Pd/C催化氢化高效脱除含氮糖中的苄基型保护基

通过抽真空脱除Pd/C催化剂表面吸附的有害气体以及利用高纯氮气对反应体系进行脱气,本实验方法能够高效脱除苄基保护的N-取代fagomine衍生物的保护基,而且哌啶环N-苄基型取代基也可以被脱去.其中,N-非苄基型取代fagomine衍生物的脱保护反应的收率为94%～98%.所有化合物的结构均经质谱和核磁共振谱确证.     

取代基对2-(4-取代苯基)-5-取代嘧啶紫外吸收能量的影响

测定了46个2-(4-X苯基)-5-Y嘧啶的紫外可见吸收光谱,研究了共轭链两端取代基X,Y对紫外最大吸收波长λmax对应的能量vmax的影响规律,提取表征基态取代基电子效应的Hammett参数σ和表征激发态取代基电子效应的激发态取代基参数σexCC对vmax建立定量结构-性质相关模型,得到了相关系数高(R2=0.948 7)、平均相对误差小(D=1.26%)的5参数模型.结果表明,取代基X,Y的共轭效应、激发态取代基效应及取代基的交叉相互作用对化合物的紫外吸收有较大影响.结合各参数前面的系数对模型的物理意义进行了合理解释,并与本课题组之前研究的取代基对2-X-5-Y嘧啶类化合物的紫外吸收能量的影响规律进行了比较.     

取代查尔酮衍生物非线性光学性质的FF/PM3理论计算

利用有限场FF/PM 3方法讨论了查尔酮类化合物的非线性光学性质 ,针对不同取代基和取代位置系统分析了分子结构、取代基的类型、取代位置对共轭有机分子电子性质及非线性光学性质的影响 .结果表明 ,取代基的引入可明显改善体系的非线性光学性质     

取代基电负性对单取代苯~(13)C化学位移的影响

本文研究了单取代苯的~(13)C化学位移与取代基电负性及取代基常数(Hammett常数)的关系。总结分析了单取代苯的取代效应,即取代基对~(13)C化学位移的影响。     

取代基的烷基链长对季铵阳离子淀粉浆膜性能的影响

以3-氯-2-羟丙基三烷基氯化铵为醚化剂,通过改变醚化剂的烷基链长和醚化剂对淀粉的用量,制备了3个系列具有不同烷基链长的季铵型阳离子淀粉,并以淀粉浆膜的断裂伸长率、断裂强度、断裂功、耐屈曲性、吸湿性及水溶时间为量化指标,研究了季铵取代基中烷基链长对淀粉浆膜性能的影响.结果表明:季铵取代基中烷基链长对淀粉的成膜性和浆膜性能有显著的影响;当季铵取代基中烷基的碳原子数不超过2时,淀粉的季铵化变性能够增加淀粉浆膜的断裂伸长率、断裂功及耐屈曲次数,改善淀粉浆膜的韧性;若烷基上的碳原子数达到3时,由于取代基团的强疏水性能,这种季铵化变性只会使淀粉的成膜性及浆膜性能下降,不宜作为纺织浆料使用.此外,在淀粉分子链上引入氯化三甲基铵羟丙基和氯化三乙基铵羟丙基,均能改善淀粉的可退浆性.根据经纱上浆对浆膜性能及可退浆性的要求,宜选择3-氯-2-羟丙基三甲基氯化铵醚化剂对淀粉进行季铵型阳离子改性.     

腈基取代脂肪族一元酸的电子结构与化学反应性

为了引导和构建结构决定性质教学思想,对腈基取代直链型脂肪族羧酸化合物的空间构象和电子结构进行了分析,结果表明α-腈基癸酸羧基C1-C2单键旋转构象能量能垒17．4758kJ／mol;腈基使碳原子电荷密度减少,腈基取代使酸性加强,羧基H原子电荷p与n的关系遵从p=0．449-0．0061n（n）（2≤n≤10）规律,腈基取代位置n-C原子与羧基碳电荷遵从p=0．716＋0．123/n（2≤n≤10）关系;腈基取代酸（HA）的体系能随与羧基的距离n增加次降低,遵从E=-631．492-0．0071n（n）（2≤n≤10）规律。     

p-取代苯基化合物荧光发射光谱中取代基效应的定量研究

对不同体系的取代苯基化合物的荧光发射光谱中的取代基效应进行了研究.其中,对于二苯乙烯衍生物、1,4-双(取代苯乙炔基)苯,激发态取代基参数(σcccx)的单参数方程的相关系数均在0.98以上;对于取代苯乙烯、取代α-甲基苯乙烯和反,反-1,4-双(β-取代苯乙烯基)苯,则用Hammett参数(σp)和σcccx的双参数方程关联,相关系数均在0.96以上.结果表明,激发态取代基参数能用于共轭化合物的荧光发射能量的定量研究.     

对称型双偶氮苯化合物的合成、表征及紫外性能探究

以对苯二胺为原料通过重氮化、偶联和亲核取代反应设计合成3类新型的对称型双偶氮苯化合物,讨论并总结合成路线和方法.通过元素分析、核磁、红外等对所得化合物进行结构分析和表征,考察酸碱度、溶剂、不同取代基对偶氮化合物紫外吸收的影响,发现此类化合物的最大吸收波长随着溶液pH的增大、溶剂极性减小、取代基共轭效应增强明显红移.     

氮苯丙烯叉基苯胺衍生物紫外光谱中的取代基效应

设计合成得到25种不同取代基的氮苯丙烯叉基苯胺衍生物,测定了其紫外吸收光谱。定量分析结果表明,氮苯丙烯叉基苯胺衍生物紫外吸收能量中碳端苯环取代基效应可用激发态取代基参数σexcc的单参数方程关联,其类似于trans-二苯乙烯的取代基效应;而氮苯丙烯叉基苯胺衍生物紫外吸收能量中氮端苯环取代基效应更适合用极性参数σp和激发态取代基参数σexcc的双参数方程定量相关,其类似于取代氮苄叉基苯胺的取代基效应。     

—取代联苯系电取代反应定位规则共振论观

—取代联苯发生亲电取代反应时,当取代基为产生-I-C效应的吸电基或供电基在联苯环上4-位或2-位时,第二个取代基主要进入,未有取代基的苯环的邻位和对位,以对位为主.若取代基为产生-I>+C效应的吸电基或供电基在联苯环上3-位时,第二个取代基主要进入有取代基的苯环的邻位和对位,以对位为主.     

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.     

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     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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