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991.
The instability of allicin makes it easily decomposed into various organic sulfur compounds, resulting in significant decrease in biological activity. In this study, allicin was firstly extracted with water, then bound with whey protein isolates (WPI) which were pretreated by ultrasound to form conjugates, and the stability, water solubility and emulsibility of conjugates were as well investigated. The research results showed that there were no significant differences in the extraction yields of allicin from water, 40% and 80% ethanol. Appropriate frequency (20/40 kHz), power (50 W/L) and time (20 min) of ultrasonic pretreatments significantly increased (P < 0.05) the sulfhydryl groups content of WPI by 35.05% over control, causing improvement in binding ability of protein to allicin. The binding process of allicin-WPI displayed good fit with Elovich kinetic model (R2 = 0.9781). The mass retention rate of the conjugates (in 60% combination rate) with ultrasonic pretreating kept at 95.97% after 14 days of storage at 25 °C, whereas allicin’s mass retention rate was only 61.79% at same storage condition. The water solubility of the prepared conjugates was significantly higher than allicin. And with optimal condition ultrasonic pretreatment of WPI, the conjugates showed the highest emulsifying capacity and emulsion stability (49.56 m2/g, 10.06 min). In conclusion, the ultrasonically pretreated allicin-WPI conjugates exhibited better stability, water solubility and emulsifying properties compared to allicin, this expands the application field of allicin. 相似文献
992.
拟平移不变拓扑锥与局部β-凸空间的共轭锥 总被引:4,自引:0,他引:4
王见勇 《数学的实践与认识》2003,33(1):89-97
[1]中提出的局部β-凸分析问题从本质上来说是一种非线性凸分析问题 .为了刻画和研究局部β-凸空间 X的共轭锥 X*β ,本文在抽象凸锥上引进具有拟平移不变性质的拓扑结构 ,第一部分重点研究局部生成拓扑锥与赋范拓扑锥 .第二部分将这两种拓扑锥的一般理论应用于局部 β - 凸空间的共轭锥 X*β 的研究 ,得到 (X*β,U| A)与 (X*β ,‖‖ )的局部生成性与完备性定理等 . 相似文献
993.
An inexpensive and readily available ionic liquid, tetrabutylammonium bromide in the molten state, efficiently catalyzes the conjugate addition of thiols to α,β-unsaturated nitriles, carboxylic ester, ketones and aldehydes as well as nitro olefins. 相似文献
994.
Joaquim J. Júdice João Patricio Luis F. Portugal Mauricio G.C. Resende Geraldo Veiga 《Computational Optimization and Applications》2003,24(1):5-35
We study and compare preconditioners available for network interior point methods. We derive upper bounds for the condition number of the preconditioned matrices used in the solution of systems of linear equations defining the algorithm search directions. The preconditioners are tested using PDNET, a state-of-the-art interior point code for the minimum cost network flow problem. A computational comparison using a set of standard problems improves the understanding of the effectiveness of preconditioners in network interior point methods. 相似文献
995.
自共轭四元数矩阵特征值的极值原理 总被引:4,自引:1,他引:3
本文将Hermite算子特征值的两个一般的极值原理推广到自共轭四元数矩阵,并给出了几个推论,同时也去掉了子空间的包含条件 相似文献
996.
模压全息图母版的拍摄研究 总被引:3,自引:1,他引:2
目前拍摄模压全息母版用的记录材料都是光刻胶.本文从它本身的特点(灵敏度低,浮雕型相位光栅和拍摄对象是散射物体等)出发,指出要拍摄出质量好的光刻胶母版应当注意到的问题.诸如拍摄参数的选择应同时考虑到衍射效率和信噪比、照明的均匀性问题、逆共轭光再现、消偏振、相干长度、外界振动对拍摄的影响问题.通过分析表明高质量的全息图不可能靠延长曝光时间来获得,使用相干性好的大功率激光束来拍摄,是非常有必要的. 相似文献
997.
F. Móricz 《Acta Mathematica Hungarica》2002,98(3):259-262
A theorem of Ferenc Lukács determines the jumps of a periodic, Lebesgue integrable function f at each point of discontinuity of first kind in terms of the partial sums of the conjugate series to the Fourier series of
f. The aim of this note is to prove an analogous theorem in terms of the Abel-Poisson means.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
998.
The present article is concerned with the Neumann control of systems modeled by scalar or vector parabolic equations of reaction-advection-diffusion type with a particular emphasis on systems which are unstable if uncontrolled. To solve these problems, we use a combination of finite-difference methods for the time discretization, finite-element methods for the space discretization, and conjugate gradient algorithms for the iterative solution of the discrete control problems. We apply then the above methodology to the solution of test problems in two dimensions, including problems related to nonlinear models. 相似文献
999.
Tran Thanh Stephan Ernst P. Zaprianov Stefan 《Advances in Computational Mathematics》1998,9(1-2):233-249
We study simple preconditioners for the conjugate gradient method when used to solve matrix systems arising from some hypersingular
and weakly singular integral equations. The preconditioners, which are of the type of hierarchical basis preconditioners,
are based on the decomposition of the piecewise-linear (respectively piecewise-constant) functions as the sum of prewavelets
(respectively derivatives of prewavelets). We prove that with these preconditioners the preconditioned systems have condition
numbers uniformly bounded with respect to the degrees of freedom. Numerical experiments support our analysis.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
1000.
Optimal control theory is applied to obtain infrared laser pulses for selective vibrational excitation in a heteronuclear
diatomic molecule. The problem of finding the optimized field is phrased as a maximization of a cost functional which depends
on the laser field. A time dependent Gaussian factor is introduced in the field prior to evaluation of the cost functional
for better field shape. Conjugate gradient method21,24 is used for optimization of constructed cost functional. At each instant of time, the optimal electric field is calculated
and used for the subsequent quantum dynamics, within the dipole approximation. The results are obtained using both Morse potential
as well as potential energy obtained using ab initio calculations. 相似文献