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   465篇
  免费   20篇
  国内免费   5篇
耳鼻咽喉   1篇
儿科学   21篇
妇产科学   11篇
基础医学   26篇
口腔科学   6篇
临床医学   31篇
内科学   75篇
皮肤病学   8篇
神经病学   16篇
特种医学   82篇
外科学   89篇
综合类   42篇
预防医学   16篇
眼科学   6篇
药学   26篇
肿瘤学   34篇
  2021年   3篇
  2020年   3篇
  2019年   2篇
  2018年   10篇
  2017年   5篇
  2016年   3篇
  2015年   6篇
  2014年   8篇
  2013年   20篇
  2012年   6篇
  2011年   11篇
  2010年   25篇
  2009年   24篇
  2008年   7篇
  2007年   13篇
  2006年   28篇
  2005年   14篇
  2004年   38篇
  2003年   16篇
  2002年   10篇
  2001年   5篇
  2000年   5篇
  1999年   3篇
  1998年   25篇
  1997年   22篇
  1996年   21篇
  1995年   28篇
  1994年   16篇
  1993年   7篇
  1992年   4篇
  1991年   3篇
  1990年   5篇
  1989年   15篇
  1988年   10篇
  1987年   7篇
  1986年   11篇
  1985年   2篇
  1984年   8篇
  1983年   9篇
  1982年   3篇
  1981年   5篇
  1980年   7篇
  1978年   4篇
  1977年   4篇
  1974年   2篇
  1972年   1篇
  1971年   1篇
  1970年   1篇
  1969年   1篇
  1968年   2篇
排序方式: 共有490条查询结果,搜索用时 13 毫秒
61.
62.
63.
A method of contrast echography with albumin-carbon dioxide foam is reported. 140 women aged 20 to 60 were investigated. By filling the uterine cavity and in some cases the tubes the sagittal and longitudinal size of the uterus were determined and tumourous nodes in the uterine well were demonstrated. Contrast echography significantly widens the scope of ultrasonography of the uterus and its adnexa.  相似文献   
64.
65.
Sephacryl beads containing an immobilized aminopropylcobalamin- transcobalamin-II complex serve as foci for the adherence of L1210 murine leukemia cells. Bead-cell interaction does not occur when (A) nonderivatized beads are used; (B) transcobalamin-II is omitted or presaturated with cyanocobalamin in the preparation of the bead complex; (C) intrinsic factor replaces transcobalamin-II; and (D) the complex is removed from beads by photolysis. These observations suggest that adherence results from the ability of transcobalamin-II to form a bridge between immobilized cobalamin on the bead and receptors in the plasma membrane of the cell.  相似文献   
66.
The partial characterization and expression of the C1q receptor (C1q-R) in relation to other complement receptors present on the surface of neutrophils has been examined, as well as the effects of free C1q on cell function. A polyclonal anti-C1q-R antibody recognizes a 68-kD neutrophil surface protein. C1q-R expression was not upregulated upon warming, priming, or exposure to FMLP, but decreased after exposure to phorbol myristate acetate (PMA), because of shedding of the receptor into the extracellular medium, as detected by enzyme-linked immunosorbent assay. CR3 and CR1 expression was upregulated from intracellular pools after cell stimulation by PMA. No evidence of intracellular pools of C1q-R was found, as assessed by immunoblotting of subcellular fractions. But C1q-R appeared to be expressed early in cell differentiation, was detected on undifferentiated HL-60 cells, and like CR3 expression, increased upon 5 days differentiation towards a neutrophil lineage. However, C1q-R expression decreased upon additional culture, whereas CR3 expression continued to increase. A large variation in the percentage of peripheral cells expressing C1q receptors in donors was observed, ranging from 13% to 100%, contrasting with CR3 receptors that exhibited less variability. Interactions between free monomeric C1q and neutrophils were also studied. Incubation of stimulated neutrophils with 10 to 100 micrograms/mL C1q resulted in a further increase in CR3 expression and adherence to albumin-coated surfaces. Staphylococci opsonized with low quantities of C1q (0.1 to 1 microgram/mL) mediated a moderate and sustained respiratory burst in neutrophils, whereas a burst of similar magnitude was generated only with free C1q at concentrations 10- to 100-fold higher. Stimulation was only partially inhibited if cells were first treated with anti-C1q-R antibody, suggesting other C1q binding proteins may be present on the cell surface. In summary, neutrophil C1q receptor is approximately 68-kD, exhibits varying expression on different subjects, and is not upregulated from intracellular stores on exposure to soluble stimuli. Stimulated, but not resting, neutrophils selectively respond to raised levels of free C1q, resulting in altered cell function and enhanced CR3 receptor expression. These studies thus suggest complex roles for C1q in neutrophil function.  相似文献   
67.
Because there is no consensus regarding the precise distribution of induced endothelial tissue factor (TF), we studied TF activity in and on tumor necrosis factor alpha-stimulated cultured human umbilical vein endothelial cells (ECs) and their underlying matrix. TF was mainly expressed on the cell surface. Only small traces were found on the apical surface suggesting that TF is predominantly located on the basolateral side of the cell membrane. The presence of TF on the cell surface was confirmed by flow cytometry. Subendothelial TF activity appeared to be dependent upon the procedure used to remove the stimulated EC monolayer. Whereas ammonium hydroxide or hypotonic lysis resulted in relatively high levels of matrix-associated TF, virtually no TF was found on the matrix after mild enzymatic detachment of stimulated ECs. Cell removal with EDTA resulted in intermediate levels of matrix-associated TF. Neither the enzymatic treatment nor EDTA degraded or removed this TF activity. Similar patterns were observed for matrix-associated TF antigen and EC surface markers. Electron microscopic analysis showed cell fragments on the matrix after monolayer lysis. The findings strongly suggest that induced endothelial TF associated with the subendothelial matrix actually represents TF on EC remnants.  相似文献   
68.
69.
Rholl  KS; Lee  JK; Ling  D; Sicard  GA; Griffith  RC; Freeman  M 《Radiology》1986,160(1):113-117
Findings of magnetic resonance (MR) imaging in acute renal rejection and acute tubular necrosis (ATN) were studied in dogs. On T1-weighted images, corticomedullary differentiation was absent in kidneys undergoing acute rejection. The loss of corticomedullary differentiation in these kidneys was secondary to a decrease in the relative signal intensity of the cortex, indicating prolongation of the T1 relaxation time of the cortex. In contrast, corticomedullary differentiation was preserved on T1-weighted images of autotransplanted kidneys and kidneys with ATN. MR imaging findings correlated with changes in water content in these three groups of kidneys. Kidneys undergoing acute rejection showed a marked increase in water content compared with kidneys in the other two groups. No change in fat content was found in any group.  相似文献   
70.
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