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   5938篇
  免费   525篇
  国内免费   259篇
耳鼻咽喉   46篇
儿科学   137篇
妇产科学   78篇
基础医学   680篇
口腔科学   186篇
临床医学   602篇
内科学   1140篇
皮肤病学   67篇
神经病学   283篇
特种医学   387篇
外国民族医学   1篇
外科学   782篇
综合类   533篇
现状与发展   2篇
预防医学   540篇
眼科学   71篇
药学   519篇
  2篇
中国医学   203篇
肿瘤学   463篇
  2023年   58篇
  2022年   142篇
  2021年   175篇
  2020年   142篇
  2019年   136篇
  2018年   161篇
  2017年   153篇
  2016年   174篇
  2015年   189篇
  2014年   279篇
  2013年   299篇
  2012年   438篇
  2011年   462篇
  2010年   286篇
  2009年   253篇
  2008年   344篇
  2007年   367篇
  2006年   294篇
  2005年   300篇
  2004年   222篇
  2003年   214篇
  2002年   195篇
  2001年   111篇
  2000年   104篇
  1999年   96篇
  1998年   73篇
  1997年   53篇
  1996年   49篇
  1995年   44篇
  1994年   53篇
  1993年   44篇
  1992年   59篇
  1991年   50篇
  1990年   44篇
  1989年   59篇
  1988年   60篇
  1987年   68篇
  1986年   60篇
  1985年   55篇
  1984年   39篇
  1983年   35篇
  1982年   24篇
  1981年   24篇
  1980年   18篇
  1979年   31篇
  1978年   24篇
  1977年   17篇
  1975年   17篇
  1974年   19篇
  1970年   13篇
排序方式: 共有6722条查询结果,搜索用时 15 毫秒
41.
PurposeTissue engineering of esophagus is required for management of long-gap esophageal atresia (LGEA). Collagenous connective tissue membranes fabricated by in-body tissue architecture (iBTA), called biosheets, can repair esophageal defects and generate tissues similar to native esophagus. However, iBTA requires second-stage surgery because of heterotopic preparation of biosheets. Our aim was to develop orthotopic iBTA for primary engineering of the esophagus by interposing a tubular mold to the esophageal defect.MethodThe cervical esophagus of six rats was transected. An acrylic tube (internal diameter 2.6 mm, length 7.0 mm) was inserted and fixed between the ends of the upper and lower esophagus, and a 3 mm-long esophageal defect was created. Four weeks later, the rats were sacrificed for histological analysis.ResultsPostoperatively the rats could intake liquid food. After four weeks, the esophageal defects were filled with regenerated tissues. Histologically the new esophageal walls stained positive for collagen type I. The inner surfaces were covered with stratified squamous epithelium that expressed pan-cytokeratin. In only one of six rats, regeneration of muscular-like tissue was suggested by positive immunohistochemical staining for desmin.ConclusionOrthotopic iBTA can regenerate a substitute esophagus with esophageal epithelium and collagenous wall. This technique may be a novel treatment for esophageal atresia with gaps of various lengths including LGEA.  相似文献   
42.
43.
目的:探讨大五人格因素与企业职工工作倦怠的关系。方法:采用工作倦怠问卷(MBI-GS)与大五人格问卷调查了506名某企业职工。结果:分层回归分析的结果显示,在控制了人口统计学变量之后,大五人格因素所解释的工作倦怠的方差变异量,在情绪衰竭、玩世不恭和职业效能三个维度分别为28%、24%和17%。具体而言,宜人性是情绪衰竭、玩世不恭和职业效能的有效预测因子;责任感是玩世不恭和职业效能的有效预测因子;情绪稳定性是情绪衰竭和玩世不恭的有效预测因子;而外向性和开放性两个维度对工作倦怠的预测作用均未达到显著水平。结论:大五人格因素能够有效预测企业职工的工作倦怠。  相似文献   
44.
组织干预对西藏高原护士工作倦怠的影响   总被引:3,自引:0,他引:3  
目的:分析组织公平对护士工作倦怠的影响,并在此基础上制定和实施组织干预措施,为预防和矫治西藏高原地区护士工作倦怠提供理论依据和实践指导。方法:对某军区下属的三所总医院的临床女性护士(均为非管理人员)309例采用马氏倦怠感通用量表和组织公平量表进行调查.以获得工作倦怠与组织公平的相互关系。对西藏军区总医院的临床女性护士(均为非管理人员)108例(含干预组54例、对照组54例)在实施组织干预措施半年后采用马氏倦怠感通用量表和组织公平量表进行调查,以检测组织干预措施对提高组织公平感和改善工作倦怠感的实效性。结果:分配公平会影响护士的情绪衰竭和玩世不恭,程序公平会影响成就感降低。组织干预措施可以提高护十的组织公平感和降低工作倦怠感.结论:通过实施组织干预措施可以预防和降低护士的工作倦怠感。  相似文献   
45.
