丙烯酸与臭氧反应机理的量子化学研究

采用密度泛函理论在MPW1K／6-31＋G（d,p）水平上研究了丙烯酸分子CH2CHCOOH与臭氧O3分子的反应机理,优化了反应势能面上各驻点的几何构型,对每一个驻点能量进行零点能校正,并采用相同的基组在MPWB1K水平和BHandHLYP水平上对各驻点的构型及能量进行验证。通过同一水平的振动频率分析确认了各稳定点和过渡态,另用内禀反应坐标（IRC）对过渡态进行验证。结果表明：丙烯酸的臭氧化反应具有较高的反应活性,并且为多通道反应,多数反应通道有OH自由基生成。反应过程中有顺反异构的COOHHCOO自由基生成,二者会沿不同的反应通道进行反应,其中syn-COOHHCOO的反应活化能较高。     

Misalignment analysis of journal bearing influenced by asymmetric deflection, based on a simple stepped shaft model

The effects of journal misalignment on a journal bearing caused by an asymmetric rotor structure are presented in this study.A new model considering the asymmetric deflection is applied.Also,the thermo-hydrodynamic of the oil film in the journal bearing and straightforward elasticity theory are considered in the analysis.Based on the structure stiffness equivalent characteristic,a simple stepped shaft can reflect the entire complex structure model.The existing lubrication model,which does not consider this angle component,is not very precise for journal bearings.Film pressure,misalignment angle,velocity field,oil leakage,and temperature field were calculated and compared in the journal bearing analysis.The results indicate that bearing performances are greatly affected by misalignment caused by the asymmetric structure.A simple stepped shaft can effectively represent a misaligned journal bearing in a rotor-bearing system.     

Quantum chemical study on the catalytic mechanism of Na/K on NO-char heterogeneous reactions during the coal reburning process

Quantum chemical simulation was used to investigate the catalytic mechanism of Na/K on NO-char heterogeneous reactions during the coal reburning process. Both NO-char and NO-Na/K reactions were considered as three-step processes in this calculation. Based on geometry optimizations made using the UB3LYP/6-31G（d） method, the activation energies of NO-char and NO-Na/K reactions were calculated using the QCISD（T）/6-311G（d, p） method; Results showed that the activation energy of the NO-Na/K reaction （107.9/82.0 kJ/mol） was much lower than that of the NO-char reaction （245.1 kJ/mol）. The reactions of NaO/KO and Na2O/K2O reduced by char were also studied, and their thermodynamics were calculated using the UB3LYP/6-31G（d） method; Results showed that both Na and K can be refreshed easily and rapidly by char at high temperature during the coal reburning process. Based on the calculations and analyses, the catalytic mechanism of Na/K on NO-char heterogeneous reactions during the coal reburning process was clarified.     

Density function theory study on the interaction between camptothecin and cytosine

Density function M06 method has been used to optimize the geometries of camptothecin-cytosine at 6-31+G* basis.Finally, thirteen stabilized complexes have been obtained.Theories of atoms in molecules (AIM) and natural bond orbital (NBO) have been utilized to investigate the hydrogen bonds involved in all the complexes.The interaction energies of all the complexes are corrected by basis set superposition error (BSSE).By the analysis of complexes interaction energy, charge density, second-order interaction energies E(2), it is indicated that the complex 6 is the most stable structure.     

取代基型钌配合物电子结构及与DNA键合倾向研究

理论运用密度泛函（DFT）方法,计算四个取代基型钌（II）多吡啶配合物[Ru（phen）2（6-R—dppz）]^2＋（R—OH,-NO2）和[Ru（phen）2（7-R—dppz）]^2＋（R=-F,-CH3）．合理解释了在主配体（dppz）上引入强拉电子的取代基（-F,-NO2）,比引入推电子取代基（-OH,-CH3）有利于提高配合物与DNA键合的能力．这是通过降低最低空轨道LUMO及相近的最低空轨道（LUMO＋X）的能量及其插入配体的布居调控的．     

挖掘机偏载条件下疲劳动态加载装置仿真研究北大核心

为研究挖掘机在偏载条件下的铰点受力并对关键结构件进行疲劳寿命试验,设计了一种加载系统实验装置。装置选取斗杆举升工况下的挖掘姿态作为研究对象,并对被试件进行了合理的二力杆简化,基于AEMSim对液压加载系统进行了建模仿真研究,得到了加载系统的阶跃响应特性和20Hz正弦激励信号下的响应特性曲线。结果表明,挖掘机被试件姿态选择具有代表性,液压加载系统能够满足不同加载频率下的系统响应需求,可用于性能试验仿真研究。     

A study of the presence of evolutionary protoconcepts in pre-high school textbooks

Abstract Elementary and middle school science texts were analyzed for the presence of evolutionary protoconcepts, which are defined as topics that prepare students to study evolution in later years. Elementary and middle school texts were content-analyzed for protoconcepts in both life science and earth science. Seventeen concepts considered important for student understanding of evolution were gleaned from the misconception literature and used to review the life science texts. Concepts used to analyze other texts were chosen by exploring all texts used in the analysis for any topics that might qualify as evolutionary protoconcepts, thus generating grounded theory. Coverage of evolutionary protoconcepts varies considerably among published textbooks. We recommend using this analysis when considering textbooks for adoption and for supplementing texts currently in use. We also recommended this type of analysis of textbooks for inclusion of other topics of interest to science education research.     

