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61.
Nohooji Ali Bagheri Toghraie Davood Pourfattah Farzad Akbari Omid Ali Mashayekhi Ramin 《Journal of Thermal Analysis and Calorimetry》2020,140(2):843-858
Journal of Thermal Analysis and Calorimetry - In the present study, the flow field and heat transfer have been simulated numerically inside a channel. The channel is under the constant heat flux.... 相似文献
62.
Ramin Ghahremanzadeh Mojtaba Mirhosseini Moghaddam Ayoob Bazgir Mohammad Mehdic Akhondi 《中国化学》2012,30(2):321-326
A four‐component reaction in the presence of Alum [KAl(SO4)2·12H2O] as an inexpensive and reusable catalyst using the ionic liquid as an effective green reaction media is reported. 相似文献
63.
Morteza Yavari 《International Journal of Theoretical Physics》2009,48(11):3169-3172
In this paper, we show that how to apply the time dependent quasi-Maxwell equations for exact solution of Einstein field equations
in vacuum for Petrov type {3,1} metric. 相似文献
64.
In this study, the effects of thermal annealing temperature on the structural and optical properties of S-doped ZnO nanobelts were investigated. The XRD pattern shows that the crystallinity of S-doped ZnO nanobelts improves with increased annealing temperature. Room temperature photoluminescence spectroscopy of the as-grown S-doped ZnO nanobelts shows no detectable ultraviolet peak with the broad peaks in the visible emission region at 480, 505, and 518 nm. A weak peak in the ultraviolet region at 383 nm appears after annealing at 400 and 600 °C. Raman spectroscopy of the sample also shows a significant change with an increase in the annealing temperature. 相似文献
65.
Measurements are reported of NH exchange rates of urea, thiourea, acetamide and thioacetamide, using line-shape analysis with natural-abundance 15N NMR spectra. Base-catalyzed NH-proton exchange of thiourea is 30–40 times faster than for urea, while the corresponding acid-catalyzed exchange is 150 times slower. The base-catalyzed proton exchange for thioacetamide is about 1000 times faster than that of acetamide at 25°C, while the corresponding acid-catalyzed exchange is some 260 times slower. 相似文献
66.
Frank A. L. Anet N. Roy Easton Issa Yavari 《Magnetic resonance in chemistry : MRC》1979,12(5):299-301
The natural-abundance 13C NMR spectra of cis,cis-1,5-cyclooctadiene monoepoxide and cis,syn,cis-1,5-cyclooctadiene diepoxide have been investigated over the temperature range of – 10 to – 180°C. Whereas the spectra of the former showed no dynamic NMR effect, two different conformations in the ratio of 3:1 were observed at low temperatures for the latter. The free-energy barrier (ΔG≠) for conversion of the major conformation to the minor conformation is calculated to be 5.9°0.2 kcal mol?1 from a line-shape analysis of spectra obtained at intermediate temperatures. It is shown that cis,syn,cis-1,5-cyclooctadiene diepoxide exists in solution in chair (major) and in twist-boat (minor) conformations of slightly different energies. Interconversion paths between these conformations are discussed. The monoepoxide is suggested to have a twist-boat conformation that is rapidly pseudorotating via a boat conformation even at – 180°C. 相似文献
67.
The 13C n.m.r. spectrum of benzofuroxan at ?15°C is assigned on the basis of selective decoupling experiments and by comparison with the 13C chemical shifts of model compounds. The 13C spectra were also measured in trifluoroacetic acid as a solvent. From the temperature dependence of the 13C spectrum of benzofuroxan in CDCl3, a barrier of 14·0 ± 0·2 kcal mol?1 is obtained for the degenerate tautomerism in this compound. 相似文献
68.
Background
We explored spatio-temporal patterns of cortical activity evoked by written words from super-ordinate and sub-ordinate semantic categories and hoped to find a differential cortical and/or temporal distribution of the brain response depending on the level of the categories. Twenty-three subjects saw 360 words belonging to six sub-ordinate categories (mammals, birds, fish, fruit, flowers, trees) within two super-ordinate categories (fauna, flora). Visually evoked magnetic fields were determined from whole-head (148-sensor) magnetoencephalography and analyzed in the source space (Minimum Norm Estimate). 相似文献69.
70.