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991.
992.
本文介绍了用SE-30毛细管柱、高速率程序升温分离13种有机磷农药。其分离效果较好,分析速度较快,有良好的线性关系和重复性。 相似文献
993.
994.
995.
996.
The use of ammonia as a carrier gas for the chromatography of aliphatic and aromatic amines has been investigated. As compared to nitrogen, ammonia gave drastically improved peak symmetry and lower capacity factors (k′) for primary and secondary amines on polar (Polyethylene glycol) and medium Polar (methylphenylcyanopropylsilicone) stationary Phases. The effect of ammonia was more Pronounced at low column temperatures. Considerably better detection limits of primary and secondary amines were obtained with ammonia as carrier gas than with nitrogen. No detrimental effects of using ammonia were observed on the gas chromatograph or on the columns over a period of about one year. 相似文献
997.
An intramolecular charge transfer (ICT) molecule,p-N,N-dimethyl-aminobenzoic acid (DMABA) has been studied in zeolite and colloidal media. The ratio of ICT to normal emission
(ICT/LE) is greatly enhanced in zeolites compared to that in polar solvents. The ICT emission of DMABA was quenched by increasing
the concentration of TiO2 colloids, while the normal emission was slightly enhanced. Upon illumination of the heteropoly acid (HPA) incorporated TiO2 colloids, interfacial electron transfer takes place from the conduction band of TiO2 to the incorporated HPA which is also excited to catalyze the photoreduction of Methyl Orange. It is found that the interfacial
electron transfer mechanism of HPA/TiO2 is quite analogous to the Z-scheme mechanism for plant photosynthetic systems. In DMABA-adsorbed TiO2/Y-zeolite the ICT/LE ratio of DMABA is quite small implying that electron transfer takes place from DMABA to the conduction
band of TiO2. This results in drastic enhancement in the photocatalytic activity of DMABA-adsorbed TiO2/Y-zeolite compared to free TiO2/Y-zeolite. 相似文献
998.
Donald Greenspan 《Journal of Physics and Chemistry of Solids》1989,50(12):1245-1249
A modern method for predicting the time and place of crack and fracture development is through molecular dynamics, which studies reactions to external forces in the small, that is, the molecular level. In quasimolecular dynamics, which is an attempt to bridge the gap between atomistic and continuum simulations, molecules are aggregated into larger units, called quasimolecules, to simulate the large scale behavior. In this first paper, quasimolecular dynamics is applied to the study of crack and fracture generation in a stressed, slotted plate made of pure copper. Conservation of mass and energy is basic to the methodology. 相似文献
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1000.
In many classification applications and face recognition tasks, there exist unlabelled data available for training along with
labelled samples. The use of unlabelled data can improve the performance of a classifier. In this paper, a semi-supervised
growing neural gas is proposed for learning with such partly labelled datasets in face recognition applications. The classifier
is first trained on the labelled data and then gradually unlabelled data is classified and added to the training data. The
classifier is retrained; and so on. The proposed iterative algorithm conforms to the EM framework and is demonstrated, on
both artificial and real datasets, to significantly boost the classification rate with the use of unlabelled data. The improvement
is particularly great when the labelled dataset is small. Comparison with support vector machine classifiers is also given.
The algorithm is computationally efficient and easy to implement. 相似文献