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   3398篇
  免费   144篇
  国内免费   57篇
耳鼻咽喉   5篇
儿科学   55篇
妇产科学   22篇
基础医学   426篇
口腔科学   38篇
临床医学   219篇
内科学   1041篇
皮肤病学   19篇
神经病学   247篇
特种医学   142篇
外科学   593篇
综合类   16篇
预防医学   104篇
眼科学   81篇
药学   288篇
中国医学   6篇
肿瘤学   297篇
  2023年   35篇
  2022年   49篇
  2021年   76篇
  2020年   33篇
  2019年   51篇
  2018年   53篇
  2017年   67篇
  2016年   67篇
  2015年   57篇
  2014年   95篇
  2013年   122篇
  2012年   185篇
  2011年   196篇
  2010年   88篇
  2009年   90篇
  2008年   180篇
  2007年   221篇
  2006年   198篇
  2005年   230篇
  2004年   216篇
  2003年   204篇
  2002年   229篇
  2001年   97篇
  2000年   80篇
  1999年   60篇
  1998年   37篇
  1997年   28篇
  1996年   36篇
  1995年   48篇
  1994年   19篇
  1993年   24篇
  1992年   38篇
  1991年   44篇
  1990年   40篇
  1989年   42篇
  1988年   31篇
  1987年   28篇
  1986年   24篇
  1985年   14篇
  1984年   14篇
  1983年   16篇
  1981年   7篇
  1980年   11篇
  1979年   14篇
  1978年   8篇
  1975年   9篇
  1973年   11篇
  1972年   12篇
  1969年   8篇
  1966年   8篇
排序方式: 共有3599条查询结果,搜索用时 15 毫秒
81.
Annals of Nuclear Medicine - The novel radiotracer, 4′-[methyl-11C]-thiothymidine (11C-4DST), was developed based on the DNA incorporation method as a cell proliferation marker. This study...  相似文献   
82.
Clinical and Experimental Nephrology - The number of patients aged ≥ 75 years and who need renal replacement therapy is steadily increasing. The study aimed to determine...  相似文献   
83.
84.
Dendritic cells (DCs) polarize naive CD4(+) T cells to either T helper 1 (Th1) or Th2 cells. We examined the role of glycogen synthase kinase 3 (GSK3) activity during DC development from murine bone marrow (BM) cells. DCs were generated by culturing lineage-marker-negative BM cells with granulocyte-macrophage colony-stimulating factor in the presence or absence of a specific inhibitor of GSK3 (Gi), SB415286, for 6 days. DCs generated in the presence (GiDC) or absence (control DC) of SB415286 similarly exhibited a conventional DC phenotype (CD11b(+) B220(-) CD8(-)). These DCs were mixed with allogeneic CD4(+) T cells and the ability to polarize Th1 or Th2 cells was evaluated. The GiDCs exhibited markedly impaired function to induce Th2 polarization compared to control DCs. In contrast, the ability of GiDCs to generate Th1 cells was slightly higher than that of control DCs. CD86 expression and CD40-mediated interleukin-6 production were completely diminished in GiDCs, which might be associated with the impaired ability of the GiDCs to induce Th2 differentiation. These results suggest that the GSK3 activity during DC development is essential for the establishment of the DC function to induce Th2, but not Th1, differentiation.  相似文献   
85.
86.
87.
The purpose of this study was to evaluate the clinical and radiographic treatment effects of percutaneous autologous concentrated bone marrow grafting in nonunion cases and to evaluate the effectiveness of this grafting procedure. We enrolled 17 cases those had atrophic changes due to continuous nonunion for over 9 months after injury and had undergone low-intensity pulsed ultrasound treatment for more than 3 months. The site of nonunion was the femur in 10 cases, the tibia in 5 cases, the humerus in 1 case, and the ulna in 1 case. They underwent percutaneous autologous concentrated bone marrow grafting and continued low-intensity pulsed ultrasound stimulation treatment after grafting. Patients were evaluated using the visual analogue scale for pain at immediately before the procedure, 3, 6, and 12 months after grafting. Plain radiographs of the affected site were taken and evaluated about the healing of the nonunion site at each clinical evaluation. As quantitative assessment, CT scans were undertaken before the procedure and 6 months after grafting. The visual analogue scale pain score was reduced consistently after grafting in all patients. About the healing at the nonunion site, 11 and 13 cases of bone union were observed at 6 and 12 months after grafting. The mean volume of callus formation based on CT images was 4,147 (262–27,392) mm3 total between grafting and 6 months. Percutaneous autologous concentrated bone marrow grafting is an effective procedure for the treatment of patients with nonunion.  相似文献   
88.
Polystyrenic microspheres in the sub 5 micrometer size range (micro-gel) with –CH2Cl active sites were synthesized via the dispersion polymerization of 4-chloromethylstyrene, divinyl benzene and methoxy polyethylene glycol acrylate. Then, theophylline residues were introduced onto the polystyrenic microspheres via the substitution of the chloride in the –CH2Cl group to prepare chelate type microspheres of μ-T2. It was found that the microspheres have co-continuous structures, monodispersed particle sizes, and excellent solvent and water wettability. Using the μ-T2 microspheres possessing theophylline residues, adsorption experiments involving the adsorption of palladium(ii), copper(ii) and platinum(iv) from acidic chloride media under both individual and mixed conditions were carried out and it was found that the μ-T2 microspheres exhibited excellent adsorption selectivity for palladium(ii) over copper(ii) and platinum(iv). It was also revealed that thiourea or ammonia solutions are the most effective in desorbing palladium ions from the microspheres. Despite being used in four adsorption–desorption cycles, the μ-T2 microspheres were still able to strongly adsorb palladium ions, with an adsorption of over 85%. In addition, the μ-T2 microspheres also showed palladium capturing ability even in very dilute palladium solutions (below 1.0 ppm). Interestingly, the μ-T2 microsphere-adsorbed palladium ions exhibited excellent catalytic activity in the Suzuki–Miyaura coupling reaction of bromobenzene and phenylboronic acid, yielding biphenyl in 100% under the conditions within 1 hour at 50 °C in water.

Sub 5 micrometer sized polystyrenic microspheres bearing theophylline residues were synthesized and used as adsorbent and catalytic support for palladium ions.  相似文献   
89.
90.
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