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991.
992.
不同气压背景下激光烧蚀Al靶产生等离子体特性分析 总被引:2,自引:0,他引:2
用时间和空间分辨诊断技术研究了脉冲激光烧蚀不同气压环境下金属Al靶过程中产生的等离子体羽的特性。 相似文献
993.
We study the equilibrium statistical mechanics of classical two-dimensional Coulomb systems living on a pseudosphere (an infinite surface of constant negative curvature). The Coulomb potential created by one point charge exists and goes to zero at infinity. The pressure can be expanded as a series in integer powers of the density (the virial expansion). The correlation functions have a thermodynamic limit, and remarkably that limit is the same one for the Coulomb interaction and some other interaction law. However, special care is needed for defining a thermodynamic limit of the free energy density. There are sum rules expressing the property of perfect screening. These generic properties can be checked on the Debye–Hückel approximation, and on two exactly solvable models, the one-component plasma and the two-component plasma, at some special temperature. 相似文献
994.
995.
N. A. Borisevich D. A. Kazberuk S. V. Mel'nichuk S. A. Tikhomirov G. B. Tolstorozhev 《Journal of Applied Spectroscopy》1995,62(3):441-446
Institute of Molecular and Atomic Physics, Academy of Sciences of Belarus, 70 F. Skaryna Ave, Minsk 220072, Belarus. Translated
from Zhurnal Prikladnoi Spektroskopii, Vol. 62, No. 3, pp. 49–55, May–June, 1995. 相似文献
996.
S.B. Segletes 《Shock Waves》1998,8(6):361-366
Some thermodynamic relations are derived along the principal Hugoniot of materials for which the Grüneisen relation is a
function of volume only. Rather than being expressed in terms of traditional thermodynamic variables, such as volume and temperature,
the relations are expressed in terms of the shock-Hugoniot behavior and of a term grouping that is related to the Grüneisen
function. By so doing, a new perspective is gained on the interrelation of thermodynamic quantities along the Hugoniot, which
may be of use in developing analytical equations of state.
Received 3 November 1997 / Accepted 30 April 1998 相似文献
997.
J. Telser H. -I. Lee E. T. Smith H. Huang P. Brereton M. W. W. Adams R. C. Conover M. K. Johnson B. M. Hoffman 《Applied magnetic resonance》1998,14(2-3):305-321
The hyperthermophilic archaeonPyrococcus furiosus contains a four-Fe ferredoxin (Pf- Fd) that differs from most other 4Fe-Fd’s in that its [Fe4S4] cluster is anchored to protein by only three cysteinyl residues.Pf- Fd also is of interest because in its reduced form, [Fe4S4]+, the cluster exhibits bothS = 1/2 andS = 3/2 spin states. Addition of excess cyanide ion converts the cluster exclusively to anS = 1/2 state (g1 = 2.09, g2 = 1.95, g3 = 1.92), however dialysis restores the EPR signal of native reduced protein indicating that the cluster is not irreversibly altered by cyanide. Both the native protein and protein in the presence of excess cyanide ion (Pf- Fd 4Fe-CN) were investigated here using the techniques of electron paramagnetic resonance (EPR) and electron-nuclear double resonance (ENDOR) spectroscopy. In particular,Pf- Fd 4Fe-CN was investigated using13CN? and C15N? ligands.13C and15N ENDOR indicated that a single cyanide ion bound directly, with the cluster showing an unusually small contact interaction (aiso(13C)~ ?3 MHz, aiso(15N) ~ 0). This is in contrast to cyanide bound to monomeric low-spin Fe(III)-containing proteins such as transferrin and myoglobin, for which the13C hyperfine coupling has a large isotropic component (aiso(13C) ≈ ?30 MHz). This small contact interaction is not due to low spin density of Fe, as57Fe ENDOR of the singly and triply labeledPf- Fd 4FeCN isotopologs, [57FeFe3S4]+ and [Fe57Fe3S4]+, show hyperfine coupling characteristic for [Fe4S4]+ clusters, particularly for the Fe to which cyanide binds. Thus, the low spin density on13C is not due to low spin density on the Fe ion to which it binds. Further theoretical work is needed to explain the contrast between the strong electronic effect of cyanide ion binding with the low spin density on the ligand. 相似文献
998.
The problem of sand production (dilatant-plastic reservoir fragmentation) in the process of pumping-out fluid through an uncased borehole is considered. Taking the dilatant change in reservoir porosity into account makes it possible to find a relation between the fluid and solid mass flow rates. There is no steady-state solution if the elasto-plastic boundary does not coincide with the supply contour. In this case a self-similar problem of well start-up with a constant production rate is considered. 相似文献
999.
The resistance to slow crack growth (SCG) was measured in binary blends of high density polyethylene (HDPE) and 5–10% concentrations of model ethylene-butene random copolymers by measuring the time to failure (tf) under a constant stress intensity. An increase of tf with the addition of the copolymer if the copolymer could crystallize and the increase was greater the higher branch density. The copolymer with 117 branches/1000C could not crystallize and therefore its blend had a tf that was less than that of the HDPE. The fracture energies of the blends as determined by their resistance to SCG were compared with the energy by rapid fracture, Jc, as previously measured by Rhee and Crist. It is concluded that SCG is more sensitive to variations in the microstructure than is rapid fracture and that the differences in SCG behavior can be qualitatively explained in terms of the differences in microstructure of the blends. ©1995 John Wiley & Sons, Inc. 相似文献
1000.
B. D. Symeopoulos P. G. Koutsoukos 《Journal of Radioanalytical and Nuclear Chemistry》1993,173(1):23-36
The formation of barium sulfate in aqueous media causes problems of insoluble scale formation. On the other hand, the coprecipitation of uranium and transuranium elements with barium sulfate has been suggested for the determination of these elements in environmental monitoring processes. Therefore, the study of barium sulfate crystal growth is required. The investigations done so far suffer from the low sensitivity of the analytical methods used. In the present work we have overcome this problem by using131Ba for the preparation of supersaturated solutions. Thus kinetics parameters such as induction time and precipitation rates were measured. The polynuclear mechanism was found to be operative at high and the spiral growth at low supersaturations. 相似文献