基于Bragg光纤光栅传感器的监测系统设计

设计了基于Bragg光纤光栅传感技术的监测系统,当光纤光栅所处环境的温度、应力、应变或其他物理量发生变化时,光栅的周期或纤芯折射率将发生变化,从而使反射光的波长发生变化,通过测量反射光中心波长的变化,就可以获得待测物理量的变化情况.该系统利用薄膜滤波器完成对外界的分布式测量,采用光强度检测,能够实现无缝监测.     

求解非埃尔米特正定方程组的广义LHSS迭代法

基于矩阵的埃尔米特和反埃尔米特分解,李良等给出了一类求解非埃尔米特正定方程组的LHSS迭代法,在系数矩阵的埃尔米特和非埃尔米特之间进行了非对称迭代,在较松弛的约束条件下即可获得收敛结果.本文对该方法做进一步研究,给出了一类求解非埃尔米特正定方程组的广义LHSS迭代方法.数值结果表明,系数矩阵经恰当分解,在处理某些问题时广义LHSS迭代法优于HSS迭代法.     

Synthesis and Mesomorphic Behavior of 3‐Alkyl‐2,5‐ bis[p‐(hexa‐2,4‐dienoyloxy)phenyl]‐Thiophene Derivatives

3‐Alkyl‐2,5‐bis[p‐(hexa‐2,4‐dienoyloxy)phenyl]‐thiophene derivatives were synthesized by using Kumada coupling and Suzuki coupling reactions as key steps. The thermotropic liquid crystalline behavior of these compounds was investigated by optical polarized microscopy, monotropic nematic mesophases were observed in such compounds.     

Photoinduced Oxidation Reaction of Benzotrifluoride with OH Radical by the Laser Flash Method

The optical transient and kinetics characterizations of the transients formed in the reaction of OH with benzotrifluoride (BTF) were performed by a laser flash photolysis technique. The results indicated that the formation of π‐type adduct of C₆H₅(OH)CF₃ was the major reaction channel, and the δ‐type adduct of C₆H₅CF₃OH formation was an additional minor process in the oxidation reaction of BTF attacked by OH radicals yielded from the photolysis of H₂O₂. Addition of OH to the CF₃ group led to the fluoride ion elimination to yield α,α‐difluorophenylcarbinol (C₆H₅CF₂OH). Trifluoromethylphenol (HOC₆H₄CF₃) of meta‐, para‐ and ortho‐substituted isomers resulted from the addition of OH to the BTF aromatic ring.     

苯氧乙酸烯丙酯的合成

对苯酚和氯乙酸的Williamson反应加以改进,使苯氧乙酸的收率达到95．4％。并以苯氧乙酸和烯丙醇为原料,活性碳负载磷钨酸为催化剂,合成了苯氧乙酸烯丙酯。考察了两个反应的主要影响因素。     

正交投影目标因子分析法及其在光度分析中的应用——稀土元素多组分混合物同时测定的研究

本文将奇异值分解法引入因子分析,较好地解决了由于矩阵亏秩引起的困难;并采用正交投影矩阵法实现目标转换,以相似性系数Q_ta作为新的目标检验判据,使计算结果得到改善.用本法测定并计算了La、Sm、Tm混合物的合成样品,获得满意的结果.     

One-Pot Synthesis of N-Boc-2, 5-bis(trimethylsilyl)pyrrolidine

Since Daly reported the structure of epibatidine and its potent analgesic activity in 19921, study on the synthesis of epibatidine and its derivatives and relationships between the structure and activity of epibatidine has received much attention2. During the course of our research for the synthesis of epibatidine derivatives, N-boc-2, 5-bis(trimethylsilyl)pyrrolidine 4 was used as the key intermediate to construct the skeleton of epibatidine via the 1, 3-dipolar cycloaddition (Scheme 1). Ac…     

周期表中一些元素的英文名称解读

在化学专业英语的学习过程中,学生最早接触的是元素周期表。本文对一些元素的英文名称采用解读式的教学方法,通过将元素的英文名称同著名科学家、特定地理名称、太阳系中的星球以及神话中的人物相关联,使元素的英文名称不再枯燥乏味,而变得生动形象,这一过程可以使学生更好地体验学习的乐趣。     

北京市高考化学实验探究题探析

以陈述性、程序性及策略性3类知识分类为切入点,重点对近10年北京市高考化学实验探究题进行分析,发现2010年及以前主要考查程序性知识,而后3类知识考查的频次趋于平均化。基于试题内容分析,认为化学教学和试题编制均应注重基础知识的内在结构,强调程序性和策略性知识,关注化学科技前沿的发展,激发学习兴趣和培养新情境中的问题解决能力,从而提高学生的科学素养。     

基于近红外光谱的人参与西洋参的快速鉴别研究

基于近红外光谱分析技术结合模式判别方法建立了一种人参和西洋参鉴别的新方法。收集根状、根须和粉末状的样品共90份,在有聚乙烯包装袋的情况下直接采集近红外光谱,去除原始光谱中包装袋的显著吸收后进行了MSC与一阶导数处理,然后采用移动窗口偏最小二乘法选择了建模光谱区间,分别建立了PLS-DA,PCA-DA和SVM判别模型,并对3种模型作了对比分析,结果表明SVM判别效果最优,其对预测集的正确判别率为100%。该方法准确、便捷,可实际应用于企业原料药材的质量控制,实现对原料药材的快速筛查。