白杨素-6-磺酸钠及其Zn(Ⅱ)、Ca(Ⅱ)配位化合物与NDA作用的研究

采用紫外、荧光、粘度法研究了白杨素-6-磺酸钠、白杨素-6磺酸双核锌及白杨素-6-磺酸四核钙与小牛胸腺DNA的结合常数分别是KNa=1.52×104L.mol-1、KZn=3.56×104L.mol-1和KCa=1.54×104L.mol-1。实验结果表明,白杨素-6-磺酸双核锌和白杨素-6-磺酸四核钙;白杨素-6-磺酸钠与DNA间的作用方主要为静电结合。     

Study on thermal stability of poled non-linear optical polymers

A logarithmic expression is proposed to describe relaxation of the polar order in side chain polymers,together with a new way of plotting temperature dependent relaxation data.This results in a straight line extending even below the glass transition temperature in the case of poled nonlinear optics (NLO) side chain polymers.A simple procedure to determine the rotational diffusion constant Dr is given and Dr values of several polymer systems have been evaluated and compared with each other.It appears that,starting from the conventional and well known poled polymer system currently applied,a further lowering of Dr by about 3 orders of magnitude is necessary in order to reach an acceptable orientational stability or lifetime of poled polymers for practical applications.Attempts have been made to introduce electron push-pull substituents into high thermostable molecular frameworks and results of preliminary measurements are reported.     

金属四重键化合物M2X4(PMe3)4(M=Cr,Mo,W;X=F,Cl,Br,I)结构和电子光谱的密度泛函理论研究

采用密度泛函理论方法,在TZ2P-STO基组水平下,对金属四重键化合物M2Cl4(PMe3)4(M=Cr,Mo,W)和Mo2X4(PMe3)4(X=F,Cl,Br,I)的几何结构进行优化,分析了电子结构,并运用TDDFT方法对其低占据激发态进行了计算.考虑相对论效应的ZORA方法能够较好地重现M2X4(PMe3)4的几何结构.M2X4(PMe3)4的电子结构分析表明其d电子的组态为σ2π4δ2,前线轨道能级顺序为πlig<πd/σd<δd<δd*.金属原子和卤素配体的改变虽然使轨道能量发生变化,但没有影响轨道的排布顺序.TDDFT方法对M2X4(PMe3)4δd→δd*和πd→δd*跃迁能量的计算较为准确,对πlig→δd*(LMCT)跃迁能量的计算误差较大.金属原子、卤素配体以及相对论效应对激发能的影响可以根据分子轨道能级的变化给予解释.     

Isolation, Mapping, DNA Sequence and RFLPs Studies of Random Single-Copy DNA Segments on Human X Chromosome

Using the total human/mouse DNA as the probe, screening has been carried out three times with in situ plaque hybridization to obtain the single-copy DNA sequence from the human X chromosome genomic library. The effective rate of screening is 1. 45%. DNAs from clones containing single-copy inserts have been analyzed by a panel of hybrid cells with or without human X chromosome. Three segments, designated by DXFD52,73,75, are mapped to the X chromosome. DXFD52 has been precisely localized on Xq12-q13 with in situ chromosomal hybridization. DXFD52 has been partially sequenced. The results indicate that DXFD52 is a new isolated single-copy segment on the X chromosome. Great progress in the RFLPs study with DXFD52 has been achieved in the population of Chongqing, Sichuan Province. The results show that the DXFD52 can be used to detect the RFLP with Hind Ⅲ, Bgl Ⅱ, and Hinf Ⅰ. DXFD52 will be a potential "landmark" for the construction of the complete linkage map of human genome and the analysis of genomic s     

Effect of Low Energy Electron Exposure on Ion Scattering Spectroscopy

The effect of low energy electron (LEE) exposure on ISS, including on the sputter peak and scatter peak as well as on ion neutralization, has been investigated for different samples. Some new results are discussed.     

A New Triterpenoid from "Gualou-xiebai-baijiu-tang" Consisting of Fructus trichosanthis and Bulbus allii mtacrostemi

A new triterpenoid saponin was isolated by bioactivity-guided isolation from "Gualou-xiebai-baijiu-tang" consisting ofFructus trichosanthisi and Bulbus allii macrostemi. Its structure was determined as 3-O-β-D-galactopyranosyl-hederagenin 28-O-β-D-xylopyranosyl (1→6)- β-D-galactopyranosyl ester by means of chemical evidences and spectral analysis.     

Determination of Pesticide Ethion by Linear Sweep Stripping Voltammetry

IntroductionOrganophosphorus pesticides( OPPs) are widelyused in agriculture as insecticides, but they are foundto contaminate agricultural products such as fruits andvegetables to variable extents. Because of their toxicproperties[1,2]and the potential r…     

粉煤灰与复合添加剂的固相反应过程分析

煤灰分中主要矿物质之间的反应对灰分特性有着重要影响。本文在具有温控的小型高温反应器中对粉煤灰和复合添加剂所组成的混合灰样进行了静态煅烧试验，并对煅烧后的灰样进行了X射线衍射分析（XRD），着重讨论了温度和时间以及复合添加剂量对灰分矿相组成特性的影响。试验结果表明：当温度低于1200℃时，灰色中主要是游离态的氧化物和部分新生成的矿物如钙黄长石，硅酸二钙；当温度在1200℃-1300℃时，灰分中的主要矿物是钙黄长石，当温度在1320℃－1350℃时，灰分主要矿物是硅酸二钙，同时存在一定量的硅酸三钙、铝酸三钙、铁铝酸四钙以及硫铝酸钙。随着灰分中氧化钙的含量增加，高碱性矿物含量逐渐增大，同时高温下加热持续时间过长，部分新生成的矿物将发生分解。     

固相萃取高效液相色谱-质谱法测定动物组织中硝基呋喃代谢产物

研究了对动物组织中4种硝基呋喃类代谢产物AOZ、AMOZ、SEM和AHD的自动固相萃取HPLC-MS分析方法，分别以2-氯苯甲醛和2-硝基苯甲醛作为衍生化试剂，分别用AMOZ-d5、AOZ-d4作内标，用ENSPE柱进行提取，以乙腈-0．1％甲酸为流动相，采用梯度洗脱，可在15min内将4种代谢产物完全分离并进行测定。回收率为85％-90％；检出限可达0．5μg／kg。采用两种衍生化方法可获得较多的定性确证信息。采用本方法研究了硝基呋喃在鸡饲养过程中的残留规律。     

Error of DIAL-measured Ozone Concentration and a Three-Wavelength Inversion Technique

Sensitivity of the error in the stratospheric ozone concentration measured by DIAL to the scattering property of the stratospheric aerosol is studied through both theoretical analysis and numerical experiment in this paper, and based on the sensitivity, a three-wavelength lidar inversion technique is proposed for a simultaneous determination of ozone concentration profile, aerosol backscatter coefficient profile and its size distribution in the stratosphere. It is found from the sensitivity study that there is a considerable effect of the stratospheric aerosol on accuracy of the ozone concentration solution. If the aerosol scattering is neglected, a large error of the solution can be obtained, especially when there is the stratospheric volcanic cloud, the error can be up to 100%. According to numerical experiments, a great improvement of the ozone concentration solution is obtained by using the present three-wavelenght inversion method.