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   5148篇
  免费   336篇
  国内免费   124篇
耳鼻咽喉   7篇
儿科学   4篇
妇产科学   1篇
基础医学   274篇
口腔科学   1741篇
临床医学   473篇
内科学   816篇
皮肤病学   122篇
神经病学   443篇
特种医学   249篇
外科学   120篇
综合类   679篇
现状与发展   2篇
预防医学   152篇
眼科学   43篇
药学   253篇
  5篇
中国医学   201篇
肿瘤学   23篇
  2024年   17篇
  2023年   94篇
  2022年   183篇
  2021年   222篇
  2020年   190篇
  2019年   192篇
  2018年   184篇
  2017年   174篇
  2016年   159篇
  2015年   143篇
  2014年   350篇
  2013年   304篇
  2012年   265篇
  2011年   268篇
  2010年   219篇
  2009年   182篇
  2008年   238篇
  2007年   223篇
  2006年   190篇
  2005年   164篇
  2004年   127篇
  2003年   127篇
  2002年   84篇
  2001年   111篇
  2000年   72篇
  1999年   49篇
  1998年   58篇
  1997年   65篇
  1996年   69篇
  1995年   64篇
  1994年   49篇
  1993年   60篇
  1992年   80篇
  1991年   61篇
  1990年   53篇
  1989年   47篇
  1988年   47篇
  1987年   45篇
  1986年   43篇
  1985年   44篇
  1984年   40篇
  1983年   42篇
  1982年   40篇
  1981年   28篇
  1980年   31篇
  1979年   15篇
  1978年   15篇
  1977年   22篇
  1976年   16篇
  1975年   24篇
排序方式: 共有5608条查询结果,搜索用时 15 毫秒
971.
AIM: The purpose of the present study was to compare 2 indices, i.e., the Eastman interdental bleeding (EIB) index and the bleeding on marginal probing (BOMP) index. The comparison was made (a) in terms of the degree of bleeding provoked and the relationship with plaque in natural gingivitis and (b) for the ability of these 2 methods to detect differences between the development of experimental gingivitis in a control group and a group in which the development of gingival inflammation was suppressed by treatment. For the present studies, subjects were selected without interdental recession of the gingival tissues. METHODS EXPERIMENT 1: In this experiment, 43 subjects having established moderate gingivitis were assessed using a random splitmouth design (1st and 3rd/2nd and 4th quadrant). Plaque was scored on all approximal sites after which the BOMP index was assessed in one half of the mouth and the EIB index in the other. RESULTS EXPERIMENT 1: The BOMP index showed a bleeding score of 84% and the EIB index of 87%. The significant correlation between plaque and gingival bleeding for the BOMP index (0.55) was higher than for the EIB index (0.44). METHODS EXPERIMENT 2: For this experiment, 25 subjects participated in an experimental gingivitis trial of the lower jaw. At baseline, first the BOMP index and immediately thereafter the EIB index were assessed at all approximal sites. Experimental gingivitis (EG) was carried out in one randomly assigned quadrant and as a treatment modality only floss was used in the other (FL). RESULTS EXPERIMENT 2: In the EG quadrant, the BOMP index increased to 69% and the EIB index to 73%. Both indices showed a significant correlation with plaque; 0.60 and 0.64 respectively. In the FL quadrant, the BOMP index increased to 38% and the EIB index to 30%. No significant correlation between both gingivitis indices and the amount of plaque was present in the FL quadrant. CONCLUSION: The ability of the BOMP index and the EIB index to assess the level gingival inflammation appears to be comparable.  相似文献   
972.
