Synthesis,Characterization and Crystal Structure of 3-o-Fluorophenyl-6-（4-decarboxydehydroabietyl）-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazole

Three novel 1,2,4-triazolo[3,4-b]-1,3,4-thiadiazoles were designed,synthesized and characterized by IR,NMR and APCI-MS.3-o-Fluorophenyl-6-(4-decarboxydehydroabietyl)-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazole(6a,C28H31FN4S) was structurally determined by single-crystal X-ray diffraction.The crystal belongs to the orthorhombic system,space group P212121 with a=6.0153(14),b=12.2577(19),c=34.055(3),V=2511.0(7)3,Z=4,Mr=474.63,Dc=1.255Mg/m3,λ=0.71073 ,μ(MoKα)=0.160 mm-1,F(000)=1008,the final R=0.0555 and wR=0.1248 for 3094 observed reflections with I2σ(I).There are six rings in the crystal structure of the title compound.The dihedral angle between 1,2,4-triazole and 1,3,4-thiadiaole rings is 1.4o,and that between 1,2,4-triazole and benzene ring D 25.5o.     

中国燃油大气铅排放量估算

依据不同时期车用汽油铅含量国家标准及汽油消费量数据,估算了我国1980—2006年的全国燃油大气铅排放量及2001—2005年分地区燃油大气铅排放量。结果表明,27年间我国因汽油燃烧共计向大气排放了约20万t铅。汽油无铅化后,燃油大气铅年排放量比从前降低了98%。     

气相色谱-负化学离子源质谱法同时检测蔬菜中103种农药残留

本文比较了负化学电离(NCI)和电子轰击电离(EI)两种电离方式下采用气相色谱-质谱(GC-MS)同时检测103种农药的灵敏度,发现在NCI方式下103个化合物信噪比分别提高1.2~447.0倍。将GC-NCI/MS方法应用于蔬菜中103种农药的检测,检出限在0.06~13.1μg/kg之间,添加水平为20μg/kg和100μg/kg时,回收率在63.5%~123.8%之间,相对标准偏差为3.6%~13.3%。研究结果表明,相对于常用的GC-EI/MS检测方法,上述103个农药更适合采用NCI方式进行GC-MS同时分析。     

浊点萃取-火焰原子吸收光谱法测定食品和饮料中的痕量铜

研究了基于非离子表面活性剂TritonX-114和螯合剂二乙基氨基二硫代甲酸钠(DDTC)的浊点萃取-火焰原子吸收光谱法测定痕量铜的分析方法.考察了影响浊点萃取效率的参数,包括pH值、DDTC浓度、TritonX-114用量、平衡温度及时间等.在优化条件下,本法的检出限(3σ)为1.55μg/L,相对标准偏差RSD为3.4%(n=7,c=100μg/L),线性范围为0～250μg/L.将该法应用于茶叶标准样品(GBW07605)、奶粉和矿泉水等样品中痕量铜的测定,其回收率在96.7%～113.5%之间.     

苯磺酸顺阿曲库铵原料中的R-S异构体和S-S异构体的高效液相色谱法测定

采用手性色谱柱(Chiralcel OD-RH 150×4.0 mm,5μm),以0.05 mol/L的KPF6缓冲液(用磷酸调节pH值为3.0)-乙腈(体积比50∶50)为流动相,在流速1.0 mL.min-1、检测波长280 nm条件下分离和测定了苯磺酸顺阿曲库铵的R-S和S-S异构体.结果表明,利用高效液相色谱法可以实现苯磺酸顺阿曲库铵的R-S和S-S异构体的手性拆分及其快速、简便、准确测定.     

Preparation and Characteristics of GaN Films on Freestanding CVD Thick Diamond Films

Prefer-oriented and fine grained polycrystalline GaN films are prepared by plasma enhanced metal organic chemical vapour deposition on nucleation surfaces of freestanding thick diamond films. The characteristics of the GaN films are characterized by x-ray diffraction, reflection high energy electron diffraction and atomic force microscopy. The results indicate that the structure and morphology of the films are strongly dependent on the deposition temperature. The most significant improvements in morphological and structural properties of GaN films are obtained under the proper deposition temperature of 400°C.     

Structural Stability and Elastic Properties of Wurtzite TIN under Hydrostatic Pressure

The structural stability and elastic properties of wurtzite thallium nitride （TIN） under hydrostatic pressure are studied for the first time by first-principles calculations. The enthalpy calculations predict that TIN undergoes a phase transition from the wurtzite structure to the rocksalt structure at 19.2 GPa with a volume collapse of 13.0%. Our calculated results also show that this nitride is ductile in nature and exhibits high elastic anisotropy. Our ground-state results are in good agreement with the data of other theoretical calculations.     

基于多分辨分析的沪深股市相关性分析

为了有效地揭示沪深股市不同交易周期股票交易的相关性,本文采用极大重叠离散小波变换,将上证指数和深圳成指高频收益率分解在不同的交易周期上,对各个周期的收益率采用semi-GPD模型作为其边缘分布分别进行拟合,在此基础上采用Copula函数方法建立同周期收益率的联合分布,度量了沪深两市同周期交易的相关性.实证表明,不同交易周期所表现出的相关性存在明显差异,并且随着交易期的增长,沪深两市非对称结构逐步明显。     

外商直接投资对安徽产业结构影响的实证分析

外商直接投资不仅为安徽带来了经济建设所急需的资金、技术和管理经验,创造了就业机会,增加了财政收入,还促进了安徽产业结构的升级。本文通过分布滞后模型分析了外商直接投资对安徽三大产业生产总值的效应,从而说明外商直接投资会对安徽产业结构产生影响。     

方阵A、B与A(○×)B的关系

利用方阵的Jordan分解与翻转矩阵等技巧,给出方阵A、B及其张量积A(○×)B性质间的关系.