全文获取类型
收费全文 | 503篇 |
免费 | 22篇 |
国内免费 | 16篇 |
专业分类
儿科学 | 33篇 |
妇产科学 | 1篇 |
基础医学 | 43篇 |
口腔科学 | 8篇 |
临床医学 | 75篇 |
内科学 | 98篇 |
皮肤病学 | 9篇 |
神经病学 | 16篇 |
特种医学 | 106篇 |
外科学 | 47篇 |
综合类 | 39篇 |
预防医学 | 14篇 |
眼科学 | 1篇 |
药学 | 33篇 |
中国医学 | 1篇 |
肿瘤学 | 17篇 |
出版年
2022年 | 2篇 |
2021年 | 4篇 |
2020年 | 2篇 |
2019年 | 6篇 |
2018年 | 4篇 |
2017年 | 4篇 |
2016年 | 6篇 |
2015年 | 10篇 |
2014年 | 14篇 |
2013年 | 18篇 |
2012年 | 22篇 |
2011年 | 9篇 |
2010年 | 25篇 |
2009年 | 18篇 |
2008年 | 11篇 |
2007年 | 18篇 |
2006年 | 11篇 |
2005年 | 13篇 |
2004年 | 3篇 |
2003年 | 11篇 |
2002年 | 7篇 |
2001年 | 9篇 |
2000年 | 10篇 |
1999年 | 15篇 |
1998年 | 24篇 |
1997年 | 27篇 |
1996年 | 25篇 |
1995年 | 20篇 |
1994年 | 19篇 |
1993年 | 17篇 |
1992年 | 3篇 |
1991年 | 8篇 |
1990年 | 11篇 |
1989年 | 24篇 |
1988年 | 21篇 |
1987年 | 13篇 |
1986年 | 11篇 |
1985年 | 8篇 |
1984年 | 7篇 |
1983年 | 8篇 |
1982年 | 4篇 |
1981年 | 7篇 |
1980年 | 10篇 |
1979年 | 2篇 |
1978年 | 5篇 |
1977年 | 2篇 |
1976年 | 4篇 |
1975年 | 2篇 |
1925年 | 1篇 |
1924年 | 1篇 |
排序方式: 共有541条查询结果,搜索用时 0 毫秒
71.
72.
73.
Percutaneous transjejunal approaches to the biliary system 总被引:2,自引:0,他引:2
74.
Duplex Doppler ultrasound (US) was used in 68 consecutive patients with focal liver lesions, including 12 hepatocellular carcinomas, one cholangiocarcinoma, 37 metastases, 15 hemangiomas, one hemangioendothelioma, and two focal nodular hyperplasias. Of the hepatocellular carcinomas, six were diffusely hyperechoic, two were hypoechoic, two were single hyperechoic lesions, and two were multifocal and hyperechoic. All ten tumors with Doppler shifts of 5 kHz or above proved to be hepatocellular carcinomas. The other two hepatocellular carcinomas showed Doppler shifts of 3 kHz. In contrast, no hemangioma showed shifts above 0.7 kHz, and ten of the 15 gave no detectable signal. Of the metastases, 20 gave no signal and 17 had signals of up to 4 kHz. Three-kilohertz signals were also obtained from a cholangiocarcinoma, a hemangioendothelioma, and focal nodular hyperplasia. Correlation with angiographic findings suggested that the high-velocity Doppler signals were associated with large pressure gradients due to arteriovenous shunting. Duplex Doppler US can therefore aid in the differential diagnosis of diffuse and focal liver lesions. 相似文献
75.
76.
77.
Robertson RT; Gallardo KA; Claytor KJ; Ha DH; Ku KH; Yu BP; Lauterborn JC; Wiley RG; Yu J; Gall CM; Leslie FM 《Cerebral cortex (New York, N.Y. : 1991)》1998,8(2):142-155
The role of basal forebrain-derived cholinergic afferents in the
development of neocortex was studied in postnatal rats. Newborn rat pups
received intraventricular injections of 192 IgG-saporin. Following survival
periods ranging from 2 days to 6 months, the brains were processed to
document the cholinergic lesion and to examine morphological consequences.
Immunocytochemistry for choline acetyltransferase (ChAT) and in situ
hybridization for ChAT mRNA demonstrate a loss of approximately 75% of the
cholinergic neurons in the medial septum and nucleus of the diagonal band
of Broca in the basal forebrain. In situ hybridization for glutamic acid
decarboxylase mRNA reveals no loss of basal forebrain GABAergic neurons.
Acetylcholinesterase histochemistry demonstrates a marked reduction of the
cholinergic axons in neocortex. Cholinergic axons are reduced throughout
the cortical layers; this reduction is more marked in medial than in
lateral cortical areas. The thickness of neocortex is reduced by
approximately 10%. Retrograde labeling of layer V cortico-collicular
pyramidal cells reveals a reduction in cell body size and also a reduction
in numbers of branches of apical dendrites. Spine densities on apical
dendrites are reduced by approximately 20-25% in 192 IgG- saporin-treated
cases; no change was detected in number of spines on basal dendrites. These
results indicate a developmental or maintenance role for cholinergic
afferents to cerebral cortical neurons.
相似文献
78.
79.
80.