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   379308篇
  免费   24348篇
  国内免费   2806篇
耳鼻咽喉   5207篇
儿科学   8233篇
妇产科学   10121篇
基础医学   53116篇
口腔科学   11803篇
临床医学   30144篇
内科学   78346篇
皮肤病学   8564篇
神经病学   27232篇
特种医学   13948篇
外国民族医学   82篇
外科学   60661篇
综合类   9970篇
现状与发展   1篇
一般理论   64篇
预防医学   17419篇
眼科学   9466篇
药学   30991篇
  1篇
中国医学   2202篇
肿瘤学   28891篇
  2021年   2625篇
  2019年   2734篇
  2018年   4529篇
  2017年   3445篇
  2016年   3538篇
  2015年   4044篇
  2014年   5712篇
  2013年   7406篇
  2012年   10041篇
  2011年   10242篇
  2010年   6207篇
  2009年   5857篇
  2008年   9472篇
  2007年   10307篇
  2006年   10220篇
  2005年   9299篇
  2004年   8804篇
  2003年   8534篇
  2002年   8201篇
  2001年   28220篇
  2000年   28770篇
  1999年   23629篇
  1998年   5161篇
  1997年   4249篇
  1996年   3832篇
  1995年   3479篇
  1994年   3103篇
  1993年   2843篇
  1992年   16049篇
  1991年   14809篇
  1990年   14156篇
  1989年   13958篇
  1988年   12579篇
  1987年   12059篇
  1986年   11102篇
  1985年   10320篇
  1984年   6911篇
  1983年   5599篇
  1982年   2718篇
  1979年   5477篇
  1978年   3347篇
  1977年   2971篇
  1975年   2641篇
  1974年   3064篇
  1973年   2865篇
  1972年   2828篇
  1971年   2773篇
  1970年   2510篇
  1969年   2544篇
  1968年   2250篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
82.
83.
The present review analyzes the accumulated data from all cases of glandular odontogenic cyst (GOC) reported in the English language literature. In the 20 years since it was first described, 111 cases have been reported, an incidence of 0.2% of odontogenic cysts. The age range is 14-75, mean 45.7, with a M/F ratio of 1.3:1. GOC has a predilection for the mandible (70%), affecting both anterior and posterior areas. It is typically radiolucent, well defined, either unilocular (53.8%) or multilocular (46.2%). Frequent perforation (61%) and of thinning of cortical plates (24.4%) indicate aggressiveness. Sufficient follow-up indicates that 30% of cases can recur. Treatment by enucleation or curettage carries the highest risk for recurrence, especially in large and multilocular lesions. Peripheral osteoectomy or marginal resection can eliminate the risk. Defined criteria for microscopic diagnosis are described, which in addition to Ki67 and p53 can help in differentiating GOC from lesions with histological similarities (cysts with mucous metaplasia, botryoid and surgical ciliated cysts, low-grade mucoepidermoid carcinoma). Definite diagnosis may not be possible in small incisional biopsies due to the focal presentation of characteristic features required for diagnosis. There is now evidence to support an odontogenic rather than a sialogenic origin.  相似文献   
84.
This study evaluated the fracture loads of three-unit all-ceramic bridges on implants; the core frameworks of the bridges were made of zirconium oxide. Three core framework designs were fabricated according to the design of the bars between the retainers: (i) straight, (ii) curved in the occlusal direction, or (iii) curved in the gingival direction. A static load was applied at the centre of the pontic, and the mean initial crack and final fracture loads were measured and compared. The core framework curved in the occlusal direction had the highest final fracture loads; there were significant differences (P < 0.05) in the mean final fracture load, whereas initial fracture load, which fractured of veneered porcelain, did not show significant differences among three designs. The all-ceramic bridges on the implants made with Procera zirconium core frameworks had high final fracture load. The core framework design that curved in the occlusal direction helped the framework withstand the occlusal load, which results in reliable prostheses, especially in the molar region.  相似文献   
85.
