2-羟基-1-氧基乙烯自由基(C2H3O2)的分子内质子转移反应的理论研究

用量子化学从头计算方法研究了2-羟基-1-氧基乙烯自由基的质子转移反应。首先, 在UHF/3-21G的水平上, 采用能量梯度法优化了反应物和过渡态的几何构型, 然后利用这两个优化的构型做了振动分析, 找出相应的振动频率和模式, 从而得到质子转移反应的活化熵值。此外, 又做了内禀反应坐标途径(IRC)。为了求得比较准确的反应势能剖面, 以便进行隧道效应校正, 用多体微扰法(二级微扰)同时在参加转移的氢原子上附加了扩散函数p(UMP_2/3-21G~+)在IRC的各点上进行能量校正。根据从以上计算结果拟合的抛物线势, 求出质子转移的隧道效应校正系数为19.9, 然后由过渡状态理论计算了此反应的比速常数为7.4×10~(11)s~(-1)。此外, 还得到了该自由基的分子内氢键键能和键长分别为19.2 kJ mol~(-1)和0.2057 nm(UMP_2/3-21G~+结果)。     

邻羟基苯基重氮氨基偶氮苯与铊(Ⅲ)的显色反应及其应用

本文研究了邻羟基苯基重氮氨基偶氮苯 (O HDAA)与Tl(Ⅲ )的显色反应。在TritonX 10 0和十二烷基苯磺酸钠 (SDBS)存在下 ,于 0 5 4～ 1 1mol·L-1氨水介质中 ,试剂与Tl(Ⅲ )形成 1∶5的稳定红色配合物 ,其最大吸收波长位于 5 2 0nm处 ,表观摩尔吸光系数为 1 4× 10 5L·mol-1·cm-1。Tl(Ⅲ )量在 0～ 6 0 0 μg·L-1之间符合朗伯 比耳定律。已用于直接测定水样及经泡沫塑料吸附分离后测定地质样品中的痕量铊 ,结果满意     

基于数据包络分析的工程监理评标决策模型研究

以工程项目业主方视角基于数据包络分析的理论和方法建立了工程监理评标决策模型.首先,分析影响工程监理活动成效的因素,提取工程监理标原始评价指标,为消除原始指标间相关性带来的影响,采用主成分分析法建立工程监理标综合评价指标体系.其次,选取合适的输入和输出指标,建立工程监理评标决策的数据包络分析(DEA)模型.最后,通过实证分析,对该评标决策模型的操作性和有效性进行验证.为业主方提供了更为科学合理的评标决策方法,为规范建筑业市场运行秩序提供理论依据.     

基于压电加速度传感器的井下机车定位系统

我国煤矿井下电机车铁路运输系统不能及时准确反映电机车运行速度和行车位置,将压电加速度传感器引入到井下机车定位系统中,通过采集电机车加速度值积分求解得出其速度和位置,实现定位功能.分析了压电式加速度传感器的基本原理;阐述了基于压电式加速度计的井下机车定位系统总体方案;完成了系统的软件设计并对加速度传感器温度漂移和随机误差进行了标定修正.最后通过模拟实验证明了其可靠性.     

AlCl3/MCM-41催化剂上桥式四氢双环戊二烯异构化反应

 分别采用介孔 MCM-41 和 SiO2 为载体制备了固载化 AlCl3 催化剂, 考察了其催化桥式四氢双环戊二烯异构化生成挂式四氢双环戊二烯反应性能. 结果表明, 180 °C 时 AlCl3/MCM-41 催化剂上挂式四氢双环戊二烯选择性可达 95.7%, 而在 AlCl3/SiO2 上仅为 86.3%. 采用 N2 吸附-脱附、Hammett 指示剂法、吡啶吸附红外光谱和化学分析等方法对催化剂进行了表征. 结果表明, AlCl3/MCM-41 催化剂较弱的表面酸性和一维孔结构有利于挂式四氢双环戊二烯的生成.     

