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   1516篇
  免费   124篇
  国内免费   28篇
耳鼻咽喉   17篇
儿科学   47篇
妇产科学   36篇
基础医学   209篇
口腔科学   24篇
临床医学   149篇
内科学   335篇
皮肤病学   19篇
神经病学   54篇
特种医学   94篇
外科学   207篇
综合类   37篇
一般理论   1篇
预防医学   47篇
眼科学   43篇
药学   101篇
中国医学   6篇
肿瘤学   242篇
  2023年   6篇
  2022年   13篇
  2021年   31篇
  2020年   17篇
  2019年   27篇
  2018年   47篇
  2017年   28篇
  2016年   32篇
  2015年   36篇
  2014年   43篇
  2013年   70篇
  2012年   87篇
  2011年   76篇
  2010年   56篇
  2009年   41篇
  2008年   68篇
  2007年   93篇
  2006年   76篇
  2005年   65篇
  2004年   68篇
  2003年   53篇
  2002年   61篇
  2001年   50篇
  2000年   49篇
  1999年   42篇
  1998年   37篇
  1997年   25篇
  1996年   20篇
  1995年   22篇
  1994年   20篇
  1993年   19篇
  1992年   35篇
  1991年   31篇
  1990年   29篇
  1989年   23篇
  1988年   24篇
  1987年   22篇
  1986年   15篇
  1985年   18篇
  1984年   16篇
  1983年   8篇
  1982年   19篇
  1981年   10篇
  1980年   9篇
  1979年   3篇
  1978年   6篇
  1977年   5篇
  1976年   3篇
  1972年   5篇
  1970年   3篇
排序方式: 共有1668条查询结果,搜索用时 21 毫秒
51.
We investigated 10 unrelated Chinese patients with type 2 Gaucher disease and performed ex vivo expression for the novel mutations to characterize their functional defects. These patients were diagnosed by enzymatic assays and clinicopathologic features over the past five years in a national centre in China. Genomic DNA was sequenced by a two-stage PCR approach for mutations in the functional GBA gene. Novel mutations were expressed with baculovirus-transfected Sf21 cells. Six novel mutations were found (in traditional nomenclature): P122L, Y363C, N382K, L383R, L385P, and M416V. Review of reported mutations indicated clustering of type 2 mutations in three regions of the GBA gene. Expression of novel mutations revealed that the enzyme defect could arise from one of two mechanisms: loss of catalytic activity (Y363C and M416V) or enzyme instability (P122L and N382K).  相似文献   
52.
Layered double hydroxide as an efficient drug reservoir for folate derivatives   总被引:11,自引:0,他引:11  
Choy JH  Jung JS  Oh JM  Park M  Jeong J  Kang YK  Han OJ 《Biomaterials》2004,25(15):3059-3064
Folic acid derivatives such as folinic acid and methotrexate (MTX) have been successfully hybridized with layered double hydroxide (LDH) by ion-exchange reaction. The X-ray diffraction patterns and spectroscopic analyses indicate that these molecules intercalated into the hydroxide interlayer space are stabilized in the tilted longitudinal monolayer mode by electrostatic interaction. No significant changes in their structural and functional properties are found in the hybrids. The cellular uptake test of MTX-LDH hybrid is carried out in the fibroblast (human tendon) and SaOS-2 cell line (Osteosarcoma, human) by in vitro MTT (3-(4,5-dimethylthiazol-2-yl) 2,5-diphenyl tetrazolium bromide) assay. The initial proliferation of SaOS-2 cell is more strongly suppressed by treatment with MTX-LDH hybrid than with MTX alone. This study clearly shows that LDH not only plays a role as a biocompatible-delivery matrix for drugs but also facilitates a significant increase in the delivery efficiency.  相似文献   
53.
