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   382300篇
  免费   21618篇
  国内免费   2780篇
耳鼻咽喉   5207篇
儿科学   8203篇
妇产科学   10080篇
基础医学   53278篇
口腔科学   11790篇
临床医学   30141篇
内科学   78463篇
皮肤病学   8562篇
神经病学   27267篇
特种医学   13928篇
外国民族医学   82篇
外科学   60620篇
综合类   9957篇
现状与发展   1篇
一般理论   64篇
预防医学   17433篇
眼科学   9452篇
药学   30996篇
  9篇
中国医学   2204篇
肿瘤学   28961篇
  2021年   2665篇
  2019年   2837篇
  2018年   4533篇
  2017年   3512篇
  2016年   3620篇
  2015年   4030篇
  2014年   5706篇
  2013年   7374篇
  2012年   10007篇
  2011年   10190篇
  2010年   6180篇
  2009年   5836篇
  2008年   9439篇
  2007年   10274篇
  2006年   10201篇
  2005年   9262篇
  2004年   8768篇
  2003年   8510篇
  2002年   8184篇
  2001年   28211篇
  2000年   28768篇
  1999年   23626篇
  1998年   5164篇
  1997年   4251篇
  1996年   3836篇
  1995年   3479篇
  1994年   3105篇
  1993年   2841篇
  1992年   16048篇
  1991年   14809篇
  1990年   14154篇
  1989年   13958篇
  1988年   12580篇
  1987年   12060篇
  1986年   11104篇
  1985年   10323篇
  1984年   6911篇
  1983年   5599篇
  1982年   2718篇
  1979年   5477篇
  1978年   3348篇
  1977年   2971篇
  1975年   2642篇
  1974年   3064篇
  1973年   2866篇
  1972年   2828篇
  1971年   2774篇
  1970年   2511篇
  1969年   2543篇
  1968年   2251篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
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   
62.
63.
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   
64.
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   
65.
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   
66.
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   
67.
A rare case of neurinoma in a 72 year-old Japanese woman derived from the hypoglossal nerve is reported. The tumour was composed of three interconnected nodules occurring simultaneously in the left submandibular and sublingual regions. The lesion, which presented as a neck mass, caused a slight left-sided hemiparesis of the tongue with tongue deviation to the affected side not noticed by the patient. An electromyographic (EMG) study revealed decreased muscle activity on the left side of the tongue muscle, indicating dysfunction of the hypoglossal nerve. EMG was useful for diagnosis.  相似文献   
68.
The purpose of this study was to clarify the relationship between lip seal and malocclusion in Japanese children. Fifty-three patients aged 7 to 14 years (mean 10.24 +/- 1.93) were selected randomly, and compared with 20 subjects with normal occlusion aged 7 to 14 years (mean 10.50 +/- 2.56). The subjects were divided into a good lip seal group and poor lip seal group by observing the distance between the upper and lower lip at rest. The variables that were analyzed for morphological evaluation included model analysis and cephalometric analysis. Noted for functional evaluation were tongue position, the size of the tonsils and adenoids and the oral muscle force measured by button pulling. In the evaluation of the degree of lip seal, there was no statistical difference between subjects with malocclusion and those with normal occlusion. Within the group with malocclusions, however, there were significant differences in overbite (p < 0.01), overjet (p < 0.01), and oral muscle force by button pulling (p < 0.05) between the good lip seal and poor lip seal groups. These results suggest that there is a need not only to correct malocclusion but also to be aware of lip sealing so that it may be improved in Japanese children.  相似文献   
69.
We investigated the effect of endogenous bradykinin on adrenaline-induced pulmonary edema (PE) by blocking bradykinin receptors. In preliminary experiments, a bolus injection of adrenaline (ADR; 10 microg/kg) solution (10 microg/ml) was determined to be an edematogenic dose for inducing PE. The lung body weight index (LBI) and incidence of PE (IPE) were determined. The IPE and LBI of the group pretreated with Des-Arg9-[Leu8]-Bradykinin (DA-BK, 50 microg/kg, 50 microg/ml) increased significantly compared with those of the control group (p<0.05). On the other hand, there were no remarkable changes in IPE and LBI in the groups pretreated with Hoe140 (D-Arginyl-[Hyp3, Thi5, D-Tic7, Oic8]-Bradykinin (100 microg/kg, 100 microg/ml), captopril (20 mg/kg, 20 mg/ml) or L-NAME (1 mg/kg, 1 mg/ml). Moreover, the IPE and LBI of the group co-treated with L-NAME and DA-BK decreased compared with the DA-BK group (p<0.05). Thus, bradykinin aggravates adrenaline-induced PE through activation of the B2 receptor by the kallikreins as a result of the ADR administration, although the precise mechanism is not known.  相似文献   
70.
BACKGROUND: While there is great interest in measuring the efficacy of root surface debridement, there is little consensus on how this might be best achieved. The aim of this study was therefore to compare four different methods of assessing root surface debridement in their ability to discriminate between ultrasonically instrumented root surfaces and non-instrumented control surfaces. METHODS: Single-session subgingival root debridement was performed by an experienced operator on 30 teeth prior to their extraction. Following extraction, efficacy of root surface debridement was measured by percentage of remaining calculus, instrument efficiency, modified instrument efficiency, and percentage apical plaque border. In addition, the effect of probing depth landmark (apical plaque border versus connective tissue attachment) on outcomes was assessed. RESULTS: The results indicated that percentage apical plaque border demonstrated highly statistically significant differences between instrumented and control surfaces (P= 0.02). No other assessment method was able to discriminate between instrumented and non-instrumented surfaces, and this may be a function of the low amount of root surface calculus in the experimental sample. In addition, choice of probing depth landmark had a notable effect on the outcomes for instrument efficiency and modified instrument efficiency. Ninety-five percent limits of agreement of interexaminer reproducibility were found to be much higher than intra-examiner measurement for all four methods of assessment. CONCLUSIONS: Percentage apical plaque border appeared to be potentially more useful than other methods for assessing the efficacy of debridement of periodontally involved root surfaces, particularly for measuring instrument penetrability.  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