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931.
Summary Several mobile phase parameters were investigated for controlling enantioselective retention and resolution on a chiral stationary
phase made in-house. The chiral selector was the enzyme amyloglucosidase, which was immobilized onto a silica support via
reductive amination. The influences of the mobile phase pH, concentration and type of uncharged organic modifier, ionic strength
and column temperature on enantios-electivity were studied. The analysis time for resolving enantiomers could be adjusted
with only a minor decrease in enantioselectivity by using a high ionic strength mobile phase buffer. This indicated a retention
mechanism involving ion-exchange interactions. It was further confirmed by the decreasing enantioselectivity of amines when
using a mobile phase pH below the isoelectric point of the native protein. Interesting effects were observed when the organic
modifier concentration was increased and also when the column temperature was raised. Both retention and enantioselectivity
increased with increasing concentration of 2-propanol in the mobile phase. Examples are given where both enantioselectivity
and retention increased with increasing column temperature. Thermodynamic studies were performed to calculate the entropy
and enthalpy constants. The results showed that, depending on mobile phase composition, the enantioselective retention may
be caused by differences in entropy or enthalpy. 相似文献
932.
光学层析技术在中央处理单元散热中的应用研究 总被引:1,自引:1,他引:0
将光学层析技术实际应用于中央处理单元(CPU)散热产生的温度场的重建中,指出了由多方面干涉投影重建三维场的实际应用意义。成功地解决了稳态场和似稳态场的我步步投影的获取问题。 相似文献
933.
通过把QMC模型参数展到σ场的一阶项来引入模型参数的核介质效应,并利用核子袋在介质中的平衡条件自洽地确定展开系数.计算结果表明袋参数及核子半径受介质影响较大,而零点运动参数则保持不变.在此基础上,分析了介质相关的模型参数对核物质状态方程及夸克凝聚的影响. 相似文献
934.
对于磁约束直流等离子体炬,用氩-氢等离子体的放电体系,研究了等离子体炬几何结构、真空室气压、弧电流、外磁场与比变化等对等离子体炬放电特性的影响。得到了影响等离子体炬宏观和微观参数变化的一些基本规律。 相似文献
935.
P. Knowles J. Deutsch J. Egger W. Fetscher F. Foroughi J. Govaerts M. Hadri K. Kirch S. Kistryn J. Lang X. Morelle O. Naviliat A. Ninane R. Prieels N. Severijns L. Simons J. Sromicki S. Vandormael P. Van Hove 《Hyperfine Interactions》1999,118(1-4):73-76
Unlike the majority of Michel parameters which are consistent with the Standard Model V-A interaction, the experimental value of ξ″(=0.65±0.36) [1] is poorly known. Our experiment will measure the longitudinal polarization,
P
L
, of positrons emitted from the decay of polarized muons. The value of P
L
, equal to unity in the Standard Model, will decrease for high energy positrons emitted antiparallel to the muon spin if the
combination of Michel parameters ξ″/ξξ′ − 1 deviates from the Standard Model value of zero.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
936.
Peter K. Anastasovski T. E. Bearden C. Ciubotariu W. T. Coffey L. B. Crowell G. J. Evans M. W. Evans R. Flower S. Jeffers A. Labounsky D. Leporini B. Lehnert M. Mészáros J. K. Moscicki P. R. Molnár H. Múnera E. Recami D. Roscoe S. Roy 《Foundations of Physics Letters》1999,12(3):251-265
The general theory of gauge fields is used to develop a theory of electrodynamics in which the fundamental structure is non-Abelian and in which the internal gauge field symmetry is O(3), based on the existence of circular polarization and the third Stokes parameter. The theory is used to provide an explanation for the Sagnac effect with platform at rest and in motion. The Sagnac formula is obtained by considering the platform in motion to be a gauge transformation. The topological phases can be described straightforwardly with non Abelian electrodynamics, which produces a novel magnetic field component for all types of radiation, a component which is proportional to the third Stokes parameter. The theory provides a natural explanation for the inverse Faraday effect without phenomenology. 相似文献
937.
938.
939.
Well-defined (101) and (001) surfaces of anatase TiO2 were studied for the first time by secondary-electron imaging and low-energy electron diffraction. Initially, both surfaces show a crystalline structure corresponding to the bulk anatase phase, buried under an atomically thin contamination layer. After mild sputtering with 500 eV Ne+ ions, we have observed a surface phase transition from tetragonal anatase to face-centered cubic titanium monoxide TiO. Subsequent annealing at 900 K restores the (1×1) anatase structure at the (101) surface. On the (001) surface, however, a (1×4) reconstruction appears. The unreconstructed structure can be recovered by exposing the surface to oxygen. These observations demonstrate the stability of the anatase surfaces and illustrate the feasibility of preparing and investigating clean surfaces of this technological important form of TiO2. 相似文献
940.
讨论等电子分子的分子 (电子数Ne=10 :HF ,H2 O ,NH3,CH4 ;Ne=14:N2 ,CO ,HCN ,C2 H2 ;Ne=18:HCl,CH3F ,H2 S ,SiH4 ,C2 H6)被电子散射的总截面与其键长、键角之间的关系 ,得到了利用键长、键角计算电子被分子散射总截面经验公式 ,并与已有的拟和公式、经验公式的计算结果进行了比较 相似文献