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   738篇
  免费   37篇
耳鼻咽喉   4篇
儿科学   11篇
妇产科学   9篇
基础医学   65篇
口腔科学   14篇
临床医学   57篇
内科学   157篇
皮肤病学   10篇
神经病学   85篇
特种医学   12篇
外科学   177篇
综合类   5篇
预防医学   67篇
眼科学   7篇
药学   37篇
中国医学   5篇
肿瘤学   53篇
  2023年   13篇
  2022年   8篇
  2021年   35篇
  2020年   26篇
  2019年   33篇
  2018年   21篇
  2017年   8篇
  2016年   17篇
  2015年   36篇
  2014年   40篇
  2013年   53篇
  2012年   65篇
  2011年   75篇
  2010年   41篇
  2009年   25篇
  2008年   35篇
  2007年   41篇
  2006年   37篇
  2005年   51篇
  2004年   27篇
  2003年   23篇
  2002年   24篇
  2001年   3篇
  2000年   3篇
  1999年   2篇
  1998年   3篇
  1997年   2篇
  1995年   1篇
  1992年   4篇
  1991年   2篇
  1990年   1篇
  1988年   4篇
  1987年   4篇
  1985年   3篇
  1983年   3篇
  1979年   3篇
  1978年   1篇
  1976年   1篇
  1974年   1篇
排序方式: 共有775条查询结果,搜索用时 31 毫秒
1.
Objective: Advanced parental age might constitute a risk factor for various disorders. We tested whether this concerns also mood disorder patients.

Methods: The study included 314 subjects (42 bipolar-BD patients; 21 manics and 21 depressives, 68 unipolar-UD, and 204 normal controls-NC). Analysis of Covariance (ANCOVA) and the calculation of the Relative Risk (RR) and the Odds Ratio (OR) were used for the analysis.

Results: Paternal age differed between NC and UD patients (29.42?±?6.07 vs. 32.12?±?5.54; p?=?.01) and manics (29.42?±?6.07 vs. 35.00?±?5.75; p?=?.001) and maternal age between NC and manics (25.46?±?4.52 vs. 31.43?±?4.75; p?<?.001) and manic and UD (31.43?±?4.75 vs. 26.75?±?6.03; p?=?.002). The RR and OR values suggested that advanced parental age constitutes a risk factor for the development of mood disorders.

Conclusions: In a non-dose dependent and gender-independent, advanced parental age constitutes a risk factor for the development of BD with index episode of mania (probably manic predominant polarity); only advanced paternal age constitutes a risk factor for the development of UD and BD with index episode of depression (probably depressive predominant polarity). This is the first study suggesting differential effect of advanced parental age depending on predominant polarity of BD.  相似文献   

2.

Introduction

Stereotactic body radiation therapy (SBRT) is a promising curative treatment for early-stage NSCLC. It is unclear if survival outcomes for SBRT are influenced by a lack of pathological confirmation of malignancy and staging of disease in these patients. In this systematic review and meta-analysis, we assess survival outcomes after SBRT in studies with patients with clinically diagnosed versus biopsy-proven early-stage NSCLC.

Methods

The main databases were searched for trials and cohort studies without restrictions to publication status or language. Two independent researchers performed the screening and selection of eligible studies. Outcomes were overall survival, cancer-specific survival, and disease-free survival. The inverse variance method and the random effects method for meta-analysis were used to assess pooled survival estimates.

Results

A total of 11,195 nonduplicate records were identified by the original search strategy. After screening by title and abstract, 1051 potentially eligible records were identified. A total of 43 articles were included. The comparative studies showed lower 3-year overall survival and lower 2-year and 5-year cancer-specific survival for biopsy-proven disease compared to clinical disease. However, 5-year overall survival was the same for both groups. For the pooled estimates, 3-year disease-free survival and 2-year cancer-specific survival were lower for biopsied disease.

