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61.
人工神经网络及其在分析化学中的应用 总被引:31,自引:1,他引:31
人工神经网络是一种新兴的计算方法,有着广阔的发展前途,目前在分析化学领域已经有了多方面的应用。本文简要介绍了人工神经网络的原理及其在分析化学中的应用。 相似文献
62.
63.
Zhang YL Qin WW Liu WS Tan MY Tang N 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2002,58(10):2153-2157
An amide-based open-chain crown ether ligand and its complexes with europium and terbium were synthesized. The complexes were characterized by elemental analysis, infrared spectra and conductivity. The europium and terbium ions were found to coordinate to the C=O oxygen atoms and pyridine nitrogen atoms. The fluorescence properties of these complexes in DMF and CH3OH/CHCl3 were studied. Under the excitation of UV light, these complexes exhibit characteristic fluorescence of europium and terbium ions. The solvent factors influencing the fluorescent intensity are discussed. 相似文献
64.
本文讨论了29个不对称色酸双偶氮膦酸型显色剂的分子联接性指数,并将其与结构选择性因子相结合,用于偶氮类剂结构与铈显色反应灵敏度的相关性研究,讨论了显色剂结构对显色反应灵敏度的影响。 相似文献
65.
Endophytes: a rich source of functional metabolites 总被引:48,自引:0,他引:48
66.
用非水滴定法和Hammett系列指示剂测定了COS水解碱改性γ-Al_2O_3催化剂的表面碱强度分布.发现表面碱强度分布不均匀与表面能量分布不均匀相呼应.采用零点酸碱强度(H_(0,max))及碱中心区域分析法,Bronsted催化定律,进一步证实COS水解反应具有明显碱催化特征,较高活性催化剂的H_(0,max)一般为10左右,对COS水解反应起主要作用的碱性中心的碱强度(H_0)为4.8≤H_0≤9.8.对碱金属氧化物改性后的γ-Al_2O_3催化剂,Bronsted规律在每个碱强度分区域内是适用的. 相似文献
67.
Anwar Usman Ibrahim Abdul Razak Hoong‐Kun Fun Suchada Chantrapromma Yan Zhang Jian‐Hua Xu 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(5):o287-o288
In the title compound, C18H13BrClNO3, the heterocyclic ring of the indole is distorted from planarity towards an envelope conformation. The orientations of the indole, oxetane, chloro and bromophenyl substituents are conditioned by the sp3 states of the spiro‐junction and the Cl‐attached C atoms. 相似文献
68.
Xiong JY Narayanan J Liu XY Chong TK Chen SB Chung TS 《The journal of physical chemistry. B》2005,109(12):5638-5643
Kinetics as well as the evolution of the agarose gel topology is discussed, and the agarose gelation mechanism is identified. Aqueous high melting (HM) agarose solution (0.5% w/v) is used as the model system. It is found that the gelation process can be clearly divided into three stages: induction stage, gelation stage, and pseudoequilibrium stage. The induction stage of the gelation mechanism is identified using an advanced rheological expansion system (ARES, Rheometric Scientific). When a quench rate as large as 30 deg C/min is applied, gelation seems to occur through a nucleation and growth mechanism with a well-defined induction time (time required for the formation of the critical nuclei which enable further growth). The relationship between the induction time and the driving force which is determined by the final setting temperature follows the 3D nucleation model. A schematic representation of the three stages of the gelation mechanism is given based on turbidity and rheological measurements. Aggregation of agarose chains is promoted in the polymer-rich phase and this effect is evident from the increasing mass/length ratio of the fiber bundles upon gelation. Continuously increasing pore size during gelation may be attributed to the coagulation of the local polymer-rich phase in order to achieve the global minimum of the free energy of the gelling system. The gel pore size determined using turbidity measurements has been verified by electrophoretic mobility measurements. 相似文献
69.
Shuang‐Jun Lin Chang‐Heng Tan Shan‐Hao Jiang Yi‐Ming Li Da‐Yuan Zhu 《Helvetica chimica acta》2006,89(11):2789-2793
Four new iridoids, buergerinins B–E ( 1 – 4 ), along with three known iridoids, were isolated from the roots of Scrophularia buergeriana. Their structures were identified on the basis of spectroscopic analysis. 相似文献
70.
Junfeng Zhou Xiaochen Dong Tao Chen Qiang Yang Qiaohua Tan Jianjun Wang 《European Polymer Journal》2007,43(5):2088-2095
A series of well-defined two-armed polymers containing a crown ether core, poly(stearyl methacrylate)-crown ether-poly(stearyl methacrylate) (PSMA-crown-PSMA), with different molecular weight were synthesized via atom transfer radical polymerization (ATRP). The resultant polymers were characterized by 1H NMR and GPC. The self-assembly behaviors of this kind of polymer in selective solvents were studied by TEM, and it was found that polymers with different molecular weight can directly self-assemble into hollow spheres, solid spheres and a monolayer film with regular pores by varying molecular weight and water content. The possible molecular packing motels for their self-assembly behaviors were proposed. 相似文献