全文获取类型
收费全文 | 1370033篇 |
免费 | 101772篇 |
国内免费 | 2044篇 |
专业分类
耳鼻咽喉 | 17514篇 |
儿科学 | 44196篇 |
妇产科学 | 36806篇 |
基础医学 | 203364篇 |
口腔科学 | 36771篇 |
临床医学 | 128218篇 |
内科学 | 270071篇 |
皮肤病学 | 28504篇 |
神经病学 | 112212篇 |
特种医学 | 50062篇 |
外国民族医学 | 266篇 |
外科学 | 193526篇 |
综合类 | 27198篇 |
现状与发展 | 3篇 |
一般理论 | 716篇 |
预防医学 | 114086篇 |
眼科学 | 31005篇 |
药学 | 100203篇 |
39篇 | |
中国医学 | 2261篇 |
肿瘤学 | 76828篇 |
出版年
2021年 | 11660篇 |
2019年 | 12045篇 |
2018年 | 15931篇 |
2017年 | 12120篇 |
2016年 | 13350篇 |
2015年 | 15404篇 |
2014年 | 21368篇 |
2013年 | 32253篇 |
2012年 | 44718篇 |
2011年 | 47674篇 |
2010年 | 27302篇 |
2009年 | 26230篇 |
2008年 | 44541篇 |
2007年 | 47587篇 |
2006年 | 46692篇 |
2005年 | 45959篇 |
2004年 | 44049篇 |
2003年 | 41907篇 |
2002年 | 40658篇 |
2001年 | 57021篇 |
2000年 | 57783篇 |
1999年 | 49135篇 |
1998年 | 14657篇 |
1997年 | 13268篇 |
1996年 | 13451篇 |
1995年 | 12708篇 |
1994年 | 11794篇 |
1992年 | 38766篇 |
1991年 | 38178篇 |
1990年 | 36906篇 |
1989年 | 35684篇 |
1988年 | 33097篇 |
1987年 | 32430篇 |
1986年 | 30891篇 |
1985年 | 29219篇 |
1984年 | 22422篇 |
1983年 | 19629篇 |
1982年 | 11967篇 |
1979年 | 21259篇 |
1978年 | 15680篇 |
1977年 | 13086篇 |
1976年 | 12088篇 |
1975年 | 13029篇 |
1974年 | 15804篇 |
1973年 | 15578篇 |
1972年 | 14677篇 |
1971年 | 13687篇 |
1970年 | 12896篇 |
1969年 | 12179篇 |
1968年 | 11334篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
11.
Michelle Y L Tang Patrick H Y Chung Hau Y Chan Paul K H Tam Kenneth KY Wong 《Journal of pediatric surgery》2019,54(2):255-257
Objective
Helicobacter pylori infection is common among Asians. However, evidence in the recent years has demonstrated a decrease in the prevalence of H. pylori infection among children and adults worldwide. Our aim was to update its prevalence in symptomatic children in our locality in the recent 12?years and compared to the results of our previous review published in 2005.Methods
A retrospective review was carried out between 2005 and 2017. All children who presented with dyspepsia or gastrointestinal bleeding and underwent oesophagogastroduodenoscopy with antral biopsy taken were included. Patient demographics, endoscopic, or histological diagnosis and the H. pylori status were recorded.Main Results
A total of 602 patients were included. There was a statistically significant decreasing trend of H. pylori infection rate between 2005 and 2017 (p?=?0.003). The overall infection rate from this study was 12.8%, compared to 25.6% from our previous review. Overall failure of eradication with first-line antibiotic therapy has increased to 29.3% from 10% in our previous review.Conclusion
There was a decrease in the prevalence of H. pylori infection among symptomatic children for the recent 12?years, comparing to our previous data from 2005. We hypothesize that the reduction in prevalence of H. pylori infection among adults and the decrease in the practice of sharing chopsticks during meals have led to a decrease in transmission of the bacteria among family members in Hong Kong. However, the failure of eradication with first line treatment was higher, possibly due to the increase in antibiotics usage and resistance.Level of Evidence
III 相似文献12.
