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   195118篇
  免费   8899篇
  国内免费   522篇
耳鼻咽喉   2450篇
儿科学   6005篇
妇产科学   4026篇
基础医学   25675篇
口腔科学   8547篇
临床医学   14800篇
内科学   43237篇
皮肤病学   4656篇
神经病学   16486篇
特种医学   5945篇
外国民族医学   26篇
外科学   23897篇
综合类   1486篇
现状与发展   2篇
一般理论   76篇
预防医学   19511篇
眼科学   3625篇
药学   11735篇
  6篇
中国医学   759篇
肿瘤学   11589篇
  2024年   499篇
  2023年   1134篇
  2022年   2330篇
  2021年   4351篇
  2020年   2934篇
  2019年   4215篇
  2018年   5541篇
  2017年   4183篇
  2016年   3909篇
  2015年   4596篇
  2014年   6311篇
  2013年   7988篇
  2012年   12240篇
  2011年   12882篇
  2010年   6596篇
  2009年   5896篇
  2008年   10081篇
  2007年   10641篇
  2006年   9812篇
  2005年   10106篇
  2004年   9522篇
  2003年   8641篇
  2002年   6578篇
  2001年   5199篇
  2000年   5148篇
  1999年   4555篇
  1998年   1720篇
  1997年   1428篇
  1996年   1400篇
  1995年   1204篇
  1994年   1155篇
  1993年   1055篇
  1992年   2726篇
  1991年   2667篇
  1990年   2428篇
  1989年   2425篇
  1988年   2184篇
  1987年   2013篇
  1986年   1872篇
  1985年   1807篇
  1984年   1305篇
  1983年   1049篇
  1982年   611篇
  1981年   540篇
  1980年   524篇
  1979年   945篇
  1978年   628篇
  1975年   558篇
  1974年   566篇
  1973年   558篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Multilevel assessment of determinants of dental caries experience in Brazil   总被引:2,自引:0,他引:2  
OBJECTIVE: To examine contextual and individual determinants of dental caries experience, documenting levels of the disease in Brazil. METHODS: The dental status of 34 550 12-year-old schoolchildren was informed by a country-wide survey of oral health comprising 250 towns and performed in 2002-2003. Indices assessing dental caries experience were compared by sociodemographic characteristics of examined children (gender, ethnic group, localization and type of school), and geographic characteristics of participating towns [the human development index (HDI), and access to fluoridated tap water]. A multilevel model fitted the adjustment of untreated caries to individual and contextual covariates. RESULTS: Better-off Brazilian regions presented an improved profile of dental health, besides having a less unequal distribution of restorative dental treatments between blacks and whites, rural and urban areas, and public and private schools. Girls [odds ratio (OR)=1.1; 95% confidence interval (CI): 1.0-1.1], blacks (OR=1.6; 95% CI: 1.5-1.7), and children studying in rural areas (OR=1.9; 95% CI: 1.7-2.0) and public schools (OR=1.7; 95% CI: 1.6-1.9) presented higher odds of having untreated decayed teeth. The multilevel model identified the fluoride status of tap water (beta=-0.3), the proportion of households linked to the water network (beta=-0.3), and the HDI (beta=-0.2), as town-level variables associated with caries levels. CONCLUSION: Dental caries experience is prone to sociodemographic and geographic inequalities. The monitoring of contrasts in dental health outcomes is relevant for programming socially appropriate interventions aimed both at overall improvements and at the targeting of resources for groups of population presenting higher levels of needs.  相似文献   
72.
73.
The aim of this study was to conduct a 1-year full esthetic evaluation of the treatment outcomes of gingival recession using the root coverage esthetic score (RES) system. One hundred patients with 195 single or multiple recessions were treated using different techniques. One year after surgery, the clinical outcomes were evaluated. Only 21 of 195 (11%) treated recessions obtained the maximum RES score (10), while 68 recessions (35%) showing complete root coverage obtained lower scores. Both single and multiple recessions treated with a coronally advanced flap with or without connective tissue grafting achieved similar RES scores. Free gingival grafts showed the lowest score.  相似文献   
74.
75.
Supernumerary teeth are an infrequent developmental anomaly that can appear in any area of the dental arch and can affect any dental organ. Multiple supernumerary teeth, or hyperdontia, is rare in people with no other associated diseases or syndromes. Conditions commonly associated with hyperdontia include cleft lip and palate, trichorhinophalangeal syndrome, cleidocranial dysplasia, and Gardner's syndrome. A black girl, aged 11 years 8 months, came for consultation; radiographs showed 81 teeth: 18 deciduous, 32 permanent, and 31 supernumerary. The main concern initially was to determine whether she was syndromic, and she was referred to a geneticist. G banding analysis showed pericentric inversion of chromosome 9; the chromosome formula was 46, XX, inv (9) (p13q21). Orthodontic treatment for this patient will be a clinical challenge because of the great number of teeth to be extracted and the alterations in the shapes of the teeth. Treatment goals should be established by a multidisciplinary team, where oral surgeon, orthodontist, periodontist, and prosthodontist come together to solve a medical and dental puzzle, eliminating the pieces that do not fit and searching for new ones to obtain an occlusion that will give the patient physiologic conditions of normality and esthetic satisfaction.  相似文献   
76.
