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991.
VPI-5是具有十八元环超大孔道的磷酸铝分子筛,在加热过程中,随着孔道中的水分子的脱除,其骨架结构转化成具有十四元环孔道的AlPO_4-8分子筛。采用XRD及骨架结构模型计算等方法研究了这一相变过程,并对相变机理进行了探讨。 相似文献
992.
Stefan TsakovskiKarima Benkhedda Elisaveta IvanovaFreddy C Adams 《Analytica chimica acta》2002,453(1):143-154
8-Hydroxyquinoline (HQ), 2-methyl-8-hydroxyquinoline (CH3-HQ), 5,7-dichloro-2-methyl-8-hydroxyquinoline (Cl2-CH3-HQ), 5,7-dibromo-8-hydroxyquinoline (Br2-HQ), 5-sulfo-7-iodo-8-hydroxyquinoline (ferron) and 5-sulfo-8-hydroxyquinoline (SO3H-HQ) were compared as chelating reagents for on-line sorption preconcentration of cobalt in a knotted reactor (KR) precoated with the reagent. The results obtained with the different HQ derivatives reveal those properties of the chelating reagent responsible for the processes taking place in the KR. The influence of hydrophobicity, acidity, stability of the cobalt chelate and type of substituents in the HQ ring system on the separate steps of the flow injection (FI) preconcentration procedure are discussed. According to the performance characteristics of the different HQ derivatives, the most important parameters for on-line preconcentration in a KR are the hydrophobicity of the reagent and the stability of the chelate complex with the analyte. 相似文献
993.
Sadafumi NishiharaTomoyuki Akutagawa Tatsuo Hasegawa Shigeki FujiyamaToshikazu Nakamura Takayoshi Nakamura 《Journal of solid state chemistry》2002,168(2):661-667
Two polymorphs of monovalent [Ni(dmit)2]− (dmit2−=2-thioxo-1,3-dithiole-4,5-dithiolate) crystals A and B, (anilinium)(18-crown-6)[Ni(dmit)2], were prepared, and the structure and magnetic properties were investigated. In these crystals, the [Ni(dmit)2]− molecules form dimers, which arranged into chains between the supramolecular cation structure (anilinium)(18-crown-6). In crystal A, supramolecular cation formed a regular stack, inducing ladder structure of [Ni(dmit)2], whose magnetism had been well fitted by spin ladder equation with the spin gap of Δ=190 K. Crystal B is ca. 3% more densely packed compared to crystal A. Due to the dense packing, supramolecular cation stack is distorted, which prevented the intermolecular interaction between [Ni(dmit)2]− dimers in direction corresponds to the ladder-leg direction in crystal A. Reflecting the [Ni(dmit)2]− arrangement, crystal B showed a temperature dependence of magnetic susceptibility well reproduced by the singlet-triplet thermal activation model, whose antiferromagnetic exchange interaction (2J) was 140 K. 相似文献
994.
Introduction As an important type of fungicides, triazole compounds are highly efficient, low poisonous and inward absorbent.1-3 At present, the studies on triazole derivatives are mainly concentrated on compounds with triazole as the only active group. The report of triazole compounds that contain both triazole group and other active group in a single molecule has rarely been found. Dialkyl-substituted dithiocarbamate salts have also shown interesting biological effects.4 N,N-Dialkyldithio-… 相似文献
995.
996.
O. V. Gusev L. N. Morozova T. A. Peganova P. V. Petrovskii N. A. Ustynyuk 《Russian Chemical Bulletin》1994,43(3):474-477
A mixture ofendo-H andexo-H isomers (1a and1b) of the (4-C5Me5H)PtCl2 complex was prepared by the reaction of K2PtCl4 with C5Me5H in MeOH. The mixture of isomers reacts with CpTl in the presence of TiBF4 to give a novel complex, [(4-C5Me5H)Pt(5-C5H5)]+BF4
–, as a mixture ofendo-H- andexo-H-isomers (2a and2b). The data of1H and13C NMR spectroscopy of the resulting complexes are discussed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 514–517, March, 1994. 相似文献
997.
D. B. Tagiev P. S. Mamedova F. A. Abdullaeva M. K. Munshieva A. A. Turabova T. G. Takhirov 《Russian Chemical Bulletin》1992,41(11):2113-2115
The catalytic activity of Ni(II) bis-(5-thiopyrazol-4-aldiminates) was found to be related to the stereochemical flexibility of these compounds in the dimerization of propylene. The propylene conversion decreases with decreasing stereochemical flexibility of the complexes resulting from an increase in the bulk of the substituent at the coordinated nitrogen atom of the NiN2S2 chelate ring.Institute of Inorganic and Physical Chemistry, Academy of Sciences of Azerbaidjan, 370143 Baku. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 11, pp. 2667–2670, November, 1992. 相似文献
998.
The kinetics of the nucleation and growth of PbO2 during the potentiostatic oxidation of PbSO4 in a lead anodic film was studied using linear sweep voltammetry, potential-step and ac impedance tracing methods. The film investigated is the partially reduced anodic PbO2 film formed by polarizing a lead electrode in 4.5 M H2SO4 solution first at 1.3 V vs. Hg|HgSO4 for 20 min and then at 0.9 V for 5 min. The nucleation and growth process begins some time after the potential step and is completed within 60 s. The pre- and post-nucleation and growth processes correspond to the growth of the anodic film formed by the oxidation of the lead substrate. The mathematical equations representing the current-time and capacitance-time transients are derived taking the background oxidation current into account. The experimental results are well fitted by these equations. The process obeys the laws of two-dimensional instantaneous nucleation and growth. 相似文献
999.
A. A. Bogolyubov N. B. Chernysheva V. V. Nesterov M. Yu. Antipin V. V. Semenov 《Chemistry of Heterocyclic Compounds》2004,40(10):1305-1309
The dehydration of two 5,5-disubstituted 4-hydroxy-4-methyl-3-phenylaminooxazolidin-2-ones into the corresponding 4-methylene-3-phenylaminooxazolidin-2-ones has been carried out. The structure of the products was confirmed by X-ray diffraction analysis.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1512–1517, October, 2004. 相似文献
1000.
Substituted 5-aryl-3-ethylidene-3H-pyrrol-2-ones were synthesized by the reaction of the corresponding 4-aryl-4-oxobutanoic acids with ketones in the presence
of aminating agents. The conditions of this reaction were developed with the use of both the conventional condensation technique
and microwave activation. The structures of the reaction products were con-firmed by elemental analysis, IR spectroscopy,
and 1H NMR spectroscopy.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 693–696, April, 2006. 相似文献