DIELECTRIC STUDIES OF UREASE AS A FUNCTION OF HYDRATION     

陆祖宏  Ronald Pethig  韦钰 《东南大学学报》1989,(2)

The steady-state electrical conductivity,as well as the dielectric propertiesbetween 2×10~(-4)Hz and 100 kHz,and at 1 GHz,are reported for urease compressed powdersamples of low hydration.The results show that the large,low frequency dielectricdispersion,known as α-dispersion,is due to the build-up of a space charge of protons atthe sample-electrode interfaces.A smaller dispersion,appearing at higher frequencies,isconcluded to be associated with hindered motions of the peptide residues in the molecularstructure of urease.The extent of these polypeptide backbone motions is shown to bestrongly depended on the extent of enzyme hydration.This work is contributed to the de-velopment of conductimetric biosensors.  相似文献   

外加因子的生物效应及其在生物技术中的应用     

李晓静  施秀芳  冯霞  阳葵 《安阳师范学院学报》2001,(2):10-12

本文讨论了生长调节剂、分散剂和超声波的生物效应以及它们在生物技术中的应用现状和前景．  相似文献   

Flat-top and low-dispersion optical interleavers based on nested prism pair structure     

张娟 《上海大学学报(英文版)》2011,15(1):31-34

A novel flat-top and low-dispersion optical interleaver using ring cavities (RCs) in a Mach-Zehnder interferometer (MZI) is proposed. It is composed of eight mirrors and two nested prism pairs. Each prism and the two mirrors behave as a RC. Phase shift of RC is a periodic function of the frequency of the input light which acts as a phase dispersive mirror. The two phase shifts needed to achieve a flat-top spectral passband are provided by Fresnel reffectivities at the prism-air interface of the two RCs. The...  相似文献   

POLYMERIZATION OF METHYL METHACRYLATE WITH ETHYLENE BRIDGED HETERODINUCLEAR METALLOCENE OF SAMARIUM AND TITANIUM-STUDY ON SYNERGISM AND KINETICS     

孙俊全  潘智达  胡蔚秋  杨士林 《Journal of Zhejiang University. Science. B》2001,(4)

ＩＮＴＲＯＤＵＣＴＩＯＮＨｅｔｅｒｏｄｉｎｕｃｌｅａｒｃｏｍｐｌｅｘｅｓａｒｅｏｆｇｒｅａｔｉｍ ｐｏｒｔａｎｃｅｆｏｒｔｈｅｓｔｕｄｙｏｆｔｈｅｓｙｎｅｒｇｉｓｔｉｃｅｆｆｅｃｔｓｆｏｕｎｄｉｎｂｉｍｅｔａｌｌｉｃｃａｔａｌｙｓｉｓ (Ａｄａｍｓ,1 988;Ｒｅｄｄｙｅｔａｌ.,1 989;Ｚｈｅｎｇｅｔａｌ.,1 989;Ｗｅｒｎｅｒｅｔａｌ.,1 992 ) ,ｗｈｉｃｈｉｎｄｉｃａｔｅｄｄｉｓｔｉｎｃ ｔｉｖｅｅｌｅｃｔｒｏｎｉｃ ,ｅｌｅｃｔｒｏｃｈｅｍｉｃａｌａｎｄｍａｇｎｅｔｉｃｐｒｏｐｅｒｔｉｅｓａｒｉｓｉｎｇｆｒｏ…  相似文献   

Oseen流动中粘性对自由表面波的影响     

卢东强 《上海大学学报(英文版)》2004,8(1):8-12

Based on the complex dispersion relation for the two-dimensional free-surface waves generated by a moving body in the steady Oseen flows, the effect of viscosity on wavelength and wave amplitude was investigated by means of an asymptotic method and a numerical analysis. A comparison between the asymptotic and numerical analysis for the viscous decay factor demonstrates the validity of the perturbation expansions for the wave profile. The numerical result shows that the wavelength of viscous wave is slightly elongated in comparison with that of inviscid wave.  相似文献   

频散效应对铁磁共振曲线的影响     

王合英  孙文博  张慧云  茅卫红 《实验技术与管理》2007,24(11):28-30,42

在铁磁共振实验中，通过铁磁共振曲线测量共振线宽十分重要，因为它表示铁磁材料磁损耗的大小。频散效应对铁磁共振曲线有明显的影响，该文从理论上分析了频散效应的物理本质以及它对铁磁共振曲线的影响，阐述了测量共振线宽的具体实验方法。  相似文献   

催化剂研究中的分散阈值参数     

邓存 《江西教育学院学报》1997,18(3):25-28

分散阈值的大小与活性组分和载体相互作用有关，是催化剂研究中的一个重要实验参数，分散阈值的测定不仅为单层分散原理广泛的应用奠定了实验基础，亦为催化剂的研制提供一种定量研究手段  相似文献   

烯烃配位聚合复合载体催化剂研究进展     

王立  封麟先 《科技通报》1992,8(2):78-82

自从Ziegler-Natta催化剂发现以来,人们已对该类催化剂作了许多的研究,以MgCl_2为载体的高效催化剂的巨大成功,引起了人们对载体和过渡金属元素的相互作用的浓厚兴趣,近年来许多文献和专利报道了对复合载体催化剂的大量的研究成果,似有可能出现具有更优特性的高效催化剂. 本文就复合载体催化剂的研究现状作一综述.  相似文献   

热解法合成P（AM-co-MAA）/SnO_2有机-无机复合微球的研究     

杨菊香  龙旭  杨晓慧 《西安文理学院学报》2011,(4):33-37

采用反相悬浮聚合法合成了聚丙烯酰胺-甲基丙烯酸（P（AM-co-MAA））微凝胶,并以其作为模板,通过热解法制备了一系列微米级、表面具有特异结构的P（AM-co-MAA）/SnO2有机-无机复合微球材料.详细考察了反应时间、SnCl4的浓度和热解温度等因素对复合微球的形貌结构的影响.通过SEM,XRD,FT-IR,TG等手段来表征复合微球的结构、形貌、含量.微球上沉积的SnO2层随着SnCl4的浓度增大而加厚.采用模板法制备复合材料具有操作过程简单、反应条件温和等特点,因此,可将此方法可进一步拓展到其他有机-无机复合材料的制备中.  相似文献   

Characterization of chaotic multiscale features on the time series of melt index in industrial propylene polymerization system     

Ting Wang  Xinggao Liu  Zeyin Zhang 《Journal of The Franklin Institute》2014

The chaos characteristics of melt index have been first explored, and the Hilbert–Huang transform method and time delay embedding method are applied to multiscale dynamic analysis on the time series of the melt index (MI) in the propylene polymerization industry. The research results show that the embedding delay is 2, the embedding dimension is 5, the correlation dimension D₂ is 1.57, and the maximum Lyapunov exponent is 0.143 for the melt index series, which provide clear evidence of chaotic multiscale features in the propylene polymerization process. Three intrinsic mode functions (IMFs) are decomposed from the melt index time series; the presence of non-integer fractal correlation dimension and positive finite maximum Lyapunov exponent are found in some IMF components. The PP melt index series are divided into two chaotic signals, a determined signal and a random signal respectively, and its complexity is therefore reduced. Furthermore, the coupling of subscale structures of the propylene polymerization is explored with the dimension of interaction dynamics and a robust algorithm for detecting interdependence. It is found that IMF(2) is the main driver in the coupling system of IMF(1)and IMF(2). All these provide a guideline for studying propylene polymerization process with chaotic multiscale theory and may offer more candidate tools to model and control propylene polymerization system in the future.  相似文献