Background: Recent studies in animals have shown pronounced resorption of buccal bone plate after immediate implantation. The sectioning of experimental material for histologic evaluation of the bone plates could provide valuable information about the possible effect of bone exposure in periodontal and implant surgeries. Methods: Twenty‐four incisors were collected from dogs. After decalcification, the blocks were immersed in paraffin and bucco‐lingual histologic sections were examined under light microscope. Some sections were reserved for immunohistochemical analysis. Results: The bone density, the width of the bone plates, and the percentage of vessels presented in the periodontal ligament and periosteum were analyzed in the buccal and lingual bone plates, which were divided corono‐apically into thirds. The buccal bone plates showed statistically higher bone density compared to the lingual bone plates in the coronal thirds. The width of both bone plates increased from the coronal to the apical third, but all the buccal thirds were significantly thinner compared to the lingual thirds. No statistically significant differences were found between the bone plates for the percentage of area occupied by the blood vessels in the periodontal ligament or periosteum. Conclusion: It is reasonable to conclude that the higher bone density, represented by the lower number of marrow spaces, in association with the thinner aspect of the buccal bone plates made them more fragile to absorb compared to the lingual bone plates, especially during mucoperiosteal procedures.  相似文献   
77.
The objective of the current study was to evaluate the sensitivity, specificity and accuracy of fine needle aspiration biopsy (FNAB) of submucous nodules from the oral cavity and head and neck region as an auxiliary diagnostic tool. Fifty patients with nodule lesions in the oral cavity and the head and neck region were selected. All of them were submitted to FNAB and to either incisional or excisional biopsy. The diagnoses from the FNABs were compared with the biopsy diagnosis as the gold standard. All the cases of FNAB were analyzed by a single oral pathologist prior to the biopsy diagnosis. The results showed that the sensitivity of FNAB was 75%, its specificity was 96% and its accuracy was 58.8%. The false positive and false negative rates were 6.7% and 13.3%, respectively. The positive predictive value was 86% and the negative predictive value was 93%. The inconclusive rate was 16/50. FNAB displayed a high success rate for identifying both malignant and benign lesions, but a low accuracy for making a final diagnosis.  相似文献   
78.
Objectives: The objectives of this study were to determine the accuracy of Periotest® to monitor primary implant stability at first‐stage surgery, to identify by multivariate analysis the variables associated with early implant failure and to compare Periotest® with radiographic study in the diagnosis of implant stability at second‐stage surgery (during osseointegration period). Material and methods: A 10‐year retrospective study was conducted on 1084 Brånemark® implants placed in 316 patients. Clinical variables, implant diameter and length, Periotest® values (PTVs) and radiological variables were analyzed in bivariate and multivariate studies in order to determine their influence on early implant failure. Results: After examination of the sensitivity and specificity values obtained for different PTV cutoff points, a cutoff PTV of ?2 was selected (84% sensitivity and 39% specificity). In the bivariate analysis, early failure was significantly related to smoking habits, implant location, bone type, implant features and PTVs (?2 and ≥?2). In the final multiple logistic model, only age (odds ratio (OR)=4.53; 95% confidence interval (CI), 1.34–15.27), smoking habits (OR=2.5; 95% CI, 1.3–4.79), bone type (OR=1.93; 95% CI, 1.01–3.7) and PTV at first surgery (OR=3.01; 95% CI, 1.5–6.02) were independently related to early failure. Conclusions: The Periotest® (with ?2 cutoff) at first surgery offers high sensitivity in the prognosis of early implant loss and shows a greater capacity to evaluate stability during the osseointegration period compared with radiographic study.  相似文献   
79.
OBJECTIVE: The objective of this in vitro study was to evaluate the influence of resin composite shade and location of the gingival margin (enamel or dentin) on the microleakage of proximal restorations on posterior teeth. Methods and MATERIALS: Sixty freshly extracted human third molars were prepared with standardized Class II box-shaped cavities with proportional size and shape, with distal gingival margins located on the enamel and mesial gingival margins on dentin. The teeth were randomly divided into 6 groups according to resin shade (n=10): G1-Incisal; G2-A1; G3-A2; G4-A3; G5-A3.5; G6-A4. The cavities were restored with a total-etch 1-bottle adhesive system and microhybrid resin composites inserted in 4 increments, light cured for 20 seconds through the occlusal surface, then an additional 60 seconds for each surface. After 1 week of immersion in distilled water, the specimens were thermocycled (500 cycles, 5 degrees -55 degrees C, 30 seconds dwell time), sealed with nail polish and immersed in 0.5% basic fuschin solution for 24 hours. The restorations were sectioned longitudinally, and microleakage was evaluated using a 0-3 score scale. RESULTS: Data were subjected to Kruskal-Wallis and Wilcoxon tests at p<0.05. No statistically significant differences between groups were observed regarding the shade of resin composite (p=0.8570). When margins (enamel or dentin) were considered separately, statistically significant differences were observed between groups (p<0.0001), with enamel margins exhibiting lower degrees of microleakage. CONCLUSION: The variation of resin composite shades utilized in this study did not influence the microleakage of Class II restorations. However, the location of the gingival margin influenced the microleakage.  相似文献   
80.
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