Stefan Benedikt Alexandru-Cristian Tuca Alen Palackic Paul Wurzer Daniel Popp Christian Tapking Lars-Peter Kamolz 《Burns : journal of the International Society for Burn Injuries》2019,45(1):220-227
Introduction
Websites serve as information and communication platforms; hence, they are important tools for the self-promotion of hospitals. In 2010, Selig et al. evaluated the online presence of burn centers in Germany, Austria, and Switzerland based on 37 quality criteria. This study aimed to re-evaluate these websites to assess their development over the past 6.5 years.Materials and methods
Websites of the German-speaking burn centers were re-evaluated according to criteria previously described by Selig et al. Particular attention was paid to specific information on burns. Additionally, the implementation of social media platforms was investigated.Results
There was an overall increase in the quality of information published on websites. There was a considerable improvement recorded, especially in the categories of “teaching” and “patient care.” However, burn-specific information was found to be still sparse. Over 50% of the hospitals were present on social media.Conclusions
Although the quality of information published on German-speaking burn center websites increased, they must be further developed, especially regarding burn-related information. Moreover, a clear structure and design could prevent long searches and facilitate an easier flow of information. The interface from websites and social media platforms appear to be an important tool for up-to-date self-promotion. 相似文献13.
D. Medenwald A. Kluttig M.E. Lacruz J. Schumann 《Nutrition, metabolism, and cardiovascular diseases : NMCD》2019,29(2):152-158
Background and Aims
Diet is known to play a decisive role in the development of coronary heart disease (CHD). One factor believed to decrease lifetime risk of CHD is the consumption of omega-3 fatty acids. Yet, conclusive evidence regarding the potential cardioprotective effects of fatty acids is far from being reached. The present study aimed to provide further evidence on the association of serum fatty acid profiles with CHD risk.Methods and Results
The CARdio-vascular Disease, Living and Ageing in Halle study (CARLA study) is an observational cohort study comprising an older adult's general population with a high level of cardiovascular risk factors. In a matched case–control design the serum fatty acid concentrations of 73 subjects with an incident fatal or nonfatal CHD event were compared to 146 controls matched for sex and age. Our data show that the participants of the CARLA study are underserved in unsaturated fatty acids with respect to current dietary recommendations. In addition, the ratio of omega-6 to omega-3 fatty acids was determined to be 8:1 which underlines the consumption of a Western-style diet enriched in omega-6 fatty acids. There were no significant differences in fatty acid patterns between cases and controls. Thus, no clear association of particular serum fatty acid levels with cardiovascular risk was found.Conclusion
Our results support the conclusion that in populations with a homogenous low level of omega-3 polyunsaturated fatty acids consumption, serum fatty acid levels are not associated with CHD risk. 相似文献14.
Conall T. Morgan Brigitte Mueller Varsha Thakur Vitor Guerra Callaghan Jull Luc Mertens Mark Friedberg Fraser Golding Mike Seed Steven E.S. Miner Edgar T. Jaeggi Cedric Manlhiot Lynne E. Nield 《The Canadian journal of cardiology》2019,35(4):453-461
Background
The purpose of the study was to evaluate the association between fetal echocardiographic measurements and the need for intervention (primary coarctation repair, staged coarctation repair, or catheter intervention) in prenatally diagnosed coarctation of the aorta.Methods
A single-centre retrospective cohort study (2005-2015) of 107 fetuses diagnosed with suspected coarctation of the aorta in the setting of an apex-forming left ventricle and antegrade flow across the mitral and aortic valves.Results
Median gestational age at diagnosis was 32 weeks (interquartile range, 23-35 weeks). Fifty-six (52%) did not require any neonatal intervention, 51 patients (48%) underwent a biventricular repair. In univariable analysis, an increase in ascending aorta (AAo) peak Doppler flow velocity (odds ratio [OR], 1.40 [95% confidence interval [CI], 1.05-1.91] per 20 cm/s; P = 0.03) was associated with intervention. No intervention was associated with larger isthmus size (OR, 0.23; P < 0.001), transverse arch diameter (OR, 0.23; P < 0.001), and aortic (OR, 0.72; P = 0.02), mitral (OR, 0.58; P = 0.001), and AAo (OR, 0.53; P < 0.001) z-scores. In multivariable analysis, higher peak AAo Doppler (OR, 2.51 [95% CI, 1.54-4.58] per 20 cm/s; P = 0.001) and younger gestational age at diagnosis (OR, 0.81 [95% CI, 0.70-0.93] per week; P = 0.005) were associated with intervention, whereas a higher AAo z-score (OR, 0.65 [95% CI, 0.43-0.94] per z; P = 0.029) and transverse arch dimension (OR, 0.44 [95% CI, 0.18-0.97]; P = 0.05) decreased the risk of intervention.Conclusions
In prenatally suspected coarctation, the variables associated with intervention comprised smaller AAo and transverse arch size, earlier gestational age at diagnosis, and the additional finding of a higher peak AAo Doppler. 相似文献15.
