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101.
Separation of 23 dansylated amino acids by micellar electrokinetic chromatography at low temperature
Summary The baseline separation of 23 dansylated amino acids (including 3 didansylated species) is reported. Lowering of the analysis
temperature and fine control of the surfactant concentration were essential in obtaining this result. Calibration graphs with
good linearity were obtained. 相似文献
102.
103.
The problem of subwavelength imaging via a photonic crystal slab lens made of two-dimensional (2D) square arrays of parallel dielectric cylinders in air is studied and discussed theoretically. The finite-difference time-domain method is employed to investigate the unique features of imaging by such lens. We confirm earlier findings that a photonic crystal slab lens can provide the imaging of a point source. By analysing the transmission properties of the proposed structure, we demonstrate that inside the all-angle negative refraction, there are some favourable directions for waves to travel. We show that the surface termination of the photonic crystal is a key parameter to obtain a good quality image. The super-resolution of two sources separated by a distance less than the wavelength is also considered. It is shown that the achievable resolution is limited by the slab length. 相似文献
104.
F. P. Korshunov A. V. Mudryi A. I. Patuk I. A. Shakin 《Journal of Applied Spectroscopy》1997,64(1):129-131
The processes of defect formation in single crystals of gallium arsenide electron-irradiated at cryogenic temperatures (∼20
K) have been investigated by the luminescence method. It is shown that at such temperatures the primary radiation-induced
defects, in particular, intrinsic interstitial atoms, can migrate in a crystal and form complexes with their participation.
Institute of Solid-State and Semiconductor Physics of the Academy of Sciences of Belarus, 17, P. Brovka St., Minsk, 220072,
Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 122–124, January–February, 1997. 相似文献
105.
Electroluminescent porous Si (PS) diodes exhibit various useful functions under a high-electric field. The experimental PS diodes are composed of thin semitransparent metal films, PS layers (about 500 nm thick in minimum), p- or n-type Si substrates and ohmic back contacts. Definite nonlinear electrical behavior (negative resistance and nonvolatile bistable memory effects) and cold electron emission phenomena appear in these PS diodes associated with the EL emission. Both the negative resistance and memory effects are related to the charging of Si nanocrystallites by field-induced carrier injection. The electron emission observed in the PS diodes formed on n+–Si substrates is caused by hot electrons tunnelling through the top contact. By an appropriate structural control of PS, the effective drift length under a high-field conduction is significantly increased, and then electrons are emitted ballistically. These functions reflect the activity of PS as a nanocrystalline confined system. 相似文献
106.
A strongly negative thixotropic behavior of solutions of partially hydrolyzed polyacrylamide in a glycerol-water mixture has been observed at high dilution. Using a Couette viscometer, time changes of viscosity at various shear rates were studied in detail. 相似文献
107.
Lattice models (on a hypercubic lattice of dimension larger than or equal to three) with spins attaining a finite number of values and finite-range interactions at low temperatures are considered. The existence of rigid interfaces as well as of surface tension under appropriate conditions is proven and the properties of corresponding Gibbs states are investigated. 相似文献
108.
A study of the effect of thermodynamic quality and viscosity of the solvent and of temperature on the negative thixotropy of poly(methyl methacrylate) solutions using criteria suggested in the preceding paper showed that the minimal shear stress is a more general criterion of hydrodynamic conditions of the formation of this effect than the minimal velocity gradient. It is assumed that the occurrence of negative thixotropy is due to the activation of macromolecules combined with their critical deformation and orientation caused by the effect of a certain minimal shear stress. A general quantitative relationship between the induction period and conditions of formation of the negative thixotropic structure was derived and experimentally tested. 相似文献
109.
WANG Dian-Fu SONG He-Shan MI Dong 《理论物理通讯》2004,42(9)
In terms of the Nambu-Jona-Lasinio (NJL) mechanism, the dynamical symmetry breaking of a simple localgauge model is investigated. An important relation between the vacuum expectation value of gauge fields and scalarfields is derived by solving the Euler equation for the gauge fields. Based on this relation the SU(3) gauge potential isgiven which can be used to explain the asymptotic freedom and confinement of quarks in a hadron. The confinementbehavior at finite temperatures is also investigated and it is shown that color confinement at zero temperature can bemelted away under high temperatures. 相似文献
110.
A modification of Armijo's step-size rule for negative curvature 总被引:10,自引:0,他引:10
Garth P. McCormick 《Mathematical Programming》1977,13(1):111-115
Armijo's step-size procedure for function minimization is modified to include second derivative information. Accumulation points using this procedure are shown to be stationary points with positive semi-definite Hessian matrices.This research was supported by the United States Army Research Office. 相似文献