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31.
32.
随着核电事业的快速发展,核电厂卸载的乏燃料越来越多。如何处置核电站乏燃料中的次锕系核素(MA)既是核燃料再利用的重要过程,又是闭式循环中的关键步骤。如果处置得当,不仅可以提高燃料的利用率,而且可以将MA变成同位素燃料电池、中子源等有用的核素。国际上认可的处置方法是分离-嬗变,但是嬗变MA的难点是嬗变堆型的选取和如何提高嬗变率。压水堆(PWR)是国内外最成熟的堆型和商业运行的主要堆型,也是现阶段最具有可能进行MA嬗变的堆型。于是,本文利用MCNP程序研究了压水堆嬗变MA的特性,通过研究MA嬗变棒的设计、添加位置和添加量等对压水堆堆芯有效增殖因子的影响,初步探索出最佳的压水堆嬗变MA的设计方案,为我国现阶段进行压水堆嬗变MA奠定了理论基础。 相似文献
33.
(1S,2R,3S)-, (1R,2R,3S)- and (1S,2R,3R)-4-amino-1,2,3-trihydroxybutylphosphonic acids were synthesised. The synthetic strategy involved preparation of the respective 4-azido-2,3-O-isopropylidene-l-threose or -d-erythrose, addition of dialkyl phosphites, separation of C-1 epimeric O,O-dibenzyl phosphonates, the reduction of azides and the removal of the protecting groups. The (2R,3S) and (2R,3R) configurations in the final products were secured by employing diethyl l-tartrate and d-isoascorbic acid as starting materials. The stereochemical course of the addition to the carbonyl groups in 4-azido-2,3-O-isopropylidene-l-threose or -d-erythrose followed that established earlier for 2,3-O-isopropylidene-d-glyceraldehyde and similar (3:1-4:1) diastereoselectivities were achieved. 相似文献
34.
We present a simplified relativistic configuration interaction method (SRCI), by which all the energy levels and oscillator strengths in each transition array can be calculated. There exist generalized quasi-sum relations for the calculated oscillator strengths in the relevant transition arrays by the SRCI and by an unresolved transition array model (UTA). Based on UTA and the detailed configuration accounting (DCA), with a fully relativistic treatment incorporated with the quantum defect theory, the X-ray absorption spectra for any middle- and high-Z plasmas or composite plasmas can be calculated with much less computational efforts. The gross features of calculated spectra by DCA-UTA are in agreement with the relevant experimental measurements, except some detailed structures in some narrow spectral ranges. Such detailed structures can be calculated by SRCI incorporated with DCA-UTA. As an illustrative example, the absorption spectra of Ge plasmas are calculated by DCA-UTA-SRCI and are in agreement with the experimental opacity data. Therefore, the theoretical method (DCA-UTA-SRCI) verified by experimental measurements will not only be a basic tool to provide “precision” opacity data for the inertial confinement fusion research (ICF) and studies in stellar physics but also can be used to analyze the relevant diagnostic measurements for ICF plasmas. 相似文献
35.
A general algorithm of evaluation of the coefficients of molecular integrals (coupling constants) appearing in the direct configuration interaction method is derived. The configurations are assumed to be spin-adapted antisymmetrized products of orthonormal orbitals. No limitation is imposed either upon the reference state (the number of the singly occupied orbitals may be arbitrary) or upon the excitation multiplicity. 相似文献
36.
Bernard Riss Marion Garreau Prisca Fricero Patricia Podsiadly Nicolas Berton Sophie Buchter 《Tetrahedron》2017,73(23):3202-3212
The absolute configuration of bisabolangelone has been established by an eleven step total synthesis of the corresponding TMS protected antipode starting from (R)-(+)-pulegone. Comparison of the TMS-derivatives by GC on a chiral column, allowed us to assign the absolute configuration of the synthetic compound and thus of the corresponding natural product. The latter has been confirmed by the Mosher's ester analysis of the known secondary carbinol derivative. 相似文献
37.
王利生 《原子与分子物理学报》1998,15(2):245-252
基于格子气体理论,提出了方阱流体及其混合物的新配位数模型和构型能表达式。新模型与Lee等人的MonteCarlo计算机模拟结果进行了比较,取得了较好的计算结果。将新模型应用于分子尺寸不同的混合物时,计算结果尤为满意。 相似文献
38.
Using a perturbational configuration interaction approach, it is found that the Fe-CO molecule has a low-spin ground state (i.e. 3–), at variance with similar compounds formed by the first transition elements of this series (e.g. Sc and Ti). Binding energies, interatomic distances and vibration frequencies have been calculated for the 3– state as well as for the 5– high-spin state.Dedicated to Professor J. Koutecký on the occasion of his 65th birthday 相似文献
39.
Some aspects of the geometry of gauge theories are sketched in this review. We deal essentially with Yang-Mills theory, discussing the structure of the space of gauge orbits and the geometrical interpretation of ghosts and anomalies. Occasionally we deal also with classical gauge theories of gravitation and in particular we study the action of the group of diffeomorphisms on the space of linear connections. Finally we comment on the mathematical interpretation of anomalies in field theories. 相似文献
40.
应用1H-1H COSY,NOESY,13C-1H COSY等2DNMR和DEPT技术,完成了赤霉酸甲酯(2),13-O-乙酰基赤霉素甲酯(3)及其3位差向异构体(4)的1H和13CNMR化学位移的全指定,并探讨了它们的相对构型,相关质子间的偶合常数也支持所得结果。 相似文献