Conclusions

Results of this systematic review and meta-analysis show a discrepancy in oncological outcomes for patients undergoing SBRT for suspected early-stage NSCLC in whom there is pathologic conformation of malignancy and those who there is only a clinical diagnose of NSCLC. These results emphasize the importance of obtaining pathologic proof of malignancy.  相似文献   
3.
4.
OBJECTIVE: The aim of this study was to evaluate, in vitro, the cariostatic effect of whitening toothpastes. METHODS AND MATERIALS: Ninety-five dental fragments were obtained from nonerupted third molars. The fragments were embedded in polystyrene resin and sequentially polished with abrasive papers (400-, 600-, and 1,000-grit) and diamond pastes of 6, 3, and 1 microm. The fragments were assigned in five groups according to toothpaste treatment: G1 = Rembrandt Plus with Peroxide; G2 = Crest Dual Action Whitening; G3 = Aquafresh Whitening Triple Protection; and the control groups: G4 = Sensodyne Original (without fluoride); G5 = Sensodyne Sodium Bicarbonated (with fluoride). The initial enamel microhardness evaluations were done. For 2 weeks the fragments were submitted daily to a de-remineralization cycle followed by a 10-minute toothpaste slurry. After that, the final microhardness tests were done. The percentage of mineral loss of enamel was determined for statistical analysis. Analysis of variance and the Tukey test were applied. RESULTS: The results did not show statistically significant differences in mineral loss among groups G1, G2, G3, and G5, which statistically differ from G4 (toothpaste without fluoride). G4 showed the highest mineral loss (P < or = .05). CONCLUSION: The whitening toothpastes evaluated showed a cariostatic effect similar to regular, nonwhitening toothpaste.  相似文献   
5.
Kobayashi CAN, Belini MR, Italiani FM, Pauleto ARC, Julianelli de Araújo J, Tessarolli V, Grizzo LT, Pessan JP, Machado MAAM, Buzalaf MAR. Factors influencing fluoride ingestion from dentifrice by children. Community Dent Oral Epidemiol 2011; 39: 426–432. © 2011 John Wiley & Sons A/S Abstract – Objective: This study assessed the percentage of the amount of dentifrice loaded onto the toothbrush that is ingested by children, taking into account age, the amount of dentifrice used during toothbrushing, and the dentifrice flavor. Methods: The sample consisted of 155 children of both genders attending public kindergartens and schools in Bauru, Brazil, divided into 5 groups (n = 30–32) of children aged 2, 3, 4, 5 and 6 years old. The dentifrices used were Sorriso? (1219 ppm F, peppermint‐flavored) and Tandy? (959 ppm F, tutti‐frutti‐flavored). The assessment of fluoride intake from dentifrices was carried out six times for each child, using 0.3, 0.6, and 1.2 g of each dentifrice, following a random, crossover distribution. Brushing was performed by the children or their parents/caregivers according to the home habits and under the observation of the examiner. Fluoride present in the expectorant and on toothbrush was analyzed with an ion‐specific electrode after HMDS‐facilitated diffusion. Fluoride ingestion was indirectly derived. Results were analyzed by 3‐way repeated‐measures anova and Tukey’s tests (P < 0.05) using the percent dentifrice ingested as response variable. Results: Age and percent dentifrice ingested for both dentifrices, and the three amounts used were inversely related (P < 0.0001). Percent dentifrice ingested was significantly higher after the use of Tandy? under all conditions of the study when compared with Sorriso? (P < 0.0001). Significant differences were observed when brushing with 0.3 g when compared with 1.2 g, for both dentifrices tested (P < 0.05). Conclusions: The results indicate that all variables tested must be considered in preventive measures aiming to reduce the amount of fluoride ingested by young children.  相似文献   
6.
Efforts to understand nervous system structure and function have received new impetus from the federal Brain Research through Advancing Innovative Neurotechnologies (BRAIN) Initiative. Comparative analyses can contribute to this effort by leading to the discovery of general principles of neural circuit design, information processing, and gene‐structure‐function relationships that are not apparent from studies on single species. We here propose to extend the comparative approach to nervous system ‘maps' comprising molecular, anatomical, and physiological data. This research will identify which neural features are likely to generalize across species, and which are unlikely to be broadly conserved. It will also suggest causal relationships between genes, development, adult anatomy, physiology, and, ultimately, behavior. These causal hypotheses can then be tested experimentally. Finally, insights from comparative research can inspire and guide technological development. To promote this research agenda, we recommend that teams of investigators coalesce around specific research questions and select a set of ‘reference species' to anchor their comparative analyses. These reference species should be chosen not just for practical advantages, but also with regard for their phylogenetic position, behavioral repertoire, well‐annotated genome, or other strategic reasons. We envision that the nervous systems of these reference species will be mapped in more detail than those of other species. The collected data may range from the molecular to the behavioral, depending on the research question. To integrate across levels of analysis and across species, standards for data collection, annotation, archiving, and distribution must be developed and respected. To that end, it will help to form networks or consortia of researchers and centers for science, technology, and education that focus on organized data collection, distribution, and training. These activities could be supported, at least in part, through existing mechanisms at NSF, NIH, and other agencies. It will also be important to develop new integrated software and database systems for cross‐species data analyses. Multidisciplinary efforts to develop such analytical tools should be supported financially. Finally, training opportunities should be created to stimulate multidisciplinary, integrative research into brain structure, function, and evolution. J. Comp. Neurol. 522:1445–1453, 2014. © 2014 Wiley Periodicals, Inc.  相似文献   
7.
8.

