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181.
《Journal of separation science》2017,40(19):3889-3897
In this study, electromembrane extraction from a flowing sample solution, termed as continuous‐flow electromembrane extraction, was developed and compared with conventional procedures for the determination of four basic drugs in real samples. Experimental parameters affecting the extraction efficiency were further studied and optimized. Under optimum conditions, linearity of continuous‐flow procedure was within 8.0–500 ng/mL, while it was wider for conventional procedures (2.0–500 ng/mL). Moreover, repeatability (percentage relative standard deviation) was found to range between 5.6 and 10.4% (n = 3) for the continuous‐flow procedure, with a better repeatability than that of conventional procedures (2.3–5.5% (n = 3)). Also, for the continuous‐flow procedure, the estimated detection limit (signal‐to‐noise ratio = 3) was less than 2.4 ng/mL and extraction recoveries were within 8–10%, while the corresponding figures for conventional procedures were less than 0.6 ng/mL and 42–60%, respectively. Thus, the results showed that both continuous flow and conventional procedures were applicable for the extraction of model compounds. However, the conventional procedure was more convenient to use, and thus it was applied to determine sample drugs in real urine and wastewater samples. 相似文献
182.
M. A. Hasankhani Fard L. Mohammadi Rad 《Numerical Functional Analysis & Optimization》2017,38(1):51-57
In this article, we study the property of norm retrievability of spanning vectors in a finite dimensional complex Hilbert space ?. Using the set of zero trace operators on ? and two sets of self-adjoint operators on ? denoted by 𝒮1,0 and 𝒮1,1, we present some equivalent conditions to the norm retrievable frames in ?. We will also show that the property of norm retrievability for n-dimensional complex Hilbert space ? with n≠2 is stable under enough small perturbation of the frame set only for phase retrievable frames. 相似文献
183.
Sudip Samanta 《Mathematical Methods in the Applied Sciences》2017,40(5):1679-1695
In the present paper, an epidemic model has been proposed and analyzed to investigate the impact of awareness program and reporting delay in the epidemic outbreak. Awareness programs induce behavioral changes within the population, and divide the susceptible class into two subclasses, aware susceptible and unaware susceptible. The existence and the stability criteria of the equilibrium points are obtained in terms of the basic reproduction number. Considering time delay as the bifurcating parameter, the Hopf bifurcation analysis has been performed around the endemic equilibrium. The direction of the Hopf bifurcation and the stability of the bifurcating periodic solutions are investigated by using the normal form theory and central manifold theorem. To verify the analytical results, comprehensive numerical simulations are carried out. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
184.
人类免疫缺陷病毒(HIV)是一种严重威胁生命的病毒,感染艾滋病毒患者一般经历四个阶段:i)艾滋病毒阴性的窗口期(W);ii)阳性的无症状潜伏期(E);iii)有症状期(Ⅰ);以及iv)移除阶段(A).为深入研究艾滋病传播过程,建立SWEIA艾滋病毒传染模型,定义基本再生数,分析无病与地方病平衡点的存在性和局部稳定性,根据2004至2015年中国艾滋病患者数据,采用遗传算法对SWEIA模型中参数进行估计.通过对基本再生数敏感性分析以及模型数值随参数不同而产生的变化,揭示艾滋病窗口期的接触率是影响艾滋病流行的主要原因之一. 相似文献
185.
本文应用混合型有限元双向分配法得到有侧移刚架的数值解。文中给出了计算机程序,具有占用内存少、收敛快等特点。文末给出了算例。 相似文献
186.
187.
为解决分析复合材料框架式结构的强度可靠性问题 ,应用最小势能原理 ,设计推导了一种具有复杂剖面形状 ,考虑横向剪切 ,承受横向集中及分布载荷作用的层合梁单元。根据一具体水平梁架的实际情况 ,结合有限元处理程序中组装总体刚度矩阵的特点 ,较好地实现了层合梁之间的不完全简支连接。分析系统强度可靠性时 ,通过可调控的运行方式 ,有效解决了挑选失效模式与离散单元数目之间的关系 ,使系统可靠性的计算更合理 相似文献
188.
施惟慧 《应用数学和力学(英文版)》1994,(12)
ASTABILITYSTUDYOFNAVIER-STOKESEQUATIONS(Ⅲ)ShiWei-hui(施惟慧)(shanghaiUniversily.Shanghai)(ReceivedJan.20.1994;CommunicatedbyChie... 相似文献
189.
非惯性参考系中弹性壳的非线性振动分析 总被引:1,自引:0,他引:1
给出了弹性壳处于非惯性参系中的运动描述,基于Hamilton原理建立了中厚壳在非惯性参考系中的非线性运动控制方程,应用多尺度法及谐波平衡法具体地分析了圆柱壳的非线性振动问题 相似文献
190.
Yu. V. Kokhanenko 《International Applied Mechanics》2006,42(7):825-831
The paper studies the three-dimensional stability of an isotropic, linear elastic, rectangular plate under a uniform tensile
load applied to its sides. The concept of free strains is used to reduce the three-dimensional problem to a two-dimensional
one. It is solved using the three-dimensional linearized theory of stability. An approximate solution of the buckling problem
is obtained by the finite-difference method. Numerical results are presented
__________
Translated from Prikladnaya Mekhanika, Vol. 42, No. 7, pp. 116–123, July 2006. 相似文献