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   694235篇
  免费   53140篇
  国内免费   1431篇
耳鼻咽喉   10310篇
儿科学   19749篇
妇产科学   20042篇
基础医学   99431篇
口腔科学   20452篇
临床医学   60326篇
内科学   131951篇
皮肤病学   13627篇
神经病学   56287篇
特种医学   28158篇
外国民族医学   141篇
外科学   108869篇
综合类   19710篇
现状与发展   2篇
一般理论   209篇
预防医学   53655篇
眼科学   16355篇
药学   51774篇
  13篇
中国医学   1290篇
肿瘤学   36455篇
  2018年   5913篇
  2015年   6197篇
  2014年   8951篇
  2013年   13468篇
  2012年   18163篇
  2011年   18981篇
  2010年   11208篇
  2009年   10431篇
  2008年   17985篇
  2007年   19701篇
  2006年   19603篇
  2005年   19276篇
  2004年   18938篇
  2003年   18297篇
  2002年   17564篇
  2001年   28555篇
  2000年   29177篇
  1999年   24732篇
  1998年   7404篇
  1997年   6843篇
  1996年   6811篇
  1995年   6401篇
  1994年   6192篇
  1992年   21335篇
  1991年   20938篇
  1990年   20498篇
  1989年   19834篇
  1988年   18533篇
  1987年   18224篇
  1986年   17355篇
  1985年   16793篇
  1984年   13103篇
  1983年   11252篇
  1982年   7147篇
  1981年   6512篇
  1980年   6143篇
  1979年   13493篇
  1978年   9632篇
  1977年   8181篇
  1976年   7436篇
  1975年   8126篇
  1974年   10105篇
  1973年   9741篇
  1972年   9255篇
  1971年   8565篇
  1970年   8191篇
  1969年   7898篇
  1968年   7127篇
  1967年   6615篇
  1966年   6100篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
82.
It has been reported that little diagnostic information concerning periodontal conditions is entered in patient records of general practitioners, but actual rates for such chart entries are unknown. Records of regular patients, seen at least annually, were randomly selected from the offices of 36 general practitioners in two North Carolina counties. In each office 80 records were selected for audit. After adjustment, the final sample consisted of 2488 audited records. Entries noting the presence or absence of 14 diagnostic conditions were identified for the five previous years and for the patient's most recent examination. The presence of a periodontal diagnosis or periodontal treatment plan was noted. The number of radiographic sets exposed in the previous five years and the age of the most recent set were determined for complete series/panoramic films and for bitewings. Across practices, the most frequent notations (20.5% within the past five years) concerned the presence of probing depths and calculus. Gingival bleeding (13%) and plaque (12%) were noted less frequently. A periodontal diagnosis was recorded in only 16.3% of the records. Annualized rates for radiographic sets were 0.09 for complete series/panoramic films and 0.50 for bitewings. These data suggest that, except for radiographs, the majority of patient records do not contain sufficient diagnostic information to describe patients' periodontal health.  相似文献   
83.
84.
85.
The aim of this study was to investigate the effect on subgingival plaque of a simplified oral hygiene regime consisting of instruction in Bass brushing without stress on interdental cleaning, scaling and root planing, in combination with subgingival pulsated jet irrigation with dilute solutions of chlorhexidine, metronidazole or placebos. Twenty-five patients, 14 women and 11 men, each with periodontal pockets ≥ 4 mm, participated in a randomized, double-blind, placebo-controlled study. The patients were assigned to 4 groups: 2 test groups (0.02% chlorhexidine and 0.05% metronidazole) and 2 placebo groups (0.01% quinine sulphate and 0.09% sodium chloride). Subgingival plaque samples were obtained from at least 4 sites in each subject on days 0 (prior to scaling and root planing), 7, 28, 56 and 84. Subgingival irrigation was terminated on d 28. Darkfield microscopy was used to assess the effects of treatment on the subgingival microflora by observing 4 morphologic groups: cocci, motile organisms, spirochetes and others (i.e. non-motile rods and filaments). All the groups showed marked beneficial changes at the end of the 28-d irrigation period, with increases in cocci and decreases in motile forms and spirochetes to less than baseline values. These beneficial effects were maintained for at least 8 weeks after irrigation was stopped. Metronidazole was more effective in reducing motile forms, but the reduction was not significant at d 84. It was concluded that pulsating monojet subgingival irrigation as part of a simplified oral hygiene program, with or without an active antimicrobial agent at low concentration, is effective in reducing the motile and spirochete portions of the subgingival microflora. These effects might be enhanced and prolonged if suitable antimicrobial solutions of higher concentration were used.  相似文献   
86.
Five film-screen combinations were used to make five density-matched panoramic radiographs of a tissue-equivalent phantom skull using the Midwest/Morita Panoral x-ray machine. The radiographs were evaluated as to their diagnostic quality by twenty dental radiologists. The results demonstrate that proper screen-film selection can significantly reduce patient exposure without compromising diagnostic quality.  相似文献   
87.
Effects of temperature (25 and 37 degrees C), pH (4.9-10.5), and CaF2 on CaHPO4.2H2O (DCPD) hydrolysis were studied in a pH-stat. Octa-calcium phosphate (OCP) was the product at pH 6.2-6.8 and 25-37 degrees C; thermodynamically stable apatitic compounds were formed at higher pH and/or higher temperature. In the presence of CaF2, apatite was the product, its crystallinity improved, and the fluoride content increased as pH of the reaction decreased. The results demonstrate the remarkable ability of fluoride to promote the hydrolysis of an acidic calcium phosphate, DCPD, to apatite.  相似文献   
88.
89.
90.
Air turbine handpieces are manufactured with a wide range of alternative design features which may influence their suitability for particular clinical procedures. In this article a general account of these features is presented and their advantages and disadvantages are discussed. Some deficiencies in current methods of stating equipment specifications are reported and suggested improvements are given. Where appropriate, general recommendations are made regarding handpiece selection for clinical practice.  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