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621.
Fazlollah Soleymani Fuad W. Khdhr Rostam K. Saeed Javad Golzarpoor 《Mathematical Methods in the Applied Sciences》2020,43(14):8192-8203
For the computation of a matrix sign function, a family of iterative methods is proposed. for some cases of the accelerator parameters, this method is proven to converge globally with higher rates of convergence. Its stability is discussed analytically as well. to illustrate the efficiency of the proposed methods from the family, several tests of various matrix sizes are considered to worked out. 相似文献
622.
623.
Javad Azizian Ali Reza Karimi Zahra Kazemizadeh Ali A. Mohammadi Mohammad R. Mohammadizadeh 《Tetrahedron letters》2005,46(36):6155-6157
11H-Indeno[1,2-b]quinoxalin-11-ones generated in situ from ninhydrin and various 1,2-phenylenediamines, catalysed by montmorillonite K10 under microwave irradiation, condense with 4-hydroxyproline to produce 11-(1H-pyrrol-1-yl)-11H-indeno[1,2-b]quinoxaline derivatives in good yields. 相似文献
624.
Mitra Ghassemzadeh Samira Bahemmat Javad Malakootikhah Bernhard Neumüller Alexander Rothenberger 《无机化学与普通化学杂志》2007,633(8):1178-1182
The reactions of AMTTO = 4‐amino‐6‐methyl‐1,2,4‐triazine‐thione‐5‐one (AMTTO, 1 ) with 2‐hydroxybenzaldehyde (salicylaldehyde) and 4‐hydroxybenzaldehyde in methanol under reflux conditions led to the corresponding Schiff‐bases ( H2L1 and H2L2 ). The reaction of H2L1 with palladium acetate in ethanol and additional recrystallization from toluene gave the tetrameric complex [Pd(L)]4·2C7H8 ( 2 ). All compounds were characterized by infrared spectroscopy, elemental analyses as well as by X‐ray diffraction studies. Crystal data for H2L1 at ?80 °C: space group P21/c with a = 1285.4(1), b = 707.7(1), c = 1348.2(1) pm, β = 109.32(1)°, Z = 4, R1 = 0.0328, H2L2 at ?80 °C: space group P43212 with a = 762.5(1), b = 762.5(1), c = 4038.9(2) pm, Z = 8, R1 = 0.025 and for 2 at ?103 °C: space group C2/c with a = 2862.5(6), b = 2847.6(6), c = 1727.8(4) pm, β = 105.18(3)°, Z = 8, R1 = 0.0704. 相似文献
625.
Javad Zolgharnein Hoomayon Tahmasebi Morteza Habibi Saeid Amani 《Journal of inclusion phenomena and macrocyclic chemistry》2004,49(3-4):231-234
The complexation of some alkali and alkaline earth cations with18-crown-6(18C6), dibenzo-18-crown-6 (DB18C6), dicyclohexyl-18-crown-6 (DCY18C6), and dibenzopyridino-18-crown-6 (DBPY18C6) in a methanol solution has been studied by a competitive potentiometric titration using Ag+/Ag electrode as a probe. The stoichiometry and stability constants of the resulting complexes have been evaluated by the MINIQUAD program. The stoichiometry for all resulting complexes was 1:1. The order of stability of Ag+ complexes with desired crown ethers varied as DBPY18C6 > DCY18C6 > 18C6 > DB18C6.The stability of the resulting complexes for each of these crown ethers varies in the order ofK+ > Na+ and Ba2+ > Sr2+ > Ca2+ > Mg2+.For each of the used metal ions the major sequence of the stability constants of the resulting complexes varies as DCY18C6 > 18C6 > DB18C6 > DBPY18C6 with minor exceptions. 相似文献
626.
Issa Yavari Mehdi Adib Hamid R. Bijanzadeh Majid M. M. Sadegi Hossein Logmani-Khouzani Javad Safari 《Monatshefte für Chemie / Chemical Monthly》2002,133(8):1109-1113
Summary. A dynamic NMR effect is observed in the 13C NMR spectra of anhydrous quinophthalone (quinoline yellow) and its monohydrate in the vicinity of 47°C and 0°C, respectively,
and is attributed to a restricted rotation around the polarized carbon–carbon double bond. The free energy of activation for
this process in anhydrous quinophthalone and the monohydrate is 65±2 and 55±2 kJ · mol−1, respectively, in CDCl3.
Received September 25, 2001. Accepted (revised) November 14, 2001 相似文献
627.
The response characteristics and selectivity coefficients of an unmodified carbon paste electrode (CPEs) towards Ag+, Cu2+ and Hg2+ were evaluated. The electrode was used as an indicator electrode for the simultaneous determination of the three metal ions in their mixtures via potentiometric titration with a standard thiocyanate solution. A three-layered feed-forward artificial neural network (ANN) trained by back-propagation learning algorithm was used to model the complex non-linear relationship between the concentration of silver, copper and mercury in their different mixtures and the potential of solution at different volumes of the added titrant. The network architecture and parameters were optimized to give low prediction errors. The optimized networks were able to precisely predict the concentrations of the three cations in synthetic mixtures. 相似文献
628.
Abbas Ali Rostami Mohammad Javad Chaichi Mostafa Sharifi 《Monatshefte für Chemie / Chemical Monthly》2007,138(10):967-971
Summary. Density (ρ) and viscosity (η) values of the binary mixtures of DMP + 1-pentanol, 1-butanol, and 1-propanol over the entire range of mole fraction at 298.15 and 303.15 K were measured in atmospheric
pressure. The excess molar volume (V
E), viscosity deviations (Δη), and excess Gibbs energy of activation for viscous flow (G*E) were calculated from the experimental measurements. These results were fitted to Redlich–Kister polynomial equation to estimate the binary interaction parameters.
The viscosity data were correlated with equations of McAllister. The calculated functions have been used to explain the intermolecular interaction between the mixing components. 相似文献
629.
As a counterpart to best approximation in normed linear spaces, best coapproximation was introduced by Franchetti and Furi.
In this paper, we shall show that if M is a separable, coproximinal subspace of X satisfying some additional conditions, then L
1 (S, M) is coproximinal in L
1(S, X).
相似文献
630.