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   2106418篇
  免费   151544篇
  国内免费   6787篇
耳鼻咽喉   28074篇
儿科学   68285篇
妇产科学   58915篇
基础医学   304696篇
口腔科学   57861篇
临床医学   194289篇
内科学   411402篇
皮肤病学   42956篇
神经病学   173657篇
特种医学   79317篇
外国民族医学   684篇
外科学   306322篇
综合类   46102篇
现状与发展   1篇
一般理论   721篇
预防医学   169613篇
眼科学   46779篇
药学   153968篇
  9篇
中国医学   4948篇
肿瘤学   116150篇
  2021年   16765篇
  2019年   17593篇
  2018年   24415篇
  2017年   18730篇
  2016年   20311篇
  2015年   23125篇
  2014年   32121篇
  2013年   49438篇
  2012年   67322篇
  2011年   71628篇
  2010年   42432篇
  2009年   39405篇
  2008年   66142篇
  2007年   69885篇
  2006年   69958篇
  2005年   67971篇
  2004年   65166篇
  2003年   62582篇
  2002年   61201篇
  2001年   92971篇
  2000年   95608篇
  1999年   80609篇
  1998年   23187篇
  1997年   21031篇
  1996年   20664篇
  1995年   19526篇
  1994年   18388篇
  1993年   17350篇
  1992年   63803篇
  1991年   62167篇
  1990年   60341篇
  1989年   57644篇
  1988年   53463篇
  1987年   52255篇
  1986年   49900篇
  1985年   47759篇
  1984年   36017篇
  1983年   30719篇
  1982年   18584篇
  1979年   32885篇
  1978年   23311篇
  1977年   19404篇
  1976年   18803篇
  1975年   19776篇
  1974年   23970篇
  1973年   23236篇
  1972年   21727篇
  1971年   20170篇
  1970年   18919篇
  1969年   17518篇
排序方式: 共有10000条查询结果,搜索用时 56 毫秒
21.
22.
According to the current nutritional recommendations issued by professional diabetes and nutrition associations, diabetic patients should keep to a diet consisting of 45–60% carbohydrates, 10–20% protein, and not more than 35% fat. However, not all of these nutritional recommendations are evidence based. For example, current studies show that the intake of insoluble roughage may be underrepresented. It is also possible that diabetic patients could benefit from keeping to the lower end of the recommended range for carbohydrates (45%) and the upper end of the range advised for protein (20%).  相似文献   
23.
24.
Bernard–Soulier syndrome (BSS) is a rare autosomal recessively inherited bleeding disorder. Pregnancy in patients with BSS is characterized by ante‐, intra‐, or postpartum haemorrhage, which may be delayed and severe. There is no consensus in the management of BSS in pregnancy and so far only 16 pregnancies in nine patients have been described. We report a further three pregnancies in two women with the syndrome. We also outline our management of pregnant patients with BSS.  相似文献   
25.
26.
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   
27.
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   
28.
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   
29.
30.
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