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排序方式: 共有2369条查询结果,搜索用时 31 毫秒
21.
Zhao Donghui Wang Hua Chen Guorong Stefania Baccaro Angelica Cecilia Mauro Falconieri L. Pilloni 《Journal of the American Ceramic Society》2006,89(11):3582-3584
Gamma-ray irradiations induced various alterations in sulfur- and selenium-based chalcogenide glasses. The absorbed dose was in the range of 0.01–3.6 MGy. The glasses exhibit prominent sensitivity to γ-ray irradiation, characterized by changes in some of the physical properties of the glasses, e.g., optical transmission, optical band gap, density, and thermal expansion coefficient. The effects on glass structure and microscopic morphology were also studied by Raman spectra and scanning electron microscopic observations. 相似文献
22.
A cost-effective system for the contactless characterisation of microresonators vibrating in out-of-plane mode is presented. The system provides swept-frequency excitation to the microresonator, detects the mechanical vibrations by a single-point triangulator made by a laser diode and a four-quadrant detector, and exploits synchronous undersampling of the readout signal to derive the frequency response of the microresonator. The system has been prototyped and tested using a piezoelectric bimorph cantilever as the resonator. A displacement resolution of around 100 nm has been obtained in the frequency range of up to some tens of kilohertz. 相似文献
23.
Mauro Sassu 《Canadian Metallurgical Quarterly》2003,129(6):607-612
A plane elastic-plastic solid body presenting kinematic hardening is used to simulate a pair of dampers at the base of a rigid structure and determine the energy dissipation under conditions of assigned, homogeneous cyclic loading. The well-known von Mises theory of plasticity is applied with the aim of obtaining analytical solutions to the problem. Such solutions are arrived at by first calculating the Odqvist parameter, which yields dimensionless relations that depend on the external loads and mechanical properties of the material. The results, in terms of dissipated energy, are given for the case of a sinusoidal process, represented with the help of dimensionless parameters useful for engineering applications. 相似文献
24.
Marcella Bonchio Mauro Carraro Martino Gardan Gianfranco Scorrano Enrico Drioli Enrica Fontananova 《Topics in Catalysis》2006,40(1-4):133-140
The incorporation of decatungstate in polymeric membranes provides new heterogeneous photocatalysts for the oxidation of organic
substrates under oxygen atmosphere at 25 °C. Photocatalytic membranes have been prepared yielding polymeric films with a high
thermal, chemical and mechanical stability (PVDF, PDMS, Hyflon). Surface spectroscopy techniques including transmittance and
reflectance UV-Vis and FT-IR have been used to assess the photocatalyst integrity within the polymeric support. Catalyst screening
has been performed under both homogeneous and heterogeneous photooxygenation conditions. The photocatalyst activity has been
evaluated in terms of the substrate conversion, turnover numbers, and recycling experiments. A membrane induced selectivity
behavior has been evidenced by comparison with homogeneous oxidations. 相似文献
25.
SL Alam JD Satterlee JM Mauro TL Poulos JE Erman 《Canadian Metallurgical Quarterly》1995,34(47):15496-15503
The cyanide-ligated form of the baker's yeast cytochrome c peroxidase mutant bearing the mutation Asn82-->Ala82 ([N82A]CcPCN) has been studied by proton NMR spectroscopy. This mutation alters an amino acid that forms a hydrogen bond to His52, the distal histidine residue that interacts in the heme pocket with heme-bound ligands. His52 is a residue critical to cytochrome c peroxidase's normal function. Proton hyperfine resonance assignments have been made for the cyanide-ligated form of the mutant by comparison with 1-D and NOESY spectra of the wild-type native enzyme. For [N82A]CcPCN, proton NMR spectra reveal two significant phenomena. First, similar to results published for the related mutant [N82D]CcPCN [Satterlee, J. D., et al. (1994) Eur. J. Biochem. 244, 81-87], for Ala82 mutation disrupts the hydrogen bond between His52 and the heme-ligated CN. Second, four of the 24 resolved hyperfine-shifted resonances are doubled in the mutant enzyme's proton spectrum, leading to the concept that the heme active site environment is dynamically microheterogeneous on a very localized scale. Two magnetically inequivalent enzyme forms are detected in a pure enzyme preparation. Varying temperature causes the two enzyme forms to interconvert. Magnetization transfer experiments further document this interconversion between enzyme forms and have been used to determine that the rate of interconversion is 250 (+/- 53) s-1. The equilibrium constant at 20 degrees C is 1.5. Equilibrium constants have been calculated at various temperatures between 5 and 29 degrees C leading to the following values: delta H = 60 kJ mol-1; delta S = 0.20 kJ K-1 mol-1. 相似文献
26.
RF Buckman MM Badellino LH Mauro JA Asensio C Caputo J Gass JD Grosh 《Canadian Metallurgical Quarterly》1993,34(5):717-25; discussion 725-7
A prospective study of 66 consecutive patients with cardiac wounds seen over a 27-month period is reported. No patient was excluded. Patients were stratified by injury mechanism and by physiologic scoring at admission using the cardiovascular-respiratory elements of the Trauma Score (CVRS). Admission cardiac rhythm was obtained in patients with a CVRS of 0 and a Glasgow Coma Scale (GCS) score of 3. Information concerning the anatomic extent of the cardiac wound, the presence or absence of tamponade, and the degree of injury to other structures was also collected prospectively. Seventy percent of the cardiac wounds were caused by gunshots. The probability of successful resuscitation was significantly related to mechanism of injury and physiologic condition on arrival. Among patients arriving with a CVRS of 0 and a GCS score of 3, survival correlated with cardiac rhythm. Pericardial tamponade did not prove to be an independent predictor of early survival. The presence of tamponade was statistically linked to the mechanism of injury. Transport by non-official conveyance was associated with a higher CVRS on arrival. Intoxication with alcohol or cocaine had no evident effect on resuscitation probability. 相似文献
27.
This paper studies the non-blocking conditions of a generic N × N multistage interconnection network, such as an omega network or an n-cube network, in which only one path connects any inlet to each outlet and different I/O paths can share interstage links. It is widely known that any of these networks is non-blocking for a compact and monotone pattern of k ≤ N I/O paths. Recently it has become very important to show the network non-blocking property for permutation sets, wider than the compact and monotone, which are usually encountered in broadband ATM networks. By using a new approach based on the concept of distance between I/O paths, we show here that these networks are non-blocking for a set of I/O paths obtained by shifting cyclically the inlets of a compact and monotone pattern of I/O paths by an arbitrary number of steps. 相似文献
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30.
Di Mauro E.C. Cootes T.F. Page G.J. Jackson C.B. 《Vision, Image and Signal Processing, IEE Proceedings -》1996,143(4):241-249
The authors present an overview of an `inspection and control' package to perform automatic quality control of industrial components, specifically electronic circuit boards. This application has grown out of a set of tools designed initially to aid the development of point distribution models (PDMs) and grey-level models (GLMs) pioneered at the Wolfson Image Analysis Unit in Manchester. These models are both generic and specific. Generic, because they can be applied to most image classification problems; specific, because they aim at the full interpretation of the variability of the objects to be modelled. The underlying vision processing techniques are based on statistical pattern matching. Two synergetic approaches have been followed. The system is trained to recognise the components from either their shape or their grey level appearance or both 相似文献