had no specificity against TT. B cells incubated with LMF-TT in the presence of a second antigen (DT) made IgG with specifity to that antigen provided the B-cell donor was immune to that second antigen. LMF-TT-containing supernates were depleted of TT antigen by Sephadex G 200 chromatography followed by passage over anti-TT immunosorbent columns. The antigen-free supernates were able to induce mitogenesis and IgG synthesis in B cells but the IgG produced failed to exhibit specificity against TT unless the TT antigen was readded to the B-cell cultures. The optimal concentration of LMF-TT (50 percent) inducing B-cell mitogenesis was different from the optimal concentration (20 percent) causing IgG synthesis by B cells. At low LMF concentrations (less than or equal 10 percent) addition of a second antigen to which the cell donor was immune caused an increase in the degree of B-cell mitogenesis. Submitogenic concentrations of LMF-TT (less than or equal to 5 percent) were still capable of inducingimmunoglobulin synthesis in B cells At these low concentrations of LMF-TT the proportion of anti-TT IgG over total IgG increased sharply. B cells from TT immune donors were separated on TT immunosorbent columns. Cells that bound to the column were more sensitive to the mitogenic and IgG synthetic effects of LMF-TT than unfractionated B cells. Thus, LMF is a nonspecific human T-cell helper factor which behaves like a polyclonal B-cell activator. However, in the presence of specific antigen (TT) the antigen-specific B cell is preferentially triggered by LMF. The experimental design of the present study does not rule out the additional presence of an antigen-specific helper factor in the supernates of TT-stimulated human T cells.  相似文献   
104.
105.
106.
107.
108.
Children with obstetric brachial plexus palsy (OBPP) most commonly have weakness of supination. There is little previous information on later progress of forearm rotation movements, although severe supination contracture has been reported in a small proportion of children. The aims of this study were to evaluate forearm rotation after initial recovery from OBPP, to define the relationship with the severity of disease, and to assess which factors might limit rotation. Measurements of active and passive pronation and supination were recorded in 56 children (37 boys and 19 girls) who had had OBPP and did not have full recovery. The mean age was 8 years (minimum, 2.5 years). Care was taken to measure forearm rotation in isolation from shoulder movements. According to the Narakas classification for severity of the original brachial plexus lesion, there were 23 group I cases, 16 group II cases, 11 group III cases, and 6 group IV cases. Twenty-one children underwent reconstructive procedures for shoulder deformity. Mallet scores for shoulder function were available for all patients. Overall pronation was more limited than supination. Active movements were more limited than passive movements. Active pronation was less than normal in 48 children, active supination was less than normal in 36, passive pronation was less than normal in 22, and passive supination was less than normal in 9. Active pronation and active and passive supination were significantly limited in children with worse Mallet scores and in Narakas group IV children. Both active supination and passive supination were decreased in children with more severe elbow flexion contractures. No significant relationship was found between forearm rotation movements and the time of biceps recovery. Many children have persisting limitation of forearm rotation after OBPP. Despite the initial weakness of supination, pronation is more often reduced in the longer term. Patients with more severe OBPP and poorer recovery of shoulder function have greater limitation of forearm rotation.  相似文献   
109.
Quito  FL; Beh  J; Bashayan  O; Basilico  C; Basch  RS 《Blood》1996,87(4):1282-1291
Fibroblast growth factor-4 (FGF-4), a highly mitogenic protein encoded by the k-fgf/hst oncogene, stimulates the growth of a variety of cells of mesenchymal and neuroectodermal origin. Addition of FGF-4 to human long-term bone marrow cultures increased both the cell density of the stromal layer and the number of hematopoietic colony forming cells in the cultures in a dose-dependent manner. Hematopoiesis in the stromal layer persisted for up to 8 months. Erythropoiesis was maintained for up to 4 weeks, but granulocytes were the predominant nonadherent cell type. Cultures treated with FGF had increased numbers of monocytes compared with control cultures and some CD14+, CD45+ monocytes could still be detected after 8 months of continuous culture. The addition of the growth factor increased the rate of growth of the stromal layer and appeared to delay its senescence. Subcultures made in the presence of FGF-4 had up to 10-fold increases in plating efficiency and grew as relatively uniform monolayers. These subcultures retained the capacity to support hematopoiesis for several months, while untreated subcultures, made without FGF-4, grew erratically and generally lost the capacity to support hematopoiesis within 4 to 6 weeks. The improved growth after subculture greatly enhanced the reliability of limit- dilution assays of multipotential hematopoietic stem cells that use stromal cell monolayers. The primary effect of FGF-4 appeared to be on the stromal cells of the long-term bone marrow cultures, but a direct effect on hematopoietic progenitors could not be ruled out.  相似文献   
110.
The authors report the clinical and laboratory findings of a patient who had severe immune hemolytic anemia due to hydrochlorothiazide (HCTZ). In this case, the HCTZ antibody reacted not only with other thiazide and thiazide-like drugs, but also with a chemically unrelated diuretic, ethacrynic acid. These results indicate that HCTZ antibody activity is not restricted solely to the thiazides and imply that therapy with any of the reactive drugs would be contraindicated for this patient. The serologic screening for drug reactivity may be useful for selecting alternative therapy for patients with drug-induced immune hemolytic anemia.  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