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101.
Hoskin PR Jones M Sandford G Turner L 《Rapid communications in mass spectrometry : RCM》2000,14(2):91-94
Perhalogenated pyridine derivatives give negative molecular ions which undergo various fragmentation processes upon negative ion chemical ionisation. The similarities between highly fluorinated negative molecular and fragment ions that are preferentially formed in the gas and solution phases are outlined. Copyright 2000 John Wiley & Sons, Ltd. 相似文献
102.
研究了具有欠完整立方烷构型的过渡金属原子簇分子的二阶非线性光学性质。利用TDDFT方法计算了选取的簇分子及相应模拟构造分子的静态和动态的一阶非线性光学超级化率(ijk);并计算了不同金属、桥原子和配体以及簇芯对该类化合物一阶超级化率的影响。选取其中的一个簇分子为基本模型,分析了该分子的电子结构和分子轨道,在微观水平上阐述了其非线性光学性质的可能起源。认为由过渡金属和硫原子组成的簇芯和与桥原子相连的配体对该类簇合物的二阶非线性光学性质的起决定性的作用。 相似文献
103.
Christopher M. Timperley Sue Kirkpatrick Mark Sandford Matthew J. Waters 《Journal of fluorine chemistry》2005,126(6):902-906
Treatment of bis(fluoroalkyl) phosphites (RFCH2O)2P(O)H, where RF was CF3 or C2F5 with sulfur in pyridine at 80 °C gave salts of structure [(RFCH2O)2P(O)SH]NC5H5 in 90 and 88% yield, respectively. The salts reacted with alkyl iodides in acetonitrile at 50 °C to furnish bis(fluoroalkyl) S-alkyl phosphorothiolates (RFCH2O)2P(O)SR, where R was Me, Et, n- and i-Pr (when RF = CF3) and Me (when RF = C2F5). Yields ranged from 21 to 57%. Bis(trifluoroethyl) S-methyl phosphorothiolate (CF3CH2O)2P(O)SMe underwent fluorination by silver(I) fluoride in acetonitrile at room temperature to yield the phosphorofluoridate (CF3CH2O)2P(O)F in 75% yield. Tris(fluoroalkyl) phosphorothionates (RFCH2O)3P = S, where RF was CF3, C2F5 and C3F7, were prepared in 30-34% yield by heating the tris(fluoroalkyl) phosphites (RFCH2O)3P and sulfur to 200 °C in a sealed tube for 8 h. 相似文献
104.
高压密封微波消解-等离子体发射光谱法测定5种蒙药中8种金属元素.实验结果表明:其中铁、锶、锰的含量较高.测定方法简便、快速、省时、稳定性好、回收率均在97.5%-105.5%.测试方法具有较好的精密度和准确度. 相似文献
105.
Recent studies at Durham on direct fluorination 总被引:1,自引:0,他引:1
Richard D. Chambers John Hutchinson Graham Sandford 《Journal of fluorine chemistry》1999,100(1-2):63-73
Developments in direct fluorination are described, which changed our perception of the viability of this methodology for selective introduction of carbon–fluorine bonds. Use of acids as solvent media is a valuable technique for electrophilic fluorination, especially with aromatic systems. Fluorinations of 1,3-dicarbonyl compounds proceed well and techniques for promoting reactivity in other carbonyl derivatives are described. ‘In-situ’ formation of other reagents, e.g. by reaction of fluorine with other halogens and with water, provides convenient methodology for halogenation and oxidation. 相似文献
106.
用描写相对论性核 核碰撞的LUCIAE模型及相应的MonteCarlo事例产生器分析了WA97最近发表的 1 5 8AGeVp Pb和Pb Pb碰撞中单奇异粒子 (Λ ,Λ)和多奇异粒子 (Ξ-,Ξ-,Ω-,Ω-)的多重数和横质量分布 .由于LUCIAE模型包含了弦碎裂微观过程中奇异夸克压低因子随碰撞体系的能量、中心度和质量的增大而增大 ,以及由它导致的相对论性核 核碰撞宏观过程中奇异粒子产额随上述三因素之增而增的物理机制 ;LUCIAE模型计算结果能较好描写WA97实验所揭示的相对论性核 核碰撞中奇异粒子产额随中心度之增而增和奇异粒子增强随奇异夸克数之增而增的实验事实 ,以及单奇异和多奇异粒子的横质量分布 . 相似文献
107.
Ben-Hao SA 《理论物理通讯》1997,27(4):507-510
We use the event generator LUClAE to analyze the WA85 data of ratio of Ω- to Ω- in reaction (200A GeV/c)S + W. The result indicates that the reproduction of WA85 data might be achieved in hadronic rescattering regime of LUCIAE and might need not to rely on the formation of QGP. 相似文献
108.
The dependence of phase transition,associated with the disassembly of hot nuclei,on the mass number of hot nuclei is investigated.By studying six hot nuclei ranging from 56Ni* to 238U*,we find that in the curves of excitation energy of hot nuclei vs.Thermodynamic temperature T(E*) of 63Cu* and heavier ones there are always two temperature plateaus,but in T(E*) of 56Ni the first temperature plateau (at lower excitation energy) shrinks into a kink. 相似文献
109.
ON THE BEHAVIOR OF PHASE TRANSITION SHOWN IN DISASSYMBLY PROCESSES OF VERY HOT AND DILUTE FINITE NUCLEAR SYSTEMS
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The behaviors of phase transition shown in disassymbly processes of very hot and dilute finite nuclear system have been exposed by using canonical (microcanonical) ensemble Monte Carlo simulation.It is explained that they result from the competition between Coulomb interaction and the effect of finiteness. 相似文献
110.
IMPROVEMENT OF THERMODYNAMICAL MONTE CARLO SIMULATION IN SU(2) PURE GAUGE FIELD THEORY ——AN APPROACH TO CONTINUUM PHYSICS LIMIT
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The thermodynamical quantities of SU(2) pure lattice gauge field have been simulated first time on the asymmetric lattice (ξ>1).The finite size effect and continuum physics limits have also been studied.The results show that the use of asymmetric lattice is of benefit to calculate the thermodynamical quantities and study the behavior of continuum physics limits.In addition,it is explained that the efficiency of the whole Monte Carlo simulation and the calculation of heat capacity will be improved quite a lot by using bias sampling technique. 相似文献