排序方式: 共有90条查询结果,搜索用时 31 毫秒
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Thermal and dielectric loss properties of Na3PO4-Pb3(PO4BiPO4 (Na2O-PbO-Bi2O3-P2O5) phosphate glasses, have been studied by the differential scanning calorimetry (DSC) and electrical factor loss (tgδ) measurements. Experiments have been carried out from ambient temperature to 500°C and show a strong influence of sodium ions on Tg and tgδ. 相似文献
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A single-chain mean-field theory is used to predict the properties of binary surfactant solutions including the critical micelle concentration (cmc). In particular, the cmc of two symmetric nonionic amphiphiles is calculated as a function of temperature in order to analyze the validity of the ideal mixing assumption, often employed in the mass action model. On comparing against literature Monte Carlo results for the same lattice model we find that although it is applicable at low temperatures and hence cmcs at low amphiphile concentrations, at higher temperatures it becomes necessary to correct for the nonideal mixing of the free chain-free chain bulk interaction. We find that a simplistic model taking into account only the repulsive interaction is sufficient to restore the excellent quantitative agreement found between a single-chain mean-field theory calculations and literature molecular simulation results at the low temperature limit. 相似文献
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Harry Adams Simon Jones Anthony J.H.M. Meijer Zaid Najah Isaac Ojea-Jiménez Andrew T. Reeder 《Tetrahedron: Asymmetry》2011,22(16-17):1620-1625
Excellent regio- and diastereoselectivity were achieved in the microwave assisted Diels–Alder reaction between (S)-9-(1-methoxyethyl) anthracene and 2-cyclopenten-1-one. The addition of Grignard reagents to the ketone cycloadduct gave poor levels of diastereoselectivity, however, the reduction was significantly more stereoselective. Flash vacuum pyrolysis of the reduced material furnished the corresponding allylic alcohol in good yield and ee. 相似文献
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Zafar Ali Khan Khattak Zia‐ur ‐Rehman Azam Khan Afzal Shah Waqar Zaid Amin Badshah Mohammed Fettouhi Atif Fazal 《Heteroatom Chemistry》2014,25(4):238-244
This article presents a new heteroleptic Zn(II) dithiocarbamate ( 1 ) having molecules linked together via H···H and π···π interactions to form a giant hexanuclear macrocycle. These macrocycles are connected together through S···H interactions to offer a unique two‐dimensional cloth‐like interwoven architecture in the solid state. The redox behavior of the complex deposited on the surface of a glassy carbon electrode was investigated in different pH media. The analyte was found to oxidize and reduce in a pH‐dependent irreversible manner. On the basis of the electrochemical findings, redox mechanistic pathways were proposed. 相似文献
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Let \(R\) be any \((n+1)!\) -torsion free ring and \(F,D: R\rightarrow R\) be additive mappings satisfying \(F(x^{n+1})=(\alpha (x))^nF(x)+\sum \nolimits _{i=1}^n (\alpha (x))^{n-i}(\beta (x))^iD(x)\) for all \(x\in R\) , where \(n\) is a fixed integer and \(\alpha \) , \(\beta \) are automorphisms of \(R\) . Then, \(D\) is Jordan left \((\alpha , \beta )\) -derivation and \(F\) is generalized Jordan left \((\alpha , \beta )\) -derivation on \(R\) and if additive mappings \(F\) and \(D\) satisfying \(F(x^{n+1})=F(x)(\alpha (x))^n+\sum \nolimits _{i=1}^n (\beta (x))^iD(x)(\alpha (x))^{n-i}\) for all \(x\in R\) . Then, \(D\) is Jordan \((\alpha , \beta )\) -derivation and \(F\) is generalized Jordan \((\alpha , \beta )\) -derivation on \(R\) . At last some immediate consequences of the above theorems have been given. 相似文献
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Zaid Ahmed Al-Anber 《Colloid Journal》2013,75(2):121-128
A theoretical approach for free Gibbs energy of microemulsion ternary systems water-oil-non-ionic surfactant of arbitrary size and shape is presented. We consider the Gibbs energy for three different geometries (flat, spherical and cylindrical) to estimate the free energy of surfactant-oil-water microemulsion. We also used a lattice-based self-consistent field (SCF) theory to calculate the free energy and the mechanical properties (the mean bending modulus k c , and the spontaneous curvature J 0, and the saddlesplay modulus $\bar k$ ) of such system. The values obtained by our theoretical approach were compared qualitatively with those predicted by SCF theory. The results of theoretical approach were in a good agreement with those of SCF in the region where the values of free energy approach zero for the flat geometry. We demonstrated that the parameters k c, J 0 and $\bar k$ strongly depend on the surfactant concentration. 相似文献
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Abdulbaset A. Zaid Mohammad Mohsin Mazahar Farooqui D.M. Janrao 《Journal of Saudi Chemical Society》2013,17(1):43-45
Proton–ligand dissociation constant of 1-cyclopropyl-1,4-dihydro-4-oxo-7-(1-piperazinyl) quinolone-3-carboxylic acid is ciprofloxacin and metal–ligand stability constants of its complexes with some metal ions have been determined potentiometrically in the presence of (0.01, 0.02 and 0.03 mol/dm3) NaClO4. The order of the stability constants of the formed complexes increases in the sequence Cu2+, Fe3+, Ni2+ and Zn2+ and decreases with increase in the concentration of ionic strength. 相似文献
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Fabrication and characterization of polymer thermo-optic switch based on mmi coupler 总被引:2,自引:0,他引:2
Abdulaziz M. Al-hetar Abu Bakar Mohammad Zaid A. Shamsan 《Optics Communications》2011,284(5):1181-1185
The 2 × 2 polymer thermo-optic switch based on MMI coupler is realized. This device is fabricated using standard fabrication techniques such as coating, photolithography, and dry etching. A crosstalk level of −36.2 dB is achieved at cross and bar states. A power consumption of 1.85 mW is applied to change the state of the switch from the cross to the bar state. A switching time of less than 0.7 ms is traced to change a state of the realized switch. 相似文献