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   4257篇
  免费   371篇
  国内免费   18篇
耳鼻咽喉   57篇
儿科学   181篇
妇产科学   158篇
基础医学   616篇
口腔科学   105篇
临床医学   348篇
内科学   666篇
皮肤病学   58篇
神经病学   313篇
特种医学   314篇
外科学   585篇
综合类   52篇
一般理论   6篇
预防医学   370篇
眼科学   248篇
药学   309篇
中国医学   5篇
肿瘤学   255篇
  2021年   45篇
  2019年   55篇
  2018年   55篇
  2017年   45篇
  2016年   52篇
  2015年   74篇
  2014年   96篇
  2013年   136篇
  2012年   172篇
  2011年   187篇
  2010年   109篇
  2009年   110篇
  2008年   175篇
  2007年   195篇
  2006年   164篇
  2005年   179篇
  2004年   138篇
  2003年   148篇
  2002年   116篇
  2001年   130篇
  2000年   145篇
  1999年   95篇
  1998年   51篇
  1997年   45篇
  1996年   48篇
  1995年   48篇
  1994年   57篇
  1993年   42篇
  1992年   86篇
  1991年   89篇
  1990年   108篇
  1989年   103篇
  1988年   92篇
  1987年   111篇
  1986年   76篇
  1985年   112篇
  1984年   79篇
  1983年   72篇
  1982年   44篇
  1981年   50篇
  1980年   35篇
  1979年   54篇
  1978年   56篇
  1977年   53篇
  1975年   36篇
  1974年   32篇
  1973年   44篇
  1972年   41篇
  1967年   31篇
  1966年   38篇
排序方式: 共有4646条查询结果,搜索用时 62 毫秒
1.
2.
Dietary habits and obesity are established in early childhood. This secondary data analysis examined changes in dietary quality among treatment-seeking preschoolers with obesity(n=13). 24-hour dietary recall data collected at baseline, post-treatment(6 months), and 6-months post-treatment follow-up(12 months) were analyzed using the Healthy Eating Index(HEI)-2010. Repeated-measures analyses of variance revealed significant improvements in overall dietary quality and reductions in empty calories from baseline to 12 months. Change in overall dietary quality was not associated with change in BMI z-score at either time point. Identifying effective strategies to increase nutrient-dense food groups(e.g., vegetables) is important for maximizing the health impact of preschool obesity interventions.  相似文献   
3.
4.

Background and purpose

We have previously shown that during the first 2 years after total hip arthroplasty (THA), periprosthetic bone resorption can be prevented by 6 months of risedronate therapy. This follow-up study investigated this effect at 4 years.

Patients and methods

A single-center, double-blind, randomized placebo-controlled trial was carried out from 2006 to 2010 in 73 patients with osteoarthritis of the hip who were scheduled to undergo THA. The patients were randomly assigned to receive either 35 mg risedronate or placebo orally, once a week, for 6 months postoperatively. The primary outcome was the percentage change in bone mineral density (BMD) in Gruen zones 1 and 7 in the proximal part of the femur at follow-up. Secondary outcomes included migration of the femoral stem and clinical outcome scores.

Results

61 of the 73 patients participated in this 4-year (3.9- to 4.1-year) follow-up study. BMD was similar in the risedronate group (n = 30) and the placebo group (n = 31). The mean difference was −1.8% in zone 1 and 0.5% in zone 7. Migration of the femoral stem, the clinical outcome, and the frequency of adverse events were similar in the 2 groups.

