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   773157篇
  免费   44892篇
  国内免费   1593篇
耳鼻咽喉   9433篇
儿科学   23253篇
妇产科学   17018篇
基础医学   124278篇
口腔科学   16816篇
临床医学   73062篇
内科学   146805篇
皮肤病学   15175篇
神经病学   57513篇
特种医学   27807篇
外国民族医学   64篇
外科学   115125篇
综合类   10972篇
现状与发展   2篇
一般理论   418篇
预防医学   59378篇
眼科学   18251篇
药学   57821篇
  7篇
中国医学   1456篇
肿瘤学   44988篇
  2021年   9076篇
  2020年   5473篇
  2019年   8982篇
  2018年   11446篇
  2017年   8422篇
  2016年   9659篇
  2015年   10977篇
  2014年   15405篇
  2013年   21890篇
  2012年   32888篇
  2011年   35580篇
  2010年   20190篇
  2009年   17961篇
  2008年   31748篇
  2007年   34287篇
  2006年   33644篇
  2005年   32932篇
  2004年   31512篇
  2003年   29765篇
  2002年   28340篇
  2001年   24453篇
  2000年   24520篇
  1999年   21152篇
  1998年   8195篇
  1997年   6861篇
  1996年   6503篇
  1995年   6166篇
  1994年   5373篇
  1992年   15631篇
  1991年   16918篇
  1990年   16918篇
  1989年   16572篇
  1988年   15230篇
  1987年   15118篇
  1986年   14079篇
  1985年   13628篇
  1984年   10579篇
  1983年   9085篇
  1982年   5500篇
  1979年   9616篇
  1978年   7113篇
  1977年   5769篇
  1976年   6075篇
  1975年   7067篇
  1974年   7877篇
  1973年   7545篇
  1972年   6934篇
  1971年   6573篇
  1970年   6125篇
  1969年   5638篇
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
31.
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   
32.
Molecular characterization of Wuchereria bancrofti is essential to develop suitable anti-filarial drugs and vaccines. We describe here isolation, sequence analysis and cloning of a partial cDNA of an enzyme superoxide dismutase from this parasite. The immunoscreening of a lambda zap W. bancrofti microfilarial (Mf) cDNA library with microfilaremic sera had resulted in the isolation of several seroreactive clones including, WbSOD. This clone contained a 309 bp insert and showed significant nucleotide and deduced amino acid sequence homologies to the superoxide dismutases of other nematode parasites. The antioxidant property of this enzyme may have important contribution in the defense mechanism of the parasite against host immune response.  相似文献   
33.
34.
35.
The reliable change index (RCI) expresses change relative to its associated error, and is useful in the identification of post-operative cognitive dysfunction (POCD). This paper examines four common RCIs that each account for error in different ways. Three rules incorporate a constant correction for practice effects and are contrasted with the standard RCI that had no correction for practice. These rules are applied to 160 patients undergoing coronary artery bypass graft (CABG) surgery who completed neuropsychological assessments preoperatively and 1 week post-operatively using error and reliability data from a comparable healthy non-surgical control group. The rules all identify POCD in a similar proportion of patients, but the use of the within subject standard deviation, expressing the effects of random error, as an error estimate is a theoretically appropriate denominator when a constant error correction, removing the effects of systematic error, is deducted from the numerator in a RCI.  相似文献   
36.
OBJECTIVE: This study was conducted to compare an otolaryngologist's experience with a cohort of epilepsy patients implanted with a vagal nerve stimulator (VNS) to previously published data. METHODS: Demographics, preoperative seizure frequency, medications, and complications were retrospectively collected from patients implanted by the senior author. Postoperative medications and seizure frequency were obtained from referring neurologists. RESULTS: Seventeen patients were implanted over a 24-month period. Average age was 28.3 years. Patients presented with petit mal (n = 3), tonic-clonic (n = 6), complex partial (n = 5), and grand mal (n = 8) seizures. Mean follow-up postimplantation was 13.5 months. Most patients had at least a 50% reduction of seizure frequency, with 3 patients being seizure free. There were no postoperative infections. One patient had left vocal cord immobility. The most common side effect was voice disturbance during device activation. CONCLUSION: Otolaryngologists are well equipped to perform VNS implantation and to diagnose and treat possible laryngeal side effects. EBM rating: C-4.  相似文献   
37.
Relationship-centered care reflects both knowing and feeling: the knowledge that physician and patient bring from their respective domains of expertise, and the physician’s and patient’s experience, expression, and perception of emotions during the medical encounter. These processes are conveyed and reciprocated in the care process through verbal and nonverbal communication. We suggest that the emotional context of care is especially related to nonverbal communication and that emotion-related communication skills, including sending and receiving nonverbal messages and emotional self-awareness, are critical elements of high-quality care. Although nonverbal behavior has received far less study than other care processes, the current review argues that it holds significance for the therapeutic relationship and influences important outcomes including satisfaction, adherence, and clinical outcomes of care.  相似文献   
38.
39.
Conclusions Limitation of this analysis is participation of limited centers. Though all the regions of the country are represented total number of procedures reported are less. Isolated CABG is commonest procedure performed in 2004. Congenital surgical procedures are more than the valvular heart disease procedure. For appropriate categorization we need standard nomenclature for various congenital surgical procedures.  相似文献   
40.
V Frecer  S Miertus 《Neoplasma》1988,35(5):525-538
A mechanistic QSAR study on N-nitrosamines (NA) was performed with the aid of the semiempirical MINDO/3 method. Both the chemical reactivity and the transport in biological medium were taken into account. The parent NA molecules and their first reaction intermediates in the metabolic activation pathway were examined for possible determinants of the relative carcinogenic potency. The correlations found support the previous suggestions concerning the metabolic C alpha radical hydroxylation of NA. The role of transport properties in the early stage of NA biotransformation was also demonstrated.  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