Coxsackievirus B3 (CVB3) infection can result in myocarditis, which in turn may lead to a protracted immune response and subsequent dilated cardiomyopathy. Human decay-accelerating factor (DAF), a binding receptor for CVB3, was synthesized as a soluble IgG1-Fc fusion protein (DAF-Fc). In vitro, DAF-Fc was able to inhibit complement activity and block infection by CVB3, although blockade of infection varied widely among strains of CVB3. To determine the effects of DAF-Fc in vivo, 40 adolescent A/J mice were infected with a myopathic strain of CVB3 and given DAF-Fc treatment 3 days before infection, during infection, or 3 days after infection; the mice were compared with virus alone and sham-infected animals. Sections of heart, spleen, kidney, pancreas, and liver were stained with hematoxylin and eosin and submitted to in situ hybridization for both positive-strand and negative-strand viral RNA to determine the extent of myocarditis and viral infection, respectively. Salient histopathologic features, including myocardial lesion area, cell death, calcification and inflammatory cell infiltration, pancreatitis, and hepatitis were scored without knowledge of the experimental groups. DAF-Fc treatment of mice either preceding or concurrent with CVB3 infection resulted in a significant decrease in myocardial lesion area and cell death and a reduction in the presence of viral RNA. All DAF-Fc treatment groups had reduced infectious CVB3 recoverable from the heart after infection. DAF-Fc may be a novel therapeutic agent for active myocarditis and acute dilated cardiomyopathy if given early in the infectious period, although more studies are needed to determine its mechanism and efficacy.  相似文献   
54.
Background In experienced hands, laparoscopic inguinal hernia repair has a low rate of recurrence, but it still can recur, and a number of reasons for this have been identified. In published studies, the majority of such cases seem to result from inadequate dissection leading to missed hernias or suboptimal mesh placement. But even with adequate dissection and proper placement of a sufficiently large mesh, recurrence sometimes happens. A number of investigators have cited mesh migration or dislocation as a possible cause, and this study examined how hip flexion affects the position of newly placed meshes and staples in totally extraperitoneal (TEP) repair of inguinal hernia.Methods After completion of the dissection and reduction of discovered hernias, a 15 × 15-cm polypropylene mesh was placed either unilaterally or bilaterally, as indicated. The preperitoneal space then was desufflated. The operating table, in an extended –20° position during surgery, was placed in a 90° position for approximately 15 s. After reinsufflation, the possibility of mesh migration and folding was investigated. Finally, the mesh was stapled, the table again extended and flexed, and the possibility of mesh migration and staple dislodgement investigated once more.Results The mesh did not migrate or become displaced from any potential hernia area, nor did any of the staples become dislodged.Conclusions Concern about mesh migration attributable to patients sitting up immediately after surgery appears to be unfounded, at least according to the findings for the current, small, simulated study group.  相似文献   
55.
Grüntzig balloon catheters were used to dilate ten esophageal strictures in eight infants and children. Five infants who had anastomotic strictures following esophageal atresia repair gained complete resolution of their strictures, usually after one or two dilatations. Three older children who had strictures following esophageal re-operation or reconstruction required longer courses of dilatations to achieve consistent esophageal patency. The technique failed in two chronic strictures of two and one-half and nine years' duration. Balloon catheter dilatation, begun in the early postoperative period, is a safe, effective method for dilating esophageal strictures.  相似文献   
56.
Chordomas are rare bone tumors and treatment is commonly based on a combination of surgery and radiotherapy. There is no standard chemotherapy treatment for chordoma. The aim of this study was to determine the expression of cyclin‐dependent kinase 4 (CDK4) in chordoma and its therapeutic implications. We evaluated CDK4 expression both in chordoma cell lines and in chordoma tissues. Also, we investigated the functional roles of CDK4 in chordoma cell growth and proliferation. Furthermore, the therapeutic implications of targeting CDK4 in chordoma were evaluated. We found CDK4 highly expressed in chordoma cell lines and in a majority (97.7%) of chordoma tissues. Higher CDK4 expression correlated with metastasis and recurrence of chordoma. Treatment of chordoma cells using CDK4 inhibitor palbociclib could efficiently inhibit chordoma cells growth and proliferation. These data demonstrate that targeting CDK4 may be useful as a novel strategy in the treatment of chordoma. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1581–1589, 2018.
