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41.
Maleš Željan Plazibat Miško Vundać Vjera Bilušić Žuntar Irena Pilepić Kroata Hazier 《平面色谱法杂志一现代薄层色谱法》2004,17(4):280-285
JPC – Journal of Planar Chromatography – Modern TLC - The flowering tops of Hypericum hirsutum, H. montanum, H. perforatum subsp. angustifolium, H. perforatum subsp. perforatum, and H.... 相似文献
42.
43.
The object of this paper has been to determine the effect of water of crystallization on magnetic properties of MgSO4. Changes in the magnetic properties of MgSO4 in depenedence on the number of waters of crystallization have been established from the magnetic susceptibility changes. The value obtained by measurement differs from that calculated by the additivity law. This disagreement can be explained by the presence of the thermally independent Van Vleck's polarization paramagnetism
p
.The paper brings forward calculations of p values for the individual hydrates of MgSO4.i H2O fori=0, 1, ..., 7. Besides, it examines what portion of the polarization paramagnetism
pi
of the overall values of
pci is due to the effect of water of crystallization. On the basis of this information the deviation from the spherical symmetry, caused by hydration of the MgSO4 molecule, has been interpreted. 相似文献
44.
V. A. Zakharov N. V. Semikolenova T. B. Mikenas A. A. Barabanov G. D. Bukatov L. G. Echevskaya M. A. Mats’ko 《Kinetics and Catalysis》2006,47(2):303-309
Data on ethylene polymerization on homogeneous and supported catalysts based on 2,6-bis(imino)pyridyl Fe(II) complexes activated by trialkylaluminums are considered (activity, the molecular-weight characteristics of polymers, the number of active sites, and the propagation rate constants). Unlike homogeneous systems, the supported catalysts prepared with the use of various carriers (SiO2, Al2O3, and MgCl2) exhibited high stability and activity at 70–80°C and produced high-molecular-weight polyethylene with a broad molecular-weight distribution (MWD). The molecular weights and MWDs of polymers and the propagation rate constant depended on the nature of the carrier only slightly. The reasons for an unusual effect of an increase in the activity of the supported catalysts in ethylene polymerization in the presence of hydrogen are discussed. 相似文献
45.
A new algorithm model-oriented for variable selection is presented in this study. It is based on the combination of genetic algorithms (GA) for hyperspace exploration, and counterpropagation artificial neural network (CP ANN) for deriving the fitness score. The proposed method performed very well on both well defined synthetic data sets and real academic data sets. 相似文献
46.
K. Przybylski T. Brylewski M. Bućko 《Journal of Thermal Analysis and Calorimetry》1995,45(5):1099-1108
Calcination conditions of the precursor powders, i.e. temperature, type of atmosphere and duration, were determined with a view to obtain superconducting powders with the most advantageous physico-chemical properties. Investigated were powders in the Y?Ba?Cu?O system prepared by the sol-gel method. Thermogravimetric examinations of the powders have revealed that the decomposition kinetics of BaCO3 determines the formation rate of the superconducting YBa2Cu3O7?x (‘123’) phase. It follows from the decomposition kinetics of BaCO3 that the process is the most intensive in argon, whereas in static air and oxygen it is the slowest. The phase composition analysis (XRD) and low-temperature magnetic susceptibility measurements of the calcinated powders, confirm the above mentioned changes in the decomposition kinetics. The reaction of barium carbonate can be completed if the calcination process is conducted at the temperature of 850°C for 25 h, yielding easily sinterable powders for obtaining single-phase superconducting bulk samples with advantageous functional parameters. 相似文献
47.
V. Milata D. Ilavsky M. Chudík Ľ. Zalibera J. Leško M. Seman A. Belicova 《Monatshefte für Chemie / Chemical Monthly》1995,126(12):1349-1358
Summary Catalytic hydrogenation of 2,3-diphenyl-6-nitroquinoxaline led to the corresponding amine1 which in turn afforded products3a-i on reaction with alkoxymethylene derivatives2a-i. Thermal cyclization of3b and3f yielded substituted pyrazinoquinolones5b and5f, respectively. Optimal conditions for the successful hydrolysis of ester5b were found. The structures of all products were deduced from their IR, UV,1H, and13C NMR spectroscopic data.Dedicated to Prof.F. Sauter on the occasion of his 65th birthday 相似文献
48.
Jože Slivnik Mateja Žvanut Borka Sedej 《Monatshefte für Chemie / Chemical Monthly》1968,99(5):1713-1717
Zusammenfassung Die Reaktion zwischen MgCO3 und wässerigen Lösungen von Hydraziniumdifluorid und Flußsäure führt zum Hydraziniumfluoromagnesat. Diese Verbindung ist auch aus Magnesiumchlorid-und Hydraziniumdifluorid-Lösungen herstellbar. Es werden röntgenographische, IR-spektrographische und thermogravimetrische Untersuchungen dieser Verbindung angegeben.
Mit 3 Abbildungen 相似文献
Hydrazinium(+2) fluoromagnesate is formed in the reaction between MgCO3 and hydrazinium difluoride dissolved in hydrogen fluoride. The reaction of magnesium chloride and an aqueous solution of hydrazinium difluoride yields the same product. The results of X-ray diffraction studies, IR spectroscopical studies and thermogravimetrical investigation are given.
Mit 3 Abbildungen 相似文献
49.
G. A. Bandurkin N. N. Chudinova G. V. Lysanova K. K. Palkina E. V. Murashova V. A. Krut’ko G. M. Balagina 《Russian Journal of Inorganic Chemistry》2006,51(2):292-305
Specific features of the textures (the preferred orientation of the nanometer building blocks) in the structures of mixed-anion
compounds—rare-earth borogermanates, germanophosphates, and borotungstates that arise from the acid-base interaction in the
Ln2O3-B2O3-GeO2, Ln2O3-GeO2-P2O5, and Ln2O3-B2O3-WO3 systems (Ln = La-Gd)—have been studied. Based on characteristic texture traits, the mixed-anion compounds of early rare-earth
elements can be divided into three groups: (i) Ln2O3: ExOy > 1, (ii) Ln2O3: ExOy = 1, and (iii) Ln2O3: ExOy < 1. Because of the dominant structural effect of the basic oxide Ln2O3 in the compounds of the first group, the structures of Nd14O8(BO3)6(GeO4)2 and Pr11O10(GeO4)(PO4)3 are composed of infinite [LnOn] bands and layers and discrete groups [EOm] located in the interband and interlayer spaces. The dominant structural effect of the acid oxides [ExOy] in the compounds of the third group leads to the appearance of ring textures composed of [LnOn], as well as to the appearance of chains and networks composed of [EOm], in the structures of Ln(BGeO5) and Ln(BO2)(WO4).
Original Russian Text ¢ G.A. Bandurkin, N.N. Chudinova, G.V. Lysanova, K.K. Palkina, E.V. Murashcva, V.A. Krut’ko, G.M. Balagina,
2006, published in Zhurnal Neorganicheskoi Khimii, 2006, Vol. 51, No. 2, pp. 334–347. 相似文献
50.