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991.
Masoumeh Vafaei-Nezhad Ghiasi Reza Shafiei Fatemeh 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2020,94(4):772-777
Russian Journal of Physical Chemistry A - This research aimed at exploring the stabilities of the conformers of 2-methoxy-2-oxo-1,3,2-dioxaphosphorinane and its methylthio and methylselenyl analogs... 相似文献
992.
Ahmad Shaabani Fatemeh Hajishaabanha Hamid Mofakham Mojtaba Mahyari Bagher Lali 《Helvetica chimica acta》2012,95(2):246-254
A novel and efficient isocyanide‐based multicomponent reaction between alkyl or aryl isocyanides 1 , 2,3‐diaminomaleonitrile ( 2 ), naphthalene‐2,3‐diamines ( 6 ) or benzene‐1,2‐diamine ( 9 ), and 3‐oxopentanedioic acid ( 3 ) or Meldrum's acid ( 4 ) or ketones 7 was developed for the ecologic synthesis, at room temperature under mild conditions, of 1,6‐dihydropyrazine‐2,3‐dicarbonitriles 5a – 5f in H2O without using any catalyst, and of 3,4‐dihydrobenzo[g]quinoxalin‐2‐amine and 3,4‐dihydro‐3,3‐dimethyl‐quinoxalin‐2‐amine derivatives 8a – 8g and 10a – 10e , respectively, in the presence of a catalytic amount of p‐toluenesulfonic acid (TsOH) in EtOH, in good to excellent yields (Scheme 1). 相似文献
993.
Ali Reza Keshtkar Fatemeh Kafshgari Mohammad Ali Mousavian 《Journal of Radioanalytical and Nuclear Chemistry》2012,292(2):501-512
Simultaneous biosorption of uranium(VI) and nickel(II) ions onto Ca-pretreated Cystoseira indica biomass was studied and compared with single uranium or nickel biosorption in a fixed-bed column. Results of single biosorption
showed the breakthrough and exhaustion time increase with the increase of the flow rate and inlet metal concentration for
both metal ions. Also, it was observed that there was an optimum flow rate of 1.4 mL min−1 (surface loading of 0.792 cm min−1) for both metal ions in the column. Results from both single and binary systems showed the adsorption capacity of C. indica for both metal ions increases with the increasing inlet concentration of each component and C. indica had a stronger affinity for uranium than nickel ions. The binary system results showed that the presence of the second component
affected the adsorption of the first one by C. indica so the antagonistic action was observed. Also, the inhibitory effect of uranium ions on the nickel adsorption was greater
than nickel ions on the uranium adsorption. The uranium and nickel breakthrough curves under different conditions were described
by the Thomas, Yoon-Nelson and Yan models. Among these models, the Yan model appeared to describe the experimental results
better. 相似文献
994.
995.
Nourallah Hazeri Malek Taher Maghsoodlou Fatemeh Mir Mehrnoosh Kangani Hamideh Saravani Ebrahim Molashahi 《催化学报》2014,(3)
Tetrahydrobenzo[b]pyran and 3,4-dihydropyrano[c]chromene derivatives were synthesized via a one-pot three-component condensation of aromatic aldehydes with malononitrile and dimedone or 4-hydroxycoumarin in excellent yields in the presence of starch solution as a highly efficient homogenous catalyst.The use of a nontoxic and biodegradable catalyst,simple work-up procedure,and short reaction time are advantages of this method. 相似文献
996.
This paper reports a practical and green method for the acetalization of carbonyl compounds as pentaerythritol diacetals and diketals derivatives using cellulose sulfuric acid as a biodegradable and reusable solid acid catalyst under thermal solvent‐free conditions. 相似文献
997.
A nonhydrostatic finite volume model is presented to simulate free surface flow in a two‐dimensional vertical plane. The algorithm is based on a projection method including the solution of the pressure Poisson equation (PPE). The model is developed in a Cartesian grid in which the size of all the cells in the computational domain, excluding those of the top layer, is constant in time. To simulate the variable water surface, the heights of the top layer cells are variable and proportional to the local water elevation. Taking the layout of the grid system into consideration, a new method is proposed to solve the PPE derived in Cartesian coordinates. In this method, the system of pressure equations is divided into two subsystems, namely a subsystem for the upper layer cells and another for the remaining cells. The coefficient matrix of the former is variable with respect to time, whereas that of the latter remains constant. Therefore, the coefficient matrix of the latter subsystem can be inversed once and saved throughout the simulation. The application of this procedure reduces the computational cost compared with other PPE solvers in certain conditions. The model is applied to simulate a series of numerical tests including strong vertical accelerations and is verified against analytical and experimental results, demonstrating satisfactory performance. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
998.
The catalytic activity of [Pd{C6H4(CH2N(CH2Ph)2)}(μ‐Br)]2 complex as an efficient, stable and catalyst that is non‐sensitive to air and moisture was investigated in the Stille cross‐coupling reaction of various aryl halides with phenyltributyltins under microwave irradiation. The substituted biaryls were produced in excellent yield in short reaction times using a catalytic amount of this complex in DMF at 100 C. The combination of dimeric complex as homogeneous catalyst and microwave irradiation and also DMF as microwave‐active polar solvent gave higher yields in shorter reaction times. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
999.
Fatemeh Mirrahimi Mohammad Ali Taher Hadi Beitollahi Rahman Hosseinzadeh 《应用有机金属化学》2012,26(4):194-198
Two amino acids – d ‐penicillamine (D‐PA) and tryptophan (TRP) – could be simultaneously determined in an aqueous solution (pH 7.0) using a novel benzoylferrocene‐modified carbon nanotube paste electrode. The results indicate that the electrode is efficient in terms of its electrocatalytic activity for the oxidation of D‐PA, leading to an overpotential reduction by more than 155 mV. Using square wave voltammetry, measurement of D‐PA and TRP in one mixture could be done independently from each other with a potential difference of about 205 mV. The proposed electrochemical sensor exhibited a linear calibration plot ranging from 1.0 × 10?6 to 8.0 × 10?4 m with a detection limit of 1.3 × 10?7 m for D‐PA. Finally, the proposed method was applied to the determination of D‐PA in a D‐PA capsule. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
1000.