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1.
在乙腈介质中合成了苯并-12-冠-4(简称B-12-C-4)和单环己基-12-冠-4(简称Cy-12-C-4)的六种希土配合物:RE(NO3)3·B-12-C-4(RE=Pr,Gd,Yb,Lu),RE(NO3)3·Cy-12-C-4(RE=La,Lu).研究了它们的IR及1HNMR性质,并测定了四种单晶的结构.用INDO法计算了Lu(NO3)3·B-12-C-4,Lu(NO3)3·Cy-12-C-4的电子结构.结果表明.B-12-C-4与希土的配合物稳定性按Pr,Gd,Yb,Lu顺序减弱,并且Cy-12-C-4与希土的配位能力大于B-12-C-4.发现冠醚分子通过自身不同程度的扭曲,改变冠醚环空穴的大小,实现与不同大小的希土离子的配位作用.  相似文献   

2.
为了研究K+、Al3+对Zn-Co-O尖晶石催化性能的影响,用Rietveld分析法测定了由共沉淀法制备的Zn-Co-O体系的结构,并考察添加K+、Al3+对该体系结构的影响.结果表明,该体系均由(CoZn)O固溶体ZnCo2O4尖晶石二相以及部分非晶态组成,添加K+、Al3+能使尖晶石相含量增加,对氧参数的影响呈相反趋势,氧参数大小规律与氧的活动性大小相对应.  相似文献   

3.
通过5-氨基水杨酸与二元羧酸进行缩聚反应,合成了六种主链含有5-氨基水杨酸的高分子化合物,用红外光谱和元素分析确定了聚合物的结构。聚合物水解实验表明,它们在酸性、中性和碱性介质中均能水解,水解速率(r)的大小依次为rpH=13.0>rpH=7.0>rpH=2.0。  相似文献   

4.
一对单体,可查到非常多数值不同的竞聚率文献值,说明无论从精度和准确性来说,竞聚率的测定和求算都可能产生很大误差。本文在单体敏感点组成进行实验,用元素分析法测定共聚物组成,用Error-in-VariableMethod(EVM)法计算苯乙烯和丙烯酸-β-羟乙酯竞聚率,分析全过程的误差来源和大小。  相似文献   

5.
通过5-氨基水杨酸与二元羧酸进行缩聚反应,合成了六种主链含有5-氨基水杨酸的高分子化合物,用红外光谱和元素分析确定了聚合物的结构。聚合物水解实验表明,它们在酸性,中性和碱性介质中均能水解,水解速率(r)的大小依次为rpH=13.0>rpH=7.0>rpH=2.0。  相似文献   

6.
一对单体,可查到非常多数值不同的竞聚率文献值,说明无论从精度和准确性来说,竞聚率的测定和求算都可能产生很大误差。本文在单体敏感点组成进行实验,用元素分析法测定共聚物组成,用Error-in-VariableMethod(EVM)[1]法计算苯乙烯(St,M1)和丙烯酸-β-羟乙酯(HEA,M2)竞聚率,分析全过程的误差来源和大小。  相似文献   

7.
钼基分子筛催化剂,由于不同分子筛的孔道大小及孔道形状不同,对甲烷芳构化反应表现出不同的催化性能,具有8元环孔道结构的小孔ERS-7分子筛没有催化活性,说明甲烷的芳构化反应离不开分子筛孔道作用,较小的孔道中不能生成苯等芳烃,具有10元环孔道结构的ZSM-5,ZSM-11和ZRP-1三种分子筛具有较好的催化性能,但由于其孔道大小及孔道形状的差别在催化行为上表现出一定的差异,具有10元环和12元环孔道结构的MCM-22分子筛,尤其对对苯等轻芳烃而言,催化性能最佳,具有12元环孔道结构的JQX-1以及中孔分子筛SBA-15,虽然上有一定的催化性能,但活性较低,研究结果表明,孔道大小,与苯分子动态直径相近或孔道稍大的分子筛是催化甲烷芳构化反应的良好载体,孔道过大或过小都不利于苯和萘等烃的生成。  相似文献   

8.
应用光谱法研究了生物大分子探针型主体分子罗丹明B-β-环糊精衍生物与DNA的相互作用及温度对该探针特性的影响,探讨了相应的主体分子与DNA分子相互作用的方式,嵌插作用能力大小以及温度对主体分子含客体分子时的影响,进一步研究了探针型主-客体分子相互识别作用及作用能力的大小,探讨了主-客体分子相互识别作用的机制。  相似文献   

9.
通过Ti(SO4)2与H2O2反应生成的配合物沉淀来制备超细TiO2-SO4^2-固体酸催化剂,考察了催化剂焙烧过程的热分解性质,确定了催化剂的焙烧温度。用XRD及TEM测定了催化剂的晶形及颗粒大小,并研究了催化剂对α-蒎烯异构反应的产物分布,主要异构产物为莰烯。α-蒎烯转化率为91%,莰烯选择率为67%。  相似文献   

10.
人工神经网络用于预测离子交换分配系数   总被引:4,自引:0,他引:4  
用前向神经和扩展的delta-bar-delta算法对主族特征价阳离子的离子交换分配系数(Kd)进行了预测,对网络结构,学习次数进行了优化并研究了学习集的大小,1nKd的均方根偏差的(RMS)小于7%。  相似文献   

11.
In this paper, we propose a method to accelerate the crystallisation of nematic liquid crystal mixtures based on crystallisation theory. This method is to hold a nematic liquid crystal sample at a temperature suitable for crystal growth after aging it at a temperature suitable for nucleation. After we specified these temperatures of a nematic liquid crystal mixture using differential scanning calorimetry, we demonstrate that the two-temperature aging method is effective for the crystallisation of other nematic liquid crystal mixtures in which the crystal-liquid crystal transition temperature has so far been undetectable.  相似文献   

