期刊文献+
共找到3篇文章
< 1 >
每页显示 20 50 100
TDDFT Study on Different Sensing Mechanisms of Similar Cyanide Sensors Based on Michael Addition Reaction 被引量:1
1
作者 李光跃 宋平 何国钟 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2011年第3期305-310,I0003,共7页
The solvents and substituents of two similar fluorescent sensors for cyanide, 7-diethylamino- 3-formylcoumarin (sensor a) and 7-diethylamino-3-(2-nitrovinyl)coumarin (sensor b), are proposed to account for their... The solvents and substituents of two similar fluorescent sensors for cyanide, 7-diethylamino- 3-formylcoumarin (sensor a) and 7-diethylamino-3-(2-nitrovinyl)coumarin (sensor b), are proposed to account for their distinct sensing mechanisms and experimental phenomena. The time-dependent density functional theory has been applied to investigate the ground states and the first singlet excited electronic states of the sensor as well as their possible Michael reaction products with cyanide, with a view to monitoring their geometries and photophysieal properties. The theoretical study indicates that the protic water solvent could lead to final Michael addition product of sensor a in the ground state, while the aprotic acetonitrile solvent could lead to carbanion as the final product of sensor b. Furthermore, the Michael reaction product of sensor a has been proved to have a torsion structure in its first singlet excited state. Correspondingly, sensor b also has a torsion structure around the nitrovinyl moiety in its first singlet excited state, while not in its carbanion structure. This could explain the observed strong fluorescence for sensor a and the quenching fluorescence for the sensor b upon the addition of the cyanide anions in the relevant sensing mechanisms. 展开更多
关键词 SENSOR FLUORESCENCE CYANIDE Sensing mechanism Time-dependent density functional theory Michael addition reaction
下载PDF
摄影曝光原理纪要(一)
2
作者 李名爵 《影像技术》 CAS 2013年第1期25-28,共4页
若要实实在在的掌握摄影曝光技术,必须对一些光度学名词概念有些了解…弄懂感光材料(胶片、相纸与电子感光元件)的感光特性,才能弄懂曝光的基本原理;曝光准则A:"景物的实际曝光范围应落在胶片的有效感光范围之内",曝光准则B:&... 若要实实在在的掌握摄影曝光技术,必须对一些光度学名词概念有些了解…弄懂感光材料(胶片、相纸与电子感光元件)的感光特性,才能弄懂曝光的基本原理;曝光准则A:"景物的实际曝光范围应落在胶片的有效感光范围之内",曝光准则B:"照片上主体影像的影调应与主体景物相符";各种测光装置(曝光表)及其用法;通过实际拍摄积累经验,才能熟练掌握曝光技术。 展开更多
关键词 光通量 光照度 光亮度 特性曲线(含:感光量、光密度D、反差、反差指数CI、有效感光范围--动态范围 标准显影程度 感光度等) 曝光/感光 曝光量 曝光不足/曝光过度 曝光准则A 曝光准则B 曝光量加法制 '区段编号Zone System'曝光法
下载PDF
胶片特性自动测量方法研究
3
作者 于志贤 梁红 +2 位作者 宋蕾 屈新岳 刘建忠 《科技开发动态》 2004年第10期7-9,共3页
本文根据当前胶片感光密度特性测量采用手工计算参数和绘制曲线的现状,提出了采用计算机系统实现自动数据采集、参数计算及曲线绘制想法,着重叙述了硬件实现方法和部分软件的设计,给出了测量数据运行结果。
关键词 胶片特性 自动测量 感光密度 数据采集
原文传递
上一页 1 下一页 到第
使用帮助 返回顶部