应用聚合酶链式反应检测国人10种牙周病可疑致病菌   总被引:5,自引:4,他引:5  
目的 :应用聚合酶链式反应分别检测国人不同牙周情况者龈下菌斑中 10种牙周可疑致病菌 ,观察其分布特点 ,并初步分析不同的细菌组合与牙周病的关系。方法 :从 3组对象 :健康组 ,龈炎组和牙周炎组中采取 12 4例龈下菌斑 ,提取DNA ,分别用 10种牙周病可疑致病菌的特异引物 ,采取聚合酶链式反应(PCR)扩增 16SrDNA片段来鉴定细菌种类。用统计软件分析细菌与各项临床指标的关系。结果 :经 χ2 检验 ,龈炎组和牙周病组牙龈卟啉菌的检出率高于健康组 (P <0 .0 5) ,牙周病组福塞氏类杆菌、中间型普里沃氏菌、齿垢密螺旋体 ,变黑普里沃氏菌的检出率高于健康组和龈炎组 (P <0 .0 5)。经Logistic回归进一步分析 ,中间型普氏沃氏菌、齿垢密螺旋体和变黑普里沃氏菌与牙周病关系更为密切 ;中间型普里沃氏菌、变黑普里沃氏菌和生痰二菌化碳噬纤维菌与附着丧失有关 ,而Pi和Td对探诊出血影响较大。结论 :我国人群的牙周病可疑致病菌的分布有自已的特点。  相似文献   
973.
Abstract. The aim of this study was to evaluate the response of microbial plaque and gingival inflammation to the placement of porcelain laminate veneers on anterior teeth. 9 patients, 7 female and 2 male (mean age of 30 years), with a total of 35 veneers were examined. The volume of gingival crevicular fluid (GCF), level of neutral proteolytic enzyme activity, gingival index (GI), plaque index (PII) and plaque bacteria vitality were measured at baseline and after the placement of veneers. The volume of GCF increased after the placement of veneers ( p =0.03). No statistically significant differences were found in proteolytic enzyme activity or GI ( p >0.05). There were statistically significant reductions in PII ( p =0.000) and plaque bacteria vitality ( p =0.018). Further research is required to assess the long-term influence of porcelain laminate veneers on gingival health and microbial plaque characteristics.  相似文献   
974.
A relatively high incidence of infection by Actinobacillus actionomycetemcomitans can be shown in subgingival plaque samples obtained from patients with juvenile periodontitis. These organisms possess a potent leukotoxin(s) which rapidly destroys isolated human polymorphonuclear leukocytes (PMNs) and monocytes. If such leukotoxins operate in vivo, they could deprive the gingival crevice area of an essential antibacterial defense mechanism. We have found that sera from juvenile periodontitis patients consistently (greater than 90%) contain antibodies which neutralize Actinobacillus actinomycetemcomitans leukotoxin(s). On the other hand, sera from normal individuals or patients with other types of periodontal disease usually amplified rather than inhibited the leukotoxic reaction. Many patients with juvenile periodontitis have demonstrable defects in PMN or monocyte chemotaxis and this may place them at risk to gingival infection by Actinobacillus actinomycetemcomitans. The immune response against these organisms could be a crucial determinant in the course of juvenile periodontitis. While this disease is relatively rare, it does cause immeasurable emotional, physical and economic hardship for patients and their families. The identification of Actinobacillus actinomycetemcomitans as a potential pathogen in this disorder may eventually lead to specific forms of therapy to prevent and eliminate infection by this organism in these patients.  相似文献   
975.
Subgingival irrigation in the maintenance phase of periodontal therapy   总被引:1,自引:0,他引:1  
The purpose of this study was to evaluate the effect of subgingival scaling versus subgingival pocket irrigation with 0.1% chlorhexidine or saline controls on the repopulation of subgingival periodontal sites with disease-associated micro-organisms following a single procedure of scaling and root planing. Additionally, pertinent clinical parameters (attachment level, plaque index, bleeding on probing) were also recorded. 375 sites in 30 individuals with previously untreated periodontal disease were thoroughly scaled and subsequently either rescaled, irrigated, or not treated at all for the following 6 months at 1-month intervals. The results show that the initial scaling and root planing procedure led to significant clinical and microbiological improvements in all experimental groups. These improvements were maintained in all but the untreated sites. Based on the observed clinical and microbiological changes, subgingival irrigation of periodontal pockets at 1-month intervals was equally effective as scaling and root planing performed at the same pace. 0.1% chlorhexidine however, being used as test irrigant, was not more effective than saline controls.  相似文献   
976.
