阿魏酸的荧光光谱与荧光量子产率

在酸性条件下,阿魏酸荧光强度随pH值的升高而增大,荧光峰的最大激发和发射波长分别为310 nm和415 nm。在碱性条件下,最大激发波长和发射波长红移到350 nm和460 nm处。随着pH值的升高,其荧光强度逐渐增大,当pH值大于10.0时,其荧光强度达到最大值且趋于稳定。阿魏酸的荧光光谱随pH值的变化是由于其分子中羧基和羟基质子的离解。以硫酸奎宁为参比,测得阿魏酸水溶液的荧光量子产率为0.006 1。     

含荧光素的荧光高分子合成及荧光性质研究

通过把荧光素引入烯类单体后与甲基丙烯酸甲酯共聚合成了含荧光素的荧光高分子 ,并检测了该聚合物在不同溶剂中的荧光性质 ,发现聚合物在乙醇中能产生很强的荧光 .此外 ,还测试了乳酸对聚合物乙醇溶液的荧光猝灭作用 .实验发现 ,该聚合物对乳酸很敏感 .浓度在 1 0 - 1 0 ～ 1 0 - 8mol· L- 1 之间的乳酸都可使聚合物荧光产生显著变化 .依此现象 ,有望研制一种测试动物体内乳酸含量的光化学传感器     

三种荧光染料的导数——同步荧光光谱解析

通过对吖啶黄，吖啶橙和罗丹明Ｂ三种荧光染料的导数－同步荧光光谱解析，建立了２组份混合荧产ｎｇ／ｍｌ级同时测定的３种“硬解析”模型，结果可应用于水文学研究衣水污染源头的查寻。     

苯基荧光酮荧光光度法测定微量锡的研究

本文应用表面活性剂存在下的胶束增溶，增敏，增稳作用，研究了溴化十六烷基三甲基铵胶束体系中，苯基荧光酮测定微量锡的荧光法及其条件，于０．６－１．０ｍｏｌ／Ｌ酸度下，试剂与锡形成橙红色的胶束络合物。在λｅｘ／λｅｍ＝５３２ｎｍ／５８５ｎｍ处产生强荧光，线性范围０－１０．０μｇ／２５ｍｌ，最低检出限１．２ｎｇ／ｍｌ，相对标准偏差３．８％《     

一种荧光增强型的GSH荧光探针

常见的生物硫醇包括半胱氨酸(Cys)、同型半胱氨酸(Hcy)以及谷胱甘肽(GSH),它们在人体中起着十分重要的作用.使用荧光探针检测此类生物硫醇具有灵敏度高、选择性好、响应时间快等优势.由于3种硫醇具有相似的化学结构(含有活性巯基),因此给这类生物硫醇的选择性检测带来挑战.本文设计了一种荧光探针(2-甲基,6-丙烯酰基喹啉)用于区分检测GSH和Cys/Hcy.通过测试该探针的光谱性质,发现在含有该探针的水溶液中加入谷胱甘肽(GSH)后,相应的荧光光谱和紫外-可见光谱都有显著的变化.相比其他分析物,发现探针在水溶液中对GSH具有较高的选择性和灵敏度.此外,考虑到该检测过程是在水相中进行的,因此该探针在生物成像方面具备潜在的使用价值.     

荧光的妙用

洗涤剂洗出的衣物为什么“比白色还要白“?犯罪分子的指纹是如何得到的?荧光棒为什么越折越亮?极光是如何形成的?本文对“借光发光”的荧光现象的介绍将使我们大开眼界，你会发现F1汽车竟然也和荧光有关系。     

二溴羟基苯基荧光酮荧光熄灭法测定钛

本文用荧光熄灭法研究了二溴羟基苯基荧光酮（ＤＢＨ－ＰＦ）为指示剂测定Ｔｉ（Ⅳ）。在吐温－８０存在下，Ｔｉ（Ⅳ）与ＤＢＨ－ＰＦ形成１：２紫红色配合物，λｅｘ２＝５０２ｎｍ，λｅｍ＝５２２ｎｍ，检测限为４μｇ／Ｌ，线性范围为４～５６μｇ／Ｌ。该方法灵敏度高，选择性好，适用于检测合金钢及铝合金中的微量钛。     

胆绿素的荧光动力学研究

研究了胆素溶液及经过热处理和添加Ｈ２Ｏ２,Ｚｎ＾２＋或表面活性剂等之后的荧光变化,发现上述处理均使胆绿素溶液的荧光强度增大,荧光增强程度因处理方法不同而异。进一步对胆绿素的碱性水溶液的不同处理方法即热处理,热处理并加Ｚｎ＾２＋热处理后加Ｚｎ＾２＋再加表面活性剂等进行时间扫描灾光动力学研究,获得了上述不同处理形式的胆素溶液的荧光强度随时间变化的规律,新配制胆绿素碱溶液经热处理,热处理后形式的胆绿素溶     

超荧光及其拍效应

本文简要阐述了超荧无的基本特征和理论描述,在此基础上,系统地研究了双原子超荧光体系的拍效应,并给出了产生拍的阈值条件     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the