  相似文献   
57.
Hare  WS 《Radiology》1986,160(1):189-192
Two modified helical basket extractors are described that have increased the success rate of removing ureteral calculi using fluoroscopy from 63% to 92%. Initially a rather stiff and expandable basket with a 20-cm filiform tip is used with coaxial catheters and sheath (stage 1). If this procedure is unsuccessful, a basket with two long cable ends is passed from the nephrostomy out through the urethra (stage 2). When used with coaxial bladder catheters, this technique allows dilatation of the vesicoureteric junction and retrograde catheterization and injection of fluids or gas to dislodge the stone prior to extraction. In a series of 38 patients, stones were removed in all but three (a success rate of 92%). In five cases small stones (less than 5 mm) were not retrieved but subsequent studies were normal. Ureteral stones were found in the abdominal ureter in 28 cases, in the pelvic ureter in seven cases, and in multiple sites in three cases. Stones were larger than 1 cm in 27.7% of cases. Postextraction mucosal edema with reduced ureteral patency was common but usually cleared in 2-3 days. Occasional complications were related to the nephrostomy.  相似文献   
58.
Five patients undergoing distal saphenous vein bypass had an attempt at intraoperative laser vaporization of a proximal coronary stenosis. Laser treatment of three patients was technically successful. One patient's successfully treated native vessel was competing with the graft at angiographic restudy 25 days after the procedure. This first human intraoperative laser recanalization trial generated questions regarding the energy source, power parameters, and catheter modifications required for satisfactory clinical laser therapy. The trial is directing future experiments toward more efficient and complete laser vaporization of atherosclerotic plaques in the human coronary vasculature.  相似文献   
59.
Objective: The current study aims to examine the factorial structure and psychometric properties of a brief version of the Reminiscence Functions Scale (RFS), a 14-item assessment tool of reminiscence functions, with Chinese older adults.Method: The scale, covering four reminiscence functions (boredom reduction, bitterness revival, problem solving, and identity) was translated from English into Chinese and administered to older adults (N = 675). Confirmatory factor analysis and hierarchical confirmatory factor analysis were conducted to examine its factorial structure, and its psychometric properties and criterion validity were examined.Results: Confirmatory factor analysis supports a second-order model comprising one second-order factor and four first-order factors of RFS. The Cronbach's alpha of the subscales ranged from 0.75 to 0.90.Conclusion: The brief RFS contains a second-order factorial structure. Its psychometric properties support it as a sound instrument for measuring reminiscence functions among Chinese older adults.  相似文献   
60.
Previous studies have shown that murine anti-CD4 monoclonal antibody, cross-linked by rabbit anti-mouse immunoglobulin, could mediate apoptosis of murine CD4+ lymphocytes when they were stimulated by T cell receptor antibody. In this study, we have shown that the murine anti-CD4 monoclonal antibody, OKT4, can induce apoptosis in human CD4+ T cells stimulated by the recall antigen tuberculin purified protein derivative (PPD) only when cross-linked by rabbit anti-mouse immunoglobulin. The chimeric anti-CD4 monoclonal antibody, cM-T412 whose Fc fragment is human, was able to cause apoptosis without cross-linking by a second antibody. Similarly, abolition of PPD-induced proliferation of peripheral blood mononuclear cells by cM-T412 did not require cross-linking with rabbit anti-human immunoglobulin. Inhibition of proliferation by cM-T412 could be reduced by pre-treating monocytes with heat-aggregated human IgG. This suggested that monocyte Fcγ receptors might be cross-linking the human Fc of cM-T412. Propidium iodide staining together with immunofluorescence showed that the apoptotic cells were indeed CD4+ lymphocytes. It is proposed that during treatment with cM-T412 in autoimmune disease such as rheumatoid arthritis, cM-T412-coated CD4 T cells, when they are subsequently stimulated by the unknown arthritogenic antigen, may undergo apoptotic cell death through cross-linking of cM-T412 on Fey receptor-positive cells within the joint.  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