目的:探讨程序公平对工作满意度、组织承诺的影响以及工作不安全感在其中的中介作用。方法:对来自国内某大型国营企业592名员工的关于程序公平、工作满意度、组织承诺和工作不安全感的问卷调查数据进行中介回归分析(Mediatingregressionanalysis)。结果:①程序公平和员工的工作满意度、组织承诺存在显著的正向关系,而和其工作不安全感之间存在显著的负向关系;②工作不安全感部分中介程序公平对整体工作满意度和组织承诺的影响。结论:通过改善程序公平,可以减少员工的工作不安全感,并进而增强其工作满意度和组织承诺。  相似文献   
46.
Nutrient-induced thermogenesis (NIT) induced by parenteral infusion of amino acid (AA) mixtures of different composition and of the same AA mixtures given via different routes (parenteral or intraportal infusion) were investigated in rats using a small animal indirect calorimeter. When 8 different AA solutions of differing composition but with the same total concentration were infused parenterally, both standard NIT (each AA is assumed to generate 3.28 kcal/g) and specific NIT (heat energy of each AA is calculated assuming that it is oxidized to carbon dioxide and water, and metabolised to urea and sulphuric acid) values of the leucine (Leu)-rich and the glycine (Gly)-rich solutions were significantly greater than those of the control solution. Removal of Leu or Gly from the respective AA solutions reversed the increase of both NIT values down to control levels. When the parenteral and portal infusion routes were used in one rat, both NIT values for parenteral infusion of the Leu-rich solution were again significantly greater than those of the control. Likewise, both NIT values for intrportal infusion of the Leu-rich solution were also significantly greater than those of the control. However, no difference in NIT values was found between parenteral and portal infusion of either solution. The result of this study indicated that Leu and Gly may be thermogenic AAs, and the thermogenic effect of Leu is not dependent upon the route of infusion.  相似文献   
47.
中药有效成分研究与复方新药开发   总被引:2,自引:0,他引:2  
100000首方剂是开发中药复方新药的宝库。12772种中药及其复方中的有效成分是开发中药复方新药的基础。逆向思维、利用文献、研究有效成分动态变化和综合作用是开发中药复方新药的几种途径  相似文献   
48.
49.
Replacement of the mitral valve in the presence of extensive calcification of the posterior annulus is a technical challenge. The heavily calcified annulus often results in difficulties of seating the prosthesis and later periprosthetic leakage. A radical calcium debridement may leave a friable and thin annulus that contributes to the risks of prosthesis dehiscence and ventricular perforation. To avoid technical difficulties and associated catastrophic complications, we devised a new technique of mitral valve replacement that allows a surgeon to implant a prosthesis securely. This technique involves inserting a larger single tilting disc mechanical valve (Medtronic Hall disc) with intra-atrial anchorage over the posterior sector of the calcified annulus, orienting the working (major) orifice of the mechanical valve anteriorly, and thereby tilting the lesser occluder segment of the disc upward into the atrium and away from the calcification in diastole. By utilizing this method, we have successfully performed mitral valve replacement in two patients who exhibited massive calcification of the posterior mitral annulus. Postoperative transeosophageal echocardiography showed excellent hemodynamic performance of the implanted valves. We therefore recommend this simple, safe, and time-saving procedure as a feasible method to deal with this surgical dilemma.  相似文献   
50.
To evaluate the effect of interferon-γ-genetransduced cells, DS mice were inoculated into their footpads with syngeneic mammary adenocarcinoma SC42 admixed with interferon-γ producing mammary adenocarcinoma SC115Kγ, which had been established by an interferon-γ-gene transduction in another syngeneic mammary adenocarcinoma SC115 using retroviral vectors. These mice rejected both tumor cells and developed resistance to subsequent challenges with either SC115 or SC42 cells inoculated into their opposite posterior footpads. These results thus indicate that systemic immunological memory to each of the independent tumor cell lines developed in these mice. Although the SC42 cells admixed with irradiated SC115Kγ cells were rejected by these mice, the SC42 cells admixed with irradiated SC115neoR, in which the neo-gene had been transduced, were observed to proliferate. Tumor rejection was reversed by an in vivo administration of anti-interferon-γ antibody, thus suggesting that locally produced interferon-γ plays an important role in tumor elimination and immunological memory induction. In conclusion, interferon-γ-gene-transduced tumor cells are therefore considered to have a therapeutic potential for other types of malignant tumor cell lines.  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