Electron Scattering by C4H10 and C6H6 in the Energy Range 100--1000eV

We investigate the applicability of the independent atom model （IAM） to elastic electron scattering from complex polyatomic molecules, namely C4H10 and C6H6, in the energy range 100-1000eV. The cross sections of the elastic electron scattering are calculated by employing the IAM together with the relativistic partial waves. The incorporation of both the modified absorption potential and the extended structural factor in the IAM makes the elastic differential cross sections and momentum transfer cross sections have a good agreement with the available experimental data. The present simple model seems to be insensitive to the complexity of the target molecules so that the proposed procedure can be quite useful for calculation of electron scattering from bio-molecules.     

Investigation on the deformation of Ne and Mg isotope chains within relativistic mean-field model

Ne and Mg isotope chains are investigated based on constrained calculations in the framework of a deformed relativistic mean-field （RMF） model with the NL075 parameter set. The calculated quadrupole deformation and binding energy are compared with other theoretical results as well as the available experimental data. It shows that the calculated deformations of Ne and Mg with the NL075 are more accurate than those obtained with the NL-SH. It is predicted that ^19,29,32Ne and ^20,31Mg maybe have a triaxial deformation and ^25-28Ne and ^27-30Mg exhibit a shape coexistence probably. The closure effect of neutron number N=8 for ^20Mg is predicted to be very weak.     

1-碘-2-锂-邻碳硼烷与环戊二烯衍生物的类Diels-Alder反应的理论研究

运用密度泛函理论的B3LYP方法对1-碘-2-锂-邻碳硼烷与亚甲基环戊二烯衍生物的类Diels-Alder反应进行了理论研究.计算结果显示：1-碘-2-锂-邻碳硼烷与亚甲基环戊二烯衍生物的类Diels-Alder反应为分步过程,需要依次经过脱LiI形成碳硼炔、碳硼炔与亚甲基环戊二烯成键、碳硼烷基1,2-σ迁移和成环四个过程才能形成与Diels-Alder反应形式相同的产物.其中碳硼烷基的1,2-σ迁移过程为整个反应的决速步,在353 K的实验条件下需要越过28.3 kcal•mol^-1的自由能垒才能形成相应的碳硼烷基降冰片烯衍生物,理论预测的反应速率与实验结果较好吻合.自然键轨道理论（NBO）分析结果显示：该反应与正常电子需求的Diels-Alder反应（NEDDA）具有相似的电子结构特征.文中还对反应底物的取代基效应进行了讨论,并得到了与实验数据基本一致的结果.     

Influence of Molecular Structure on the Dimerization Reactivity of Germaaromatic Compounds： a Theoretical Study

Density functional theory (DFT) calculations, at the B3LYP/6-311G** level of theory, were performed to study the reaction mechanism and potential energy surface of the [2 + 2], [4 + 2] and [4 + 4] dimerization reactions of some germaaromatic compounds. The influence of reactant's molecular structure and benzene solvent on the potential energy surface of the studied reactions was investigated. Our calculation results show that [2 + 2] and [4 + 4] reactions are concerted and synchronous processes; while [4 + 2] reactions proceed via a concerted but asynchronous way in general. [2 + 2] and [4 + 2] reactions of germabenzenes and 1-germana- phthalene proceed much more easily than the corresponding [4 + 4] reaction, both thermo- dynamically and kinetically; while most [4 + 2] paths have lower activation barrier than the corres- ponding [2 + 2] ones. As the number of six-membered aromatic rings in reactant molecules becomes larger, [2 + 2], [4 + 2] and [4 + 4] reactions become easier to proceed. The influence of substituents at the Ge atom of germabenzenes on the potential energy surface of [2 + 2] and [4 + 2] reactions correlates with their electronic properties and volume. Solvent effect is not crucial for the potential energy surfaces of the studied reactions.