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   711297篇
  免费   44897篇
  国内免费   1227篇
耳鼻咽喉   9217篇
儿科学   23298篇
妇产科学   17604篇
基础医学   110495篇
口腔科学   19988篇
临床医学   63907篇
内科学   134626篇
皮肤病学   16193篇
神经病学   49613篇
特种医学   25761篇
外国民族医学   76篇
外科学   104576篇
综合类   14849篇
现状与发展   2篇
一般理论   160篇
预防医学   51457篇
眼科学   16367篇
药学   54043篇
  13篇
中国医学   2390篇
肿瘤学   42786篇
  2019年   5586篇
  2018年   7877篇
  2017年   6135篇
  2016年   6852篇
  2015年   7554篇
  2014年   10270篇
  2013年   15378篇
  2012年   20488篇
  2011年   21486篇
  2010年   12717篇
  2009年   11929篇
  2008年   19984篇
  2007年   21506篇
  2006年   21896篇
  2005年   20433篇
  2004年   19982篇
  2003年   18940篇
  2002年   18448篇
  2001年   36325篇
  2000年   36894篇
  1999年   30377篇
  1998年   7875篇
  1997年   6662篇
  1996年   6969篇
  1995年   6627篇
  1994年   6096篇
  1993年   5589篇
  1992年   22967篇
  1991年   22924篇
  1990年   22310篇
  1989年   22076篇
  1988年   20035篇
  1987年   19417篇
  1986年   18467篇
  1985年   17305篇
  1984年   12697篇
  1983年   10741篇
  1982年   5921篇
  1979年   11520篇
  1978年   8128篇
  1977年   6832篇
  1976年   6594篇
  1975年   7269篇
  1974年   8499篇
  1973年   8141篇
  1972年   7659篇
  1971年   7127篇
  1970年   6878篇
  1969年   6309篇
  1968年   5780篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
73.
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   
74.
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   
75.
76.
77.
The sensitivity of methodology for measuring the concentration of fluorine species in saliva and in plaque has been tested. Human subjects mouth-rinsed daily with aqueous solutions of NaF and Na2FPO3. Samples of unstimulated whole saliva and of plaque were collected twice weekly at least 18 hr after treatment application. Oral fluoride concentrations rose from placebo values for approximately two weeks before attaining equilibrium and returned to baseline when daily mouthrinsing was stopped. Mean elevated oral fluoride concentrations increased significantly with increasing applied NaF concentration in the range 0-1000 ppm F (0-0.053 mol/L). There appeared to be a linear relationship between saliva and plaque fluoride. The ability of fluoride treatments to sustain elevated oral fluoride levels between daily applications may be of major importance in caries control.  相似文献   
78.
A cellular blue nevus located on the palate of a 72-year-old female is reported. This intraoral finding is uncommon and should be distinguished from clinical entities it closely resembles. Practitioners should be aware that a pigmented palatal lesion in fact may be a malignant melanoma. Surgical excision with microscopic examination is the only means by which an accurate diagnosis can be made.  相似文献   
79.
80.
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