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   1700170篇
  免费   133537篇
  国内免费   29698篇
耳鼻咽喉   19723篇
儿科学   48449篇
妇产科学   40589篇
基础医学   237175篇
口腔科学   41861篇
临床医学   181123篇
内科学   306461篇
皮肤病学   30411篇
神经病学   129448篇
特种医学   61831篇
外国民族医学   590篇
外科学   216599篇
综合类   97668篇
现状与发展   86篇
一般理论   489篇
预防医学   141273篇
眼科学   39328篇
药学   138402篇
  438篇
中国医学   27330篇
肿瘤学   104131篇
  2022年   18744篇
  2021年   28905篇
  2020年   21103篇
  2019年   23104篇
  2018年   28169篇
  2017年   23722篇
  2016年   23697篇
  2015年   31612篇
  2014年   41357篇
  2013年   50741篇
  2012年   71647篇
  2011年   77723篇
  2010年   48160篇
  2009年   42166篇
  2008年   63378篇
  2007年   65363篇
  2006年   64630篇
  2005年   62272篇
  2004年   53800篇
  2003年   51369篇
  2002年   47999篇
  2001年   68652篇
  2000年   70210篇
  1999年   60171篇
  1998年   19803篇
  1997年   18358篇
  1996年   17114篇
  1995年   16158篇
  1994年   14786篇
  1993年   12960篇
  1992年   43788篇
  1991年   42705篇
  1990年   41066篇
  1989年   38756篇
  1988年   35738篇
  1987年   34755篇
  1986年   33019篇
  1985年   31286篇
  1984年   23380篇
  1983年   19897篇
  1982年   11919篇
  1979年   20983篇
  1978年   14929篇
  1977年   12158篇
  1976年   11949篇
  1975年   12173篇
  1974年   14873篇
  1973年   14555篇
  1972年   13441篇
  1971年   12465篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
42.
43.
44.
OBJECTIVE: A series of nasopharyngeal appliance designs is presented that represents our evolving experience over a 20-year period in the adjunctive use of prosthetic stents in the surgical correction of nasopharyngeal stenosis. DESIGN: Retrospective assessment of effectiveness of two nasopharyngeal stenosis hollow stent designs in a consecutive series of patients for relief of nasal obstructive symptoms. SETTING: Tertiary academic medical center, Craniofacial Program at Children's Hospital. PATIENTS: Four patients with nasopharyngeal stenosis were treated with a preoperatively fabricated stent made from a clasped palatal appliance onto which hollow acrylic conduits were extended through surgically re-created pharyngeal ports. A subsequent set of four patients with nasopharyngeal stenosis were treated with intraoperatively-fashioned silastic grommets, as opposed to palatal appliances. INTERVENTIONS: Postoperative intraoral stenting of nasopharyngeal ports. MAIN OUTCOME MEASURES: Maintenance of pharyngeal port opening after 1 year, improvement in nasal airway obstructive symptoms. RESULTS: The palatal appliance stents were less well tolerated and had a lower maintenance of port patency after device removal (4 of 8, 50%). The silastic grommets provided better retention into the ports and increased patient tolerance, as well as better 1-year port maintenance (6 of 8, 75%). CONCLUSIONS: The grommet stent appliance offers numerous advantages over a conventional dental-clasped appliance for prosthetic nasopharyngeal stenting, including obviation of extensive preoperative preparation, ease of insertion and removal, and exchange of air during the stenting period. Improved nasopharyngeal patency with this device may be due to greater patient tolerance and subsequent longer use.  相似文献   
45.
The present study compared four different sites and conditions for the measurement of maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) in 38 spontaneous breathing tracheotomised patients. Of the patients, 28 had chronic obstructive pulmonary disease (COPD). The four different conditions were: 1) through a cuff inflated cannula (condition A); 2) through the mouth with a deflated cannula (condition B); 3) through the mouth with a phonetic uncuffed cannula (condition C); and 4) through the mouth after stoma closure (condition D). Five trials in each condition were performed using a standardised method. The measurement of both MIP and MEP differed significantly depending on the condition of measurement. MIP taken in condition A was significantly higher when compared with conditions B, C and D. MEP in condition A was significantly higher when compared with condition B and D. In condition A the highest frequency of the best measurement of MIP and MEP was observed at the fourth and fifth effort, respectively. The same results were obtained after the selection of only COPD patients. In conclusion, respiratory muscle assessment differs significantly depending on measurement condition. Measurement through inflated cannula tracheotomy yields higher values of both maximal inspiratory and maximal expiratory pressure.  相似文献   
46.
Chronic obstructive pulmonary disease (COPD) is characterised by a local pulmonary inflammatory response to respiratory pollutants and by systemic inflammation. Tumour necrosis factor (TNF)-alpha has been implicated in systemic effects of COPD and operates by binding the p55 (R1) and p75 (R2) TNF-alpha receptors. To investigate the contribution of each TNF-alpha receptor in the pathogenesis of COPD, the present study examined the effects of chronic air or cigarette smoke (CS) exposure in TNF-alpha R1 knockout (KO) mice, TNF-alpha R2 KO mice and wild type (WT) mice. CS was found to significantly increase the protein levels of soluble TNF-alpha R1 (by four-fold) and TNF-alpha R2 (by 10-fold) in the bronchoalveolar lavage of WT mice. After 3 months, CS induced a prominent pulmonary inflammatory cell influx in WT and TNF-alpha R1 KO mice. In TNF-alpha R2 KO mice, CS-induced pulmonary inflammation was clearly attenuated. After 6 months, no emphysema was observed in CS-exposed TNF-alpha R2 KO mice in contrast to WT and TNF-alpha R1 KO mice. CS-exposed WT and TNF-alpha R1 KO mice failed to gain weight, whereas the body mass of TNF-alpha R2 KO mice was not affected. These current findings suggest that both tumour necrosis factor-alpha receptors contribute to the pathogenesis of chronic obstructive pulmonary disease, but tumour necrosis factor-alpha receptor-2 is the most active receptor in the development of inflammation, emphysema and systemic weight loss in this murine model of chronic obstructive pulmonary disease.  相似文献   
47.
48.
49.
Here we report how the different types of regional muscle involvement, i.e. bulbar, ocular or generalized, in patients with myasthenia gravis (MG) influence the mental aspects of quality of life. Clinical examination according to Osserman was performed in 48 MG patients (45 women, three men; mean age 54, SD 12 years). Each patient was at the time for clinical evaluation asked to fill out the disease-specific Myasthenia Gravis Questionnaire (MGQ) and the Short-Form 36-item questionnaire for health survey (SF-36) as patient-oriented tools. We related the regional domains (generalized domain, bulbar domain and ocular domain) of the MGQ and the clinical findings, respectively, with mental quality of life as assessed by SF-36. Bulbar and generalized involvement results in impairment of mental aspects of quality of life, whereas ocular involvement does not.  相似文献   
50.
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