萃取阻抑光度法间接测定痕量硫脲

研究了在pH 4.5的柠檬酸盐缓冲溶液介质中, 利用硫脲对钒(Ⅴ)催化溴酸钾氧化邻氨基酚显色反应的阻抑作用, 用萃取平衡控制反应时间和水相中邻氨基酚的浓度及反应程度, 通过测量424 nm下有机相的吸光度, 建立了萃取催化光度法测定痕量硫脲的新方法。在最佳实验条件下, 测定硫脲的线性范围为0.020~1.20μg/mL,检出限为1.4×10-8 g/mL。对1.00μg/mL硫脲进行11次平行测定的相对标准偏差为3.8%。用于水样中硫脲的测定, 结果满意。     

教学艺术研究──从说书人的“惊堂木”谈学生的课堂注意力

教学艺术研究──从说书人的“惊堂木”谈学生的课堂注意力龚秋纹，刘怀乐（四川重庆师范学院６３００４７）（四川重庆巴蜀中学６３００１３）要使学生集中注意力，教师充分利用课堂４０分钟，让每分钟都有助于提高课堂教学效率，这是本文想要谈及的内容。生理心理学的研...     

发光材料BaAl2Si2O8∶Eu2+的物相结构与发光性能

A phosphor, Ba_0.97Al₂Si₂O₈∶Eu²⁺, was synthesized by high temperature solid-phase method at different temperatures. The samples were characterized by TG/DTA, XRD and fluorescence spectroscopy. The results show that the main phase for host of these luminescence materials is barium feldspar BaAl₂Si₂O₈∶Eu²⁺ and there is a transition from hexagonal crystal system to monoclinic crystal system in the process of the sintering of barium feldspar. The luminescent phenomen of barium feldspar with hexagonal structure can not be observed under the excitation of ultraviolet lamp of 365 nm while the barium feldspar with monoclinic structure has excellent luminescence properties. The excitation spectra of all these samples show broad band spectra ranging from 250～390 nm with peak at λ_ex of 357 nm,which indicates that these samples can be effectively excited by near ultraviolet ; the emission spectra range from 380～600 nm with peak at λ_em of 433 nm. The luminescent intensity increases then decreases with the concentration of doping Eu²⁺ ions. When the concentration of dopants is 2.5mol%, the luminescent intensity reaches the maximum value. When the concentration of Eu²⁺ ions changes from 0.5mol% to 2.5mol%, the emission peak has a red shift from 427 nm to 440 nm.     

发光材料BaAl2Si2O8∶Eu^2＋的物相结构与发光性能

硅酸盐类物质作为发光材料基质．发光中心和基质相互作用能量较低。可使发光中心离子直接吸收激发能量,利于提高发光效率。目前。研究较多的硅酸盐类发光材料为Zn2SiO4、Sr2MgSi2O7、Ba3MgSi2O8等。铝硅酸钡通常归属于硅酸盐范畴,铝硅酸盐的结构复杂、物相组成变化多样．一般实验条件下很难获得单一物相产物。碱土金属铝硅酸盐作为发光材料基质由来已久,     

综合创新设计实验:“均相反应、异相回收”[PIMPS]H2PW12O40双功能催化剂在酯化、氧化反应中的应用*

磺酸类离子液体及多酸催化剂是近年来应用广泛的2类高效环境友好型催化剂,实现2类催化剂组装成单组分双功能化环保型催化剂并运用到大学有机化学实验中,替代现行实验中常用的强腐蚀性、强氧化性的浓硫酸,是未来实验内容改革的方向之一。本实验合成的[PIMPS]H₂PW₁₂O₄₀(PIMPS=1-丙基-3-磺酸基丙基咪唑磺酸盐)催化剂经¹H NMR、IR确证了结构,并将其应用于苯甲酸乙酯合成、苯甲硫醚氧化反应中。实验结果表明,此单组分催化剂具有酸催化、氧化催化双功能特性,催化效果良好,具有可重复使用、无腐蚀性等显著优点。在催化反应中兼具均相催化和非均相催化特点,催化剂能够实现在反应体系中的均相反应、异相回收。通过此实验的开展,培养了学生依据绿色化学理念发现问题、解决问题的创新能力和创新意识,有利于学生深入理解单组分双功能催化剂的概念,有效地达到理论和实践的有机结合。     

