高次谐波示波计时电位法

本文提出了高次谐波示波计时电位法。ＥＴ，ｄＥ／ｄｔ－ｔ曲线的二次或三次谐波信号可以利用由双Ｔ滤波器构成的选频放大器获得，谐波幅值使用万用表测量，讨论了直流电流大小和溶解氧对高次谐小谐波幅值的影响，实验结果表明，谐波示波图的重现性良好，谐波幅值与去极剂浓度有线性关系。     

Trace formulae for irreducible polynomials over with minimal order roots in

The extension field where q is a prime divisor of (P−1), has a unique structure. This paper describes this unique structure and uses it to derive formulas relating the trace values for elements in . These formulas can be refined for certain elements to produce a formula for the trace.     

Mean residual life order of convolutions of heterogeneous exponential random variables

In this paper, we study convolutions of heterogeneous exponential random variables with respect to the mean residual life order. By introducing a new partial order (reciprocal majorization order), we prove that this order between two parameter vectors implies the mean residual life order between convolutions of two heterogeneous exponential samples. For the 2-dimensional case, it is shown that there exists a stronger equivalence. We discuss, in particular, the case when one convolution involves identically distributed variables, and show in this case that the mean residual life order is actually associated with the harmonic mean of parameters. Finally, we derive the “best gamma bounds” for the mean residual life function of any convolution of exponential distributions under this framework.     

喹诺酮类药物的示波测定

喹诺酮类药物属于人工合成抗生素 ,至今已开发或正在开发的约 5 0多种 ,成为抗感染药物中最活跃的研究领域之一 ,是一类有巨大潜力的新型抗菌药 .喹诺酮类药物的测定 ,大多采用高效液相色谱法 [1～ 3 ] .但高效液相色谱仪的价格昂贵 ,测定对样品的处理要求较高 ,应用受到限制 .示波分析法具有仪器简单、操作简便、选择性高等优点 ,用此法测定吡哌酸、诺氟沙星含量已有报道 [4～ 6] .本文进一步研究了依诺沙星 (ENX)、环丙沙星(CPLX)、氧氟沙星 (OFLX)、氟罗沙星 (FLRX)和司帕沙星 (SPLX)等 5种喹诺酮类药物的示波测定条件及方法 .S…     

Electrochemistry of Europium in Aqueous and Aqueous Formamide Solutions

Abstract

The electrochemical behavior of the system Eu(III)/Eu(II) in aqueous formamide solutions was studied by current reversal chronopotentiometry at a mercury pool electrode, in 1 M NaClO₄ The results indicate that double layer effects must be considered rather that ion solvation effects when explaining the influence of formamide on the Eu(III)/Eu(II) electrode reaction.     

A Packed Graphite Cell for Thin-Layer Electrochemistry

Abstract

A thin-layer electrochemical cell, which consists of a bed of graphite granules, is described and evaluated for chronopotentiometric experiments. The dependence of transition time on concentration is linear (within 3%) for a single component and the transition time of a component is independent of the concentrations of other electroactive materials in the solution.     

Interval weight generation approaches for reciprocal relations

In this paper, we propose methods to derive interval weight vectors from reciprocal relations for reflecting the inconsistency when decision makers provide preferences over alternatives (or criteria). Several goal programming models are established to minimize the inconsistency based on multiplicative and additive consistency, respectively. Especially, if we obtain a crisp weight vector from a reciprocal relation, then it is consistent. Then, we extend the proposed methods to incomplete reciprocal relations and interval reciprocal relations and develop the corresponding models to derive interval weight vectors. Several examples are also given to compare the developed methods with the existing ones.     

Direct Determination of Copper in Biodiesel Using Stripping Analysis

A simple, effective, and low‐cost protocol for copper determination in biodiesel, with no sample decomposition, is reported. Samples were diluted in an ethanol‐water solution (with HCl as supporting electrolyte) generating a homogeneous mixture at which copper was directly detected using stripping chronopotentiometry using a gold working‐electrode. The optimized mixture was 100 µL (0.088 g) of biodiesel, 15 mL of ethanol, and 5 mL of 0.1 mol L^?1 HCl aqueous solution. The estimated detection limit was 200 ng g^?1 (300‐s deposition time). The elimination of the sample treatment step offers the possibility of on‐site measurements in association with commercially‐available portable potentiostats.     

Sums of reciprocal Stekloff eigenvalues

Let 0 = λ₁ < λ₂ ≤ λ₃ ≤ … be the Stekloff eigenvalues of a plane domain. The paper is concerned with formulas for ∑^∞₂λ^(–2)_j in simply and doubly connected domains. In the simply connected case it is proven that the disk minimized this sum. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

L1空间正系数多项式的倒数逼近

本文讨论了L^1空间函数的正系数多项式的倒数逼近的Jackson型估计问题，并证明了：如果f(χ)∈L[0,1]^1，f(χ)≥0，f(χ)不恒等号0，则存在一个次数不超过n正系数多项式qn(χ)∈Пn( )，使得||f-1/qn||L^1≤Cω(f,n^-1/2)L^1，其中Пn( )表示所有次数不超过n的正系数多项式的全体。