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   3226618篇
  免费   261976篇
  国内免费   6647篇
耳鼻咽喉   45959篇
儿科学   102114篇
妇产科学   89149篇
基础医学   452667篇
口腔科学   92445篇
临床医学   295412篇
内科学   631566篇
皮肤病学   69020篇
神经病学   271743篇
特种医学   126908篇
外国民族医学   1186篇
外科学   484688篇
综合类   78353篇
现状与发展   4篇
一般理论   1331篇
预防医学   262395篇
眼科学   76481篇
药学   236420篇
  5篇
中国医学   6552篇
肿瘤学   170843篇
  2018年   34557篇
  2017年   26519篇
  2016年   29459篇
  2015年   33289篇
  2014年   47938篇
  2013年   72586篇
  2012年   97921篇
  2011年   103511篇
  2010年   61065篇
  2009年   58440篇
  2008年   97278篇
  2007年   103257篇
  2006年   104286篇
  2005年   101467篇
  2004年   97340篇
  2003年   93646篇
  2002年   91635篇
  2001年   150830篇
  2000年   155548篇
  1999年   130988篇
  1998年   38390篇
  1997年   34786篇
  1996年   34448篇
  1995年   33030篇
  1994年   30724篇
  1993年   28791篇
  1992年   103535篇
  1991年   99536篇
  1990年   95864篇
  1989年   92159篇
  1988年   85472篇
  1987年   84071篇
  1986年   79249篇
  1985年   75721篇
  1984年   57797篇
  1983年   49246篇
  1982年   30168篇
  1981年   26834篇
  1979年   53484篇
  1978年   37747篇
  1977年   31653篇
  1976年   29755篇
  1975年   31001篇
  1974年   38124篇
  1973年   36431篇
  1972年   34180篇
  1971年   31435篇
  1970年   29733篇
  1969年   27663篇
  1968年   25613篇
排序方式: 共有10000条查询结果,搜索用时 125 毫秒
941.
Liposarcomas are extremely rare in the mediastinum. They may achieve considerable size before causing any symptoms. Mediastinal liposarcomas may invade surrounding structures like the pericardium or the superior vena cava. Complete surgical excision is the optimal treatment in resectable cases. Excision of adjacent structures like the pericardium may be needed if the tumor infiltrates them. We report on a case of a giant liposarcoma of the mediastinum involving both hemithoraces and extending into the neck, which was successfully managed by complete surgical excision.  相似文献   
942.
943.
At the time of hire, 4059 of 6522 healthcare workers required a 2-step tuberculin skin test; 114 workers (2.8%) demonstrated a boosted reaction after the second step. Boosted reactions were significantly associated with male sex and older age. A verbal history of previous tuberculin skin test results was not a reliable indicator of baseline tuberculin skin test status at the time of hire.  相似文献   
944.
945.
946.
INTRODUCTION: There are no measures of health-related absenteeism and presenteeism validated for use in the large and increasing US Spanish-speaking population. Before using a Spanish translation of an available English-language questionnaire, the linguistic validity of the Spanish version must be established to ensure its conceptual equivalence to the original and its cultural appropriateness. OBJECTIVE: The objective of this study was to evaluate the linguistic validity of the US Spanish version of the Work Productivity and Activity Impairment questionnaire, General Health Version (WPAI:GH). METHODS: A US Spanish translation of the US English WPAI:GH was created through a reiterative process of creating harmonized forward and back translations by independent translators. Spanish-speaking and English-speaking subjects residing in the US self-administered the WPAI:GH in their primary language and were subsequently debriefed by a bilingual (Spanish-English) interviewer. RESULTS: US Spanish subjects (N = 31) and English subjects (N = 35), stratified equally by educational level, with and without a high school degree participated in the study. The WPAI-GH item comprehension rate was 98.6% for Spanish and 99.6% for English. Response revision rates during debriefing were 1.6% for Spanish and 0.5% for English. Responses to hypothetical scenarios indicated that both language versions adequately differentiate sick time taken for health and non-health reasons and between absenteeism and presenteeism. CONCLUSION: Linguistic validity of the US Spanish translation of the WPAI:GH was established among a diverse US Spanish-speaking population, including those with minimal education.  相似文献   
947.
