全文获取类型
| 收费全文 | 3102634篇 |
| 免费 | 217068篇 |
| 国内免费 | 4524篇 |
专业分类
| 耳鼻咽喉 | 43305篇 |
| 儿科学 | 100466篇 |
| 妇产科学 | 83357篇 |
| 基础医学 | 452220篇 |
| 口腔科学 | 86162篇 |
| 临床医学 | 279483篇 |
| 内科学 | 594716篇 |
| 皮肤病学 | 68938篇 |
| 神经病学 | 242051篇 |
| 特种医学 | 117924篇 |
| 外国民族医学 | 676篇 |
| 外科学 | 466575篇 |
| 综合类 | 63183篇 |
| 现状与发展 | 13篇 |
| 一般理论 | 1044篇 |
| 预防医学 | 235921篇 |
| 眼科学 | 72472篇 |
| 药学 | 236552篇 |
| 18篇 | |
| 中国医学 | 6578篇 |
| 肿瘤学 | 172572篇 |
出版年
| 2021年 | 24289篇 |
| 2019年 | 24701篇 |
| 2018年 | 34342篇 |
| 2017年 | 26165篇 |
| 2016年 | 29494篇 |
| 2015年 | 33090篇 |
| 2014年 | 46420篇 |
| 2013年 | 69361篇 |
| 2012年 | 95362篇 |
| 2011年 | 101620篇 |
| 2010年 | 60269篇 |
| 2009年 | 56701篇 |
| 2008年 | 95078篇 |
| 2007年 | 101492篇 |
| 2006年 | 102386篇 |
| 2005年 | 99060篇 |
| 2004年 | 94882篇 |
| 2003年 | 91480篇 |
| 2002年 | 88600篇 |
| 2001年 | 146214篇 |
| 2000年 | 150389篇 |
| 1999年 | 126291篇 |
| 1998年 | 35655篇 |
| 1997年 | 31319篇 |
| 1996年 | 31605篇 |
| 1995年 | 29701篇 |
| 1994年 | 27328篇 |
| 1993年 | 25762篇 |
| 1992年 | 97219篇 |
| 1991年 | 94527篇 |
| 1990年 | 92647篇 |
| 1989年 | 89177篇 |
| 1988年 | 81720篇 |
| 1987年 | 80096篇 |
| 1986年 | 75202篇 |
| 1985年 | 71678篇 |
| 1984年 | 53041篇 |
| 1983年 | 45062篇 |
| 1982年 | 26284篇 |
| 1979年 | 48528篇 |
| 1978年 | 34135篇 |
| 1977年 | 29035篇 |
| 1976年 | 27029篇 |
| 1975年 | 29583篇 |
| 1974年 | 35068篇 |
| 1973年 | 33561篇 |
| 1972年 | 31733篇 |
| 1971年 | 29989篇 |
| 1970年 | 27641篇 |
| 1969年 | 26462篇 |
排序方式： 共有10000条查询结果，搜索用时 15 毫秒
11.
Accuracy and Precision of Acetabular Component Placement With Imageless Navigation in Obese Patients
Leonard T. Buller Alexander S. McLawhorn Jose A. Romero Peter K. Sculco David J. Mayman 《The Journal of arthroplasty》2019,34(4):693-699
Background
Obesity is a risk factor for acetabular component malposition when total hip arthroplasty is performed with manual techniques. The utility of imageless navigation in obese patients remains unknown. This study compared the accuracy and precision of imageless navigation for component orientation between obese and nonobese patients.Methods
A total of 459 total hip arthroplasties performed for osteoarthritis using imageless navigation were reviewed from a single surgeon’s institutional review board–approved database. Einzel-Bild-Roentgen Analyse determined component orientation on 6-week postoperative anteroposterior radiographs. Mean orientation error (accuracy) and precision were compared between obese (body mass index ≥ 30 kg/m2) and nonobese patients. Regression analysis evaluated the influence of obesity on component position.Results
The difference in mean inclination and anteversion between obese and nonobese groups was 1.1° (43.0° ± 3.5°; range, 35.8°-57.8° vs 41.9° ± 4.4°; range, 33.0°-57.1° and 24.9° ± 6.3°; range, 14.2°-44.3° vs 23.8° ± 6.6°; range, 7.0°-38.6°, respectively). Inclination precision was better for nonobese patients. No difference in inclination accuracy or anteversion accuracy or precision was detected between groups. And 83% of components were placed within the target range. There was no relationship between obesity (dichotomized) and component placement outside the target ranges for inclination, anteversion, or both. As a continuous variable, increased body mass index correlated with higher odds of inclination outside the target zone (odds ratio, 1.06; P = .001).Conclusion
Using imageless navigation, inclination orientation was less precise for obese patients, but the observed difference is likely not clinically relevant. Accurate superficial registration of landmarks in obese patients is achievable, and the use of imageless navigation similarly improves acetabular component positioning in obese and nonobese patients.Level of Evidence
Therapeutic Level IV. 相似文献12.