多硝基芳香化合物撞击感度的理论研究

采用密度泛函的方法，在3—21G基组水平上，对五种多硝基芳香化合物TNA(Ⅰ)、2，3．4，6-四硝基苯胺(Ⅱ)、五硝基苯胺(Ⅲ)、DATB(Ⅳ)、TATB(Ⅴ)炸药的撞击感度进行了理论研究，探讨苯环上引入氨基和硝基对该类炸药撞击敏感度的影响。结果表明，利用Mulliken键级可以很好的解释分子的撞击感度，氨基引入苯环后，炸药的撞击感度减小，硝基引入苯环后，撞击感度也发生了变化，其撞击敏感度顺序为：Ⅰ＞Ⅲ＞Ⅱ＞Ⅳ＞Ⅴ。     

中学化学教学实施研究性学习的探索

为了推动中学化学教学，全面、科学地认识在中学化学教学中实施研究性学习的重要性，对研究性学习的含义、实施研究性学习的意义进行阐述，并对中学化学研究性学习的途径和实施方法做初步探讨．     

高职化工类人才培养的困境及策略

针对一线化工技能人才短缺而高职院校化工类生源却日趋紧张的现象,从此类学生的学情和校情两方面分析了产生这些现象的原因,并提出了相应策略:对学生进行针对性的辅导和教育,采取分层和分文理班教学的方法,改善实训条件,提升教师素质,健全教师质量考核机制.     

信息不对称理论与企业信息资源管理

信息不对称理论是近年来信息经济学领域的热点问题。通过对信息不对称理论以及信息资源管理中信息的产生和流通过程的阐述,分析了信息不对称理论对信息资源管理的重要指导意义,并对信息资源管理过程中应该采取的策略进行了研究。     

胍乙啶在人体内形成一氧化氮的量子化学研究

采用直接药物设计中的全新药物设计方法,以胍乙啶(C9H20N4)为研究对象,利用MOPAC软件包的AM1计算方法探讨了其在体内各种酶作用下通过氧化末端氮原子N(3)而合成一氧化氮的机理。通过研究化合物的中间产物(species B、C、D、E)的能量、相关键长和相关原子净电荷变化,我们讨论了这个机制的合理性。     

贵州三种冷水花化学成分预试研究

初步考察贵州湿生冷水花、粗齿冷水花、纤细冷水花的化学成分.采用化学反应鉴别方法对以上三种冷水花的水提取液、乙醇提取液、石油醚提取液进行鉴别.经检测发现,这三种冷水花中可能含有多糖、皂苷、多肽、还原糖、鞣质、有机酸、香豆素、黄酮类、挥发油等多种化学成分,为贵州冷水花属植物的进一步研究提供了依据.     

水岩作用对云冈石窟石雕风化破坏的化学效应研究

本文运用地质、水文地质等方法研究了影响云冈石窟石雕保存的水和盐的来源问题,采用化学方法全面分析了云冈石窟二泉窟、洞窟渗水、石窟区大气降水(雨水及雪水)的水化学特征;分析了云冈石窟各层岩石样品以及其中盐类的化学组份和物质成分及含量。讨论了云冈石窟石雕快速风化过程中发生的一系列复杂的水岩化学效应,其中包括:碳酸盐胶结物的溶解、碎屑长石的水解、盐类矿物的结晶和氧化铁及氢氧化铁矿物形成和转变。     

关于量子力学教学的几点思考

量子力学在物理学研究中起着基础与支柱作用,因此量子力学课程教学自然成为本科物理教学一个极为重要的组成部分.结合教学实际,从教学内容、教学模式等方面,探讨了《量子力学》教学中应注意的问题并提出改进建议.     

基于DSP的DTMF信号的产生和检测

DTMF信号是音频电话中的拨号信号,广泛用于新一代电话机.本文介绍一种基于TMS320C54x系列DSP芯片的DTMF信号的产生和检测方法,使得DTMF信号的产生和检测变准确、迅速和简单.     

基于半导体量子点的量子计算的物理实现

利用半导体量子点导带中电子的自旋作为量子信息的载体,设计了量子计算的方案,该方案不需要利用量子位之间的相互作用,所有的操作只是单量子位的操作。     

胞嘧啶碱基与羟基自由基反应的密度泛函理论

羟基自由基(·OH)进攻嘧啶碱基是破坏核酸造成DNA断链损伤的重要原因之一.采用密度泛函(DFT)理论中B3LYP方法在6-31+G(d,p)基组水平上对胞嘧啶(cysotine,简写为C)受羟基自由基进攻形成的各种可能产物自由基进行几何全优化.根据总能量、键长和自旋密度的计算结果,从理论上确认了C-1、C-3、C-4和C-5位加成机制.得产物自由基C1OH·、C3OH·、C4OH·、C5OH.,且C1OH·、C5OH·易与邻位H脱水得一个更稳定的产物自由基,而C3OH·、C4OH·不易脱水与相邻位H脱水得一个更稳定的产物自由基,这些稳定自由基的形成造成DNA断链损.     

函数在图像编码技术中的应用

介绍了DFT＆DCT的概念,主要变换形式及在图像通信系统中的现状,通过分析DCT讨论了离散余弦函数编码技术在图像通信系统中的应用     

以量子围栏中的单粒子为工质的量子卡诺循环

构造了以量子围栏中的单粒子为工作物质的量子卡诺循环模型,量子围栏的哈密顿量期望值相当于经典卡诺循环中热源的温度,该量子卡诺循环由两个等能（等温）过程和两个绝热过程组成。分析得到,量子围栏卡诺循环的等温过程和绝热过程和经典卡诺循环的等温过程和绝热过程相似,推得量子卡诺循环的效率表示式,该表示式与经典可逆卡诺循环效率的表示式类似。