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高德智 《数学的实践与认识》2002,32(6):1021-1026
本文讨论了两类 M/M/1 动态系统的数学模型 ,利用常微分方程所描述的 M/M/1 系统的结果证明了较复杂的偏微分方程所描述的 M/M/1 系统的一些性质 ,该方法简化了已有结果 相似文献
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半参数EV模型参数的二阶段估计 总被引:2,自引:0,他引:2
本文综合核函数法 ,最小二乘法 ,利用二阶段估计的方法求出了 EV模型中参数的估计量 ,并研究了它的强相合性以及渐近正态性 . 相似文献
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The semi‐IPN hydrogels consisting of poly(methacrylic acid) and guar gum (GG) are prepared at room temperature using water as solvent. 5‐aminosalicylic acid (5‐ASA) is entrapped in the hydrogel in the synthesis of hydrogel and all entrapment efficiencies are found above 85%. The hydrogel shows excellent pH‐sensitivity. It exhibited minimum swelling in an acidic pH medium through the formation of a complex hydrogen‐bonded structure and maximal swelling due to the electrostatic repulsion due to the ionization of the carboxylic groups in pH 7.4 medium. The degradation in vitro shows that the degree of degradation (R%) depended on the concentration of cross‐linking agent and content of GG. The hydrogel shows a minimum release of 5‐ASA due to the complex hydrogen bonded structure of the hydrogels in the medium of pH 2.2. The enzymatic degradation of hydrogels by cecal bacteria can accelerate the release of 5‐ASA entrapped in the hydrogel in pH 7.4 medium. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
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In this paper, we consider ‐symmetric perturbations of a semi‐classical self‐adjoint operator on the real axis in the case of a simple well potential Schrödinger operator. We assume that the potential is analytic and we show that the eigenvalues are left real by the perturbation. 相似文献
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带机器准备时间的平行机ordinal排序及近似算法 总被引:1,自引:0,他引:1
本文研究带机器准备时间的m台平行机ordinal在线排序问题。讨论了在极小化最大机器完工时间和极小化最大工件完工时间两种目标下的不同下界和相应的在线近似算法。对第一个目标,我们得到了3/2的下界和最坏情况界为2-1/m的近似算法。对第二个目标,我们得到了最坏情况为m的最好近似算法。我们还对一些特殊情况进行了分析。 相似文献
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Seyed Morteza Naghib Mohammad Rabiee Eskandar Omidinia Payam Khoshkenar 《Electroanalysis》2012,24(2):407-417
We investigated a L ‐phenylalanine (L ‐phe) biosensor, functionalized through enzyme immobilization on a polymer‐blend film. The electron mediator 3,4‐dihydroxybenzaldehyde (3,4‐DHB) was employed at the electrode surface to improve direct oxidation of NADH to NAD+ and no additional reagents is required to be added to the sample solution. The bioactivated electrode was coated with a semi‐permeable cellulose acetate membrane in order to prevent dissolution of biofunctionalized polymer‐blend film. This constructed enzyme electrode is the first selective biosensor for phenylketonuria (PKU) detection. The sensitivity of the enzyme electrode was determined as 12.014 mA/M cm2. The Michaelis–Menten and current responses as well as sensitivity of the electrode showed improved values than those of previous works. This selective biosensor presented an excellent electroanalytical response for L ‐phe, with a high steady‐state current being obtained after 20 s. The sensitivity of our biodevice is quite sufficient for the purpose of PKU detection because the reference range of clinical concern for L ‐phenylalanine concentration is CL ‐phe>0.5 mM. This surface‐bioactivated enzyme electrode retained more than 80 % of its electrocatalytic activity after 16 days. 相似文献
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