Vishnu Ambur Peter Park John P. Gaughan Scott Golarz Frank Schmieder Paul Van Bemmelen Eric Choi Ravi Dhanisetty 《Journal of vascular surgery》2019,69(2):491-496
Objective
Patient selection for open lower extremity revascularization in patients with chronic kidney disease (CKD) remains a clinical challenge. This study investigates the impact of CKD on early graft failure, postoperative complications, and mortality in patients undergoing lower extremity bypass for critical limb ischemia.Methods
The National Surgical Quality Improvement Program database was queried for all patients with critical limb ischemia from 2012 to 2015 who underwent lower extremity bypass using the targeted vascular set. The glomerular filtration rate was calculated using the Chronic Kidney Disease Epidemiology Collaboration Study equation. CKD categories were determined from the National Kidney Foundation Kidney Disease Outcomes Quality Initiative staging criteria. Patients were classified into three groups: CKD stages 3 or lower (mild to moderate CKD), CKD stages 4 or 5 (severe CKD), and on hemodialysis (HD). Multiple variable analysis was used to examine graft failure, mortality, and postoperative complications.Results
The Surgical Quality Improvement Program database identified 6978 patients who underwent infrainguinal lower extremity arterial bypass during the study period. There were 6101 patients (87.4%) with mild to moderate CKD, 327 (4.7%) with severe CKD, and 550 (7.9%) on HD. Patients with severe CKD and on HD were more likely to have revascularization for tissue loss (54.9% vs 68.8% and 74.7%; P < .01). Patients with severe CKD and those on HD had higher rates of early graft failure, postoperative myocardial infarction, and rates of reoperation. Multiple variable analysis confirmed these results showing that HD was associated with postoperative myocardial infarction, readmission, and increased mortality. It also demonstrated that severe CKD was associated with graft failure (odds ratio [OR], 1.67; 95% confidence interval [CI], 1.12-2.50; P = .01), postoperative myocardial infarction (OR, 2.16; 95% CI, 1.35-3.45; P < .01), and readmission (OR, 1.38; 95% CI, 1.06-1.80; P = .02). Other factors associated with graft failure include functional status (OR, 1.39; 95% CI, 1.08-1.80; P = .01), African American race (OR, 1.72; 95% CI, 1.39-2.13; P < .01), and distal bypass (OR, 1.33; 95% CI, 1.09-1.61; P < .01).Conclusions
CKD is a significant predictor of perioperative morbidity after lower extremity bypass. Patients with severe CKD have worse postoperative outcomes without increased mortality. Those on HD have worse survival and postoperative outcomes. 相似文献16.
