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   147879篇
  免费   10775篇
  国内免费   662篇
耳鼻咽喉   1798篇
儿科学   3705篇
妇产科学   2736篇
基础医学   19022篇
口腔科学   3298篇
临床医学   15048篇
内科学   29938篇
皮肤病学   1963篇
神经病学   12981篇
特种医学   5785篇
外国民族医学   3篇
外科学   23573篇
综合类   2228篇
现状与发展   1篇
一般理论   182篇
预防医学   13523篇
眼科学   3120篇
药学   10597篇
  2篇
中国医学   186篇
肿瘤学   9627篇
  2023年   715篇
  2022年   1115篇
  2021年   2690篇
  2020年   1556篇
  2019年   2536篇
  2018年   3092篇
  2017年   2259篇
  2016年   2375篇
  2015年   2879篇
  2014年   4230篇
  2013年   6411篇
  2012年   9328篇
  2011年   9928篇
  2010年   5538篇
  2009年   5106篇
  2008年   8850篇
  2007年   9507篇
  2006年   9075篇
  2005年   9189篇
  2004年   8831篇
  2003年   8306篇
  2002年   8180篇
  2001年   1752篇
  2000年   1540篇
  1999年   1816篇
  1998年   1773篇
  1997年   1425篇
  1996年   1393篇
  1995年   1352篇
  1994年   1172篇
  1993年   1122篇
  1992年   1129篇
  1991年   1153篇
  1990年   1040篇
  1989年   982篇
  1988年   1010篇
  1987年   978篇
  1986年   1011篇
  1985年   1086篇
  1984年   1092篇
  1983年   1022篇
  1982年   1218篇
  1981年   1266篇
  1980年   1056篇
  1979年   806篇
  1978年   779篇
  1977年   706篇
  1976年   622篇
  1975年   556篇
  1974年   577篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
INTRODUCTION: The purposes of this review were to evaluate the effectiveness of computer-aided learning (CAL) in orthodontic education, to make evidence-based recommendations for the use of CAL in orthodontics, and to develop guidelines for conducting comparative trials to evaluate CAL as a mode of learning in orthodontic education. METHODS: Medline, the Cochrane Library Database, ERIC, CINAHL, LISA, Psycinfo, and IPA were searched for randomized controlled trials evaluating the effectiveness of CAL in orthodontics. Outcome measures included objectively measured posttest scores on multiple choice, written, or oral tests; performance on a clinical procedure or clinical interview; time spent on CAL programs to learn the material presented; and responses to questionnaires conveying participants' attitudes toward various modes of learning. RESULTS: Four randomized controlled trials comparing CAL with conventional teaching fulfilled the inclusion criteria and met the cutoff quality assessment checklist (QAC) score of > or = 8. Each study was assessed for quality by 2 independent reviewers. The validity and strength of the selected studies were assessed by using a QAC for an educational intervention. CONCLUSIONS: The controlled trials of CAL in orthodontics that met our QAC cutoff score of 8 were split, with 2 showing that CAL enjoyed a significant advantage over conventional teaching, 1 showing no difference, and 1 showing that the conventional tutorial method was better. More high-quality trials evaluating the effectiveness of CAL in orthodontics are needed. CAL programs in orthodontics elicit mostly positive responses and attitudes from students toward learning.  相似文献   
72.
SYSTEMATIC REVIEW CONCLUSION: Increased incidence and severity of external apical root resorption (EARR) occurred in patients undergoing comprehensive orthodontic therapy, especially when therapy involved higher levels of force than those commonly used for orthodontic tooth movement. CRITICAL SUMMARY ASSESSMENT: Results from a high-quality systematic review of 11 randomized clinical trials (RCTs) suggests that EARR has a multifactorial etiology; is associated with comprehensive orthodontics; supports the clinical use of light forces, especially during intrusion of teeth; and requires higher-quality research. EVIDENCE QUALITY RATING: Limited.  相似文献   
73.
This article reviews the history of tooth whitening and its rapid evolution and briefly discusses tooth whitening agents and protocols. The active ingredients and mode of action during the whitening process are explained. The factors affecting the speed of whitening and its final results are discussed, as well as adverse effects and safety precautions. Protocols are explained in detail, and the predicted outcomes, including those for tetracycline-stained teeth, are covered.  相似文献   
74.
