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排序方式: 共有1898条查询结果,搜索用时 15 毫秒
931.
Katrina Müller Cristian Figueroa Constanza Martínez Marcela Medel Elias Obreque Alvaro Peña-Neira Irene Morales-Bozo Héctor Toledo Remigio O. López-Solis 《Food quality and preference》2010,21(5):569-574
The volume of saliva in the mouth of sensory panelists was measured by a dilution assay using a freshly prepared beetroot extract as probe solution. An aliquot of the extract absorbing linearly at 531-nm (probe) was placed in the mouth, mixed with saliva and returned to a clean container within a period of time shorter than the one spanning a single swallowing cycle. Beetroot pigments were neither partitioned into sub-fractions of saliva nor affected spectroscopically by their mixing with saliva. Three-milliliter was the minimum volume of probe per assay for a determination to be reliable. Observed volumes of saliva in the mouth of 13 panelists were distributed over the range 230–1310 μL with a median of 704 μL and a mean and standard deviation of 696 ± 312 μL. All but one of the subjects displayed salivary volumes within 1.41 standard deviations from the mean. Duplicate determinations per subject showed a median deviation of 13.5%. The procedure yielded highly repeatable and reproducible measurements. 相似文献
932.
Sonia Ben Abdelkhalek Nabil Kallel Sami Kallel Thierry Guizouarn Octavio Peña Mohamed Oumezzine 《Journal of Superconductivity and Novel Magnetism》2013,26(11):3171-3180
The transport properties and conduction mechanism in La0.6Sr0.4Mn1?2x Fe x Cr x O3 (0≤x≤0.3) have been investigated. The undoped samples show metal–semiconductor transition with a peak of resistivity at a temperature T P , whereas for all doped compounds the semiconducting behavior persists in the whole temperature range. The insertion of Cr3+ and Fe3+ ions leads to the increase of resistivity because the simultaneous substitution of Fe3+ and Cr3+ for Mn3+ reduces the number of available hopping sites for the Mn e g↑ electron and suppresses the double-exchange mechanism. It was found that the transport mechanism for substituted samples is dominated by the variable range hopping of small polarons between localized states in a model where the various parameters estimated from Mott’s relation obey the variable range hopping (VRH) mechanism. 相似文献
933.
934.
Leaving the Prison: Permitting Partner Choice and Refusal in Prisoner's Dilemma Games 总被引:2,自引:0,他引:2
Esther Hauk 《Computational Economics》2001,18(1):65-87
We propose a simple rule of thumb on how to choose one's game partner thatallows economic agents who care about the future to learn to cooperate inthe iterated prisoner's dilemma. This rule of thumb uses partner selectionstrategically to reward cooperative behavior and teach defectors a lesson.This reward and punishment scheme leads to higher payoffs of non-exploitivestrategies and slowly converts defectors, who are attracted by the higherpayoffs, into non-exploitive types. Simulations show that the convergence tostable cooperative behavior is rather fast. 相似文献
935.
Albert P. C. Chan Esther H. K. Yung Patrick T. I. Lam C. M. Tam S. O. Cheung 《Construction Management & Economics》2013,31(7):699-718
A number of procurement selection systems have been developed over the last decade. The use of multi-attribute decision analysis has been considered the foremost technique for examining client needs and the weightings of preferences from experts for each procurement system in the most objective way available. However, the major difficulty of these selection models lies in the lack of consensus among the experts on the utility factor of the selection criteria. To overcome these deficiencies, a Delphi technique was adopted to develop a multi-attribute model. Four rounds of Delphi surveys were conducted. A statistically significant consensus on the weighting of the utility factors for each procurement system was obtained from eight experts. The results vividly reveal that the Delphi method is a powerful and appropriate technique for deriving objective opinions in a rather subjective area such as the multi-attribute model for the selection of procurement system. 相似文献
936.
Maria Esther Zugasti Arantza Zornoza María del Mar Goñi José Ramón Isasi Itziar Vélaz Carmen Martín 《Drug development and industrial pharmacy》2013,39(10):1264-1270
Background: The influence of β-cyclodextrin (β-CD) polymers on drug release from hydroxypropyl methylcellulose (HPMC) matrices has not been reported in the literature. Aim: The influence of monomeric β-CD and both soluble and insoluble β‐CD polymers on drug release from tablets containing either 30% or 50% hydroxypropyl methylcellulose has been studied using diflunisal (DF) as model drug. Method: The DF-β-CD inclusion complex (1:1 M) was prepared by coevaporation and characterised using X-ray diffraction, differential thermal analysis, and IR spectroscopy. The dissolution assays were performed according to the USP paddle method. Results: The incorporation of β-CD in the complexed form increases drug release from hydroxypropyl methylcellulose tablets in comparison with the physical mixture because of the better solubilization of the drug. The soluble polymer promotes drug release to a higher extent than the physical mixture with monomeric β-CD, but the insoluble polymer, which is itself a hydrogel, gives rise to the most retarded release profile, probably by retention of the drug in its structure. The formulations containing physical mixtures with either β‐CD or the soluble polymer present an optimum adjustment to zero-order release kinetics, and the inclusion complex followed non-Fickian diffusion according to the Korsmeyer–Peppas model. Conclusion: The release profile of DF from a HPMC matrix can be modulated in different ways by the use of either monomeric or polymeric β-CD. 相似文献
937.
