全文获取类型
收费全文 | 37087篇 |
免费 | 3208篇 |
国内免费 | 72篇 |
专业分类
耳鼻咽喉 | 302篇 |
儿科学 | 1201篇 |
妇产科学 | 1157篇 |
基础医学 | 4829篇 |
口腔科学 | 662篇 |
临床医学 | 5962篇 |
内科学 | 6390篇 |
皮肤病学 | 576篇 |
神经病学 | 3313篇 |
特种医学 | 1045篇 |
外科学 | 3759篇 |
综合类 | 636篇 |
一般理论 | 71篇 |
预防医学 | 4876篇 |
眼科学 | 549篇 |
药学 | 2146篇 |
中国医学 | 28篇 |
肿瘤学 | 2865篇 |
出版年
2023年 | 196篇 |
2022年 | 271篇 |
2021年 | 611篇 |
2020年 | 489篇 |
2019年 | 872篇 |
2018年 | 896篇 |
2017年 | 668篇 |
2016年 | 779篇 |
2015年 | 856篇 |
2014年 | 1093篇 |
2013年 | 1711篇 |
2012年 | 2353篇 |
2011年 | 2402篇 |
2010年 | 1329篇 |
2009年 | 1262篇 |
2008年 | 2295篇 |
2007年 | 2407篇 |
2006年 | 2430篇 |
2005年 | 2302篇 |
2004年 | 2138篇 |
2003年 | 2041篇 |
2002年 | 1935篇 |
2001年 | 533篇 |
2000年 | 495篇 |
1999年 | 481篇 |
1998年 | 507篇 |
1997年 | 388篇 |
1996年 | 391篇 |
1995年 | 380篇 |
1994年 | 324篇 |
1993年 | 313篇 |
1992年 | 356篇 |
1991年 | 309篇 |
1990年 | 294篇 |
1989年 | 325篇 |
1988年 | 252篇 |
1987年 | 267篇 |
1986年 | 264篇 |
1985年 | 297篇 |
1984年 | 242篇 |
1983年 | 225篇 |
1982年 | 232篇 |
1981年 | 191篇 |
1980年 | 204篇 |
1979年 | 165篇 |
1978年 | 125篇 |
1977年 | 127篇 |
1976年 | 120篇 |
1975年 | 106篇 |
1974年 | 119篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Marike Gabrielson Mattias Hammarström Magnus Bäcklund Jenny Bergqvist Kristina Lång Ann H Rosendahl Signe Borgquist Roxanna Hellgren Kamila Czene Per Hall 《International journal of cancer. Journal international du cancer》2023,152(11):2362-2372
Tamoxifen prevents recurrence of breast cancer and is suggested for preventive risk-reducing therapy. Tamoxifen reduces mammographic density, a proxy for therapy response, but little is known about its effects in remodelling normal breast tissue. Our study, a substudy within the double-blinded dose-determination trial KARISMA, investigated tamoxifen-specific changes in breast tissue composition and histological markers in healthy women. We included 83 healthy women randomised to 6 months daily intake of 20, 10, 5, 2.5, 1 mg of tamoxifen or placebo. The groups were combined to “no dose” (0-1 mg), “low-dose” (2.5-5 mg) or “high-dose” (10-20 mg) of tamoxifen. Ultrasound-guided biopsies were collected before and after tamoxifen exposure. In each biopsy, epithelial, stromal and adipose tissues was quantified, and expression of epithelial and stromal Ki67, oestrogen receptor (ER) and progesterone receptor (PR) analysed. Mammographic density using STRATUS was measured at baseline and end-of-tamoxifen-exposure. We found that different doses of tamoxifen reduced mammographic density and glandular-epithelial area in premenopausal women and associated with reduced epithelium and increased adipose tissue. High-dose tamoxifen also decreased epithelial ER and PR expressions in premenopausal women. Premenopausal women with the greatest reduction in proliferation also had the greatest epithelial reduction. In postmenopausal women, high-dose tamoxifen decreased the epithelial area with no measurable density decrease. Tamoxifen at both low and high doses influences breast tissue composition and expression of histological markers in the normal breast. Our findings connect epithelial proliferation with tissue remodelling in premenopausal women and provide novel insights to understanding biological mechanisms of primary prevention with tamoxifen. 相似文献
2.
Elizabeth D. Krebs Robert B. Hawkins J. Hunter Mehaffey Clifford E. Fonner Alan M. Speir Mohammed A. Quader Jeffrey B. Rich Leora T. Yarboro Nicholas R. Teman Gorav Ailawadi 《The Journal of thoracic and cardiovascular surgery》2019,157(4):1533-1542.e2
Objectives
Expedient extubation after cardiac surgery has been associated with improved outcomes, leading to postoperative extubation frequently during overnight hours. However, recent evidence in a mixed medical-surgical intensive care unit population demonstrated worse outcomes with overnight extubation. This study investigated the impact of overnight extubation in a statewide, multicenter Society of Thoracic Surgeons database.Methods
Records from 39,812 patients undergoing coronary artery bypass grafting or valve operations (2008-2016) and extubated within 24 hours were stratified according to extubation time between 06:00 and 18:00 (day) or between 18:00 and 6:00 (overnight). Outcomes including reintubation, mortality, and composite morbidity-mortality were evaluated using hierarchical regression models adjusted for Society of Thoracic Surgeons predictive risk scores. To further analyze extubation during the night, a subanalysis stratified patients into 3 groups: 06:00 to 18:00, 18:00 to 24:00, and 24:00 to 06:00.Results
A total of 20,758 patients were extubated overnight (52.1%) and were slightly older (median age 66 vs 65 years, P < .001) with a longer duration of ventilation (4 vs 7 hours, P < .001). Day and overnight extubation were associated with equivalent operative mortality (1.7% vs 1.7%, P = .880), reintubation (3.7% vs 3.4%, P = .141), and composite morbidity-mortality (8.2% vs 8.0%, P = .314). After risk adjustment, overnight extubation was not associated with any difference in reintubation, mortality, or composite morbidity-mortality. On subanalysis, those extubated between 24:00 and 06:00 exhibited increased composite morbidity-mortality (odds ratio, 1.18; P = .001) but no difference in reintubation or mortality.Conclusions
Extubation overnight was not associated with increased mortality or reintubation. These results suggest that in the appropriate clinical setting, it is safe to routinely extubate cardiac surgery patients overnight. 相似文献3.
Factors predicting the development of pressure ulcers in an at‐risk population who receive standardized preventive care: secondary analyses of a multicentre randomised controlled trial 下载免费PDF全文
4.
5.
6.
Toshiro Hara Rony Chanoch-Myers Nathan D. Mathewson Chad Myskiw Lyla Atta Lillian Bussema Stephen W. Eichhorn Alissa C. Greenwald Gabriela S. Kinker Christopher Rodman L. Nicolas Gonzalez Castro Hiroaki Wakimoto Orit Rozenblatt-Rosen Xiaowei Zhuang Jean Fan Tony Hunter Inder M. Verma Kai W. Wucherpfennig Itay Tirosh 《Cancer cell》2021,39(6):779-792.e11
7.
8.
9.
10.