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141.
142.
L. Toke P. Tétényi Jr. I. Petneházy 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3-4)
Abstract We found, that dialkyl phosphite 1 and oxo-compound 2 in an equilibrium reaction give an adduct α-hydroxyphosphonate 5 un -der phase-transfer catalytic conditions [K2CO3/TEBA/dichloroethane or aromatic solvents (solid-liquid PTC); 50% NaOH/TEBA/dichloroethane or benzene (liquid-liquid PTC)]. On the other hand 3, is transformed to phosphate 4 or to α-alkoxyphosphonate 5 in the presence of alkylating agent using PTC circumstances. 相似文献
143.
Sonia Degeratu P. Rotaru S. Rizescu N. G. Bîzdoacă 《Journal of Thermal Analysis and Calorimetry》2013,111(2):1255-1262
The study concerns an experimental model using a SMA spring actuator for improving the whole performance of a barrier structure. The study is, specifically, focused on the thermal analysis of the SMA spring material and on determination of the SMA spring working time periods at different values of the activating electric current inducing different phase changing speeds. 相似文献
144.
Thin MoO2 films were electrodeposited on a selenium pre-deposited SnO2|glass plate. The photoelectrochemical properties of MoO2 films were investigated in 0.1 M Na2SO4 solution by the ultraviolet–visible spectrophotometry, linear sweep voltammetry, and altering current impedance measurement techniques. It was found that under illumination with the incident light of λ?=?366 nm, the photo response of the MoO2|SnO2|glass electrode resulted from the MoO2 layer, while the SnO2 layer served as a sink for photogenerated charge carriers. The MoO2 film exhibited n-type conductivity. A schematic band structure diagram of MoO2 in 0.1 M Na2SO4 solution was constructed. The flat band potential (E fb), the donor concentration (N D), the photogeneration current efficiency depended on MoO2 film thickness. The [Fe(CN)6]4?/3? redox PEC cell with MoO2|SnO2|glass plate as a photoanode was constructed. Power output characteristics such as the open circuit voltage (V OC), short circuit current (I SC), the fill factor (FF), and the light-to-electrical conversion efficiency (η) were determined. The maximum light-to-electrical conversion efficiency exhibited by the PEC cell was 0.94 %. 相似文献
145.
The conditions of formation of strong two‐center one‐electron bonds in neutral compounds are discussed. Both molecular orbital and valence bond analyses show that good candidates are adducts of radicals .AR3 (A=C, Si, Ge) of low ionization energy (IE) with boranes BX3 of high electron affinity (EA). This is confirmed by ab initio calculations. The bond energy of adducts of B(CF3)3 with various radicals ranges from 18 kcal mol?1 for .CH3 to approximately 40 kcal mol?1 for Me3Si., and a clear correlation with IE–EA difference is found. This allows one to expect B(CF3)3, among other fluoroboranes, to be an efficient radical scavenger. 相似文献
146.
Marcel Špulák Zdeněk Novák Karel Palát Jiří Kuneš Jana Pourová Milan Pour 《Tetrahedron》2013,69(6):1705-1711
Contrary to a number of reports, alkylations of the privileged 3,4-dihydroquinazoline scaffold provide N3-alkylated products, and not 4-alkoxyquinazolines. To correctly assign the structure, 13C NMR shifts of the –Z–CHn– (Z=O, N) fragment are necessary; resonances in the 45–55 ppm range are indicative of N3-alkylation. Treatment of 3,4-dihydroquinazoline-4-one with p-TsCl afforded the N3-tosylated compound, whose reaction with an amine yielded the corresponding N3-alkyl derivative. A mechanism corroborated by 15N-labeling involving pyrimidine ring opening and recyclisation is proposed. Finally, the unambiguous preparation of 4-alkoxyquinazolines is described via treatment of 3,4-dihydroquinazoline-4-ones with PCl5 followed by an alkoxide. 相似文献
147.
Benoît Driesschaert Philippe Levêque Bernard Gallez Jacqueline Marchand-Brynaert 《Tetrahedron letters》2013
A stable RGD-conjugated triarylmethyl (TAM) radical 3 has been synthesized in a straightforward three-step sequence. CT-03 ‘the Finland trityl’ which is a very popular contrast agent for electron paramagnetic resonance imaging has been covalently bound to the NH2-ending of a pentapeptide commonly used to target integrins and confers tissue selectivity. Moreover, this new TAM radical is stable and sensitive to molecular oxygen. 相似文献
148.
Ahmed A. K. Mohammed Peter A. Limacher Benoît Champagne 《Journal of computational chemistry》2013,34(17):1497-1507
The finite field method, widely used for the calculation of static dipole polarizabilities or the first and second hyperpolarizabilities of molecules and polymers, is thoroughly explored. The application of different field strengths and the impact on the precision of the calculations were investigated. Borders could be defined and characterized, establishing a range of feasible field strengths that guarantee reliable numerical results. The quality of different types of meshes to screen the feasible region is assessed. Extrapolation schemes are presented that reduce the truncation error and allow to increase the precision of finite field calculations by one to three orders of magnitude. © 2013 Wiley Periodicals, Inc. 相似文献
149.
Viorel Cîrcu Doina Mănăilă-Maximean Constantin Roşu Monica Iliş Yann Molard Florea Dumitraşcu 《Liquid crystals》2013,40(2):123-132
A series of ortho-metallated Pd and Pt complexes containing an imine ligand carrying three alkoxy chains and N-benzoylthiourea derivatives as co-ligands were prepared and their liquid crystalline properties investigated. Their structures were assigned based on elemental analysis, IR and 1H NMR spectroscopy, whereas thermal properties were investigated by differential scanning calotimetry and polarising optical microscopy. All the compounds exhibit monotropic transitions involving nematic and smectic A phases, with the mesomorphic behaviour strongly related to the type of N-benzoylthiourea as well as the metal centre used. The thermally stimulated depolarisation current technique was employed to determine the conduction mechanism, phase transition temperature and the activation energies for one of the ortho-metallated Pd complexes. 相似文献
150.
Marie Frederiksen Katrin Vorkamp Rossana Bossi Frank Rigét Maria Dam Bo Svensmark 《International journal of environmental analytical chemistry》2013,93(15):1095-1109
The brominated flame retardants hexabromocyclododecane (HBCD) and tetrabromobisphenol A (TBBPA) are high-production-volume chemicals. In recent years, their presence has been reported in sediment and biota from the marine environment. In this study, an analytical method was developed for the simultaneous determination of HBCD, TBBPA, and the possible metabolite dimethyl-TBBPA. The method was applied in a preliminary screening of egg, liver, and adipose tissue of marine biota from Greenland and the Faroe Islands. α-HBCD was detected in 35 of 36 analysed samples from the Arctic, indicating a ubiquitous presence of α-HBCD in the environment. β- and γ-HBCD were found in 10 and 14 samples, respectively. TBBPA and dimethyl-TBBPA were not detected in any of the samples indicating limited or no transport of these compounds to remote areas. 相似文献