Electrochemical oxidation behavior of hydroxypivalaldehyde in the ionic liquids

The similar electrochemical oxidation behaviors of hydroxypivalaldehyde in ionic liquids （ILs） medium, C4MIMPF6, C4MIMBF4 and CsMIMPF6, are investigated using classic electrochemical methods, respectively. Only the product, hydroxypivalic acid is detected by high performance liquid chromatography （HPLC）. It can be conferred that the electrochemical oxidation of hydroxypivalaldehyde consists of two successive one-electron irreversible reactions at glass carbon （GC） electrode and the possible reaction mechanism in the ILs is proposed firstly. The diffusion coefficients of hydroxypivalaldehyde are obtained according to the electrochemical characteristics of hydroxypivalaldehyde in C4MIMPF6, C4MIMBF4 and CsMIMPF6.     

气相色谱-质谱法测定氟涂料中全氟辛酸及其盐类物质

超声萃取技术萃取氟涂料中的全氟辛酸及其盐类物质,萃取液经固相萃取、浓缩后与乙酰化试剂反应,以全氟癸酸甲酯为内标物内标法进行定量测定.对气相色谱-质谱条件进行选择,方法的线性范围为1.0～1×105μg·L-1,相关系数为0.9997,检出限为0.1μg·L-1,在高低两种浓度水平(100 μg·L-1及1000 μg·L-1 PFOA)进行精密度和回收率试验,所得相对标准偏差分别为4.24%和3.58%,回收率在86%～111%之间.     

关于数学中的公理化方法

公理化方法(以下简称公理法)的广泛使用,是现代数学的一大特点。 一、公理化方法的沿革 数学中的公理法起源于欧几里得的《几何原本》(或简称《原本》)。欧几里得基于当时所积累的丰富的几何事实,把一些基本概念(点、线、平面)加以定义,而后选择一些几何的基本命题叫做公理(欧氏     

A Novel Synthesis of (-)-10-epi-α-Cyperone

The eudesmane derivative, (-)-10-epi-α-cyperone 1, is widely used as a chiral starting material for the synthesis of other fused-ring sesquiterpenes1. The first synthetic work was reported by Howe and co-workers via condensation of (+)-dihydrocarvone 2 with 1-diethylaminopentan-3-one methiodide in 32% yield2. Previously, our group reported the synthesis of compound 1 by treating ketone 2 with ethyl vinyl ketone (EVK) directly under different conditions1a, but the yields were not satisfacto…     

The Inclusion Interval of Basic Coneigenvalues of a Matrix

In this paper,a compound-type inclusion interval of basic coneigenvalues of(com- plex)matrix is obtained.The corresponding boundary theorem and isolating theorem are given.     

广义Hamilton系统的有效稳定性

利用Lochak的同步逼近法证明了广义Hamilton系统的有效稳定性. 在考虑的系统中, 作用变量和角变量的维数可以不同.     

证明论及其发展

(一) 众所周知,Russell悖论的出现曾经引起数学史上关于数学奠基问题的第三次大论战。 Hilbert为了保卫古典数学陆续于本世纪20年代前后发表了证明论(即元数学)的主张。他认为:包括Cantor集论在内的古典数学是“我们最有价值的宝藏”,而传统逻辑中的排中律是“普遍有效的”,应该保存这些古典数学的“有成效的概念结构和推理方法”。然而“绝对无穷概念的命题确实是超越人们直观性证据之外”的东西,它“是通过人们的心智过程被插入或外推出来的概念”。但是实无穷在数学思维中是不可缺少的,应     

DSC and NMR Study on the Inclusion Complex of Lappaconitine with b-Cyclodextrin

Lappaconitine (Figure 1) is a diterpenoid alkaloid, naturally occurring in roots and rhizomes of Aconitum and delphinium1. Lap reveals bradycardic and hypotensive activity2. But its application is restrained owing to its poor water solubility, toxicity and side effects on humans. In a number of pharmaceutical studies, b-CD has been reported to interact with many drug molecules to form inclusion complexes for improving the water solubility of drugs, and reducing their toxicity3. We have p…     

Ar＋TlF体系的转动非弹性散射

本文用一种新的方法求解A+BC体系的转动非弹性散射问题,即在径向耦合方程的势能耦合项中只取对角项,并用Morse势拟合Lennard-Jones势,从而可得去耦合径向方程的两个解集。渐近分析表明,此两个解集分别相应于入射波和出射波。将总波函数按总角动量的本征函数展开,展开系数为常数乘以上述得到的径向函数。再将总波函数代入Schrdinger方程,则可得到散射矩阵。计算结果表明,本法比IOS法更接近CC法,但计算量比后者少得多,且方法严谨。     

FIBONACCI SEQUENCE AND CANTOR'S TERNARY SET

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