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   1300155篇
  免费   99309篇
  国内免费   2042篇
耳鼻咽喉   18738篇
儿科学   45951篇
妇产科学   35535篇
基础医学   184561篇
口腔科学   33975篇
临床医学   112579篇
内科学   262443篇
皮肤病学   28880篇
神经病学   101451篇
特种医学   52006篇
外国民族医学   660篇
外科学   199542篇
综合类   27728篇
现状与发展   1篇
一般理论   386篇
预防医学   96737篇
眼科学   29100篇
药学   96391篇
  25篇
中国医学   2504篇
肿瘤学   72313篇
  2018年   13744篇
  2017年   10367篇
  2016年   11488篇
  2015年   12881篇
  2014年   17983篇
  2013年   27164篇
  2012年   37350篇
  2011年   39466篇
  2010年   23563篇
  2009年   22426篇
  2008年   37667篇
  2007年   40340篇
  2006年   40461篇
  2005年   39337篇
  2004年   38375篇
  2003年   37169篇
  2002年   36435篇
  2001年   64504篇
  2000年   66982篇
  1999年   56818篇
  1998年   15309篇
  1997年   13888篇
  1996年   14303篇
  1995年   13546篇
  1994年   12856篇
  1993年   11885篇
  1992年   44793篇
  1991年   43735篇
  1990年   42438篇
  1989年   40351篇
  1988年   37105篇
  1987年   36429篇
  1986年   33803篇
  1985年   32458篇
  1984年   24270篇
  1983年   20391篇
  1982年   11796篇
  1981年   10761篇
  1980年   9588篇
  1979年   21501篇
  1978年   14921篇
  1977年   12621篇
  1976年   11769篇
  1975年   12724篇
  1974年   14756篇
  1973年   14214篇
  1972年   13023篇
  1971年   11792篇
  1970年   11122篇
  1969年   10076篇
排序方式: 共有10000条查询结果,搜索用时 5 毫秒
991.
Oral submucous fibrosis (OSF) is a high risk precancerous condition, predominantly affecting Indians. Consumption of chilli was hypothesized as an etiologic factor on the basis of ecological observations and a solitary animal experimental study. Subsequent epidemiologic studies that included case-series reports, large cross-sectional surveys, case-control studies, cohort and intervention studies have identified areca nut as the major etiologic agent. Tissue-culture studies involving human fibroblasts, areca nut extracts and areca nut alkaloids supported this etiologic hypothesis by showing fibroblastic proliferation and increased collagen formation. Currently, the role of genetic susceptibility and that of autoimmunity are receiving attention. The influence of nutritional factors, if any, remains unclear.  相似文献   
992.
The British Association of Oral and Maxillofacial Surgeons (BAOMS) and the Royal College of Surgeons of Edinburgh (RCSEd) have had leading roles in organisation, assessment and improvement of surgical training in the United Kingdom. This was particularly well illustrated by the establishment of the fellowship examination in Oral and Maxillofacial Surgery (FRCSEd, OMFS).  相似文献   
993.
This study measured the temperature in and around mandibular fractures in 20 anaesthetized patients. A fine calibrated thermocouple attached to a digital thermometer was used to measure temperature at the bone surface margin of a mandibular fracture and 5 and 10 mm from the fracture; within the fracture against the bone at 5, 7 and 10 mm depths and at the base of 7 mm deep biopsy cavities 5 and 10 mm distant from the fracture line immediately after biopsy, then 1 and 2 min later. On the surface the temperature was approximately 1 degrees C warmer than at the 5 and 10 mm sites distant from the fracture. Temperature reduced at the 1 and 2 min readings after the biopsy cavity cutting. This study confirmed that the surface temperature is lower than internal bone temperatures.  相似文献   
994.
