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   1076751篇
  免费   69956篇
  国内免费   2312篇
耳鼻咽喉   15897篇
儿科学   32248篇
妇产科学   31004篇
基础医学   150034篇
口腔科学   31964篇
临床医学   90382篇
内科学   210554篇
皮肤病学   24369篇
神经病学   85178篇
特种医学   42886篇
外国民族医学   349篇
外科学   166800篇
综合类   24765篇
现状与发展   6篇
一般理论   353篇
预防医学   73782篇
眼科学   25165篇
药学   79977篇
  18篇
中国医学   2378篇
肿瘤学   60910篇
  2018年   9545篇
  2015年   9460篇
  2014年   13466篇
  2013年   20229篇
  2012年   26458篇
  2011年   27950篇
  2010年   16607篇
  2009年   16119篇
  2008年   26884篇
  2007年   29446篇
  2006年   29735篇
  2005年   28875篇
  2004年   28161篇
  2003年   27297篇
  2002年   26829篇
  2001年   51058篇
  2000年   52272篇
  1999年   44374篇
  1998年   11756篇
  1997年   10781篇
  1996年   10388篇
  1995年   9795篇
  1994年   9246篇
  1993年   8613篇
  1992年   34265篇
  1991年   33042篇
  1990年   32406篇
  1989年   31619篇
  1988年   29476篇
  1987年   29097篇
  1986年   27963篇
  1985年   26475篇
  1984年   19780篇
  1983年   16784篇
  1982年   10067篇
  1981年   9175篇
  1979年   19161篇
  1978年   13608篇
  1977年   11863篇
  1976年   10686篇
  1975年   12092篇
  1974年   14547篇
  1973年   14042篇
  1972年   13458篇
  1971年   12557篇
  1970年   11975篇
  1969年   11511篇
  1968年   10803篇
  1967年   9587篇
  1966年   8970篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
103.
104.
The relationship between volatile fatty acids (VFAs) in pus and infecting bacterial species was examined in order to establish a rapid identification system for anaerobic microorganisms in purulent inflammation in the oro-maxillary region. VFAs were detected by the direct injection of pus into gas-liquid chromatography (GLC). Bacterial examination was carried out by anaerobic culture using blood agar plates. The bacterial identification was carried out mainly according to the VPI manual. Analysis of the direct VFA patterns of each sample resulted in 5 groups. The following bacterial species were the main isolates in each group: Streptococcus intermedius in Group A, Peptostreptococcus micros in Group B, Fusobacterium nucleatum in Group C, Bacteroides gingivalis in Group D, and Peptostreptococcus anaerobius in Group E. The profile of VFAs produced in the PYG culture medium of the above isolated bacteria was compared with the direct VFA patterns. Agreement ratios between direct and PYG VFA patterns were as follows: Group A, 47.1%; Groups B and C, 45.0%; Group D, 87.5%; and Group E, 62.9%. The acetic acid concentration was more than 14 x 10(-4) meq/ml in Group B, the butyric acid concentration was more than 7 x 10(-4) meq/ml in Group C, and the iso-caproic acid concentration was more than 14 x 10(-4) meq/ml in Group E. In these cases, it was found that the agreement ratios between the direct and PYG FVA pattern were high. In Group D, irrespective of the concentration of iso-valeric acid detected, the agreement ratio was very high. The antibiotic susceptibility of the isolates was studied. Efficiency rates of ABPC, PIPC, CCL, CEZ, CMZ, SBT/CPZ, JM, CLDM, MINO and GM were relatively low and resistant rates were high for the gram-negative rods.  相似文献   
105.
