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排序方式: 共有274条查询结果,搜索用时 15 毫秒
81.
The selective intermacromolecular complex formation between p-bromophenol-formaldehyde copolymer (PPF) and poly(vinyl pyrrolidone) (PVP) and poly(ethylene oxide) (PEO) has been investigated. PVP has been found to have greater ability for complex formation compared to PEO with respect to PPF. An open-chain mechanism has been proposed for the substitution reaction between PVP and PPF-PEO complex. The abnormal behaviour of viscosity curves has been interpreted on the basis of probable association between the nonionic polymers. 相似文献
82.
Chemically prepared amorphous Fe-Ni-B alloy particles 总被引:1,自引:0,他引:1
S. Mørup S. A. Sethi S. Linderoth C. Bender Koch M. D. Bentzon 《Journal of Materials Science》1992,27(11):3010-3013
Amorphous Fe-Ni-B alloy particles have been prepared by chemical reduction of Fe2+ and Ni2+ in aqueous solution by NaBH4. It was found that within a limited range of NaBH4 concentrations and pH values of the metal salt solution the particles are amorphous. Outside this range the precipitates are partly crystalline. The magnetic hyperfine fields of the amorphous particles, estimated from57Fe Mössbauer spectroscopy, are similar to those of amorphous ribbons with the same compositions. 相似文献
83.
84.
85.
Pratyush Tewari Guneet Sethi Mark W. Horn Michael T. Lanagan 《Journal of Materials Science: Materials in Electronics》2009,20(10):1001-1007
Zirconia-P(VDF-TrFE) double-layered laminar composites are experimentally investigated to understand inorganic–organic interfacial
effects in composite dielectrics. The DC and AC electrical response of the individual phases were characterized in addition
to the zirconia-P(VDF-TrFE) composite. The measured real part of permittivity for the laminar composite is found to be higher
than theoretically calculated values using series mixing rules for zirconia and P(VDF-TrFE). Additional polarization of the
composite structure can be attributed to either the presence of interfacial polarization of zirconia and P(VDF-TrFE) or modification
of polymer. Impedance spectroscopy has shown that dielectric properties of laminar composites are dominated by zirconia thin
films in low frequency region. The impedance spectroscopy shows that zirconia blocks charge carrier motion and hence partially
contribute towards additional interfacial polarization in the laminar composite. The dielectric response of the laminar composite
was also modeled through a Maxwell–Wagner interfacial polarization mechanism, which was found to inadequately describe the
polarization response. Equivalent circuit modeling of the composite has revealed an additional interfacial circuit element
for the additional polarization, suggesting a structurally modified polymer at the interface. 相似文献
86.
Loring David W.; Sethi Kapil D.; Lee Gregory P.; Meador Kimford J. 《Canadian Metallurgical Quarterly》1990,4(3):191
Hallervorden-Spatz disease (HSD) is a rare progressive disorder characterized by iron deposition in the globus pallidus and zona reticularis of the substantia nigra. The cases of 2 Black female patients (aged 20–38 yrs) with diagnoses of probable HSD are evaluated, based on typical clinical course in conjunction with magnetic resonance imaging abnormalities restricted to the region of the globus pallidus. Ss' deficits included slowed cognitive processing speed, motor sequencing difficulty, constructional dyspraxia, and impaired recent memory functions. The constellation of behavioral deficits can be attributed to dysfunction of the frontal lobe, basal ganglia, or disruption of their functional interconnections. Additional deficits in language and visuospatial processing were also observed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
87.
Knowledge representation and sharing using visual semantic modeling for diagnostic medical image databases. 总被引:1,自引:0,他引:1
Adrian S Barb Chi-Ren Shyu Yash P Sethi 《IEEE transactions on information technology in biomedicine》2005,9(4):538-553
Information technology offers great opportunities for supporting radiologists' expertise in decision support and training. However, this task is challenging due to difficulties in articulating and modeling visual patterns of abnormalities in a computational way. To address these issues, well established approaches to content management and image retrieval have been studied and applied to assist physicians in diagnoses. Unfortunately, most of the studies lack the flexibility of sharing both explicit and tacit knowledge involved in the decision making process, while adapting to each individual's opinion. In this paper, we propose a knowledge repository and exchange framework for diagnostic image databases called "evolutionary system for semantic exchange of information in collaborative environments" (Essence). This framework uses semantic methods to describe visual abnormalities, and offers a solution for tacit knowledge elicitation and exchange in the medical domain. Also, our approach provides a computational and visual mechanism for associating synonymous semantics of visual abnormalities. We conducted several experiments to demonstrate the system's capability of matching synonym terms, and the benefit of using tacit knowledge in improving the meaningfulness of semantic queries. 相似文献
88.
Ravi Sethi 《Software》1981,11(6):623-628
A declaration mechanism is proposed that allows common type information to be factored into a type expression, yet allows related but distinct types to be declared together. The mechanism is a unification of declarations in Pascal and C. The choice of syntax is quite important. The proposed syntax uses a postfix operator for dereferencing pointers instead of the prefix operator * for pointer dereferencing in C. 相似文献
89.
A patient is reported with episodes of epileptic laughter, crying, and running occurring alone or in combination. He was found to have discrete, well-circumscribed tumour of the left temporal lobe. The neurology of these epileptic events is discussed in relation to the pathological lesion. 相似文献
90.
Himani Sharma Kanika Sethi P. Markondeya Raj Rao Tummala 《Journal of Materials Science: Materials in Electronics》2012,23(2):528-535
System integration and miniaturization demands are driving component technologies towards integrated thin films with higher
volumetric efficiencies and component densities. Among the various system components, achieving higher densities with capacitors,
integrated in thin film form has been a major challenge for the past few decades. This paper reports the first proof-of-concept
demonstration of a novel silicon-compatible high-density capacitor technology. The key novelty stems from the tremendous enhancement
in surface area from thin and porous copper nanoelectrodes and conformal alumina dielectric on such nanoelectrodes. Atomic
Layer Deposition was chosen as the dielectric process because of its self-limiting, defect-free and conformal deposition on
3-D structures. Alumina with its moderate permittivity and superior dielectric properties over large voltage ranges was employed
as the representative dielectric. Thin copper particulate electrodes with conformal counter electrodes showed 10 times higher
capacitance density compared to the planar devices, with similar leakage properties. Thicker electrodes showed enormous enhancement
in surface area but inferior leakage properties. Combination of compositional and morphological techniques was used to show
alumina conformality on complex 3-D structures of copper particulate electrode. Capacitance–Voltage and Current–Voltage characterizations
were carried out to confirm the feasibility of the novel high density 3-D capacitor structure. 相似文献