Stephan Koter Tina U. Cohnert Korbinian B. Hindermayr Jörg Lindenmann Maximilian Brückner Wolfgang K. Oswald Georg Werkgartner Doris Wagner 《Journal of vascular surgery》2019,69(4):1227-1232
Objective
Low psoas muscle area is shown to be an indicator for worse postoperative outcome in patients undergoing vascular surgical. Additionally, it has been associated with longer durations of hospital stay in patients with cancer who undergo surgery and subsequently greater health care costs in Europe and the United States. We sought to evaluate this effect on hospital expenditure for patients undergoing vascular repair in a health care system with universal access.Methods
Skeletal muscle mass was assessed on preoperative abdominal computed tomography scans of patients undergoing open aortic aneurysm repair in a retrospective fashion. The skeletal muscle index (SMI) was used to define low muscle mass. Health care costs were obtained for all patients and the relationship between a low SMI and higher costs was explored using linear regression and cross-sectional analysis.Results
We included 156 patients (81.5% male) with a median age of 72 years undergoing elective surgery for infrarenal abdominal aortic aneurysm in this analysis. The median SMI for patients with low skeletal muscle mass was 53.21 cm2/kg and for patients without, 70.07 cm2/kg. Hospital duration of stay was 2 days longer in patients with low skeletal muscle mass as compared with patients with normal (14 days vs 11 days; P = .001), as was duration of intensive care stay (3 days vs 1 day; P = .01). The median overall hospital costs were €10,460 higher for patients with a low SMI as compared with patients with a normal physical constitution (€53,739 [interquartile range, €45,007-€62,471] vs €43,279 [interquartile range, €39,509-€47,049]; P = .001). After confounder adjustment, a low SMI was associated with a 14.68% cost increase in overall hospital costs, for a cost increase of €6521.Conclusions
Low skeletal muscle mass is independently associated with higher hospital as well as intensive care costs in patients undergoing elective aortic aneurysm repair. Strategies to reduce this risk factor are warranted for these patients. 相似文献13.
Stress Testing Versus CT Angiography in Patients With Diabetes and Suspected Coronary Artery Disease
Abhinav Sharma Adrian Coles Nishant K. Sekaran Neha J. Pagidipati Michael T. Lu Daniel B. Mark Kerry L. Lee Hussein R. Al-Khalidi Udo Hoffmann Pamela S. Douglas 《Journal of the American College of Cardiology》2019,73(8):893-902
Background
The optimal noninvasive test (NIT) for patients with diabetes and stable symptoms of coronary artery disease (CAD) is unknown.Objectives
The purpose of this study was to assess whether a diagnostic strategy based on coronary computed tomographic angiography (CTA) is superior to functional stress testing in reducing adverse cardiovascular (CV) outcomes (CV death or myocardial infarction [MI]) among symptomatic patients with diabetes.Methods
PROMISE (Prospective Multicenter Imaging Study for Evaluation of Chest Pain) was a randomized trial evaluating an initial strategy of CTA versus functional testing in stable outpatients with symptoms suggestive of CAD. The study compared CV outcomes in patients with diabetes (n = 1,908 [21%]) and without diabetes (n = 7,058 [79%]) based on their randomization to CTA or functional testing.Results
Patients with diabetes (vs. without) were similar in age (median 61 years vs. 60 years) and sex (female 54% vs. 52%) but had a greater burden of CV comorbidities. Patients with diabetes who underwent CTA had a lower risk of CV death/MI compared with functional stress testing (CTA: 1.1% [10 of 936] vs. stress testing: 2.6% [25 of 972]; adjusted hazard ratio: 0.38; 95% confidence interval: 0.18 to 0.79; p = 0.01). There was no significant difference in nondiabetic patients (CTA: 1.4% [50 of 3,564] vs. stress testing: 1.3% [45 of 3,494]; adjusted hazard ratio: 1.03; 95% confidence interval: 0.69 to 1.54; p = 0.887; interaction term for diabetes p value = 0.02).Conclusions
In diabetic patients presenting with stable chest pain, a CTA strategy resulted in fewer adverse CV outcomes than a functional testing strategy. CTA may be considered as the initial diagnostic strategy in this subgroup. (PROspective Multicenter Imaging Study for Evaluation of Chest Pain [PROMISE]; NCT01174550) 相似文献14.
