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   1909218篇
  免费   127614篇
  国内免费   2634篇
耳鼻咽喉   25904篇
儿科学   61428篇
妇产科学   50534篇
基础医学   280551篇
口腔科学   51187篇
临床医学   172226篇
内科学   369711篇
皮肤病学   41818篇
神经病学   150043篇
特种医学   70644篇
外国民族医学   404篇
外科学   284815篇
综合类   38040篇
现状与发展   10篇
一般理论   701篇
预防医学   148343篇
眼科学   43827篇
药学   140875篇
  49篇
中国医学   3678篇
肿瘤学   104678篇
  2021年   16011篇
  2019年   16606篇
  2018年   22342篇
  2017年   16694篇
  2016年   18712篇
  2015年   20890篇
  2014年   29488篇
  2013年   43989篇
  2012年   60940篇
  2011年   64739篇
  2010年   38438篇
  2009年   36263篇
  2008年   60620篇
  2007年   64458篇
  2006年   65137篇
  2005年   63178篇
  2004年   60319篇
  2003年   57734篇
  2002年   56151篇
  2001年   87337篇
  2000年   89384篇
  1999年   74956篇
  1998年   21689篇
  1997年   19099篇
  1996年   19463篇
  1995年   18302篇
  1994年   16842篇
  1993年   15870篇
  1992年   57668篇
  1991年   56160篇
  1990年   54819篇
  1989年   52615篇
  1988年   48378篇
  1987年   47273篇
  1986年   44169篇
  1985年   42227篇
  1984年   31293篇
  1983年   26794篇
  1982年   16044篇
  1979年   28601篇
  1978年   20433篇
  1977年   16948篇
  1976年   16260篇
  1975年   17422篇
  1974年   20864篇
  1973年   19760篇
  1972年   18570篇
  1971年   17622篇
  1970年   16268篇
  1969年   15543篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
Short term data were obtained from 74 patients who recieved comprehensive periodontal treatment using a split mouth approach to test three variables; subgingival curettage, pocket elimination surgery, and modified Widman flap procedure. The patients initially had an average interproximal loss of attachment of 3.2 mm and an average interproximal pocket depth of 3.9 mm. Evaluation of the data indicate that after 4 to 6 weeks: 1. All three surgical procedures reduce pocket depths. In order of effectiveness they are: pocket elimination surgery, modified Widman flap, and subgingival curettage. 2. Pocket elimination surgery reduces pockets more than subgingival curettage on the buccal, lingual and interproximal, and more than the modified Widman flap on the lingual. The modified Widman flap procedure reduces pockets more interproximally than subgingival curettage. 3. Subgingival curettage results in a gain of attachment interproximally, and on the lingual side, while the modified Widman flap resulted in a gain of attachment interproximally only. 4 Pocket elimination surgery resulted in a loss of attachment buccally. 5 Subgingival curettage results in a more favorable postoperative attachment level on all surfaces than did pocket elimination surgery.  相似文献   
993.
α-l-Fucosidase activities were determined using p-nitrophenyl-α-l-fucoside (p-NPF) and de-sialized porcine submandibular glycoprotein (DS-PSG) as substrates. Dental plaque and whole saliva possessed enzyme activity against both substrates. Parotid and submaxillary-sublingual saliva exhibited the activity on p-NPF, but did not on DS-PSG.  相似文献   
994.
A series of preventive methods in combination have been used to reduce dental caries in children including dental health education, prophylaxes, pit and fissure sealants, topical application of fluoride and restorative care. Prophylaxes, sealant, and fluoride procedures are repeated every six months. Two-year results show reductions of occlusal caries increments of 74.3% for first graders and 77.1% for sixth graders. Sealant loss, as defined in this study, varied from 33% to 90% with the highest loss occurring in the newly erupted permanent molars during the first six months of the project. These high sealant loss rates are thought to be related to the age of the population which was designed to include children at the ages of peak eruption of permanent molar teeth (ages six and twelve). These teeth were often only minimally erupted and maintaining the dry field required for sealant retention was extremely difficult. However, in spite of these high rates of sealant loss, caries reduction on occlusal surfaces was highly significant in comparision to that of children who did not receive sealants.  相似文献   
995.
996.
Application of the "Wits" appraisal.   总被引:9,自引:0,他引:9  
The "Wits" appraisal is intended as a diagnostic aid to be used in conjunction with other analyses. Whereas the popularly used ANB angular reading is a simple method of measuring degree of jaw disharmony, there are many instances in which this reading is suspect. The "Wits" appraisal permits easy identification of these shortcomings and substitutes a reasonably reliable means of measuring extent of anteroposterior jaw disharmony.  相似文献   
997.
998.
999.
The purpose of this retrospective study was to elucidate potential confounding factors affecting initial stability of miniscrews inserted to enhance orthodontic anchorage. Four hundred and seven miniscrews inserted in 168 patients treated by 17 orthodontic residents were analysed in a consecutive chart review. The outcome variable was the stability of the miniscrew, measured as a dichotomous variable, 0 if the miniscrew loosened during a 1 week period after insertion to the time of orthodontic force application and a value of 1 otherwise. Potential confounding variables examined were gender, age, jaw, insertion site, tissue type, length and diameter of the miniscrew, and number of previous insertions. Generalized estimating equations (GEE) methods were used to estimate the influence of each factor on stability for the correlated binary outcomes of each patient. A weighted analysis for the GEE approach was also performed for the convergence calculation of the estimation procedure due to a value of 0 in one of the cells. Crude odds ratio (cOR) and adjusted odds ratio (aOR) and their 95 per cent confidence intervals (CI) were calculated for this purpose. The overall success rate after 1 week was 93.1 per cent (379/407). The screws inserted by more experienced clinicians (more than 20 miniscrews) were found to have approximately a 3.6-fold higher success rate of initial stability compared with those inserted by less experienced clinicians after adjusting for the insertion site (aOR = 3.63, P = 0.015). The results of the present study suggest that the initial stability depends on insertion site and clinician experience.  相似文献   
1000.
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