全文获取类型
| 收费全文 | 1478850篇 |
| 免费 | 110051篇 |
| 国内免费 | 2587篇 |
专业分类
| 耳鼻咽喉 | 18702篇 |
| 儿科学 | 46612篇 |
| 妇产科学 | 38965篇 |
| 基础医学 | 217374篇 |
| 口腔科学 | 38828篇 |
| 临床医学 | 139470篇 |
| 内科学 | 292398篇 |
| 皮肤病学 | 30172篇 |
| 神经病学 | 122798篇 |
| 特种医学 | 54014篇 |
| 外国民族医学 | 276篇 |
| 外科学 | 211432篇 |
| 综合类 | 28813篇 |
| 现状与发展 | 3篇 |
| 一般理论 | 870篇 |
| 预防医学 | 123415篇 |
| 眼科学 | 33861篇 |
| 药学 | 107146篇 |
| 13篇 | |
| 中国医学 | 2324篇 |
| 肿瘤学 | 84002篇 |
出版年
| 2021年 | 13958篇 |
| 2019年 | 14478篇 |
| 2018年 | 18589篇 |
| 2017年 | 14141篇 |
| 2016年 | 15535篇 |
| 2015年 | 18019篇 |
| 2014年 | 25326篇 |
| 2013年 | 37606篇 |
| 2012年 | 52846篇 |
| 2011年 | 56040篇 |
| 2010年 | 32163篇 |
| 2009年 | 30306篇 |
| 2008年 | 51853篇 |
| 2007年 | 55201篇 |
| 2006年 | 54629篇 |
| 2005年 | 53910篇 |
| 2004年 | 51330篇 |
| 2003年 | 48805篇 |
| 2002年 | 46909篇 |
| 2001年 | 57855篇 |
| 2000年 | 58431篇 |
| 1999年 | 50095篇 |
| 1998年 | 16019篇 |
| 1997年 | 14432篇 |
| 1996年 | 14520篇 |
| 1995年 | 13716篇 |
| 1994年 | 12608篇 |
| 1993年 | 11783篇 |
| 1992年 | 39295篇 |
| 1991年 | 38650篇 |
| 1990年 | 37300篇 |
| 1989年 | 36089篇 |
| 1988年 | 33529篇 |
| 1987年 | 32858篇 |
| 1986年 | 31340篇 |
| 1985年 | 29636篇 |
| 1984年 | 22992篇 |
| 1983年 | 20151篇 |
| 1982年 | 12538篇 |
| 1979年 | 21575篇 |
| 1978年 | 16059篇 |
| 1977年 | 13343篇 |
| 1976年 | 12370篇 |
| 1975年 | 13219篇 |
| 1974年 | 15999篇 |
| 1973年 | 15707篇 |
| 1972年 | 14816篇 |
| 1971年 | 13786篇 |
| 1970年 | 12989篇 |
| 1969年 | 12218篇 |
排序方式： 共有10000条查询结果，搜索用时 0 毫秒
1.
2.
3.
4.
Vestibular function laboratories utilize a multitude of diagnostic instruments to evaluate a dizzy patient. Caloric irrigators, oculomotor stimuli, and rotational chairs produce a stimulus whose accuracy is required for the patient response to be accurate. Careful attention to everything from cleanliness of equipment to threshold adjustments determine on a daily basis if patient data are going to be correct and useful. Instrumentation specifications that change with time such as speed and temperature must periodically be checked using calibrated instruments. 相似文献
5.
6.
7.
8.
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9.
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10.
Adilson Cunha Ferreira Edward Araujo Júnior Wellington P. Martins João Francisco Jordão Antônio Hélio Oliani Simon E. Meagher 《The journal of maternal-fetal & neonatal medicine》2015,28(14):1706-1710
Objective: To assess the quality of images and video clips of fetal central nervous (CNS) structures obtained by ultrasound and transmitted via tele-ultrasound from Brazil to Australia.Methods: In this cross-sectional study, 15 normal singleton pregnant women between 20 and 26 weeks were selected. Fetal CNS structures were obtained by images and video clips. The exams were transmitted in real-time using a broadband internet and an inexpensive video streaming device. Four blinded examiners evaluated the quality of the exams using the Likert scale. We calculated the mean, standard deviation, mean difference, and p values were obtained from paired t tests.Results: The quality of the original video clips was slightly better than that observed by the transmitted video clips; mean difference considering all observers = 0.23 points. In 47/60 comparisons (78.3%; 95% CI?=?66.4–86.9%) the quality of the video clips were judged to be the same. In 182/240 still images (75.8%; 95% CI?=?70.0–80.8%) the scores of transmitted image were considered the same as the original.Conclusion: We demonstrated that long distance tele-ultrasound transmission of fetal CNS structures using an inexpensive video streaming device provided images of subjective good quality. 相似文献