Interpretation

Although risedronate prevents periprosthetic bone loss postoperatively, a decrease in periprosthetic BMD accelerates when therapy is discontinued, and no effect is seen at 4 years. We do not recommend the use of risedronate following THA for osteoarthritis of the hip.Adaptive bone remodeling around the femoral stem following total hip arthroplasty (THA) results in regional loss of bone mass, especially in proximal parts of the femur—most of which takes place within the first postoperative year (Bodén et al. 2006, Sköldenberg et al. 2006). Periprosthetic bone loss may predispose to periprosthetic fracture, aseptic loosening, and difficulties at revision surgery (Lindahl 2007, Streit et al. 2011, Sköldenberg et al. 2014).The bisphosphonate (BP) risedronate has been used successfully to prevent osteoporotic fractures, mainly in the hip and vertebrae, by inhibiting osteoclast activity (McClung et al. 2001). In recent years, the possible use of BPs to prevent or ameliorate periprosthetic adaptive bone resorption, osteolysis, and implant migration has been investigated thoroughly in animal models and humans. The short-term results of several studies showing the effects of postoperative BP treatment in reducing periprosthetic bone loss up to a year after the arthroplasty have already been published (Venesmaa et al. 2001, Wilkinson et al. 2001, Hennigs et al. 2002, Wilkinson et al. 2005, Arabmotlagh et al. 2006).We have previously found that risedronate given once a week for 6 months after THA reduces periprosthetic bone resorption around an uncemented femoral stem in the first and second postoperative year (Sköldenberg et al. 2011). We now report the 4-year outcome in the same cohort.  相似文献   
5.
6.
7.
8.
There is no commonly accepted standardized terminology for oral diagnoses. The purpose of this article is to report the development of a standardized dental diagnostic terminology by a work group of dental faculty members. The work group developed guiding principles for decision making and adhered to principles of terminology development. The members used an iterative process to develop a terminology incorporating concepts represented in the Toronto/University of California, San Francisco/Creighton University and International Classification of Diseases (ICD)-9/10 codes and periodontal and endodontic diagnoses. Domain experts were consulted to develop a final list of diagnostic terms. A structure was developed, consisting of thirteen categories, seventy-eight subcategories, and 1,158 diagnostic terms, hierarchically organized and mappable to other terminologies and ontologies. Use of this standardized diagnostic terminology will reinforce the diagnosis-treatment link and will facilitate clinical research, quality assurance, and patient communication. Future work will focus on implementation and approaches to enhance the validity and reliability of diagnostic term utilization.  相似文献   
9.
Effect of pulsed electromagnetic fields on orthodontic tooth movement   总被引:3,自引:0,他引:3  
The purpose of this study was to determine whether the application of a simple surgically noninvasive, pulsed electromagnetic field could increase both the rate and amount of orthodontic tooth movement observed in guinea pigs. In addition, the objective was to evaluate the electromagnetic field's effects on bony physiology and metabolism and to search for possible systemic side effects. Laterally directed orthodontic force was applied to the maxillary central incisors of a sample of 40 young male, Hartley guinea pigs (20 experimental, 20 control) by means of a standardized intraoral coil spring inserted under constricting pressure into holes drilled in the guinea pigs' two maxillary central incisors. During the experimental period, the guinea pigs were placed in specially constructed, plastic animal holders with their heads positioned in an area of uniform electromagnetic field. Control animals were placed in similar plastic holders that did not carry the electrical apparatus. The application of a pulsed electromagnetic field to the experimental animals significantly increased both the rate and final amount of orthodontic tooth movement observed over the 10-day experimental period. The experimental animals also demonstrated histologic evidence of significantly greater amounts of bone and matrix deposited in the area of tension between the orthodontically moved maxillary incisors. This increase in cellular activity was also reflected by the presence of significantly greater numbers of osteoclasts in the alveolar bone surrounding the maxillary incisors of the experimental animals. After a 10-day exposure to pulsed electromagnetic field, minor changes in serologic parameters relating to protein metabolism and muscle activity were noted. The results of this study suggest that it is possible to increase the rate of orthodontic tooth movement and bone deposition through the application of a noninvasive, pulsed electromagnetic field.  相似文献   
10.
BACKGROUND: Non-steroidal anti-inflammatory agents inhibit the production of cyclooxygenase (COX) products and can attenuate bone loss. In this double-masked, placebo-controlled, randomized clinical trial, the efficacy of celecoxib (COX-2 inhibitor) was evaluated in conjunction with scaling and root planing (SRP) in subjects with chronic periodontitis (CP). METHODS: A total of 131 subjects were randomized to receive SRP and either celecoxib (200 mg) or placebo every day for 6 months. Clinical outcomes were assessed every 3 months for 12 months as mean changes from baseline. Primary efficacy parameters included clinical attachment level (CAL) and probing depth (PD). Secondary outcomes included percentages of tooth sites with CAL loss or gain > or =2 mm, changes in bleeding on probing (BOP), plaque index, and mobility. Prior to analysis, tooth sites were grouped based on baseline PD as shallow (1 to 3 mm), moderate (4 to 6 mm), or deep (> or =7 mm). RESULTS: Mean PD reduction and CAL gain were greater in the celecoxib group, primarily in moderate and deep sites, throughout the study (PD: 3.84 mm versus 2.06 mm, P <0.001; CAL: 3.74 mm versus 1.43 mm, P <0.0001 for deep sites at 12 months). The celecoxib group also exhibited a greater percentage of sites with > or =2 mm CAL gain and fewer sites with > or =2 mm CAL loss. Both groups showed improved plaque control and BOP scores. Demographic, social, and behavioral factors did not affect treatment outcomes. CONCLUSIONS: Celecoxib can be an effective adjunctive treatment to SRP to reduce progressive attachment loss in subjects with CP. Its beneficiary effect persisted even at 6 months postadministration. However, given the increased cardiovascular risks associated with the use of this drug, close patient supervision and strict adherence to dosage and administration guidelines established by the Unites States Food and Drug Administration are of paramount importance.  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