Endoscopy is widely used in the diagnosis and treatment of temporomandibular joint disorders. This paper introduces arthro-endoscopy as a new method of treatment for temporomandibular joint dislocation. As this method is minimally invasive, it is suitable for medically compromised patients who cannot tolerate open surgery.  相似文献   
86.
87.
A growing number of patients go to orthodontic practices to receive orthodontic re-treatment, but their reasons for seeking re-treatment are uncertain. By means of a standardized questionnaire this study investigates the patients'experiences with the initial orthodontic treatment, applied retention procedures, and the patients'expectations and motivational reasons for re-treatment. In total 100 patients were asked to complete the questionnaire, 88 of them actually filled it out. The study subjects showed an above average educational level, with a considerably higher percentage of females than males seeking re-treatment. Fixed appliances were used most frequently during the first course of treatment and most patients had been fitted with a removable retention plate or fixed retention wire at the conclusion of their first treatment; almost 40% of the patients did not receive any kind of retention appliance. Patients sought re-treatment mostly on their own initiative, as opposed to their initial treatment, when they were mostly referred by dentists or orthodontists. This revealed itself in patients' high levels of motivation for re-treatment. Moreover, patients appeared to have realistic impressions of the time and cost involved in re-treatment.  相似文献   
88.
BACKGROUND: Periodontitis is associated with increased prevalence of cardiovascular morbidity and mortality; however, the nature of this association is unclear. There is a rationale that indicates that the presence of periodontal pockets which can harbor pathogenic microorganisms and evoke a host response could elicit a systemic effect. The hypothesis of this study is that periodontal pockets may be associated with elevated blood lipid levels, a known risk factor for atherosclerotic disease. METHODS: The periodontal health of 10,590 Israeli military service men and women was assessed using the Community Periodontal Index of Treatment Needs (CPITN). The relationship of blood lipids and periodontal disease and CPITN index was tested, controlling for factors that are related to elevated cholesterol levels, including high body mass index (BMI), age, diastolic blood pressure, and smoking. RESULTS: The presence of periodontal pockets was positively associated with higher cholesterol and low density lipoprotein (LDL) cholesterol blood levels in men. No significant association was found in women. CONCLUSIONS: In this large cohort study, the presence of periodontal pockets as measured by CPITN was positively associated with total cholesterol and LDL-cholesterol. The findings of the study support the reports linking increased prevalence of cardiovascular mortality among patients with periodontal disease.  相似文献   
89.
Porphyromonas gingivalis has been shown to attack host defense systems through proteolytic cleavage of a wide variety of members of the systems. In this study, we examined the ability of P. gingivalis culture supernatant to alter the expression of human T cell surface proteins. As judged by flow cytometric analysis, detection of CD4 expression was completely eliminated by the supernatant, but CD8 was less sensitive. When the culture supernatant was added with reducing agents, proteolytic activity was enhanced, resulting in the cleavage of CD8. Mitogenic response of T cells to phytohemagglutinin or concanavalin A was decreased by the treatment of the cells with the culture supernatant of P. gingivalis. The three forms of gingipains (high molecular mass arginine-specific gingipain, arginine-specific gingipain 2 and lysine-specific gingipain) purified from the culture supernatant of P. gingivalis actively cleaved CD4 and CD8 on human T cells, indicating that proteolytic activity of the culture supernatant was due to gingipains. These results suggest that cysteine proteinases like gingipains released from P. gingivalis cleave T cell surface proteins and impede T cell function.  相似文献   
90.
There have been many reports on congenital anomalies associated with cleft lip and/or palate (CL/CLP) in Japan. However, these reports included data only on patients who came to hospitals; thus the real situation regarding these anomalies remains unclear. Therefore, we surveyed newborns at all delivery facilities in the central area of Japan for the presence of these anomalies, following their progress for 12 consecutive years; at the end of that time, questionnaires were collected and analyzed. In this article, we describe our results.  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