Toothbrushing force in relation to plaque removal   总被引:1,自引:0,他引:1  
Abstract This was a 2-part study. The purpose of the 1st part was to examine the relationship between brushing force and plaque removal efficacy comparing a regular manual toothbrush (M) with an electric toothbrush the Braun Oral-B Plak Control* (B). The study consisted of a single oral prophylaxis followed by 5 experiments which differed solely in respect to toothbrushing force. At baseline (after 24-h plaque accumulation), the amount of dental plaque was evaluated and subsequently, the subject's mouth was brushed by a dental hygienist. Brushing was carried out in a random split-mouth order. Either the 1st and 3rd quadrants or the 2nd and 4th quadrants were brushed with 1 toothbrush and the 2 remaining quadrants with the other. The available time for the brushing procedure was 2 min. After brushing, the amount of remaining dental plaque was assessed. The force used in experiment 1 through 5 was 100, 150, 200, 250, 300 g, respectively. The results show that when brushing force is increased, more plaque is removed with either of the two brushes. Except for the high brushing force (300 g), the electric toothbrush removed more plaque than the manual brush. The purpose of the 2nd part was to evaluate the habitual brushing force which individuals use with various toothbrushes. Besides a manual toothbrush (M), 3 electric toothbrushes were examined, the Rotadent® (R). Interplak® (I) and Braun® (B). 20 subjects were selected on the basis of being ‘good brushers” (plaque score at screening <25%). At baseline, each subject randomly received 1 of the 4 brushes. They were allowed a training period of 3 weeks at the end of which they were asked to abstain from brushing for at least 24 h. The plaque (Turesky modification of the Quigley & Hein) was scored, after which the subjects brushed their teeth (2 min) with the assigned toothbrush equipped with a strain gauge. A computer set–up measured (100 Hz) and calculated the mean brushing force. After brushing, the amount of remaining plaque was assessed. The design of the study was a 4-way cross-over. The results show that with a manual brush, considerably more force is used than with the electric brushes (R=96. 1 = 119. B= 146, M=273). No significant relation between brushing force and plaque removal was demonstrated for any of the brushes.  相似文献   
977.
BACKGROUND: Chlorhexidine (CHX) mouth rinse/spray can still be considered the gold standard in the chemical prevention of plaque formation and development of gingivitis. The product unfortunately has some side effects, such as extrinsic tooth staining, poor taste, taste disturbance, sensitivity changes in tongue, pain and irritation because of the alcohol content. These side effects led to the search of new formulations. METHODS: In this double-blind, randomized, long-term, parallel study, 48 moderate periodontitis patients rinsed for 6 months (starting immediately after a "one-stage, full-mouth" disinfection) with one of the following products: CHX 0.2%+alcohol (Corsodyl), CHX 0.05%+ cetyl pyridinium chloride (CPC) 0.05% and no alcohol (Perio-Aid Maintenance, a new formulation), or the placebo of the latter. After 1, 3 and 6 months a series of clinical and microbiological parameters were recorded for the supra- and subgingival area as well as for saliva. RESULTS: Although there was a significant treatment impact (mechanical debridement) in all groups, both CHX solutions further decreased both plaque and gingivitis indices (p<0.001 and p<0.05, respectively), when compared with placebo. This was also reflected by additional reductions in the number of CFU/ml of aerobic and especially anaerobic species and by a suppression of Streptococcus mutans (versus an overgrowth for the placebo), in all niches. Differences between both CHX solutions were never encountered. The subjective ratings were slightly in favour of the new CHX-CPC formulation when compared with the other CHX-alcohol formulation, especially for taste of the product (p<0.05), but less impressive for the staining of teeth and tongue. CONCLUSIONS: The results of this study demonstrated the potential of a new CHX 0.05%+CPC 0.05% non-alcoholic formulation as an effective antiplaque agent for long-term use with reduced subjective side effects.  相似文献   
978.