PURPOSE: Our goal was to report on the incidence of sedation failures in our outpatient oral surgery clinic. Sedation failure is the inability to complete a procedure under intravenous sedation. There is very little in the oral surgery literature on this subject. MATERIALS AND METHODS: Proper Institutional Review Board approval was obtained from the appropriate governing body for this project. The medical records of 539 intravenous sedation patients treated at the Oral and Maxillofacial Surgery Clinic at our institution were retrospectively evaluated to determine the incidence of failed sedation. Patients sedated with midazolam and fentanyl were placed in group A. There were 323 patients in group A. We placed patients sedated with midazolam, fentanyl and methohexital into group B. There were 216 patients in group B. The gender, medical history, type of procedure being performed, amount of drug given, and the patient's vital signs throughout the procedure were recorded. RESULTS: There were 9 failed sedations with a rate of 1.6% (9/539); 3 in group B (1%) and 6 in group A (2%). Five of our failures were undergoing multiple tooth extractions. Two of the failures were undergoing surgical removal of impacted third molars. Two patients underwent mandibular fracture reduction. Failure was attributed to increased agitation and combativeness, uncontrolled hypertension, tachycardia and desaturation. CONCLUSION: The mandible fracture population and multiple teeth extraction patients had higher rates of failure than other groups. This may be the result of procedure length, type of procedure, or a preoperative anxiety and attitude toward treatment expressed by the patient making sedation unpredictable. Level of training and experience of the practitioner may contribute to sedation failure. These results allow us to develop a prospective study protocol of outpatient sedation and to quantify more detailed information about preoperative anxiety, medical status, and social history than we had available during our chart review. More specific conclusions may help us determine if certain patient populations are at a higher risk for failed sedations.  相似文献   
75.
The purpose of this in vitro study was to evaluate quantitatively the effectiveness of three different restorative materials used as an intracoronal barrier to prevent microleakage of endodontically treated teeth. Fifty-five extracted human single-canal teeth were used in this study. The teeth were endodontically prepared and obturated. Forty-five teeth were randomly assigned to three experimental groups: group 1: sealed with Ketac-Cem (3M ESPE, St Paul, MN) (n = 15), group 2: sealed with Clearfil Protect Bond/Clearfil AP-X (Kuraray, New York, NY) (n = 15), and group 3: sealed with Maxcem (Kerr, Orange, CA) (n = 15). Ten teeth were also randomly assigned to a negative control group (n = 5) and a positive control group (n = 5). Microleakage was tested by using a sterile two-chamber bacterial method and Enterococcus faecalis was used as a microbial marker. Samples were incubated aerobically at 37 degrees C for 120 days. Bacterial leakage was determined by change in turbidity in the medium. Statistical analysis was performed using a Wald chi-square test. No significant difference (p > 0.05) in bacterial leakage was found between the three experimental groups tested. All positive controls leaked within 60 days and broth of the negative control group remained clear throughout the entire experimental period.  相似文献   
76.
BACKGROUND: During the last 15 years, a substantial number of population-based, clinical, laboratory, and animal studies have been published that reported findings on the relationship between periodontal disease and cardiovascular disease. The Periodontitis and Vascular Events (PAVE) pilot study was conducted to investigate the feasibility of a randomized secondary prevention trial to test whether treatment of periodontal disease reduces the risk for cardiovascular disease. This article describes the occurrence of adverse events during the pilot study. METHODS: The PAVE pilot study was a multicenter, randomized trial comparing periodontal therapy to community dental care. Baseline and follow-up clinic visits included a periodontal examination; blood, subgingival plaque, and crevicular fluid specimen collection; and medical and dental histories. Telephone follow-up contacts were scheduled to occur 3 months after randomization and every 6 months thereafter to assess adverse events or endpoints. RESULTS: Cardiovascular adverse events occurred with similar frequency (23 versus 24 [P = 0.85] in the community control and the treatment groups, respectively). There were 15 serious adverse events (SAEs) with a non-significantly higher percentage occurring in the community care group (6.6% versus 3.3%; P = 0.19). A time-to-event analysis of patterns of SAEs indicated that subjects in the periodontal therapy group tended to be less likely to experience an SAE over the entire 25 months of the study. CONCLUSION: For those individuals who remained in the study, it appears that provision of periodontal scaling and root planing treatment to individuals with heart disease resulted in a similar pattern of adverse events as seen in the community care group, which also received some treatment.  相似文献   
77.
78.
79.
The purpose of this study was to examine how patients perceived the professionalism of University of Minnesota School of Dentistry students, faculty, and staff. Professionalism is defined by the authors as an image that will promote a successful relationship with the patient. Patients within comprehensive care clinics were asked to assess physical attributes and behaviors of the dental care providers using a questionnaire. The patients read statements dealing with characteristics of the dental care providers and responded as to whether they agreed, were neutral, or disagreed with the statement. The surveyed population consisted of 103 males and 97 females, 64 percent of whom lacked insurance coverage. Fifty-one percent of the patients were between the ages of forty-four and sixty-nine, but the overall age distribution was dispersed over a range of eighteen to one hundred. Our research found that all dental care providers displayed a professional appearance as well as behavior. The attire of the dental care provider affected the comfort and anxiety levels of patients, as did first impressions of both students and faculty. Most patients reported that students and faculty displayed effective time management and used appropriate language during the appointment. Finally, hairstyle, makeup, and jewelry appeared to have little effect on patients' opinions of the various dental care providers.  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