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1.
本文报导的方法是在南京大学高鸿教授研究的K_3Fe(CN)_6示波极谱滴定法(在PH8的K_2HPO_4—KH_2PO_4—KBr底液中,用0.04660mol/LK_3Fe(CN)_6标准溶液对纯抗坏血酸测定)的基础上,考虑到L—抗坏血酸(以下简称V_e)在碱性、中性介质中稳定性差,如用于V_e含量很微的果蔬测定,对结果影响大。本文改为H_2C_2O_4—KBr的酸性介质作底液,用 相似文献
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Interaction of tetrandrine with human serum albumin: a fluorescence quenching study. 总被引:4,自引:0,他引:4
Chun Wang Qiu-Hua Wu Cai-Rui Li Zhi Wang Jing-Jun Ma Xiao-Huan Zang Na-Xin Qin 《Analytical sciences》2007,23(4):429-433
The interaction of tetrandrine with human serum albumin (HSA) was studied by measuring fluorescence quenching spectra, synchronous fluorescence spectra and ultra-violet spectra. The fluorescence quenching spectra of HSA in the presence of tetrandrine showed that tetrandrine quenched the fluorescence of HSA. The quenching constants of tetrandrine on HSA were determined using the Stern-Volmer equation. Static quenching and non-radiation energy transfer were the two main reasons leading to the fluorescence quenching of HSA by tetrandrine. According to the F?rster theory of non-radiation energy transfer, the binding distances (r) and the binding constants (K(A)) were obtained. The thermodynamic parameters obtained in this study revealed that the interaction between tetrandrine and HSA was mainly driven by a hydrophobic force. The conformational changes of HSA were investigated by synchronous spectrum studies. 相似文献
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Shu-Liang Zang Qing-Guo Zhang Ming Huang Bin Wang Jia-Zhen Yang 《Fluid Phase Equilibria》2005,230(1-2):192-196
This paper reports that an ionic liquid (IL) has been prepared by directly mixing InCl3 and 1-methyl-3-ethylimidazolium chloride (EMIC) with molar ratio 1/1 under dry argon atmosphere. The densities, and surface tension of the pure IL were determined at temperature range of 293.15 to 343.15 ± 0.1 K. The volumetric properties and the properties of surface for ionic liquid based on group III were discussed by Glasser's theory and Yang's interstice model. 相似文献
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The development of display technology has continuously increased the requirements for image resolution. However, the imaging systems of many cameras are limited by their physical conditions, and the image resolution is often restrictive. Recently, several models based on deep convolutional neural network (CNN) have gained significant performance for image super-resolution (SR), while extensive memory consumption and computation overhead hinder practical applications. For this purpose, we present a lightweight network that automatically searches dense connection (ASDCN) for image super-resolution (SR), which effectively reduces redundancy in dense connection and focuses on more valuable features. We employ neural architecture search (NAS) to model the searching of dense connections. Qualitative and quantitative experiments on five public datasets show that our derived model achieves superior performance over the state-of-the-art models. 相似文献
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Jinxia Xu Yueyan Zang Fanyong Yan Jingru Sun Yuyang Zhang Chunhui Yi 《Particle & Particle Systems Characterization》2021,38(11):2100201
Carbon dots (CDs) are emerging photoluminescent materials with excellent optical properties. However, the lack of active sites in primitive CDs has limited their development applications. Herein, functionalized carbon dots (Z-CDs) are successfully prepared by surface modification of CDs with mono (6-amino-6-deoxy) cyclodextrin (β-CD). The introduction of β-CD increases the spatial potential resistance between CDs, which effectively reduces the self-quenching effect. Moreover, the conjugated domains of Z-CDs are expanded, which improves the optical properties with a quantum yield of 48.74%. Z-CDs are able to be used in the sequential detection of morin and Al3+, and the fluorescence mechanisms are confirmed to be internal filtration effect and fluorescence resonance energy transfer, respectively. The limits of detection are 0.817 and 0.231 × 10−6 m . This study not only provides an idea to solve the problem of self-quenching of CDs but also enriches the detection means of flavonoids and ions, which is expected to be applied to biosensing and environmental monitoring. 相似文献
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Zusammenfassung Ein neuartiges Rheometer zur Ermittlung der rheologischen Eigenschaften von Polymerlösungen im linear-viskoelastischen Bereich wird vorgestellt. Durch Anwendung der Laser-Doppler-Anemometrie, die eine im hydro-dynamischen Sinn störungsfreie Meßmethode darstellt, ist es möglich, niedrig-viskose bis hin zu wasserähnlichen Proben zu vermessen.Zur Bewältigung der in großer Zahl anfallenden Daten und Rechenoperationen findet ein Mikrocomputer-System Verwendung. Es erledigt im einzelnen die Aufgaben Versuchsablauf-Steuerung, Meßwerterfassung, Auswertung, Dokumentation und graphische Darstellung der Ergebnisse.Anhand von Messungen an newtonschen Flüssigkeiten werden der Funktionsnachweis erbracht und die Betriebsbereiche der Ringspaltsysteme unterschiedlichen Durchmessers ermittelt.Die viskoelastischen Eigenschaften von wäßrigen Polyethylenoxid- und Polyacrylamid-Lösungen niedriger Viskosität lassen sich über einen Frequenzbereich von 0,1 bis 100 Hz messen. Die Ergebnisse werden mit Hilfe der komplexen Viskositätsfunktion dargestellt. Daraus läßt sich als gleichwertige Darstellung das diskrete Relaxationsspektrum eines konkreten Stoffgesetzes gewinnen.
A novel rheometer for determining the elastic characteristics of polymeric solutions in the linear-viscoelastic region is described. Laser-Doppler anemometry, which does not introduce hydrodynamic disturbances, is used to enable low viscosity liquids including water-like samples to be measured.A microcomputer system is utilized to control the experiments, store and analyse the measured data, and provide graphical representations of the results. Measurements on Newtonian liquids verified the validity of the method and allowed the operational regions of the annulus systems with different diameters to be determined.The elastic characteristics of low viscosity aqueous solutions of polyethyleneoxide and polyacrylamide can be measured at frequencies from 0.1 to 100 Hz. The results are presented using the complex viscosity function. As a result the discrete relaxation spectrum of a special material law can be obtained as an equivalent representation.相似文献
10.
Effect of local structure on electron paramagnetic resonance spectra for trigonal [Cr(H2O)6]3+coordination complex in the sulfate alums series: a ligand field theory study 下载免费PDF全文
A simple theoretical method is introduced for studying the interrelation between electronic and molecular structures.By diagonalizing the 120 × 120 complete energy matrices,the relationships between zero-field splitting(ZFS) parameter D and local distortion parameter △θ for Cr 3+ ions doped,separately,in α-and β-alums are investigated.Our results indicate that there exists an approximately linear relationship between D and △θ in a temperature range 4.2-297 K and the signs of D and △θ are opposite to each other.Moreover,in order to understand the contribution of spin-orbit coupling coefficient ζ to ZFS parameter D,the relation between D and ζ is also discussed. 相似文献