全文获取类型
收费全文 | 5302篇 |
免费 | 320篇 |
国内免费 | 32篇 |
专业分类
耳鼻咽喉 | 54篇 |
儿科学 | 126篇 |
妇产科学 | 61篇 |
基础医学 | 833篇 |
口腔科学 | 140篇 |
临床医学 | 504篇 |
内科学 | 1151篇 |
皮肤病学 | 163篇 |
神经病学 | 516篇 |
特种医学 | 248篇 |
外科学 | 771篇 |
综合类 | 21篇 |
一般理论 | 2篇 |
预防医学 | 283篇 |
眼科学 | 50篇 |
药学 | 399篇 |
中国医学 | 3篇 |
肿瘤学 | 329篇 |
出版年
2023年 | 22篇 |
2022年 | 46篇 |
2021年 | 100篇 |
2020年 | 75篇 |
2019年 | 100篇 |
2018年 | 146篇 |
2017年 | 110篇 |
2016年 | 142篇 |
2015年 | 114篇 |
2014年 | 158篇 |
2013年 | 234篇 |
2012年 | 306篇 |
2011年 | 328篇 |
2010年 | 219篇 |
2009年 | 207篇 |
2008年 | 328篇 |
2007年 | 335篇 |
2006年 | 295篇 |
2005年 | 278篇 |
2004年 | 261篇 |
2003年 | 262篇 |
2002年 | 228篇 |
2001年 | 69篇 |
2000年 | 75篇 |
1999年 | 69篇 |
1998年 | 55篇 |
1997年 | 45篇 |
1996年 | 31篇 |
1995年 | 26篇 |
1994年 | 35篇 |
1993年 | 23篇 |
1992年 | 39篇 |
1991年 | 42篇 |
1990年 | 42篇 |
1989年 | 44篇 |
1988年 | 33篇 |
1987年 | 32篇 |
1986年 | 33篇 |
1985年 | 35篇 |
1984年 | 42篇 |
1983年 | 30篇 |
1982年 | 25篇 |
1980年 | 23篇 |
1979年 | 28篇 |
1978年 | 37篇 |
1977年 | 30篇 |
1975年 | 23篇 |
1974年 | 23篇 |
1972年 | 21篇 |
1971年 | 23篇 |
排序方式: 共有5654条查询结果,搜索用时 31 毫秒
71.
72.
73.
Quantification of magnetic resonance spectroscopy signals using the phantom replacement method requires an adequate correction of differences between the acquisition of the reference signal in the phantom and the measurement in vivo. Applying the principle of reciprocity, sensitivity differences can be corrected at low field strength by measuring the RF transmitter gain needed to obtain a certain flip angle in the measured volume. However, at higher field strength the transmit sensitivity may vary from the reception sensitivity, which leads to wrongly estimated concentrations. To address this issue, a quantification approach based on the principle of reciprocity for use at 3T is proposed and validated thoroughly. In this approach, the RF transmitter gain is determined automatically using a volume‐selective power optimization and complemented with information from relative reception sensitivity maps derived from contrast‐minimized images to correct differences in transmission and reception sensitivity. In this way, a reliable measure of the local sensitivity was obtained. The proposed method is used to derive in vivo concentrations of brain metabolites and tissue water in two studies with different coil sets in a total of 40 healthy volunteers. Resulting molar concentrations are compared with results using internal water referencing (IWR) and Electric REference To access In vivo Concentrations (ERETIC). With the proposed method, changes in coil loading and regional sensitivity due to B1 inhomogeneities are successfully corrected, as demonstrated in phantom and in vivo measurements. For the tissue water content, coefficients of variation between 2% and 3.5% were obtained (0.6–1.4% in a single subject). The coefficients of variation of the three major metabolites ranged from 3.4–14.5%. In general, the derived concentrations agree well with values estimated with IWR. Hence, the presented method is a valuable alternative for IWR, without the need for additional hardware such as ERETIC and with potential advantages in diseased tissue. 相似文献
74.
Depeursinge A Vargas A Gaillard F Platon A Geissbuhler A Poletti PA Müller H 《International journal of computer assisted radiology and surgery》2012,7(1):97-110
Purpose
Clinical workflows and user interfaces of image-based computer-aided diagnosis (CAD) for interstitial lung diseases in high-resolution computed tomography are introduced and discussed. 相似文献75.
76.
77.
78.
Andreas Linkermann Jan Hinrich Br?sen Maurice Darding Mi Kyung Jin Ana B. Sanz Jan-Ole Heller Federica De Zen Ricardo Weinlich Alberto Ortiz Henning Walczak Joel M. Weinberg Douglas R. Green Ulrich Kunzendorf Stefan Krautwald 《Proceedings of the National Academy of Sciences of the United States of America》2013,110(29):12024-12029
Regulated necrosis (RN) may result from cyclophilin (Cyp)D-mediated mitochondrial permeability transition (MPT) and receptor-interacting protein kinase (RIPK)1-mediated necroptosis, but it is currently unclear whether there is one common pathway in which CypD and RIPK1 act in or whether separate RN pathways exist. Here, we demonstrate that necroptosis in ischemia–reperfusion injury (IRI) in mice occurs as primary organ damage, independent of the immune system, and that mice deficient for RIPK3, the essential downstream partner of RIPK1 in necroptosis, are protected from IRI. Protection of RIPK3-knockout mice was significantly stronger than of CypD-deficient mice. Mechanistically, in vivo analysis of cisplatin-induced acute kidney injury and hyperacute TNF-shock models in mice suggested the distinctness of CypD-mediated MPT from RIPK1/RIPK3-mediated necroptosis. We, therefore, generated CypD-RIPK3 double-deficient mice that are viable and fertile without an overt phenotype and that survived prolonged IRI, which was lethal to each single knockout. Combined application of the RIPK1 inhibitor necrostatin-1 and the MPT inhibitor sanglifehrin A confirmed the results with mutant mice. The data demonstrate the pathophysiological coexistence and corelevance of two separate pathways of RN in IRI and suggest that combination therapy targeting distinct RN pathways can be beneficial in the treatment of ischemic injury. 相似文献
79.
Kajsa Henning Abrahamsson Ulf Berggren Sven G. Carlsson 《Acta odontologica Scandinavica》2013,71(1):37-43
Phobic reactions can often be a significant health problem for fearful dental patients. This is true in particular for individuals with long-time avoidance and elevated general psychological distress. The aim of this study was to investigate the expression of dental fear among 67 dental phobic individuals with a low versus high degree of general fear. Reported etiologic background factors, avoidance time, general psychological distress and psychosocial manifestations and consequences of dental phobia were studied. No significant difference in dental anxiety level between individuals with low versus high general fear was found, and both groups reported high frequencies of negative dental experiences. The low-fear group reported a longer (though not statistically significant) average avoidance time than the high-fear group. However, patients with a high level of general fear showed a significantly higher degree of psychological distress, and also reported stronger negative social consequences from their dental anxiety. These results indicate that the character of dental fear might be different between different groups of fearful patients, which makes the condition psychologically handicapping. Such aspects should be assessed in the diagnostic analysis of patients with severe dental anxiety. In particular, assessments of signs of general psychological distress are warranted. 相似文献