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901.
902.
C W Ponton J J Eggermont S G Coupland R Winkelaar 《The Journal of the Acoustical Society of America》1992,91(3):1576-1586
Previous studies of human auditory development using frequency-specific auditory brain-stem responses (ABRs) have reported that maturation for both peak and interpeak latencies occurs earlier for responses generated by low-frequency stimuli. In two of these studies, low-frequency ABRs presumed to originate from apical locations in the cochlea were likely dominated by activity from higher frequency regions closer to the base. In the present study, the high-pass noise-masking technique was used to generate derived ABRs that represent activity from isolated place specific regions along the basilar membrane. Analysis of auditory brain-stem maturation based on I-V interpeak latency differences with adult means revealed a frequency-specific pattern of development. Developmental changes occurred faster and mature function was attained earlier for ABRs from the mid-center-frequency (CF) derived conditions than from either the highest or lowest CF derived conditions. The differential maturation of mid-CF derived ABRs may reflect the delayed effects of the pattern of development that occurs in the cochlea. 相似文献
903.
R. Szymczak K. Zaveta H. Szymczak H. -Q. Guo H. Kronmü ller 《Journal of magnetism and magnetic materials》1994,130(1-3):363-366
The temperature dependence of magnetization of a nanocrystalline Fe60Co30Zr10 alloy annealed at various temperatures to varying crystal sizes was investigated down to 5 K in the field range up to 5 T. The fitting procedure gave T3/2 as the leading term irrespective of the crystal size. We suggest that the increase of the coefficient by this term for smaller crystals may be connected to an increased relative volume of their surface. 相似文献
904.
Sulfide cluster-derived ensembles are promising models of the active sites in commercial hydrotreatment catalysts. A series of sulfide clusters were adsorbed intact onto high-surface-area γ-alumina, magnesium oxide and activated carbon supports, then pretreated to produce highly dispersed catalytic ensembles with sizes similar to those of their precursor clusters. The activities of the bimetallic cluster-derived catalysts were significantly higher than those of the monometallic catalysts. We took this as evidence that direct interactions between molybdenum and the promoter element cause the promotional effect observed in commercial hydrotreatment catalysts. The hydrodesulfurization and hydrodenitrogenation activities correlated with the extent of molybdenum reduction. Our results suggested that the active sites in promoted hydrotreatment catalysts are centered on molecular-scale ensembles containing molybdenum, sulfur and the promoter element. 相似文献
905.
The nature of the propagation center in the cationic polymerization of N-benzoyl-8-octanelactam initiated by octanoylium hexachlcroantimonate, SbCl5, and Ph3CAsF6 in perdeuterated tetrachloroethane or its mixture with o-dichlorobenzene was studied using 1H, 13C, 19F, 31P, 75As, and 121Sb nuclear magnetic resonance (NMR) of model oligomers and the products of their end-capping with triphenylphosphine. In all cases, the nature of the propagation center has been found to be of an acylium ion pair with an SbCl6? or AsF6? counterion coordinated with the nearest benzoylamide group and cosolvated by the solvent. © 1994 John Wiley & Sons, Inc. 相似文献
906.
M. R. Nuriddinova V. M. Malikov A. Yu. Kushmuradov A. I. Saidkhodzhaev 《Chemistry of Natural Compounds》1992,28(6):551-552
A microcolumn HPLC fingerprint method has been developed for the epigeal organs ofFerula kuhistanica andF. tenuisecta. The possibility has been shown of control by the microcolumn HPLC method of the qualitative and quantitative yields of ferutinin
in the initial plant raw material and in preparations extracted from it, and also at each stage of the isolation of the desired
product. The method is universal and does not depend on species and chemical composition of the plant.
Institute of the Chemistry of Plant Substances, Uzbekistan Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh
Soedinenii, No. 6, pp. 635–636, November–December, 1992. 相似文献
907.
The complexation of Ho3+ in HoCl3 and KOH solutions at 25°C and saturated vapor pressure was studied by an indicator spectrophotometric technique, and the pH values of the investigated solutions were determined. The stability constants of the hydroxo complexes of Ho3+ were measured over a range of pH 9.25–10.10 and at μ≤ 4 × 10?4 and extrapolated to zero ionic strength. 相似文献
908.
Lahiouel R. Pierre J. Siaud E. Galera R. M. Besnus M. J. Kappler J. P. Murani A. P. 《Zeitschrift für Physik B Condensed Matter》1987,67(2):185-191
Magnetic properties, electrical resistivity, specific heat and magnetic excitations have been investigated in Heusler phases CeInAg2–xCux. The hybridization continuously increases from CeInAg2 (antiferromagnetic Kondo lattice) to CeInCu2 (heavy fermion compound). The specific heat coefficient for this last compound is found to reach 1.2 J/mole. K2 at 1.4 K, the Kondo temperature is 6 K and the Wilson ratio is close to 2. 相似文献
909.
R. C. Batra 《Journal of Elasticity》1987,17(1):3-8
It is shown that the force on a lattice defect in an elastic body is, like the force on a disclination in a nematic liquid crystal, a real force which, for equilibrium, must be balanced by an external force applied to the closed surface enclosing the defect. 相似文献
910.
This paper studies the application of the continuous sensitivity equation method (CSEM) for the Navier–Stokes equations in the particular case of shape parameters. Boundary conditions for shape parameters involve flow derivatives at the boundary. Thus, accurate flow gradients are critical to the success of the CSEM. A new approach is presented to extract accurate flow derivatives at the boundary. High order Taylor series expansions are used on layered patches in conjunction with a constrained least‐squares procedure to evaluate accurate first and second derivatives of the flow variables at the boundary, required for Dirichlet and Neumann sensitivity boundary conditions. The flow and sensitivity fields are solved using an adaptive finite‐element method. The proposed methodology is first verified on a problem with a closed form solution obtained by the Method of Manufactured Solutions. The ability of the proposed method to provide accurate sensitivity fields for realistic problems is then demonstrated. The flow and sensitivity fields for a NACA 0012 airfoil are used for fast evaluation of the nearby flow over an airfoil of different thickness (NACA 0015). Copyright © 2005 John Wiley & Sons, Ltd. 相似文献