Zymosan-induced chemiluminescence was investigated in whole blood and in neutrophils: in both, the peak count was frequently elevated in Beh?et's disease, and was significantly higher than in healthy controls; similarly the peak time was shorter. There were more uncommon serotypes of Streptococcus sanguis in the oral flora of patients with Beh?et's disease. Common serotypes were present in the flora of healthy controls, but not in patients with the disease. The percentage of Strep. sanguis in the oral flora was significantly correlated with the level of chemiluminescence response. Thus infection with uncommon serotypes of Strep. sanguis may play a role in the aetiology of Beh?et's disease.  相似文献   
106.
Trimetaphosphatase was used as a lysosomal marker in the ruffle-ended maturation ameloblasts and associated papillary cells. Morphometric analysis was carried out of the percentage area of these cells (density) occupied by the various enzyme-reactive lysosomal structures. The density of total TMPase-positive lysosomal structures, tubular lysosomes and multivesicular bodies in ruffle-ended ameloblasts were all significantly greater (p less than or equal to 0.05) in early than in late maturation enamel formation. In papillary cells the same was true of tubular lysosomes, whereas the greater density of enzyme-positive total structures in early maturation was not statistically significant when compared to late maturation. These findings demonstrate a corresponding pattern between enamel-organ lysosomal activity and the period of early enamel maturation when most enamel protein is lost. They support the likely involvement by ruffle-ended ameloblasts and papillary cells in absorption and degradation of exogenous enamel proteins.  相似文献   
107.
A panoramic radiograph obtained during orthodontic treatment revealed an intracoronal radiolucency within an unerupted permanent second molar. This unusual entity was successfully treated by surgical and endodontic intervention, followed by restorative and orthodontic treatment. These treatments enabled the tooth to maintain pulpal vitality, erupt, complete root formation, and function. This report will review the proposed etiologies for this condition, discuss the need for surgical intervention, and present the details of the case.  相似文献   
108.
Association of smoking with periodontal treatment needs   总被引:1,自引:0,他引:1  
A total of 344 Jerusalem hospital personnel participated in the present survey which examined periodontal needs according to CPITN (a measure of treatment needs) and smoking habits. Females and younger subjects were found to be generally periodontally healthier than their male and older counterparts. The effect of both smoking and the number of cigarettes smoked were shown to have a clearly deleterious effect on periodontal status when assessed using the CPITN. Younger women were found to be most susceptible to this effect.  相似文献   
109.
A study was conducted on 21 cases of ameloblastoma (a type of tumor containing an embedded tooth) and 87 cases of dentigerous cyst. The former cases were selected from among those which had been diagnosed histopathologically. Using radiographs of these lesions, the following parameters were measured: 1) the distance between the cement-enamel junction of the embedded tooth and its attachment to the cystic wall; 2) the area of the radiolucent image (similar to the area with a cystic appearance). From measurements of the former parameter, it appeared that the embedded tooth extends more toward the root apex in ameloblastoma than in dentigerous cyst, whereas the latter parameter indicated that the radiolucent area varies in size slightly in ameloblastoma, but tends to be smaller in dentigerous cyst. Moreover, with regard to clustering between ameloblastoma and dentigerous cyst, no definite tendency was detected on distance, whereas only ameloblastoma without dentigerous cyst was seen above 20 cm2 of area.  相似文献   
110.
Microleakage of seven temporary restorative materials was evaluated in endodontic access preparations made in teeth restored with amalgam. Ten teeth were used for each of the seven materials: Cavit, Cavit-G, TERM, zinc phosphate cement, polycarboxylate cement, glass ionomer cement, and IRM. A class I amalgam was placed in the occlusal surface of each experimental tooth and an endodontic access preparation was made entirely within the amalgam. Then the access preparation was restored with one of the temporary restorative materials, and microleakage was evaluated using a fluid filtration technique. The amount of microleakage was quantitated by measuring the fluid flow at 15 min, 1 h, 24 h, 1 wk, and 2 wk after insertion of the temporary restoration. Cavit, Cavit-G, TERM, IRM, and glass ionomer cement all provided excellent seals while zinc phosphate cement and polycarboxylate cement provided less effective seals.  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