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   1611877篇
  免费   123521篇
  国内免费   2546篇
耳鼻咽喉   21756篇
儿科学   52942篇
妇产科学   46226篇
基础医学   227911篇
口腔科学   47243篇
临床医学   141120篇
内科学   315373篇
皮肤病学   34115篇
神经病学   130418篇
特种医学   64755篇
外国民族医学   474篇
外科学   243933篇
综合类   39721篇
现状与发展   3篇
一般理论   544篇
预防医学   122953篇
眼科学   36527篇
药学   121405篇
  37篇
中国医学   2974篇
肿瘤学   87514篇
  2018年   14824篇
  2016年   12942篇
  2015年   15035篇
  2014年   20655篇
  2013年   31352篇
  2012年   42551篇
  2011年   44750篇
  2010年   26337篇
  2009年   25304篇
  2008年   42998篇
  2007年   45239篇
  2006年   46048篇
  2005年   44671篇
  2004年   44091篇
  2003年   42177篇
  2002年   41289篇
  2001年   75681篇
  2000年   78327篇
  1999年   66387篇
  1998年   17732篇
  1997年   16334篇
  1996年   16314篇
  1995年   16021篇
  1994年   15072篇
  1993年   14217篇
  1992年   55427篇
  1991年   53775篇
  1990年   52561篇
  1989年   50832篇
  1988年   47221篇
  1987年   46560篇
  1986年   44284篇
  1985年   42843篇
  1984年   32033篇
  1983年   27565篇
  1982年   16144篇
  1981年   14436篇
  1980年   13564篇
  1979年   30460篇
  1978年   21064篇
  1977年   17764篇
  1976年   16694篇
  1975年   17574篇
  1974年   21486篇
  1973年   20672篇
  1972年   18853篇
  1971年   17770篇
  1970年   16289篇
  1969年   15268篇
  1968年   13949篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
981.
A double-blind study was undertaken to determine the effects of megadose ascorbic acid supplementation on plasma ascorbate levels, polymorphonuclear neutrophil (PMN) chemotaxis and clinical and biochemical determinations of inflammatory progression in individuals with a mean daily ascorbate intake level of approximately twice the recommended daily allowances. Results indicate that although the group receiving ascorbate supplementation demonstrated a significant increase in plasma levels of the vitamin as compared to a placebo group, no significant differences with respect to PMN chemotaxis or responses to experimental gingivitis were found between the groups.  相似文献   
982.
983.
The emotional impact of orthognathic surgery and conventional orthodontics   总被引:3,自引:0,他引:3  
Previous research by the authors has pointed to depressive reactions among orthognathic surgery patients during the fixation-removal stage and up to 9 months later. However, less is known about emotional shifts among persons who choose to undergo conventional orthodontic treatment after considering surgical orthodontics. In the current study, a standard measure of mood states was applied to 90 surgical patients and 66 who had considered surgery but decided against it. Of these, 33 were undergoing orthodontic treatment and 33 were having no treatment. The mood scale and measures of personality were first applied before surgery and then during orthodontic treatment, just after surgery, at fixation removal, and 6 months after surgery. Nonsurgical respondents completed questionnaires at the same time as their matched surgical respondents. Scores on tension and fatigue increased significantly among surgical patients from before surgery to immediately after surgery and dropped to presurgical levels when fixation was removed. Anger-hostility increased at fixation removal but declined within 5 months. Postsurgical discomfort, pain, and paresthesia, and interpersonal and oral function problems were correlated with postsurgery emotional state. On the later questionnaires, which corresponded to the later periods of orthodontic treatment, patients who had opted for conventional orthodontic treatment reported that they experienced greater depression, anger, and tension. These patients may be particularly vulnerable to emotional problems because their orthodontic treatment may be more complex and of longer duration than that of the typical orthodontic patient. These results point to the importance of continued psychological support for both orthodontic and surgical patients throughout their course of treatment.  相似文献   
984.
The periodontal health of 30 adult epileptic patients treated with either sodium valproate or phenytoin was compared with a control group (n = 15) of otherwise healthy patients. The 3 groups were matched for age and sex. Patients on phenytoin therapy showed significantly higher plaque scores (P less than 0.05), gingival index (P less than 0.05) and pocketing (P less than 0.05) than patients in the control group. The % of gingival hyperplasia was significantly higher (P less than 0.05) in the phenytoin-treated patients than those on sodium valproate or in the control group. However, patients on phenytoin therapy had significantly less bone loss than those on sodium valproate (P less than 0.05) or in the control group (P less than 0.01). No significant differences were observed between the sodium valproate group and the control group on any of the parameters assessed. The results from this study would suggest that sodium valproate has no unwanted effects on periodontal health and may be considered a safe alternative, regarding the periodontal aspects, to phenytoin for the treatment of adult onset epilepsy.  相似文献   
985.
Three methods were used to obtain a ratio of the maxillary to the mandibular anterior teeth, with results of 1.29, 1.30, and 1.31. It can be concluded that a ratio of 1.30 is sufficient to determine the approximate width of the six maxillary anterior teeth when given the size of the mandibular natural anterior teeth. This ratio should be valid to select a maxillary denture mold of sufficient width mesiodistally to obtain a Class I canine relationship. However, the ratio may need a slight adjustment to compensate for the intentional disocclusion of the maxillary denture teeth with the natural mandibular teeth. In Fig. 1 the canine to canine measurement of the mandibular anterior teeth was 35 mm; when multiplied by a factor of 1.30, a maxillary measurement of 45.5 mm is obtained. The denture teeth were to be set with approximately 1 mm of horizontal overjet and 1 mm of vertical overlap (Fig. 2), therefore a slightly larger mold of 48.5 mm was chosen (Fig. 3). This maxillary mold produced a Class I canine relationship (Fig. 4). The 48.5 mm ratio of the chosen maxillary mold to the mandibular measurement of 35 mm yielded a ratio of 1.38. When this ratio of 1.38 is applied, the desired prosthetic mold is not always available. There is a range of acceptability above and below the desired ratio.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
986.
Fibronectin (Fn) was localized in duct cells by means of a light and electron microscopic immunohistochemical technique. The subcellular localization demonstrated that Fn is synthesized in these cells and thus not exclusively produced by cells with a mesodermal background. Fn concentration, as measured by radioimmunoassay, was higher in saliva from the minor salivary glands than in unstimulated whole saliva, whereas Fn was undetectable in stimulated parotid saliva. Fn is thus a conspicuous component in unstimulated resting saliva. Fn may be an important factor, negative or positive, for the integrity of the oral hard and soft tissues because it has the capability to bind and agglutinate microorganisms.  相似文献   
987.
988.
989.
990.
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