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71.
用高密度等离子体模型可以计算出一整套输运参数,并且在很宽的等离子体温度和密度范围内有合理的精度,可广泛应用于Z箍缩等离子体、激光聚变和磁约束聚变等领域,并将这个模型计算出的各种输运参数拟合成了实用的公式。 相似文献
72.
Proton induced X-ray emission has been used to measureL-subshell and total ionization cross-sections of Au, Pb and Bi in the energy range of 200–350 keV. The ionization cross-sections have been extracted using the X-ray spectra and other quantities like fluorescence yields, transition probabilities, relative widths and Coster-Krönig fraction etc. involved in the process. The results have been compared with the cross-sections measured before and discussed in the light of known theories regarding the ion-atom collisions. 相似文献
73.
Guido Momerency Karel Van Cauwenberghe Ernst A. De Bruijn Allan T. Van Oosterom Martin S. Highley Peter G. Harper 《Journal of separation science》1994,17(9):655-661
A method is described for the determination of the antitumor agent iphosphamide and seven of its metabolites in the plasma of cancer patients by multiple ion monitoring (MIM) GC-MS, mainly using the electron capture chemical ionization mode, of stable methyl and/or trifluoroacetyl derivatives. The metabolites determined were 2- and 3-dechloroethyliphosphamide, 4-ketoiphosphamide, carboxyiphosphamide, iphosphamide mustard, and two previously undetected metabolites, chloroethylamine and 1,3-oxazolidine-2-one. The isolation of the acidic and neutral metabolites was performed by solid phase extraction on to C18 adsorbent at pH 4. The weakly acidic iphosphamide mustard, isolated under these conditions with a yield of ca 50%, was measured as a stable methyltrifluoroacetyl derivative, in contrast to the corresponding phosphoramide mustard of the isomer cyclophosphamide which decomposes during derivatization. Chloroethylamine and 1,3-oxazolidine-2-one were isolated with high yield by liquid extraction with ethyl acetate at pH 10. Selective measurement of several metabolite derivatives with similar retention times was performed by multiple ion monitoring MS of specific ion masses, using a methyl phenyl siloxane capillary column previously employed in the study of cyclophosphamide metabolites. Quantitation of metabolites in patient plasma samples could be performed in the concentration range 3 ng to 20 μg per ml of original plasma. 相似文献
74.
Yang Lingxia Ge Debiao Wei Bing 《International Journal of Infrared and Millimeter Waves》2003,24(11):1893-1897
A modified formulation for fringe component of diffraction coefficient is implemented to TD-EEC method. An example of diffraction by perfectly conducting plate is used to illustrate our scheme. Comparing with the FDTD results we observe that the improved expression for fringe component is more accurate than that of Michaeli's formulation. This high frequency time domain technique is available for treating the bistatic scattering problems for millimeter waves. 相似文献
75.
复合广义齐次Poisson过程的多险种破产概率 总被引:11,自引:0,他引:11
于文广 《应用数学与计算数学学报》2003,17(2):63-69
本文推广了经典的复合泊松风险模型,建立了两类复合广义齐次poisson过程的多险种破产模型.对于新模型,我们得到了初始资本为u的破产概率φ(u)的精确表达式以及特殊情况下φ(0)的表达式,并且导出了调节系数方程和调节系数R的上下界. 相似文献
76.
The patterns of absorption and reflection of an ultrashort laser pulse by a plasma with a solid-state density, which are realized in the mode of the normal skin effect, are studied. It is shown that a decrease in low-power pulse duration shorter than the period corresponding to the fundamental frequency of radiation leads to an increase in the absorption coefficient. If the pulse power is so high as to provide electron heating during a time shorter than the reciprocal fundamental frequency, nonlinear suppression of absorption takes place and the spectrum of the reflected radiation contains odd harmonics of the fundamental frequency. 相似文献
77.
78.
Joanna Tarasińska 《Applications of Mathematics》2003,48(1):67-72
Two estimates of the regression coefficient in bivariate normal distribution are considered: the usual one based on a sample and a new one making use of additional observations of one of the variables. They are compared with respect to variance. The same is done for two regression lines. The conclusion is that the additional observations are worth using only when the sample is very small. 相似文献
79.
The optical properties—reflectivity, real part of the refractive index, absorption coefficient as well as the thermal and electrical conductivity of AlSi-alloy/SiCp composite were measured. The optical parameters and both conductivities decreased with the increase of SiCp particles volume in AlSi-alloy matrix. This decrease was almost linear for the volume fraction of SiCp particle up to 10 vol% of the total mass of the composite. For the 15 vol% of SiCp particles, the departure from linearity is connected with the presence of additional phases in AlSi-alloy/SiCp composite materials. The measured temperature dependencies of optical reflectivity and electrical conductivity for AlSi-alloy/SiCp 15 vol% are of metallic character. Modelling of the interaction of the CO2 laser radiation with AlSi-alloy/SiCp 15 vol% composite should allow to estimate the initiation time at which the surface composite reaches melting temperature. 相似文献
80.