Rb蒸气中激光诱导5P和5D态的布居数变化

在Rb蒸气中观察了荧光强度的增强与减弱.5P3/2态荧光的减弱是由于激光激发5P3/2—→5D5/2的跃迁造成的,5D5/2态原子碰撞转移到5D3/2,产生5D3/2—→5P1/2的辐射,增加了5P1/2态的布居,从而使5P1/2—→5S1/2的荧光增强.激光诱导布居数的变化由相应荧光的强度信号的增减来检测,利用速率方程组,得到了受激发射(即5D5/2—→5P3/2)速率为2.0×108s-1,精细结构碰撞转移(即5D5/2—→5D3/2)截面为6.4×10-14cm2.     

五磷酸铈、锰晶体的发光

本文用蒸发溶液法生长了一系列CeP5O14:Mn晶体,测定了它们的组成和结构.测定了晶体的吸收光谱,激发光谱和发射光谱,观察到Ce3+→Mn2+之间的能量转移和在此体系中锰离子在545nm附近和665nm附近两个波段同时进行发射,并随着锰含量的增加,665nm的荧光强度下降而545nm的强度增加.     

多指数曲线拟合分析正电子湮没寿命谱的方法

通过非晶态金属等样品e⁺湮没寿命谱的分析, 研究了分析中的几个实际问题. 包括拟合起点的选择, 各寿命组份的相对强度归一化和寿命谱尾部实验点的影响等. 建立了实际可行的二组份拟合计算程序.     

利用BaF2晶体快速闪烁发光性质改进正电子湮没寿命谱仪

测量BaF2晶体闪烁发光长短两种寿命成分的光电子产额,利用它的短成分发光极快的特点研制核辐射探测中的定时探测器,采用于正电子湮没寿命谱仪中使谱仪的时间分辨率由FWHM=270ps(ps:微微秒)改进到190ps(计数效率不改变)或者使计数效率提高10倍(时间分辨率相同)。     

2,3-环戊烯并吡啶的多相催化合成

以丙烯醛和环戊酮为原料,用固定床多相催化法合成了2,3-环戊烯并吡啶,收率65%(以环戊酮质量计算),含量高于50%.     

A nonenzyme glucose sensor based on Cu/Ni/CMWCNTs nanocompositesEI北大核心CSCD

Copper-nickel bimetallic nanoparticles decorated on carboxylated multi-walled carbon nanotubes （Cu/Ni/CMWCNTs）were prepared by using a simple one-pot solvothermal method,which was then employed to construct a highly sensitive non-enzymatic glucose sensor. The modified electrode showed high sensitivity and stability in glucose detection,which was mainly attributed to the synergistic effect of the compact copper-nickel nanocomposite and carboxylated multi-walled carbon nanotubes that possessing high specific surface area to increase the number of active sites and to improve the electrocatalytic activity of the modified electrode. The phase structure and morphology of the material were characterized by X-ray diffraction and scanning electron microscope; the electrochemical performance of the sensor was studied by cyclic voltammetry and chronoamperometry. The sensor had a sensitivity of 1949.1 μµA·L/（mmol·cm2）for glucose detection in the linear range of 1.0-8000 μµmol/L at a potential of 0.55 V,and the detection limit was 0.2 μµmol/L. The sensor was also applied to measure the concentration of glucose in serum samples. The developed nanocomposites sensor has the potential prospect to monitor blood glucose. © 2023, Youke Publishing Co.,Ltd. All rights reserved.     

基于UPLC-Q-TOF MS技术的陈皮陈化年份鉴别方法研究

建立了一种陈皮陈化年份的鉴定方法。利用超高效液相色谱-四极杆串联飞行时间质谱(UPLC-Q-TOF MS)对陈皮的主要化学成分进行鉴定,研究了不同陈化年份陈皮样品中化学成分的变化规律,结合统计分析方法发现了6个同分异构体在陈皮陈化过程中的相互转化规律。结果表明,6个分子式为C₂₀H₂₂O₇的五甲氧基黄烷酮同分异构体中,前3个化合物含量随年份的增加而降低,后3个化合物含量随年份的增加而升高,其比值与陈化年份具有显著的线性关系。利用该6个特征性成分的转化因子(S),建立了陈皮陈化年份计算模型,相关系数(r²)为0.90。训练集样品的年份预测误差均不大于2年。盲样测试结果中90.0%样品的年份预测误差不大于2年。该方法准确可靠,为陈皮陈化年份的鉴定提供了科学依据。     

高阶Dirichlet型积分的计算和统一表达式

Dirichlet积分在物理学和信号处理领域有着重要的应用.采用复分析的方法对高阶Dirichlet型积分进行了求解和计算,证明了一般情况下统一的数学表达式.     

THE STABILITY OF STATIONARY SOLUTION FOR OUTFLOW PROBLEM ON THE NAVIER-STOKES-POISSON SYSTEM

In this article, we are concerned with the stability of stationary solution for outflow problem on the Navier-Stokes-Poisson system. We obtain the unique existence and the asymptotic stability of stationary solution. Moreover, the convergence rate of solution towards stationary solution is obtained. Precisely, if an initial perturbation decays with the algebraic or the exponential rate in space, the solution converges to the corresponding stationary solution as time tends to infinity with the algebraic or the exponential rate in time. The proof is based on the weighted energy method by taking into account the effect of the self-consistent electric field on the viscous compressible fluid.