Background

Flexible endoscopy is an integral part of surgical care. Exposure to endoscopic procedures varies greatly in surgical training. The Society of American Gastrointestinal and Endoscopic Surgeons has developed the Fundamentals of Endoscopic Surgery (FES), which serves to teach and assess the fundamental knowledge and skills required to practice flexible endoscopy of the gastrointestinal tract. This report describes the validity evidence in the development of the FES cognitive examination.

Methods

Core areas in the practice of gastrointestinal endoscopy were identified through facilitated expert focus groups to establish validity evidence for the test content. Test items then were developed based on the content areas. Prospective enrollment of participants at various levels of training and experience was used for beta testing. Two FES cognitive test versions then were developed based on beta testing data. The Angoff and contrasting group methods were used to determine the passing score. Validity evidence was established through correlation of experience level with examination score.

Results

A total of 220 test items were developed in accordance with the defined test blueprint and formulated into two versions of 120 questions each. The versions were administered randomly to 363 participants. The correlation between test scores and training level was high (r = 0.69), with similar results noted for contrasting groups based on endoscopic rotation and endoscopic procedural experience. Items then were selected for two test forms of 75 items each, and a passing score was established.

Conclusions

The FES cognitive examination is the first test with validity evidence to assess the basic knowledge needed to perform flexible endoscopy. Combined with the hands-on skills examination, this assessment tool is a key component for FES certification.  相似文献   
9.

Background

Guidelines recommend the use of bioprosthetics for abdominal wall reinforcement in contaminated fields, but the evidence supporting the use of biologic over synthetic non-absorbable prosthetics for this indication is poor. Therefore, the objective was to perform a systematic review of outcomes after synthetic non-absorbable and biologic prosthetics for ventral hernia repair or prophylaxis in contaminated fields.

Methods

The systematic literature search identified all articles published up to 2013 that reported outcomes after abdominal wall reinforcement using synthetic non-absorbable or biologic prosthetics in contaminated fields. Studies were included if they included at least 10 cases (excluding inguinal and parastomal hernias). Quality assessment was performed using the MINORS instrument. The main outcomes measures were the incidence of wound infection and hernia at follow-up. Weighted pooled proportions were calculated using a random effects model.

Results

A total of 32 studies met the inclusion criteria and were included for synthesis. Mean sample size was 41.4 (range 10–190), and duration of follow-up was >1 year in 72 % of studies. Overall quality was low (mean 6.2, range 1–12). Pooled wound infection rates were 31.6 % (95 % CI 14.5–48.7) with biologic and 6.4 % (95 % CI 3.4–9.4) with synthetic non-absorbable prosthetics in clean-contaminated cases, with similar hernia rates. In contaminated and/or dirty fields, wound infection rates were similar, but pooled hernia rates were 27.2 % (95 % CI 9.5–44.9) with biologic and 3.2 % (95 % CI 0.0–11.0) with synthetic non-absorbable. Other outcomes were comparable.

Conclusions

The available evidence is limited, but does not support the superiority of biologic over synthetic non-absorbable prosthetics in contaminated fields.  相似文献   
10.
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