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91.
The linear compactness theorem is a variant of the compactness theorem holding for linear formulas. We show that the linear fragment of continuous logic is maximal with respect to the linear compactness theorem and the linear elementary chain property. We also characterize linear formulas as those preserved by the ultramean construction. 相似文献
92.
Thermotropic copolyesters containing an isophthalate unit and mesogenic 4, 4′-bis (ω-hydroxyalkyloxy) biphenyls (n = 3, 4, 6) with different numbers of methylene units have been synthesized by melt polymerization. The number-average molar mass (Mn) was estimated from end group analysis by 1H NMR. The copolymer compositions were also obtained from 1H NMR. The thermal behavior of the copolymers containing even-even (n = 4, 6) and odd-even (n = 3, 4) pairings has been investigated and is also compared with that of the analogous homopolymers. The copolymers exhibit reduced melting point and extending liquid crystalline range identified using polarizing microscopy and DSC. All of the obtained compounds were characterized by conventional spectroscopic methods. 相似文献
93.
Rouhalla Bagheri Khirud B. Chakraborty Gerald Scott 《Polymer Degradation and Stability》1983,5(3):197-203
The effectiveness of galvinoxyl (G·(I)) as a thermal antioxidant in polypropylene at 140°C is dependent on the prior processing treatment of the polymer. A characteristic fluctuation of antioxidant activity with time of processing is shown to be associated with the extent of conversion of galvinoxyl to hydrogalvinoxyl (GH) in the polymer. It is concluded that the main stabilisation mechanism involved is deactivation of alkylperoxyl radicals (CB-D) by GH but secondary processes (CB-D and CB-A) involving G· may also make a contribution. 相似文献
94.
A pyrrole-based polymer was synthesized and applied as a new sorbent for solid-phase extraction (SPE) of some environmental pollutants from water samples. Polypyrrole (PPy) was synthesized by chemical oxidation of the monomer in nonaqueous solution. SPE of selected phenols, pesticides, and polyaromatic hydrocarbons (PAHs) from aqueous samples were performed using 200 mg PPy. The determination was subsequently carried out by gas chromatography-flame ionization detection (GC-FID) and gas chromatography-mass spectrometry (GC-MS). The polymer showed much higher recoveries for aromatic compounds than aliphatics. Preconcentration of sample volumes up 11 led to acceptable recoveries for aromatic and other tested polar compounds. The R.S.D. for a river water sample spiked with phenols, pesticides and PAHs at sub-ppb level was lower than 10% (n = 3) and limits of detection for these compounds were between 15 and 120 ng l(-1). 相似文献
95.
Seyed M. Bagheri 《Mathematical Logic Quarterly》2006,52(2):125-133
We prove some preservation theorems concerning inductive and model‐complete theories in the framework of semi‐classical logic introduced in [1]. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
96.
Hamid R.?MemarianEmail author Mohammad?Bagheri Dietrich?D?pp 《Monatshefte für Chemie / Chemical Monthly》2004,135(7):833-838
Summary. In continuation of previous work some novel 3,5-diacetyl-1,4-dihydropyridine derivatives were synthesized and their photochemical behavior was studied under oxygen and argon atmosphere. Oxidation of the dihydropyridine ring and formation of pyridine derivatives was the result of the reaction. The presence of oxygen affects not only on the rate of oxidation, but also the formation of some unidentified by-products was observed on irradiation under this atmosphere. 相似文献
97.
Zahra Abdi Dr. Robabeh Bagheri Dr. Mohammad Reza Mohammadi Prof. Zhenlun Song Dr. Mikaela Görlin Prof. Holger Dau Prof. Dr. Mohammad Mahdi Najafpour 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(4):1330-1336
All studies on oxygen-evolution reaction by Mn oxides in the presence of cerium(IV) ammonium nitrate (CAN) have been so far carried out by synthesizing Mn oxides in the first step. And then, followed by the investigation of the Mn oxides in the presence of oxidants for oxygen-evolution reaction (OER). This paper presents a case study of a new and promising strategy for in situ catalyst synthesis by the adding MnII to either CAN or KMnO4/CAN solution, resulting in the formation of Mn-based catalysts for OER. The catalysts were characterized by scanning electron microscopy, energy-dispersive spectroscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray absorption spectroscopy, and X-ray photoelectron spectroscopy. Both compounds contained nano-sized particles that catalyzed OER in the presence of CAN. The turnover frequencies for both catalysts were 0.02 (mmol /molMn⋅s). 相似文献
98.
99.
Beheshtian Javad Peyghan Ali Ahmadi Bagheri Zargham Kamfiroozi Mohammad 《Structural chemistry》2012,23(5):1567-1572
Structural Chemistry - The interactions between BN nanocluster of B12N12 and small molecules (H2, NO, N2, and CH4) were investigated by using density functional computations, exploiting the... 相似文献
100.