紫外吸收光谱测定氢键强度的实验讨论

通过对丙酮、环已烷、乙醇等溶液的光谱分析，探讨含杂原子基团的有机化合物在极性溶剂中，与溶剂分子形成氢键而导致n→π＊跃迁，吸收带发生位移的规律。     

1-甲基-酰胺基蒽醌中分子内电荷转移的理论研究

本文采用密度泛函理论(DFT)和含时密度泛函理论(TD-DFT)对1-甲基-酰胺基蒽醌(MAAQ)的基态和激发态性质做了一系列计算研究.在基态,MAAQ中酰胺基与蒽醌分子是共平面的,并且酰胺基和蒽醌分子之间形成了一个分子内氢键C=O…H-N. S_0→S_1的跃迁属于一个明显的π→π~*特性.在第一单重激发态,MAAQ具有两个稳定结构(平面构型nMAAQ和扭曲的构型tMAAQ).其中,nMAAQ是占优势的构象.同时,在MAAQ的溶剂中,观察不到tMAAQ的发射光谱.在激发态,MAAQ发生了扭曲的分子内电荷转移(TICT)过程.在基态MAAQ与F~-形成了一个分子间氢键F…H-N,而激发态MAAQ-F~-复合物发生了激发态分子间质子转移现象.     

紫红质色基-视黄醛骨架异构化机理探讨

运用休克尔分子轨道（ＨＭＯ）理论对紫红质中的色基－视黄醛骨架异构化现象进行了讨论挖计算结果表明：紫红质中视黄醛骨架共轭体系π→π＊跃迁的最大吸收峰λｍａｘ＝５６３ｎｍ，这与紫红质的λｍａｘ＝４９８ｎｍ相近，但列接近受压紫红质的实验结果λｍａｘ＝５３４ｎｍ；且视黄醛骨架结构共轭体系中Ｃ１１－Ｃ１２之间激发态的π键级为１．５８６０。明显小于基态π键级１．７４６９值，故当紫红质吸收光能进入激发态之后，１     

气相丙酮分子与带电离子的低激发态特性

采用密度泛函理论中的B3P86方法,在6-311++G(d,p)基组水平上,优化气相丙酮分子及带电离子的基态稳定几何构型,并用含时密度泛函理论(TD-DFT)方法,研究气相丙酮分子和离子的低激发态特性.结果表明:随着分子获得电子数目的增加,体系能量逐渐增加;S1激发态能量与基态能量差值ΔE减小;分子荧光波长急剧增加;电子跃迁轨道数减少.     

苯并三唑及其取代衍生物电子结构与光谱性质的理论研究

应用密度泛函理论(DFT)方法对苯并三唑(BTA)及其不同取代衍生物进行理论计算,讨论不同取代基对BTA分子的几何结构及电子结构的影响;同时,利用单激发组态相互作用(CIS)方法获得分子最低激发态结构,应用含时密度泛函理论(TD-DFT)方法研究分子的电子光谱性质.结果表明,BTA及其不同取代衍生物分子从基态到激发态的跃迁中,几何结构变化主要表现在苯环及共轭杂环的键长方面,最强跃迁均由分子的HOMO→LUMO跃迁贡献,由轨道对称性可知为π→π*跃迁.BTA分子中引入不同取代基,均导致吸收和发射光谱谱线红移.     

二芳基全氟环戊烯化合物闭环体的含时密度泛函理论研究

采用B3LYP／6—31G（d）方法对二芳基全氟环戊烯闭环体进行量子化学理论计算研究，探讨了活性碳位引入H，CH3，OCH3，NH2，CCH，CN，cF3基团对分子基态几何构型的影响．在此基础上，运用TD／B3LYP／6—31G（d）方法计算了其电子吸收光谱，得到了最大吸收波长与实验值相吻合．研究还发现该类分子的最低单重激发态（S1）主要源自分子内HOMO→LUMO（π→π＊）跃迁，通过分析其前线分子轨道，合理解释了不同取代物吸收光谱的差异．     

卵磷脂的红外光谱和紫外光谱研究

本文采用红外分光光度法分析卵磷脂的吸收光谱，给出吸收峰的波数和相应的分子振动性质．考察ＣＣｌ４，ＣＨ２Ｃｌ２和ＣＨＣｌ３三种溶剂中卵磷脂的紫外吸收光谱，讨论溶剂极性对卵磷脂分子π－π＊电子跃迁吸收峰的影响，给出卵磷脂分子聚集体激子态跃迁吸收峰的位置．     

丙酮S1（n,π）态光解离机理的理论研究

用从头算自洽场方法在３－２１Ｇ水平上研究了丙酮在ｎ→π＾＊激发单态（Ｓ１（ｎ，π＾＊））势能表面上的光解反应。优化出的反应场Ｓ１（ｎ，π＾＊）态的丙酮分子的几何构型偏离Ｃ２ｖ对称性的基态构型，即Ｏ原子弯出３个Ｃ原子的平面３９．３°，且甲基的旋转角度为５０．５°。该结论与实验的结果取得了一致。该反应途经一个Ｃ１对称性的过渡态而分解为一个ｎ→π＾＊激发态的乙酰基和一个基态的甲基。计算的反应活化位垒和垂     

激发态DNA碱基对分子间相互作用的理论研究

[目的]利用本课题组发展的定量分析方法研究激发态DNA碱基对分子间相互作用的本质,以及不同类型的电子跃迁对DNA碱基对分子间相互作用的影响.[方法]采用广义Kohn-Sham能量分解分析方法(generalized Kohn-Sham based energy decomposition analysis, GKS-EDA),对两种Waston-Crick构型和两种stacked构型的DNA碱基对分子间相互作用本质进行理论研究.[结果]对于Waston-Crick构型的碱基对,n→π^*跃迁削弱了轨道极化作用但加强了电子相关作用,激发态分子间相互作用由电子相关作用主导,而π→π^*跃迁对分子间氢键影响较小;对于stacked构型的碱基对,π→π^*跃迁削弱了静电相互作用但增强了电子相关作用.[结论] Waston-Crick构型碱基对分子间相互作用本质受电子激发跃迁影响较大,而电子激发跃迁基本不改变stacked构型碱基对分子间相互作用本质.     

气相Val分子与带电离子低激发态特性的理论研究

采用密度泛函B3LYP方法,所有C、O、N、H原子在6-311+G(2df)基组水平上,优化气相Val中性分子和带电离子基态稳定几何构型.在6-311++G(d,p)基组水平上,采用TD-DFT方法,研究气相Val中性分子、离子低激发态的特性.结果表明:随着分子获得电子数目的增加,体系能量逐渐增加;S1激发态能量与基态能量差值ΔE减小;分子荧光波长急剧增加;S2激发态电子跃迁轨道数没有改变.     

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.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

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