收费全文 | 6142篇 |
免费 | 374篇 |
国内免费 | 22篇 |
耳鼻咽喉 | 72篇 |
儿科学 | 137篇 |
妇产科学 | 95篇 |
基础医学 | 878篇 |
口腔科学 | 378篇 |
临床医学 | 484篇 |
内科学 | 1281篇 |
皮肤病学 | 136篇 |
神经病学 | 466篇 |
特种医学 | 539篇 |
外科学 | 680篇 |
综合类 | 54篇 |
一般理论 | 1篇 |
预防医学 | 572篇 |
眼科学 | 63篇 |
药学 | 462篇 |
1篇 | |
中国医学 | 31篇 |
肿瘤学 | 208篇 |
2023年 | 53篇 |
2022年 | 125篇 |
2021年 | 168篇 |
2020年 | 130篇 |
2019年 | 134篇 |
2018年 | 187篇 |
2017年 | 149篇 |
2016年 | 153篇 |
2015年 | 178篇 |
2014年 | 253篇 |
2013年 | 317篇 |
2012年 | 434篇 |
2011年 | 454篇 |
2010年 | 235篇 |
2009年 | 261篇 |
2008年 | 343篇 |
2007年 | 338篇 |
2006年 | 297篇 |
2005年 | 233篇 |
2004年 | 173篇 |
2003年 | 174篇 |
2002年 | 158篇 |
2001年 | 129篇 |
2000年 | 111篇 |
1999年 | 90篇 |
1998年 | 106篇 |
1997年 | 100篇 |
1996年 | 90篇 |
1995年 | 79篇 |
1994年 | 53篇 |
1993年 | 67篇 |
1992年 | 27篇 |
1991年 | 25篇 |
1990年 | 42篇 |
1989年 | 62篇 |
1988年 | 47篇 |
1987年 | 59篇 |
1986年 | 66篇 |
1985年 | 73篇 |
1984年 | 42篇 |
1983年 | 33篇 |
1982年 | 36篇 |
1981年 | 34篇 |
1980年 | 42篇 |
1979年 | 13篇 |
1978年 | 24篇 |
1977年 | 29篇 |
1976年 | 26篇 |
1975年 | 24篇 |
1969年 | 20篇 |
Introduction and Aims
Frequent premature ventricular contractions (PVCs) originating from the right ventricular outflow tract (RVOT) are usually considered a benign entity and the ECG is typically normal. The aim of this study was to assess whether upward displacement of the ECG to the second intercostal space (ICS) would reveal any abnormal pattern.Methods
A total of 18 consecutive patients with apparently normal hearts were studied, mean age 44±16 years, 12 women, who underwent catheter ablation of the RVOT due to frequent PVCs. A 12-lead ECG was performed in the standard position and repeated in a higher position, at the level of the second ICS. Three-dimensional bipolar electroanatomical voltage mapping (EVM) was performed in all patients and low voltage areas (LVAs) were defined as areas with amplitude <1.5 mV.Results
The ECG in the second ICS was normal in eleven patients but in seven (39%) it revealed a pattern of ST-segment elevation in V1. EVM revealed the presence of LVAs in six patients (33%) which included the earliest activation site (EAS) in five. The ST elevation was associated with the presence of LVAs (p<0.0001) and with the LVAs at the EAS (p=0.002).Conclusion
In this group of patients with apparently normal hearts and with frequent PVCs of the RVOT, upward displacement of the ECG revealed the presence of ST elevation in more than one third of patients, and the ST elevation was associated with the presence of LVAs in the RVOT. 相似文献Methods: A targeted literature review and meetings with clinical experts (dermatologists) were conducted to identify AD-related sign, symptom, and impact concepts. Results were harmonized and used to construct two draft PRO questionnaires: the Atopic Dermatitis Symptom Scale (ADerm-SS; 11 items) and the Atopic Dermatitis Impact Scale (ADerm-IS; 10 items). The content validity and questionnaire content were evaluated via qualitative concept elicitation/cognitive debriefing interviews with adult patients with moderate-to-severe AD.
Results: From the literature (n?=?13 articles), 13 sign and symptom and 43 impact concepts were identified, while 21 sign and symptom and 48 impacts were elicited from experts (n?=?3). During the patient interviews (n?=?15), 19 sign and symptom and 41 impact concepts were reported, the majority of which were evaluated by the ADerm-SS and ADerm-IS, thus substantiating the content of both questionnaires. Additionally, patients interpreted both questionnaires as intended by the developers.
Conclusions: The ADerm-SS and ADerm-IS can be regarded as content-valid PRO questionnaires for moderate-to-severe AD. 相似文献