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超导量子干涉仪与声核共振现象相结合探测封闭铅金属壳内表面的微量氧化情况
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作者 张继波 令狐克寰 +3 位作者 吴倩红 聂瑞娟 喻凤梅 王福仁 《北京大学学报(自然科学版)》 EI CAS CSCD 北大核心 2017年第5期801-809,共9页
设计内表面微量氧化的封闭Pb^(207)(I=1/2)金属圆筒模型与球壳模型,在使用超导量子干涉仪测量内表面氧化物β-Pb^(207)O声核信号的前提下,分别进行公式推导与验证,为后续实验测量半导体材料中的偶极矩耦合信号进行理论计算。在相应的条... 设计内表面微量氧化的封闭Pb^(207)(I=1/2)金属圆筒模型与球壳模型,在使用超导量子干涉仪测量内表面氧化物β-Pb^(207)O声核信号的前提下,分别进行公式推导与验证,为后续实验测量半导体材料中的偶极矩耦合信号进行理论计算。在相应的条件下,得到超导量子干涉仪磁通变化与可测量的氧化物质量范围以及所加外场之间的关系,并探讨使用超导量子干涉仪探测封闭金属圆筒与球壳内表面氧化物的声核共振现象的可行性与优越性。最后,设计了一套使用超导量子干涉仪测量声核参量的实验方案。 展开更多
关键词 超导量子干涉仪 声核共振 磁偶极矩耦合
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Imaging of the gastrointestinal tract-novel technologies 被引量:3
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作者 Jens Brφndum Frφkjr Asbjφrn Mohr Drewes Hans Gregersen 《World Journal of Gastroenterology》 SCIE CAS CSCD 2009年第2期160-168,共9页
Imaging of the gastrointestinal tract is very useful for research and clinical studies of patients with symptoms arising from the gastrointestinal tract and in visualising anatomy and pathology. Traditional radiologic... Imaging of the gastrointestinal tract is very useful for research and clinical studies of patients with symptoms arising from the gastrointestinal tract and in visualising anatomy and pathology. Traditional radiological techniques played a leading role in such studies for a long time. However, advances in non-invasive modalities including ultrasound (US), computed tomography (CT), positron emission tomography (PET), magnetic resonance imaging (MRI), etc, have in the last decades revolutionised the way in which the gastrointestinal tract is studied. The resolution of imaging data is constantly being improved and 3D acquisition, tools for fi ltering, enhancement, segmentation and tissue classif ication are continually being developed. Additional co-registration techniques allow multimodal data acquisition with improved classif ication of tissue pathology. Furthermore, new functional imaging techniques have become available. Altogether, the future of gastrointestinal imaging looks very promising which will be of great benef it in clinical and research studies of gastrointestinal diseases. The purpose of this review is to highlight the capabilities of the newest techniques to explore the detailed morphology, biomechanical properties, function and pathology of the gastrointestinal tract. 展开更多
关键词 Computed tomography Gastrointestinaltract IMAGING Magnetic resonance RADIOLOGY ULTRASOUND
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Separation of Acearylenes from High-Temperature Coal Tar
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作者 周建石 马全领 +1 位作者 宗志敏 魏贤勇 《Transactions of Tianjin University》 EI CAS 2012年第5期378-383,共6页
High-temperature coal tar was extracted with petroleum ether (PE) under ultrasonic irradiation and the extracts were analyzed with gas chromatograph/mass spectrometer. The acearylene fractions including acenaphthyle... High-temperature coal tar was extracted with petroleum ether (PE) under ultrasonic irradiation and the extracts were analyzed with gas chromatograph/mass spectrometer. The acearylene fractions including acenaphthylene, aceanthrylene and cyclopentapyrene were enriched together and named E, which was then transferred to a car- tridge in Isolera-One flash chromatography. Three groups of compounds were eluted out with ethyl acetate/PE mixed solvent (volume ratio 1:9) and named E1, E2 and E3 according to their main components. Acenaphthylene accounted for 78.2% in El, aceanthrylene 71.6% in E2 and cyclopentapyrene 75.9% in E3, respectively. The three groups of acearylenes were purified by Sephadex LH-20 column chromatography with ethanol/cyclohexane mixed solvent (vol- ume ratio 1:4), and then confirmed with nuclear magnetic resonance spectrometer. This method indicates that flash chromatography has a good effect on separating the compounds with a similar structnre after extraction under ultrasonic irradiation. 展开更多
关键词 SEPARATION acearylenes coal tar
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