OBJECTIVE: Our objective was to evaluate complete unilateral cleft lip and palate repair outcome in the Cleft Unit in Perth, Western Australia, by assessment of dentoalveolar relationships. DESIGN: This is a retrospective study. SETTING: Our subjects were individuals under the care of the cleft team in Perth, Western Australia. PARTICIPANTS: All patients with unilateral cleft lip and palate and available 6-year casts who had been born since January 1, 1985, were identified from the cleft unit's database. The nature of the cleft was verified by examination of birth study models and photographs. A total of 54 such patients were identified. MAIN OUTCOME MEASURES: Main outcome measures were identified through dental arch relationship grading of study models using the 5 Year Old Study Model Index. RESULTS: Interexaminer and intraexaminer agreement kappa statistics revealed good to very good agreement using this index. The results indicate that the surgical outcome was graded as excellent, good, or fair for 77% of patients and poor or very poor for 23% of patients. CONCLUSIONS: The results of the Western Australia study compare favorably to the overall U.K. outcome (the Clinical Standards Advisory Group study) but unfavorably to the results of some European centers, such as Oslo.  相似文献   
995.
This paper reports on a survey of the duration, funding, and assessment of postgraduate specialist orthodontic training, the requirement for postgraduate training prior to entering specialist orthodontic training and registration of specialist orthodontists in Europe. A questionnaire and explanatory letter were mailed to all members of the EURO-QUAL BIOMED II project. Answers were validated during a meeting of project participants and by fax, when necessary. Completed questionnaires which were subsequently validated, were returned by orthodontists from 23 countries. The results indicated that a period of postgraduate training, prior to entering specialist orthodontic training was required in 12 of the responding countries. Specialist orthodontic training was reported as lasting 2 years in three countries, 3 years in 17, and for 4 years in three. Part-time training was reported as a possibility in four countries. In 21 of the 23 countries specialist training was reported to take place in full or part within universities, with some training taking place in government clinics in four countries. In five countries some or all training was reported to take place in specialist practices. Training was said to be funded solely or partially by governments in 15 of the 23 countries, to be solely self-funded in five countries, and partly or solely funded by universities in six countries. A final examination at the end of specialist training was reported to be held in 21 of the 23 countries. The nature of this examination varied widely and there was no such examination in two countries. Twelve of the 23 countries reported that they had a specialist register for orthodontics; 11 that they had no register. In none of the countries surveyed was there a requirement for those on a register to undergo periodic reassessment of competence once they are on the register. It was concluded that there was wide diversity in all aspects of specialist orthodontic training and registration within the countries surveyed.  相似文献   
996.
The purpose of this study was to analyze factors influencing the duration of treatment in a sample of patients treated by a combined orthodontic/orthognathic surgery approach. Presurgical and postsurgical treatment times were assessed for 315 patients processed through an orthognathic team over a 7-year period. The median total treatment duration for all patients was 21.9 months, the median presurgical duration was 15.4 months, and the median postsurgical duration was 5.9 months. Treatment involving extractions resulted in significantly increased presurgical and total treatment times. Treatments performed in the university clinic showed reduced presurgical duration and increased postsurgical duration compared to treatments carried out by specialists outside the university. Presurgical, postsurgical, and total treatment times were significantly reduced when the orthodontist had treated 10 or more patients during the period. An earlier regimen of orthodontic treatment did not appear to have a significant effect on treatment duration.  相似文献   
997.
Abstract. Drug regimens for transplantation often consist of multiple therapeutic agents and may result in drug-induced gingival overgrowth (DIGO). The aim of this study was to investigate the contribution of individual drugs in renal transplant patients. 147 adults (19–84 years) and 60 juveniles (3–18 years) were scored for DIGO and other clinical variables. Duration of treatment, dosage of drugs per kg body weight and serum cyclosporin levels were recorded. 44% of adults and 27% of children had DIGO. All patients were receiving prednisolone. More adults than children were administered cyclosporin, the reverse was true of azathioprine ( P 0.01), Explanatory models were evaluated by stepwise ordinal polynomial logistic regression. Statistically significant explanation ( P 0.05) of DIGO was afforded by prednisolone, nifedipine and azathioprine concentrations in adults and by cyclosporin, nifedipine and azathioprine concentrations in juveniles. Prednisolone and azathioprine were inversely related to the degree of DIGO. Plaque and irregularity scores, lip coverage and mouthbreathing status showed significant additional explanation in adults, replacing nifedipine and azathioprine in the final model. Irregularity was additionally explanatory in children, but no other clinical variables. A larger proportion of the variance of DIGO was explained by the available variables in children than in adults (pseudo r 2=0.50 versus 0.25). The degree of DIGO in renal transplant patients is influenced by the dosage of a number of individual components of multiple drug therapy independently of the presence of local clinical factors.  相似文献   
998.