Classifying land cover based on calibrated full-waveform airborne light detection and ranging data

The capability of the parameters derived from waveform data in discriminating objects is assessed and the effect of the relative calibration of full-waveform data in discriminating land-cover classes is evaluated. Firstly, a non-linear least-squares method with the Levenberg-Marquardt algorithm is used to fit the return waveforms by a Gaussian function. Gaussian amplitude, standard deviation, and energy are extracted. Secondly, a relative calibration method using the range between the sensor and the target based on a radar equation is applied to calibrate amplitude and energy. The change in transmit pulse energy is also considered in this process. A support vector machine classifier is used to distinguish the study area into non-vegetated area （including roads, buildings, and vacant lots）, grassland, needle-leaf forests, and broad- leaf forests. The overall classification accuracy ranges from 79.33% to 87.6%, with the combination of the two groups of the three studied parameters. Calibrated data classification accuracy is improved from 1.20% to 6.44%, thus resulting in better forest type discrimination. The result demonstrates that the parameters extracted from the waveforms can be applied effectively in identifying objects and that relative calibrated data can improve overall classification accuracy.     

校际“同课异构”课的观察比较视角

阐述校际"同课异构"课观察比较的主要视角,并以"氯气的性质"课例进行说明,同时提出校际"同课异构"课实施的建议。     

阻抑动力学分光光度法测定痕量镉

基于在盐酸介质中,镉(Ⅱ)对溴酸钾氧化甲基蓝褪色反应有显著的阻抑作用,建立了测定痕量镉(Ⅱ)的动力学方法.以604nm为测定波长,镉(Ⅱ)在0.01-1.7μg·mL-1内呈线性关系,检出限为5.6×10-3μg·mL-1.测定了动力学参数,该阻抑反应为一级反应,表观反应速率常数为1.58×10-3s-1,活化能为67.89kJ·mol-1.方法用于环境水样中痕量镉(Ⅱ)的测定,相对标准偏差为4.35％,回收率为96.1％-99.0％.     

中药小分子阿魏酸和丹皮酚与人血清白蛋白的竞争结合作用研究

用亲和色谱研究了两种中药小分子阿魏酸(FA)、丹皮酚(PAE)在人体生理条件缓冲溶液(pH7.4)条件下与人血清白蛋白(HSA)的相互作用.从药物分子在蛋白质分子上有多种类型相互独立的结合位点的假定出发,应用Langmuir吸附模型和竞争置换分析研究了FA,PAE与HSA的竞争性相互作用.结果表明,FA,PAE与HSA之间存在一类位点,且FA与PAE竞争HSA上的indole位点(siteⅡ).根据热力学参数推测出FA,PAE与HSA之间的作用力主要为氢键作用.从FA,PAE竞争HSA上同一位点的角度,对中医用药中常将含有FA与含有PAE的中药配伍使用,以提高疗效的临床用药现象进行了解释.     

拉曼光谱技术在色谱分析检测中的应用

讨论了色谱分离与拉曼光谱检测的联用技术。表面增强拉曼光谱技术和紫外共振拉曼光谱技术克服了常规拉曼光谱技术所固有的灵敏度低的问题,所设计的与液相色谱联用的装置可以获取色谱柱流出液的拉曼光谱。评价了联用装置的重现性、动态范围和分析潜力,发现表面增强拉曼光谱仪和紫外共振拉曼光谱仪都可以作为薄层色谱、液相色谱法的检测器,可提供待测组分的结构信息,其灵敏度和其它常用检测器相似。