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   4603129篇
  免费   330007篇
  国内免费   10237篇
耳鼻咽喉   64998篇
儿科学   150067篇
妇产科学   126193篇
基础医学   655152篇
口腔科学   131758篇
临床医学   427168篇
内科学   879568篇
皮肤病学   104378篇
神经病学   374041篇
特种医学   175355篇
外国民族医学   1402篇
外科学   685156篇
综合类   101542篇
现状与发展   15篇
一般理论   1904篇
预防医学   370155篇
眼科学   108098篇
药学   338418篇
  18篇
中国医学   8789篇
肿瘤学   239198篇
  2018年   50206篇
  2017年   38072篇
  2016年   43636篇
  2015年   49969篇
  2014年   69958篇
  2013年   106278篇
  2012年   141523篇
  2011年   150581篇
  2010年   90969篇
  2009年   86373篇
  2008年   140656篇
  2007年   149619篇
  2006年   151413篇
  2005年   146444篇
  2004年   140912篇
  2003年   135452篇
  2002年   130769篇
  2001年   204613篇
  2000年   210466篇
  1999年   178194篇
  1998年   53985篇
  1997年   47410篇
  1996年   47403篇
  1995年   45728篇
  1994年   42204篇
  1993年   39752篇
  1992年   141372篇
  1991年   137549篇
  1990年   133868篇
  1989年   129405篇
  1988年   119520篇
  1987年   117418篇
  1986年   111034篇
  1985年   106543篇
  1984年   80196篇
  1983年   68385篇
  1982年   41003篇
  1981年   37014篇
  1979年   73747篇
  1978年   52757篇
  1977年   44594篇
  1976年   41988篇
  1975年   45010篇
  1974年   53944篇
  1973年   51500篇
  1972年   48564篇
  1971年   45495篇
  1970年   41910篇
  1969年   40181篇
  1968年   36890篇
排序方式: 共有10000条查询结果,搜索用时 22 毫秒
11.
12.
13.
14.
15.
16.
17.
随着婴儿潮、人口老龄化及新技术的广泛应用,人们对听力保健的需求显著增加。在美国,听力保健服务由助听设备专员、耳鼻喉科医生和听力师3类人员提供,其中听力师提供除医疗、手术外宽泛的听力保健服务。美国的听力保健服务体系及听力师教育体系经历了一个渐进的过程:20年前对从业人员的学历要求是听力学硕士,随着对服务质量要求的提高和服务范围的扩大,美国听力师逐渐要求专业博士学位(Au.D),毕业后还需3~4年的专门教育才能成为一名听力师。听力师教育有统一的标准,大学课程要通过听力教育认证委员会(the Accreditation Commission for Audiology Education, ACAE)或学术认证委员会(the Council on Academic Accreditation,CAA)的多程序严格的认证才能被承认。美国听力师需求存在巨大缺口,但是各国听力学教育标准不统一及听力师收入与教育投资不匹配,阻碍了更多的人进入这一领域。美国试图通过改变教育模式,降低教育成本及革新教学方法等改善听力师教育状况,但是听力师教育体系远未完善。  相似文献   
18.
19.

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   
20.

Background

In the emergency department, rib fractures are a common finding in patients who sustain chest trauma. Rib fractures may be a sign of significant, underlying pathology, especially in the elderly patients where rib fractures are associated with significant morbidity and mortality. To date, no studies have evaluated the ability of ultrasound to detect rib fractures using cadaver models and subsequently use this model as a teaching tool.

Objectives

The purpose of this study was to determine if it is possible to generate rib fractures on cadaver models which could be accurately identified using ultrasound.

Methods

This was a cross-sectional study performed during one session at a cadaver lab. A single hemithorax from four adult cadavers were used as models. Single rib fractures on each of rib five through eight were created. Four subjects, blinded to the normal versus fractured ribs, were asked to identify the presence of a fracture on each rib.

Results

A total of 8 of 16 potential ribs had fractured induced by study staff. Mean accuracy was 55% for all subjects. The overall sensitivity and specificity for detecting rib fractures was 50% (CI: 31.89–68.11) and 59.38% (CI: 35.69–73.55) respectively. The overall PPV and NPV was 55.17% and 54.29% respectively.

Conclusions

In this pilot study, subjects were not able to detect induced rib fractures using ultrasound on cadaver models. The use of this model as a teaching tool in the detection of rib fractures requires further investigation.  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