Five cases of ameloblastic fibrosarcomas (AFS) are reported. The tumour was characterized histologically by a biphasic pattern: the malignant mesenchymal component had the features of an intermediate grade fibrosarcoma in 3 cases, malignant fibrous histiocytoma and osteogenic sarcoma in 2 cases. The epithelial odontogenic component had a benign appearance cytologically. In 1 patient, in the recurrence only the malignant mesenchymal component was present.AFS is a fully malignant tumour, in fact 1 patient died of the tumour after inadequate surgical treatments, and 2 patients had a recurrence after intralesional surgery.The treatment of choice was achieved when surgery with wide surgical margins was performed. As MFH and OGS features are present in the malignant mesenchymal component of this tumour we prefer to use the broad term ameloblastic sarcoma instead of AFS.  相似文献   
999.
PURPOSE: The purpose of this in vitro investigation was to evaluate the effects of air-powder polishing on the shear bond strength of two adhesive systems used for direct orthodontic bracket bonding. METHODS: Ninety-six third molar teeth were randomly assigned to be bonded with metal brackets using either a no-mix (System 1+) or a two-paste (Concise) orthodontic adhesive resin. Twelve samples in each test group were air-powder polished for either 0, 15, 30, or 60 seconds. The shear bond strength was determined for each bracket using the Instron. Scanning electron microscopy determined bond fracture patterns of tested samples. RESULTS: Mean shear bond strength values from baseline to 60 seconds varied from 22.9+/-1.9 megapascal units (MPa) to 18.2+/-4.1 MPa for Concise and from 15.5+/-2.1 MPa to 14.6+/-1.9 MPa for System 1+. A two-factor analysis of variance showed air-powder polishing significantly affected the mean shear bond strength of one adhesive. Results showed a significant decrease (p < or = .05) in the mean shear bond strength of the Concise adhesive at 60 seconds of air-powder polishing when compared to the 0-, 15-, and 30-second treatments. No significant within group time effect of air-powder polishing was found for System 1+. Differences in the fracture pattern of the Concise 60-second air-powder polishing group may account for the decrease in mean bond strength seen after treatment. CONCLUSION: Although in vitro results showed decreased bond strength for Concise, these values were well above the minimum values needed for successful bonding. Therefore, use of air-powder polishing on orthodontic bracket adhesive systems does not appear to be contraindicated.  相似文献   
1000.
The increased frequency and severity of candidal infections in human immunodeficiency virus (HIV)-infected individuals has prompted the wide use of antifungals, such as amphotericin B, ketoconazole, and fluconazole, resulting in the emergence of drug-resistant strains of Candida albicans. To study this phenomenon in an ethnic Chinese cohort, we isolated multiple colonies of Candida from the oral cavities of 16 HIV-infected patients on single and subsequent sequential visits over a period of 12 months. Ten of the 16 patients had sporadic episodes of oropharyngeal candidiasis (Group A), while the remainder were asymptomatic with respect to this condition (Group B). Oral rinses were collected and immediately processed in the laboratory for the isolation of C. albicans in a standard manner. A total of 433 C. albicans isolates were tested for their susceptibility to amphotericin B, ketoconazole and fluconazole by an agar diffusion method using the commercially available E-test. All tested isolates demonstrated variable susceptibility to amphotericin B, ketoconazole and fluconazole. The minimum inhibitory concentration (MIC) of the isolates for amphotericin B, ketoconazole and fluconazole ranged from <0.002-1.5 microg/ml, <0.002-4.0 microg/ml and <0.016-32 microg/ml, respectively. Sequential isolates of a few patients demonstrated variable susceptibility to all the antifungals, and no discernible MIC pattern emerged either in group A or B over time. Interestingly, significant variation in antifungal susceptibility was also noted in isolates obtained from the same patient on a single visit. Sequential yeast isolates in 9 of 16 patients (56%) demonstrated significant differences in MIC within and between visits for both amphotericin B and ketoconazole, while a lower percentage--44%(7/16)--exhibited this trait for fluconazole. Our study demonstrates the diversity in antifungal susceptibility in either commensal or "infective" oral strains of C. albicans in HIV disease, and shows the need for vigilance for the emergence of resistant strains, and for frequent antifungal susceptibility studies.  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