OBJECTIVES: To compare 2 prototype powered toothbrush (PTB) heads (A, B) to a marketed head (Sensiflex 2000) for plaque removing efficacy on the Philips/Jordan HX2550 PTB. MATERIALS AND METHODS: A 2-week, 3-group, single-blind trial recruited 78 volunteers (18-25). Plaque indices (PIs) were recorded at screening and 14 days later at baseline. Subjects were stratified (gender and PI) and then asked to abstain from oral hygiene measures for 48 h. A supervised episode of brushing with the allocated PTB head followed. Subjects then used the PTBs at home for the next 12 days before being asked to abstain from all oral hygiene measures for another 48 h prior to a second supervised brushing episode. Plaque was scored using a new modification of the Quigley & Hein Index (PI) at full mouth (FM), interproximal (IP) and smooth surfaces (SS). PIs were recorded before and after the supervised brushing episodes to enable the means of the within subject differences (pre- to post-brushing) to be compared between groups (ANOVA/t-tests). RESULTS: There were no significant differences in PI between groups at baseline or prior to the supervised brushings (p>0.05). Highly significant, mean reductions in PIs (approximately 1/2 of one PI unit) were observed for design B compared with the Sensiflex 2000 at FM and IP sites (p<0.0001) for both supervised brushing episodes. A significant reduction in PI at SS was seen only after the first brushing episode (p=0.0004). For design A, PI reductions were consistently greater than those for the Sensiflex 2000 but differences were only significant at the p<0.05 level. CONCLUSION: It is concluded that this model of clinical trial has sufficient power to demonstrate clinical superiority with respect to plaque removal for PTBs and can be used for testing one or more prototype designs of brush heads.  相似文献   
979.
To elucidate the nature of dentine hypersensitivity, the effects of plaque control on the patency and occlusion of dentinal tubules were investigated systematically in situ using human dentine slabs embedded in partial dentures. The dentine slabs were divided into three groups. In group I, the dentine slabs were kept in an oral cavity without plaque control. In group II, plaque was removed mechanically by brushing. Plaque control was carried out chemically using chlorhexidine in group III. After being kept in the oral cavities for 1, 2 and 3 weeks, the slabs were removed from the partial denture, followed by SEM observation to determine the morphological changes of the dentinal tubules. When no attempt was made to remove plaque, the diameter of tubule orifices increased to 390% of the original values within 3 weeks. In contrast, dentinal tubules were found to be occluded, i.e. the tubule orifices became <20% of the original value within 1 week when plaque control efforts were made, using either method of plaque control. We conclude that plaque control plays one of the key roles in the patency versus occlusion of dentinal tubules, and thus in the aetiology and natural reparative process of dentine hypersensitivity.  相似文献   
980.
Glucosyltransferases from Streptococcus mutans are thought to play an important role in bacterial adherence to the tooth surface. The goal of the present study was to determine the effect of the deletion of the gtfC gene, which encodes a glucosyltransferase that catalyses primarily the formation of insoluble glucan (mutan), on colonization of S. mutans in a mixed-species biofilm model of supragingival plaque. A gtfC deletion mutant of S. mutans UA159 grew poorly in biofilms on a polystyrene surface in Todd–Hewitt medium containing sucrose, but biofilm formation in the semi-defined fluid universal medium (FUM) was not affected. The S. mutans gtfC mutant colonized with the same efficiency as the wild-type strain when grown together with five other species in a mixed-species biofilm on hydroxyapatite in a mixture of FUM and saliva with pulses of sucrose and showed the same ability to demineralize enamel in vitro . Colonization of mutant and wild-type strains was also equal in an association experiment in specific-pathogen-free rats. However, the gtfC mutant gave rise to more dentinal fissure lesions and smooth surface caries than the wild-type strain; this could be caused by a change in diffusion properties as a result of to the lack of mutan.  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