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61.
62.
Philip C. Bulman Page Genna A. Parkes Harry Heaney J. Steven Wailes 《Tetrahedron letters》2008,49(49):6951-6954
A number of oxazolidines derived from ketones and aminoalcohols have been prepared in excellent yields using microwave irradiation. In most cases, conventional reflux failed to provide any of the desired products. 相似文献
63.
It is shown how the invariance of the Born—Oppenheimer potential energy to overall translations and rotations of a molecule can be used to reduce the computational labor required for derivative evaluations at various orders. 相似文献
64.
65.
Numerical solutions have been obtained for the exact equations describing the propagation of periodic axisymmetric waves in a rigid cylindrical tube. Results were obtained for air over a range of conditions corresponding to shear wave numbers (s = R √?ω/μ) from 0·2 to 5000 and reduced frequencies (k = ωR/a) from 0·01 to 6. For conciseness and convenient application, the results for the attenuation and phase shift coefficients are given in the form of simple polynomials for the ranges 5 ? s ? 5000 and 0·01 ? k ? 6. This range covers virtually all values of tube diameter and sound frequency likely to be met in practical situations that are consistent with a continuum gas model. 相似文献
66.
67.
A.G. Page S.V. Godbole K.H. Madraswala Madhuri J. Kulkarni Vanita S. Mallapurkar B.D. Joshi 《Spectrochimica Acta Part B: Atomic Spectroscopy》1984,39(4):551-557
Feasibility studies have been carried out on the use of a graphite electrode assembly for the introduction of U3O8 solid samples into a continuously running low-powered argon inductively coupled plasma for the assay of trace metallic elements in uranium. The d.c. arc carrier distillation procedure has been adopted here for the selective volatilisation of analyte elements from the refractory matrix by injecting analyte vapours into the central zone of the plasma using Scribner-Mullin electrodes covered with a graphite lid having a central opening. The experimental parameters have been optimised for the direct determination of B, Be, Cd, Co, Cr, Cu, Fe, K, Li, Mn, Na, Ni and Pb in U3O8 powders. The analytical performance of the method has been checked by analysing spiked U3O8 samples and is seen to be comparable to or better than d.c. arc methods for these analytes. These results indicate that the carrier-distillation-ICP combination shows promise as a sensitive and precise method for analysis of trace metallic elements in a refractory matrix with a complex spectrum. 相似文献
68.
G. B. Scott D. E. Lacklison J. L. Page J. Hewett 《Applied Physics A: Materials Science & Processing》1976,9(1):71-77
The absorption (α) and Faraday rotation (θ) spectra of 14 garnets belonging to the series Bi
x
Sm3-x
Fe5-y
Ga
y
O12 (0<x<1.05, 0.8<y<1.15) have been measured between 15 000 cm−1 and 19 000 cm−1. The figure of merit (θ/α) at 17 850 cm−1 (560 nm) increases linearly with increasing bismuth concentration up tox∼0.6 where it begins to increase less rapidly. For operation of magneto-optic display devices at 17 850 cm−1 there is no advantage in using garnets in this series withx>0.8. The Faraday rotation at 17 850 cm−1 increases linearly with bismuth concentration whereas the absorption coefficient increases more rapidly. The presence of
Bi3+ increases the intensity of all Fe3+ pair transitions in the garnet system as a result of the increased superexchange induced by Bi3+. This is in keeping with the observation that the intensity of the6A1g
(S)→4T1g
(G) transition in (RE)3Fe5O12 (RE=Er, Y, Dy, Gd, Eu) increases on traversing the above RE series as do the Curie temperatures of these iron garnets. 相似文献
69.
70.