12.
A novel method to fabricate a two-dimensional (2D) crystal of protein molecules has been developed. The method enables us to control both the position of nucleation and the direction of the crystal growth. The crystal obtained using a protein molecule, ferritin, was found to be composed of a number of densely packed single crystal domains with an unprecedentedly large size of approximately 100 microm(2). This method also reveals characteristic behavior of the spatiotemporal evolution of the crystal; for example, "fusion" of the crystal domains, which is never observed in an ordinary crystal composed of atoms or ions, was demonstrated. Our approach could have potential in fabricating extraordinarily large and highly ordered nanoparticle arrays of organic or inorganic materials.  相似文献   

13.
Latex piezoelectric immunoassay is a method for detection of agglutination of antibody- or antigen-bearing latex by immunoreaction using a piezoelectric quartz crystal; the agglutination decreases the oscillation frequency of the crystal. This is advantageous in that coating the surface of the crystal followed by fixation of antibody or antigen is unnecessary. There is, however, a drawback, and to improve this, we designed a micro-cell in which only one side of the crystal is exposed to the solution. A method for regenerating the crystal was also devised. Measurement was carried out using a calibration curve of the frequency change against rheumatoid factor activity. The improvement made it possible to use one crystal repeatedly and reproducibility was satisfactory. The calibration curve became almost independent of the crystal used.  相似文献   

14.
A method of direct calculation of lattice sums in three-dimensional crystals is reported. The method is based on annihilation of some lowest multipole moments of the unit cell by a redefinition of the unit cell content. As a result, properties of the infinite crystal can be calculated as usual by taking a finite cluster of unit cells, but surrounded by an additional surface layer of a charge density (e.g., a layer of point charges). This charge density distribution produces the electric field approximating that one of the rest of the infinite crystal. The method proposed is easily applicable in the SCFLCAO procedure as well as in any method using a cluster representation for an infinite crystal. The validity of the infinite crystal model for a finite crystal is also discussed.  相似文献   

15.
1 0 0 directed ammonium dihydrogen phosphate single crystal has been grown using the uniaxially solution-crystallization method of Sankaranarayanan–Ramasamy (SR). The size of the grown crystal is 40 mm in diameter and 50 mm in thickness. The grown crystals were characterized by UV–vis spectroscopy, Vickers hardness and dielectric studies. Comparing the 1 0 0 plane of the conventional method grown ADP crystal with 1 0 0 directed SR method grown ADP crystal, optical transparency, dielectric constant and Vickers hardness number are increased and dielectric loss is decreased in SR method grown crystal.  相似文献   

16.
An ab initio method for calculating the energies of excess-electron bands in a molecular crystal is developed. These energies represent the electron affinities of a crystal. The present method employs a tight-binding approximation to describe the molecules in a crystal and a set of local functions to describe the excess electron. One- and many-electron formulations of the method are given, the latter takes into account the effect of polarization of all the molecules in the crystal by the excess electron. A scheme for approximate determination of the electronic-correlation corrections to the one-electron bands is developed and applied to calculation of the excess-electron bands in the HCP helium crystal.  相似文献   

17.
A method for immunoassay of CRP (C-reactive protein) was developed using a piezoelectric quartz crystal. Previous immunoassays using a piezoelectric crystal have required the formation of a thin film on the crystal, to which an antibody is affixed. The occurrence of antigen-antibody reaction increases the weight attached to the crystal surface, which causes a reduction in the oscillation frequency. In our method, the frequency reduction was observed using antibody-bearing latex without any film. One possible mechanism of the frequency change is that the crystal acts as a sensing apparatus for viscosity or density change in the solution due to aggregation of latex particles. The detection limit was almost the same as that for latex photometric immunoassay (LPIA). The present method has been designated as latex piezoelectric immunoassay (LPEIA).  相似文献   

18.
由BaY2F8晶体的结构特点和粉晶X射线衍射(XRD)数据,分析了该晶体的结晶习性。晶体结构中的强键为Y-F2-Y键,该键沿[001]方向伸展成链状,是晶体的优势生长方向。晶体的平衡稳定形态由斜方柱{130},{021}组成,晶体呈沿[001]方向发育的轴状习性。温度梯度法生长所得晶体的切片分析,证实了以上结论。BaY2F8晶体系采用提拉法等强制方法获得。  相似文献   

19.
差示扫描量热法(DSC)定量测试阿德福韦酯晶型的研究   总被引:2,自引:1,他引:1  
红外光谱(FTIR)和x-射线衍射(XRD)测试表明阿德福韦酯药物具有A、E2种晶型.利用差示扫描量热法(DSC)对阿德福韦酯药物的不同晶型进行了定量测试方法的研究,该方法的依据是药物的不同晶型具有不同的熔点和熔融热焓,根据熔融热焓的量可以定量测试药物中某种晶型的含量,为指导生产工艺研究和产品品质的判断提供快速准确及有效的测试方法。  相似文献   

20.
ABSTRACT

In this paper, a three-dimensional modelling of nematic liquid crystal (NLC) under the combined action of applied voltage and microwave signal is presented. The analytical method applied in the modelling is detailed. In previous research, the modelling of liquid crystal usually uses a small signal wave, and neglected its effect on the orientation of liquid crystal. In this paper, we take the microwave signal into consideration in the calculation of liquid crystal orientation, and get the influence of the power of microwave signal on the orientation. The variations of the relative permittivity of liquid crystal E7 with the power of microwave signals at 30 GHz are obtained. This method is applicable for the modelling of NLC under high power signals excitation.  相似文献   

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