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991.
992.
D. W. Taylor V. Villas-Boas Q. Lu M. F. Rossignol F. P. Missell D. Givord S. Hirosawa 《Journal of magnetism and magnetic materials》1994,130(1-3):225-236
We studied the coercivity in magnets of composition R17Fe83−χBχ (R = Nd, Pr and χ = 8, 30), using measurements of the coercive field Hc, its angular dependence, and the magnetic viscosity coefficient Sv, for temperatures between 4.2 and 500 K. The results are discussed in relation to a model which does not specifically consider the detailed mechanisms involved in magnetization reversal, but which provides information about the magnetic properties in the activation volume v where magnetization reversal is initiated. It is concluded that the ordering temperature in v tends to be slightly smaller than in the bulk and that the room temperature anisotropy in v is not strongly reduced with respect to the bulk value. Finally, a direct evaluation of the dipolar interactions is in good agreement with results obtained from Hc(T). 相似文献
993.
The deep-inelastic deuteron structure function (SF) F2D in the covariant approach in the light-cone variables is considered. The neutron SF F2n is extracted from the deuteron and proton experimental data taking into account the relativistic deuteron model and the parametrization of F2n is obtained. The effect of the relativistic Fermi motion is estimated to be 6% at x0.7. The extracted neutron SF is used to verify the Gottfried sum rule. It is shown that the violation of the flavour symmetry of the sea can be large with increasing Q2. 相似文献
994.
G. Carelli A. Di Siena N. Ioli A. Moretti G. Moruzzi F. Strumia 《International Journal of Infrared and Millimeter Waves》1994,15(4):619-633
We have measured the frequencies of four CH3OH far-infrared laser lines that were previously known only by wavelength measurement. Two of these lines turned out to be doublets, bringing the total number of measured lines to six. We can now confirm the assignments of five of them and definitely disprove the assignments proposed for the sixth.In particular we confirm the assignments for the four strong laser lines at 205 and 208 µm pumped by the 9-P(34) CO2 laser line. These lines share a common upper level in the first excited CO-stretch state, and terminate in the upper and lower levels of a hybrid state with J=5. Heterodyne frequency measurements and conventional microwave spectroscopy show that both lines are split into two components approximately 3.5 MHz apart. The origin of this further splitting is interpreted as a perturbed K-splitting.Work supported by Consiglio Nazionale delle Ricerche -Italia 相似文献
995.
996.
Dimitrios Tsikas Frank-Mathias Gutzki Jürgen C. Frölich 《Fresenius' Journal of Analytical Chemistry》1992,342(1-2):95-97
Summary A reversed-phase HPLC method for the determination of nitrite and nitrate in aqueous solutions, biological buffers and human urine is described. The method is based on the conversion of nitrite and nitrate into their 1-nitro-2,4,6-trimethoxybenzene (NTBM) derivatives by using 1,3,5-trimethoxybenzene and concentrated sulphuric acid. NTMB is extracted by benzene, the solvent evaporated, the residue reconstructed in methanol/water (3/4, v/v) and subsequently analyzed by reversed-phase HPLC and UV detection (360 nm). The specificity of the nitration reaction, good reproducibility (C.V. 6.2%) and high sensitivity (8.4 ng nitrite) show the applicability of this method to the quantitative analysis of nitrite and nitrate in several matrices including human urine. 相似文献
997.
998.
999.
本文观察到了KNbO_3:Fe晶体的时间微分效应,并用这个微分效应进行了图像追踪的演示,为KNbO_3:Fe晶体在光折变器件领域的应用进行了有益的探索。 相似文献
1000.