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941.
942.
A Monte-Carlo model is described which has been developed for calculation of multiply scattered LIDAR returns. Results are shown for the common problem selected by the MUSCLE (MUltiple SCattering LIDAR Experiments) group for intercomparison, which represents a typical ground-based cloud-sensing scenario. This is contrasted with returns from the same cloud sensed by a space-based LIDAR, where multiple-scattering effects are much greater. The magnitude of multiple-scattering effects is seen to be largely determined by the optical depth across the receiver field of view at the cloud. 相似文献
943.
The behaviour of La-containing strontium zirconate based ceramics is revised. La additions contribute to improve the sinterability
of these materials, but transport properties are also affected. Sr1−xLaxZrO3+δ show some unusual changes in transport properties when samples are exposed to H2-containing atmospheres and then reoxidized. Nevertheless, the transport properties of (Sr,La)(Zr,Y)O3−δ, are still mainly dependent on Y additions, at least for cases when the fraction of Y exceeds the fraction of La. In addition,
lanthanum causes significant changes in lattice parameters. A combination of conductivity measurements in different atmospheres,
ion blocking experiments, and emf measurements has been used to demonstrate that electron hole conductivity increases with
temperature, and the protonic contribution drops. The transport properties at temperatures lower than about 800 °C might be
affected by structural changes.
Paper presented at the 2nd Euroconference on Solid State Ionics, Funchal, Madeira, Portugal, Sept. 10–16, 1995 相似文献
944.
L. J. Yamí n S. E. Blanco J. M. Luco F. H. Ferretti 《Journal of Molecular Structure》1997,390(1-3):209-215
The isomerization mechanism of 2′(OH)chalcone (1) in flavanone (2) was studied. The calculations were performed with the semiempirical method AM1, using totally optimized molecular geometries. A 6-step mechanism including several equilibrium states was proposed. It was concluded that: (a) At the conformational equilibrium of 1 there could be 43.9% of s-cis conformer; (b) The acid dissociation of 1 trans-s-trans is considerable; (c) The EE, ΔHf and net charges show that the rotation of ring A of 1 and the formation of ring C of 2 occurs without greater impairments; (d) Although the keto structure is the most stable one, the enolate of 2 is present in the reaction medium; (e) The conversion of enol of 2 in the keto form would be the limiting step of the analyzed isomerization rate. 相似文献
945.
Diane L. Levesque Eng-Chi Wang Dau-Chang Wei Cherng-Chyi Tzeng Raymond P. Panzica Fardos N. M. Naguib Mahmoud H. El Kouni 《Journal of heterocyclic chemistry》1993,30(5):1399-1404
A new series of potent uridine phosphorylase inhibitors have been prepared from barbituric acid. Among them, 1-[(2-hydroxyethoxy)methyl]-5-)(m--benzyloxy)benzylbarbituric acid ( 37 , BBBA) is the most promising having a Ki value of 1.1 ± 0.2 nM with uridine phosphorylase from human liver. The new inhibitors are easily synthesized and are better inhibitors of human uridine phosphorylase than their uracil counterparts. 相似文献
946.
After carefull analysis in a turbulent zero-pressure gradient flow, various simple algebraic turbulence models were applied to the almost separated flow on the upperside of an airfoil at incidence. The Johnson-King and Horton non-equilibrium (or rate equation) models give clearly improved results. 相似文献
947.
L. B. Sjogren H. -X. L. Liu X. -H. Qin C. W. Domier N. C. Luhmann 《International Journal of Infrared and Millimeter Waves》1993,14(6):1201-1216
Device alternatives for millimeter-wave beam control arrays are examined. For the control function, a wide range of semiconductor device as well as bulk material alternatives are considered. In addition, alternatives to the traditional metal strip are considered for the passive electromagnetic array element. This work should provide a broader perspective regarding the choices available for the optimized design of new beam control arrays. 相似文献
948.
949.
950.
V. L. Bratman G. G. Denisov A. V. Savilov 《International Journal of Infrared and Millimeter Waves》1995,16(3):459-471
A relatively high level of the minimal electron energy at the gyrotron output even at very large spread in pitch factor is explained. An estimation of the recuperation efficiency, which can be obtained due to this effect, is given. 相似文献