15.
16.
Hanna Lee Mary K. Tan Andrew T. Yan Paul Angaran Paul Dorian Claudia Bucci Jean C. Gregoire Alan D. Bell Martin S. Green Peter L. Gross Allan Skanes Charles R. Kerr L. Brent Mitchell Jafna L. Cox Vidal Essebag Brett Heilbron Krishnan Ramanathan Carl Fournier Shaun G. Goodman 《The Canadian journal of cardiology》2019,35(2):160-168
Background
Physicians treating nonvalvular atrial fibrillation (AF) assess stroke and bleeding risks when deciding on anticoagulation. The agreement between empirical and physician-estimated risks is unclear. Furthermore, the association between patient and physician sex and anticoagulation decision-making is uncertain.Methods
We pooled data from 2 national primary care physician chart audit databases of patients with AF (Facilitating Review and Education to Optimize Stroke Prevention in Atrial Fibrillation and Coordinated National Network to Engage Physicians in the Care and Treatment of Patients with Atrial Fibrillation Chart Audit) with a combined 1035 physicians (133 female, 902 male) and 10,927 patients (4567 female and 6360 male).Results
Male physicians underestimated stroke risk in female patients and overestimated risk in male patients. Female physicians estimated stroke risk well in female patients but underestimated the risk in male patients. Risk of bleeding was underestimated in all. Despite differences in risk assessment by physician and patient sex, > 90% of patients received anticoagulation across all subgroups. There was modest agreement between physician estimated and calculated (ie, CHADS2 score) stroke risk: Kappa scores were 0.41 (0.35-0.47) for female physicians and 0.34 (0.32-0.36) for male physicians.Conclusions
Our study is the first to examine the association between patient and physician sex influences and stroke and bleeding risk estimation in AF. Although there were differences in agreement between physician estimated stroke risk and calculated CHADS2 scores, these differences were small and unlikely to affect clinical practice; further, despite any perceived differences in the accuracy of risk assessment by sex, most patients received anticoagulation. 相似文献17.
18.
19.
N. V. Bashmakova G. N. Chistiakova I. A. Gazieva Y. M. Trapeznikova D. O. Mazurov 《Gynecological endocrinology》2015,31(10):31-33
AbstractThis study was undertaken to compare the concentrations of pro- and anti-angiogenic growth factors, nitric oxide (NO) stable metabolites in maternal serum and embryonic left ventricular (LV) isovolumic relaxation time (IRT, ms) during the first trimester in two groups of women: with pregnancy conceived by assisted reproductive technologies (ART, n?=?39) and normally conceived (control group, n?=?68) pregnancy. The concentration of vasoconstrictor endothelin 1 was 45.5 times more in ART than in control group. On the contrary, the concentrations of NO stable metabolites in ART were 1.9 times less than in control women. The assessment of angiogenic suppressors in ART women demonstrates the decrease in s-endoglin concentration was 1.6 times and in soluble receptor to vascular endothelial growth factor concentration was 2.0 times in comparison with control group. There was a significant increase in LV IRT in ART embryos in comparison to control ones. These data suggest significant changes in pro- anti-angiogenic factors balance and increase in vascular impedance in ART-conceived embryos. 相似文献
20.
K.-C. Sung D.-C. Seo S.-J. Lee M.-Y. Lee S.H. Wild C.D. Byrne 《Nutrition, metabolism, and cardiovascular diseases : NMCD》2019,29(5):489-495