全文获取类型
收费全文 | 267215篇 |
免费 | 7809篇 |
国内免费 | 507篇 |
专业分类
耳鼻咽喉 | 2308篇 |
儿科学 | 8815篇 |
妇产科学 | 4341篇 |
基础医学 | 28424篇 |
口腔科学 | 3809篇 |
临床医学 | 21393篇 |
内科学 | 51200篇 |
皮肤病学 | 2159篇 |
神经病学 | 25211篇 |
特种医学 | 12661篇 |
外国民族医学 | 1篇 |
外科学 | 44101篇 |
综合类 | 3079篇 |
一般理论 | 194篇 |
预防医学 | 24244篇 |
眼科学 | 4523篇 |
药学 | 15080篇 |
中国医学 | 762篇 |
肿瘤学 | 23226篇 |
出版年
2023年 | 768篇 |
2022年 | 1254篇 |
2021年 | 3285篇 |
2020年 | 1823篇 |
2019年 | 2835篇 |
2018年 | 24742篇 |
2017年 | 19331篇 |
2016年 | 21613篇 |
2015年 | 3720篇 |
2014年 | 4689篇 |
2013年 | 5747篇 |
2012年 | 14369篇 |
2011年 | 28303篇 |
2010年 | 22693篇 |
2009年 | 14999篇 |
2008年 | 25447篇 |
2007年 | 27381篇 |
2006年 | 6401篇 |
2005年 | 7912篇 |
2004年 | 8537篇 |
2003年 | 9067篇 |
2002年 | 6740篇 |
2001年 | 874篇 |
2000年 | 885篇 |
1999年 | 833篇 |
1998年 | 1080篇 |
1997年 | 905篇 |
1996年 | 655篇 |
1995年 | 659篇 |
1994年 | 541篇 |
1993年 | 514篇 |
1992年 | 401篇 |
1991年 | 409篇 |
1990年 | 414篇 |
1989年 | 363篇 |
1988年 | 341篇 |
1987年 | 300篇 |
1986年 | 310篇 |
1985年 | 315篇 |
1984年 | 373篇 |
1983年 | 328篇 |
1982年 | 363篇 |
1981年 | 338篇 |
1980年 | 302篇 |
1979年 | 153篇 |
1978年 | 201篇 |
1977年 | 184篇 |
1976年 | 138篇 |
1975年 | 139篇 |
1974年 | 151篇 |
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
71.
72.
73.
Christine E. Marx William T. Trost Lawrence J. Shampine Robert D. Stevens Christine M. Hulette David C. Steffens John F. Ervin Marian I. Butterfield Daniel G. Blazer Mark W. Massing Jeffrey A. Lieberman 《Neuropsychopharmacology》2006,60(12):1287-1294
BACKGROUND: Few data are currently available investigating neurosteroids (NS) in Alzheimer's disease (AD). The NS allopregnanolone may be decreased in serum and plasma in patients with AD, but it is unclear if allopregnanolone is also reduced in brain. Because a number of NS exhibit neuroprotective effects and impact cognitive performance in rodent models, these molecules may be relevant to the pathophysiology of neurodegenerative disorders. We therefore investigated prefrontal cortex (PFC) NS levels in AD. METHODS: Neurosteroid levels (allopregnanolone, pregnenolone, dehydroepiandrosterone [DHEA]) were determined in postmortem PFC in 14 male subjects with AD and 15 cognitively intact male control subjects by gas chromatography/mass spectrometry preceded by high-performance liquid chromatography purification. RESULTS: Subjects with AD exhibit significant reductions in allopregnanolone compared with cognitively intact control subjects (median levels = 2.50 ng/g vs. 5.59 ng/g, respectively; p = .02). Allopregnanolone levels are inversely correlated with neuropathological disease stage (Braak), r = -.49, p = .007. Median DHEA levels are elevated in subjects with AD (p = .01). CONCLUSIONS: Subjects with AD demonstrate significant reductions in PFC allopregnanolone levels, a finding that may be relevant to neuropathological disease stage severity. Neurosteroids may have utility as candidate biomarkers in AD. 相似文献
74.
75.
76.
We evaluated the acquisition and performance of a high-precision locomotor task in patients with Parkinson's disease (PD) and healthy subjects. All subjects walked on a treadmill and had to step repetitively as low as possible over an obstacle without touching it. During blocks 1 and 2, the subjects had full vision and received additional acoustic warning and feedback signals. During block 3, vision became restricted. Changes in foot clearance and the number of obstacle hits were evaluated. Initially, PD patients performed poorer and improved foot clearance slower. After task repetition, the groups performed similarly. Restricting vision deteriorated performance in both groups. The similar performance of PD patients after task repetition might indicate that adequate training could improve adaptive locomotor behavior in PD patients. 相似文献
77.
78.
79.
This article describes the proceedings of the 2006 Annual Meeting of the Fetal Alcohol Spectrum Disorders Study Group (FASDSG), which was held in Baltimore, Maryland on June 24, 2006. The meeting was held in conjunction with the annual meeting of the Research Society on Alcoholism and was supported by a grant from the National Institute on Alcohol Abuse and Alcoholism. The 2005-2006 FASDSG officers, Daniel J. Bonthius (President), Heather Carmichael Olson (Vice-President), and Jennifer Thomas (Secretary-Treasurer), organized the meeting. Nationally prominent speakers delivered plenary lectures on topics of newborn screening, ethics, and neuroscience. Selected members of the FASDSG provided brief scientific data (FASt) reports, describing new research findings. Representatives from national agencies involved in fetal alcohol syndrome (FAS) research, treatment, and prevention provided updates regarding priorities, funding, and agency activities. Presentations were also made by the 2006 Student Merit Award recipient and by the 2006 Rosett Award recipient. The meeting served as a forum for clinicians, neuroscientists, psychologists, social scientists, and other professionals to discuss recent advances in FAS research and to identify the most important gaps in the understanding of alcohol-induced teratology. 相似文献
80.