全文获取类型
收费全文 | 34218篇 |
免费 | 6027篇 |
国内免费 | 94篇 |
专业分类
耳鼻咽喉 | 212篇 |
儿科学 | 987篇 |
妇产科学 | 2003篇 |
基础医学 | 2021篇 |
口腔科学 | 276篇 |
临床医学 | 17396篇 |
内科学 | 4921篇 |
皮肤病学 | 223篇 |
神经病学 | 2211篇 |
特种医学 | 527篇 |
外科学 | 2415篇 |
综合类 | 207篇 |
一般理论 | 15篇 |
预防医学 | 3827篇 |
眼科学 | 367篇 |
药学 | 946篇 |
中国医学 | 12篇 |
肿瘤学 | 1773篇 |
出版年
2024年 | 95篇 |
2023年 | 894篇 |
2022年 | 308篇 |
2021年 | 767篇 |
2020年 | 930篇 |
2019年 | 703篇 |
2018年 | 1582篇 |
2017年 | 1708篇 |
2016年 | 1798篇 |
2015年 | 1874篇 |
2014年 | 2082篇 |
2013年 | 2605篇 |
2012年 | 1637篇 |
2011年 | 2031篇 |
2010年 | 1720篇 |
2009年 | 1927篇 |
2008年 | 1689篇 |
2007年 | 1631篇 |
2006年 | 1575篇 |
2005年 | 1356篇 |
2004年 | 1215篇 |
2003年 | 1145篇 |
2002年 | 970篇 |
2001年 | 572篇 |
2000年 | 353篇 |
1999年 | 516篇 |
1998年 | 705篇 |
1997年 | 780篇 |
1996年 | 701篇 |
1995年 | 633篇 |
1994年 | 473篇 |
1993年 | 386篇 |
1992年 | 298篇 |
1991年 | 288篇 |
1990年 | 265篇 |
1989年 | 219篇 |
1988年 | 179篇 |
1987年 | 154篇 |
1986年 | 160篇 |
1985年 | 178篇 |
1984年 | 138篇 |
1983年 | 119篇 |
1982年 | 110篇 |
1981年 | 124篇 |
1980年 | 83篇 |
1979年 | 97篇 |
1978年 | 71篇 |
1977年 | 75篇 |
1976年 | 77篇 |
1972年 | 95篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
82.
83.
84.
BEVERLY HAVENS RN MN MPH INGRID SWENSON RN DPH 《Journal of obstetric, gynecologic, and neonatal nursing : JOGNN / NAACOG》1986,15(5):406-411
Seventy-four 8th- and 10th-grade students attending a private girls' school in Hawaii were queried about their perceptions of and preparation for menstruation using a questionnaire administered in a health education class. Eighty percent had already started menstruating. The most frequently cited perceptions by the respondents referred to both the inconveniences and the normalcy of menstruation. Many were first informed about menstruation by their mothers and stated that they also first informed their mothers when they started menstruating. Surprise, fear, and embarrassment were common initial reactions, while strong negative or positive emotions were more rare. Only 35% wanted boys and girls together during class discussion, but 89% stated that boys needed to be informed about menstruation. The most frequent reasons cited for noncoed settings were the girls' concern about their comfort in openly discussing menstruation. Thirty-eight percent thought parents should inform other siblings when they started menstruation, although almost half gave specific conditions the parents should consider. The majority thought the fifth to sixth grades were the best times to introduce menstruation content. 相似文献
85.
86.
87.
Kathryn Nichol Sean P. Deeny Joseph Seif Kevin Camaclang Carl W. Cotman 《Alzheimer's & dementia》2009,5(4):287-294
BackgroundHuman studies on exercise, cognition, and apolipoprotein E (APOE) genotype show that ε4 carriers may benefit from regular physical activity.MethodsWe examined voluntary wheel-running, memory, and hippocampal plasticity in APOE ε3 and APOE ε4 transgenic mice at 10–12 months of age.ResultsSedentary ε4 mice exhibited deficits in cognition on the radial-arm water maze (RAWM), a task dependent on the hippocampus. Six weeks of wheel-running in ε4 mice resulted in improvements on the RAWM to the level of ε3 mice. Hippocampal brain-derived neurotrophic factor (BDNF) levels were similar in ε3 and ε4 mice, and after exercise BDNF was similarly increased in both ε3 and ε4 mice. In sedentary ε4 mice, tyrosine kinase B (Trk B) receptors were reduced by 50%. Exercise restored Trk B in ε4 mice to the level of ε3 mice, and in ε4 mice, exercise dramatically increased synaptophysin, a marker of synaptic function.ConclusionsOur results support the hypothesis that exercise can improve cognitive function, particularly in ε4 carriers. 相似文献
88.
FDA’S Perspectives on Cardiovascular Devices 总被引:1,自引:0,他引:1
Eric A. Chen Sonna M. Patel-Raman Kathryn O’Callaghan Matthew G. Hillebrenner 《Journal of cardiovascular translational research》2009,2(2):143-146
The Food and Drug Administration (FDA) decision process for approving or clearing medical devices is often determined by a
review of robust clinical data and extensive preclinical testing of the device. The mission statement for the Center for Devices
and Radiological Health (CDRH) is to review the information provided by manufacturers so that it can promote and protect the
health of the public by ensuring the safety and effectiveness of medical devices deemed appropriate for human use (Food, Drug
& Cosmetic Act, §903(b)(1, 2(C)), December 31, 2004; accessed December 17, 2008 ). For high-risk devices, such as ventricular assist devices (VADs), mechanical heart valves, stents, cardiac resynchronization
therapy (CRT) devices, pacemakers, and defibrillators, the determination is based on FDA’s review of extensive preclinical
bench and animal testing followed by use of the device in a clinical trial in humans. These clinical trials allow the manufacturer
to evaluate a device in the intended use population. FDA reviews the data from the clinical trial to determine if the device
performed as predicted and the clinical benefits outweigh the risks. This article reviews the regulatory framework for different
marketing applications related to cardiovascular devices and describes the process of obtaining approval to study a cardiovascular
device in a U.S. clinical trial. 相似文献
89.
90.