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991.
992.
Hong Tao Gao Dong Mei Dai Tong Hua Li 《中国化学快报》2007,18(4):495-498
Non-negative matrix factorization(NMF)is a technique for dimensionality reduction by placing non-negativity constraints onthe matrix.Based on the PARAFAC model,NMF was extended for three-dimension data decomposition.The three-dimension non-negative matrix factorization(NMF3)algorithm,which was concise and easy to implement,was given in this paper.The NMF3algorithm implementation was based on elements but not on vectors.It could decompose a data array directly without unfolding,which was not similar to that the traditional algorithms do.It has been applied to the simulated data array decomposition andobtained reasonable results.It showed that NMF3 could be introduced for curve resolution in chemometrics. 相似文献
993.
Two new compounds from Zingiber officinale 总被引:1,自引:0,他引:1
Yu Zhao Qiao Feng Tao Rong Ping Zhang Chang Xin Zhou Hui Dou Shu Yun Shi Ye Cheng Xiao Lian Li Sun Su Zeng Ke Xin Huang Xiao Dong Zhang Xiao Kun Li 《中国化学快报》2007,18(10):1247-1249
A new cyclic diarylheptanoid,1,5-epoxy-3-hydroxy-1-(3-methoxy-4,5-dihydroxyphenyl)-7-(4-hydroxyphenyl)-heptane (1),as well as a new monoterpene,10-O-β-D-glucopyranosyl-hydroxy cineole (2) were isolated from the rhizomes of Zingiber officinale. The structures of compounds 1 and 2 were established based on their spectral data.In addition,the antioxidant activities of these compounds were also measured. 相似文献
994.
分子印迹技术在样品前处理中的应用 总被引:18,自引:2,他引:18
分子印迹聚合物具有选择性高、稳定性好及制备简单的特点,可用于生物、医药、环境样品等复杂基体中痕量分析物的高选择性分离与富集,因此在样品前处理中的应用特别引人关注.本文介绍了分子印迹技术的基本原理,综述了分子印迹技术在样品前处理中应用的研究进展. 相似文献
995.
The gas-phase photocatalytic oxidation of aniline on a new kind of porous nano-TiO2 composite films is investigated. The composite film was prepared on glass fiber with the water glass as binders and dilute
H2SO4 solution as solidifying reagent. The surface characters were observed by scanning electron microscope. The photocatalytic
degradation of aniline on the composite films was carried out in a TiO2/UV system. Some important factors affecting the photodegradation, such as the concentration of TiO2, the initial concentration of aniline, and the existing water vapor, are also studied. The product of photocatalytic oxidation
was detected by Fourier transform-Infrared. The partial intermediate products were absorbed on TiO2 surface, which resulted in catalyst deactivation. But when it was irradiated under UV illumination or solar irradiation for
some time, the catalyst could be reused without loss of catalytic activity.
Translated from the Journal of Wuhan University (Natural Science Edition), 2005, 51(2) (in Chinese) 相似文献
996.
High dispersion and electrocatalytic properties of palladium nanoparticles on single-walled carbon nanotubes 总被引:1,自引:0,他引:1
Palladium (Pd) nanoparticles were electrochemically dispersed on single-walled carbon nanotubes (SWNTs) by electroreduction of octahedral Pd(IV) complex formed on the SWNT surface. The structure and nature of the resulting Pd-SWNT composites were characterized by transmission electron microscopy and X-ray diffraction. The electrocatalytic properties of the Pd/SWNT electrode for hydrazine oxidation have been investigated by cyclic voltammetry; high electrocatalytic activity of the Pd/SWNT electrode can be observed. This may be attributed to the high dispersion of palladium catalysts and the particular properties of SWNT supports. The results imply that the Pd-SWNT composite has good potential applications in fuel cells. 相似文献
997.
Odd/even effect in the chain length on the enthalpy of micellization of gemini surfactants in aqueous solution 总被引:1,自引:0,他引:1
Li Y Li P Wang J Wang Y Yan H Thomas RK 《Langmuir : the ACS journal of surfaces and colloids》2005,21(15):6703-6706
The micellization properties of cationic symmetric gemini surfactants, [CmH(2m+1)(CH3)2N(CH2)6N(CH3)2CmH(2m+1)]Br2 (designated as CmC6CmBr2, with m = 7, 8, 9, 10, 11, 12, and 16), has been investigated by isothermal titration microcalorimetry. The critical micelle concentration (CMC) and enthalpy of micellization (DeltaHmic) were determined from calorimetric titration curves. The linear decreasing of log CMC with increasing the length of the hydrophobic chain is consistent with an increase in the hydrophobicity of the alkyl chain. Interestingly, with increasing the length of the alkyl chain, the DeltaHmic values of the surfactants with even numbered alkyl chains vary from endothermic to exothermic, whereas the DeltaHmic values of the surfactants with odd numbered alkyl chains are all endothermic and tend to become more endothermic. The pronounced even/odd effect in DeltaHmic is discussed with respect to the "donor-acceptor" interaction. 相似文献
998.
Li W Nelson DP Jensen MS Hoerrner RS Javadi GJ Cai D Larsen RD 《Organic letters》2003,5(25):4835-4837
Imidazo[1,2-a]pyrimidine can be arylated at the 3-position with aryl bromides in the presence of base and a catalytic amount of palladium. This provides an efficient one-step synthesis of 3-arylimidazo[1,2-a]pyrimidines from the unsubstituted heterocycle. [reaction: see text] 相似文献
999.
1000.
Strong adhesion and smooth conductive surface via graft polymerization of aniline on a modified glass fiber surface 总被引:1,自引:0,他引:1
The goal of this paper is to prepare surface-conductive glass fibers. The fibers were first hydroxylated, after which they were reacted with 3-bromopropyltrichlorosilane to form a bromopropylsilane monolayer, which was further reacted with aniline to substitute the bromine atoms. The surface-bound aniline molecules were used as active sites for the graft polymerization of polyaniline (PANI). The composition, structure and the morphology of the modified glass fiber surface were examined by X-ray photoelectron spectroscopy, scanning electron microscopy, and Fourier transform infrared spectroscopy. The method generated a smooth and homogenous thin layer of PANI on the surface of the glass fiber with a surface conductivity of about 6 S/cm, hence larger than the usual value ( approximately 1 S/cm) of the bulk polyaniline. 相似文献