To investigate the phenotypic consequences of a deranged lymphangiogenesis in relation to tissue fluid accumulation and the possible role of inflammation in the pathogenesis of lymphoedema, we measured determinants of transcapillary fluid filtration and inflammatory mediators in the interstitial fluid in genetically engineered Chy mice, a model for primary congenital lymphoedema (Milroy's disease). Although initial lymphatics were not present in dermis in any of the areas studied (fore paw, hind paw, thigh and back skin) interstitial fluid pressure ( P if), measured with micropipettes, and tissue fluid volumes were significantly increased only in the areas with visible swelling – the fore and hind paw, whereas interstitial colloid osmotic pressure (COPif) was increased in all the skin areas examined. A volume load of 15% of body weight resulted in a more pronounced increase in P if as well as a four-fold increase in interstitial fluid volume in Chy relative to wild-type (wt) mice, showing the quantitative importance of lymphatics for fluid homeostasis during acute perturbations. A similar level of proinflammatory markers in interstitial fluid in early established lymphoedema (3–4 months) in Chy and wt suggests that inflammation does not have a major pathogenetic role for the development of lymphoedema, whereas a reduced level of the immunomodulatory cytokine interleukin (IL)-4 may result in a reduced immunological defence ability and thus lead to the increase in inflammatory cytokines IL-2 and IL-6 observed at a later stage (11–13 months). Our data suggest that primary lymphoedema results in a high interstitial fluid protein concentration that does not induce an interstitial inflammatory reaction per se , and furthermore shows the paramount importance of the initial lymphatics in tissue fluid homeostasis, especially during perturbations of transcapillary fluid balance.  相似文献   
948.
BACKGROUND: An augmented reality tool for computer assisted surgery named X-Scope allows visual tracking of real anatomical structures in superposition with volume rendered CT or MRI scans and thus can be used for navigated translocation of bony segments. METHODS: In a feasibility study X-Scope was used in orthognathic surgery to control the translocation of the maxilla after Le Fort I osteotomy within a bimaxillary procedure. The situation achieved was compared with the pre-operative situation by means of cephalometric analysis on lateral and frontal cephalograms. RESULTS: The technique was successfully utilized in 5 patients. Maxillary positioning using X-Scope was accomplished accurately within a range of 1mm. The tool was used in all cases in addition to the usual intra-operative splints. A stand-alone application without conventional control does not yet seem reasonable. CONCLUSION: Augmented reality tools like X-Scope may be helpful for controlling maxillary translocation in orthognathic surgery. The application to other interventions in cranio-maxillofacial surgery such as Le Fort III osteotomy, fronto-orbital advancement, and cranial vault reshaping or repair may also be considered.  相似文献   
949.
950.
High levels of tumor necrosis factor-alpha (TNF-alpha), a pro-inflammatory cytokine, are present in the wound fluid of chronic nonhealing wounds. This leads to increased inflammation, cytokine expression, and ultimately results in impaired wound healing and tissue destruction. Etanercept is a recombinant fusion protein that consists of the soluble TNF receptor (p75) linked to the Fc portion of human IgG1. It is an effective inhibitor of TNF-alpha and has been shown to provide rapid and sustained improvement in rheumatoid arthritis by acting as a soluble receptor binding TNF-alpha and preventing its proinflammatory activities. Therefore, the aim of this study was to determine whether Etanercept could inhibit TNF-alpha activity in chronic wound fluid. Wound fluid was collected from the venous leg ulcers of 16 different patients. The effect of Etanercept on TNF-alpha activity was evaluated using both a TNF-alpha bioassay and an enzyme-linked immunoassay. Etanercept was found to reduce the cytotoxic effect of chronic wound fluid on L929 fibroblasts by approximately 30% and neutralized TNF-alpha binding in the enzyme-linked immunoassay by up to 80%. Direct application of Etanercept to chronic wounds may therefore reduce the inflammatory activity of TNF-alpha, which could reduce the chronicity of venous leg ulcers and thus aid in the healing of these wounds.  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