Abstract Using the approximation of small fluctuations around a stationary solution, photon statistics and quadrature variances are derived in stimulated Raman and hyper-Raman scattering including the coupling of pumping, Stokes, anti-Stokes and phonon modes. The depletion of pump light is included. Compared to Raman scattering, additional regimes to generate anti-bunched, sub-Poisson and squeezed light were found caused by self-interaction of the pump mode. It was possible to include effects of nonlinear dynamics, initial squeezing of radiation and phonon system, external noise and losses. 相似文献
938.
Esther Pérez Marcos Curty David J. Santos Priscila Garcìa-Fernández 《Journal of Modern Optics》2013,60(6-7):1035-1047
Abstract A general class of authentication schemes for arbitrary quantum messages is proposed. The class is based on the use of sets of unitary quantum operations in both transmission and reception, and on appending a quantum tag to the quantum message used in transmission. The previous secret between partners required for any authentication is a classical key. We obtain the minimal requirements on the unitary operations that lead to a probability of failure of the scheme less than one. This failure may be caused by someone performing a unitary operation on the message in the channel between the communicating partners, or by a potential forger impersonating the transmitter. 相似文献
939.
Effect of using Erythritol as a Sucrose Replacer in Making Spanish Muffins Incorporating Xanthan Gum
Sandra Martínez-Cervera Esther de la Hera Teresa Sanz Manuel Gómez Ana Salvador 《Food and Bioprocess Technology》2012,5(8):3203-3216
Spanish muffins are sweet, high-calorie baked products which are highly appreciated for their good taste and soft texture. The aim of this work was to evaluate the suitability of erythritol and of its combination with xanthan gum and double quantities of leavening agent for replacing sucrose in Spanish muffins and to understand their functionality in a muffin system. The linear viscoelastic properties of the batter during heating, its specific gravity and bubbles, muffin weight loss during baking and muffin bubbles, height, volume, and instrumental texture were studied. Both erythritol and sucrose increase in the temperature at which the viscoelastic functions increased with temperature. In comparison with the reduced sucrose muffins, the use of erythritol increased the number of air bubbles in the batter. The height of the muffins also increased in the presence of erythritol when compared to the corresponding reduced sucrose muffins, although the volume did not. Erythritol was not effective in diminishing the increased hardness associated with sucrose reduction, but the combination of erythritol with xanthan gum and a double quantity of leavening agent significantly improved the muffin volume (from 94 cm3 for 100% erythritol formulation to 108 cm3 for 100% erythritol–xanthan double-leavening agent formulation) and significantly decreased the hardness (from 75 N for 100% erythritol formulation to 25 N for 100% erythritol–xanthan double leavening agent formulation). 相似文献
940.
González-Flores D Gamero E Garrido M Ramírez R Moreno D Delgado J Valdés E Barriga C Rodríguez AB Paredes SD 《Food & function》2012,3(1):34-39
Red grapes contain elevated amounts of antioxidant compounds (polyphenols) that may potentially prevent cell aging, cardiovascular disease and oxidation-related disorders. Since functional drinks are presently one of the most dynamic sectors of the market, the present work was aimed at evaluating the possible antioxidant effect of an experimental grape juice in terms of urinary 6-sulfatoxymelatonin (aMT6-s) and total antioxidant capacity in young (20 ± 10 yr-old), middle-aged (45 ± 10 yr-old) and elderly (75 ± 10 yr-old) individuals. Grapes (Vitis vinifera cv. Tempranillo) were de-stemmed, racked and pressed. The juice was subsequently stabilized by high hydrostatic pressure (HHP). Participants consumed 200 mL of grape juice twice a day (as the lunch and dinner desserts) for 5 days. First-void morning urines were collected before treatment (basal values), the day immediately after the last ingestion of juice (assay), and one day afterwards (post-assay). aMT6-s and total antioxidant capacity were quantified using commercial ELISA and colorimetric assay kits, respectively. The intake of grape juice cv. Tempranillo induced a significant increase of urinary aMT6-s and total antioxidant capacity in the three groups of age analyzed as compared to their corresponding basal and post-assay values. These functional/nutraceutical properties may be of interest for a prospective commercialization of the grape juice. The novel technology used for juice stabilization may be suitable for introducing into the market a product with high sensory and nutritional quality, as it has been shown in this study. 相似文献