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Chen  Lu  Yang  Feng  Song  Yong-li 《应用数学学报(英文版)》2023,39(3):675-695
Acta Mathematicae Applicatae Sinica, English Series - In this paper, we are concerned with a predator-prey model with Holling type II functional response and Allee effect in predator. We first...  相似文献   
995.
A straightforward model for deposition and evaporation on discrete cells of a finite array of any dimension leads to a matrix equation involving a Sylvester–Kac type matrix. The eigenvalues and eigenvectors of the general matrix are determined for an arbitrary number of cells. A variety of models to which this solution may be applied are discussed.  相似文献   
996.
ABSTRACT

The modification of decomposition rate of the potassium persulfate initiator during the synthesis of “two-stage latexes” polystyrene-ethyl acrylate (EtA) of butyl acrylale (BuA) and of 2-ethylhexyl acrylate (EHA) is studied. This rate is minimum for BuA and maximum for EHA, in good agreement with the value of solubility parameters. The appearance of poryacrvlaf.es determines the existence of water bonded to the polar polymer. The amount of water bonded increases in the sequence PEtA?PBuA?PEHA, function of the modification of the diameters of the particles resulted from the latexes obtained.  相似文献   
997.
High surface area silicon carbide-derived carbons (Si-CDCs) synthesized by chlorination of beta silicon carbide (βSiC) with two different particle sizes (6 μm and 50 nm) show different porosities with graphitic structure. Transmission electron microscopy, Raman spectroscopy and argon (Ar) and carbon dioxide (CO2) sorption analyses are used to examine the textural properties of the Si-CDCs. The results show that the particle size of the precursor affects the surface area and porosity of carbons. Furthermore, an additional heat treatment of the Si-CDC with 50-nm particle size for 24 h at 1,000 °C results in a collapse of the pore structure and reduces the surface area. The capacitive behaviours are investigated in H2SO4 and in tetraethyl ammonium tetrafluoroborate (TEABF4)/acetonitrile (AN). The electrochemical performance of the Si-CDCs is influenced by the particle size, surface area, pore volume and pore size distribution. The Si-CDCs exhibit capacitances in 1 M H2SO4 of up to 179 F g?1 and very stable charge–discharge performance over 5,000 cycles. This study shows the crucial importance of ultramicropores less than 1 nm combined with nanosized particles for achieving high capacitance in aqueous electrolyte. Moreover, the graphitic degree at the surface of the Si-CDCs enhances considerably the rate capability and stability in both electrolytes.  相似文献   
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Use of the calcium-ethylenediamine and sodium-liquid ammonia reduction systems for the ring opening of dihydropyran derivatives was studied. (Z)-Alkenyl alcohols and (E)-alkenyl alcohols were stereoselectively synthesized respectively.  相似文献   
1000.
Terpinyl acetate, an important natural flavor, can be synthesized by esterification of α-pinene with acetic acid under acidic conditions. In this work, seven acidic ionic liquids were first synthesized, using octadecylamine ethoxylates (AC 1810, AC 1815, AC 1820, and AC 1830) as the cations, and characterized by FT-IR, 1H NMR, and 13C NMR spectroscopy. The ionic liquids were then used as catalysts in the synthesis of terpinyl acetate. The effect of preparation conditions on catalyst performance was examined. It was found that the acidic ionic liquid 1-(3-sulfonic acid)propyl-3-poly(ethylene glycol) octadecylamine polyoxyethylene ether tetrafluoroborate ([PAC1815]+[BF4]?) was an excellent catalyst for synthesis of terpinyl acetate. The effects of the conditions used for preparation of terpinyl acetate were examined in detail, and the optimum preparation conditions were obtained. Under the optimum conditions, the yield of terpinyl acetate reached 35.70 %. When the catalyst was reused for the 5th time, the yield of terpinyl acetate was still 32.00 %. The results showed that effective separation and recycling of catalyst could contribute to developing a new strategy for synthesis of terpinyl acetate.  相似文献   
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