Paul Macadam Kim D. Simperingham John B. Cronin 《Journal of Science and Medicine in Sport》2019,22(3):348-352
Objectives
Arm swing is a distinctive characteristic of sprint-running with the arms working in a contralateral manner with the legs to propel the body in a horizontal direction. The purpose of this study was to determine the acute changes in kinematics and kinetics when wearable resistance (WR) of 1 kg (equivalent to ~1% body mass) was attached to each forearm during over ground short distance (20 m) maximal sprint-running.Design
Cross-sectional study.Methods
Twenty-two male amateur rugby athletes (19.4 ± 0.5 years; 97.0 ± 4.8 kg; 180.4 ± 7.2 cm) volunteered to participate in the study. Radar and Optojump were used to examine kinematic and kinetics between WR and unloaded sprint-running conditions.Results
No significant (p < 0.05) differences were found at 2 m or 5 m between conditions, however, the WR condition resulted in a significant increase in 10 m, 20 m and 10–20 m split time (all, ~2%, small effect size) compared to the unloaded condition. Significant decreases were also found in theoretical maximum velocity (V0) (?1.4%, small effect size) and relative peak horizontal power production (Pmax) (?5.5%, small effect size). Step length (2.1%, small effect size) and contact time (6.5%, medium effect size) were significantly increased, while step frequency (?4.1%, small effect size) and flight time (?5.3%, medium effect size) were significantly decreased.Conclusions
WR forearm loading provides a movement specific overload of the arms which significantly alters step kinematics and sprint times ≥10 m. 相似文献17.
Hemolytic disease of fetus and newborn (HDFN) imposes great healthcare burden being associated with maternal alloimmunization against parental-inherited fetal red blood cell antigens causing fetal anemia or death. Noninvasive prenatal analysis (NIPT) provides safe fetal RHD genotyping for early identification of risk pregnancies and proper management guidance. We aimed to conduct systematic review and meta-analysis on NIPT's beneficial application, in conjunction with quantitative maternal alloantibody analysis, for early diagnosis of pregnancies at risk. Search for relevant articles was done in; PubMed/Medline, Scopus, and Ovid (January 2006April 2020), including only English-written articles reporting reference tests and accuracy data. Nineteen eligible studies were critically appraised. NIPT was estimated highly sensitive/specific for fetal RHD genotyping beyond 11-week gestation. Amplifications from ≥2 exons are optimum to increase accuracy. NIPT permits cost-effectiveness, precious resources sparing, and low emotional stress. Knowledge of parental ethnicity is important for correct NIPT result interpretations and quantitative screening. Cut-off titer ≥8-up-to-32 is relevant for anti-D alloantibodies, while, lower titer is for anti-K. Alloimmunization is influenced by maternal RHD status, gravida status, and history of adverse obstetrics. In conclusion, NIPT allows evidence-based provision of routine anti-D immunoprophylaxis and estimates potential fetal risks for guiding further interventions. Future large-scale studies investigating NIPT's non-RHD genotyping within different ethnic groups and in presence of clinically significant alloantibodies are needed. 相似文献
18.
Thiago E. Sabino Vivian I. Avelino-Silva Clara Cavalcantte Silvia P. Goulart Olinda C. Luiz Luiz A.M. Fonseca 《AIDS care》2021,33(1):31-38
ABSTRACT This study focused on factors associated with antiretroviral therapy (ART) adherence and quality of life among transgenderwomen in Sao Paulo, Brazil, using univariable and adjusted analysis. Adherence was evaluated with a self-report tool and with HIV viral load (VL) measurement. PROQOL-HIV was used to assess quality of life. 106 TGW with median 41 years old were included; most were white (56%) and had >10 years of education (57%). Median time since HIV/AIDS diagnosis was 10 years. Overall, participants had high T CD4+ counts (median 659 cells/mm3) and most (75%) had undetectable HIV VL. 85% were considered adherent using self-report (95%CI 77-91), whereas 72% (95%CI 62-80) were considered adherent when self-report and undetectable HIV VL were analyzed jointly. Older age was associated with higher ART adherence; each year increase in age was associated with 5% higher odds of adherence (p?=?0.021). Quality of life ranged from good-excellent in 5 of 8 domains. Younger age, lower education, higher time since HIV diagnosis, comorbidities, illicit drugs use and depression were associated with lower PROQOL scores in specific domains in univariable analysis, while depression was also associated with lower total PROQOL score even after adjustment for age, comorbidities and time since HIV diagnosis (p?=?0.048). 相似文献
19.