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991.
Mingzhi Jin Xuewu Liu Yurong Wang Milan Liu Yuqing Jia 《Hyperfine Interactions》1992,70(1-4):1211-1214
EuBa2(Cu1-xFex)3O7-x has been investigated by the57Fe and151Eu Mössbauer effect. The57Fe Mössbauer spectra of the EuBa2(Cu1xFex)3O7-y without or with DC electric current (the current strength I=0.5A) around the superconducting transition temperature have been measured. The results indicate that the isomer shift (IS) and the quadrupole splitting (QS) of the Fe replacing the Cu(2) vary neither with increasing the Fe content nor with the small DC eletric, current passing the superconductor and that the IS and the QS of the Fe replacing the Cu(1) vary with the Fe content. Especially, the IS and the QS of the Fe (D3) replacing the Cu(1) are changed when the small electric current passes the superconductor at 80K. 相似文献
992.
993.
R. Jiang M. B. Hu B. Jia R. L. Wang Q. S. Wu 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,54(2):267-273
This paper studies a new model, which considers the effects of
drivers reaction delay in the Nagel-Schreckenberg model. We studied
the traffic flow properties in the new model under both periodic and
open boundary conditions. The fundamental diagram, spatio-temporal
patterns, density-density correlation functions, relaxation time,
and distance headway distribution are investigated. Several
interesting results are reported, for example, (i) the jam becomes
less condensed when the delay effect is considered; (ii) the
distance headway of the new model exhibits a multi-peak distribution
when randomization p is small; (iii) for large p, the
distribution of distance headway follows a power law in the new
model; (iv) under open boundary conditions, the existence of a
stationary jam near the left boundary will lower the flow rate. 相似文献
994.
水母雪莲化学成分的研究(Ⅱ) 总被引:8,自引:0,他引:8
前文已报道从水母雪莲(Saussurea Medusa Maxim)中分得4种黄酮甙,本文报道另外6种化合物的分离和鉴定。 1 化合物Ⅰ—Ⅳ物化性质及分离鉴定 1.1 化合物Ⅰ 黄色结晶,m.p.:249~251℃,水解所得甙元鉴定为木樨草素,纸层析检出鼠李糖和葡萄糖。MS(FAB):m/z 595(M~++1),287(M~++H-葡萄糖基-鼠李糖)。化合物I与木樨草素的~(13)C NMR比较,C_6、C_8、C_(10)分别向低场位移1.1、1.0、1.8 ppm,而C,向高场移动 相似文献
995.
提出一种分析非平行波导间耦合的简明方法-耦合系数推广法.利用这种方法,导出一种新的非平行双波导的耦合方程,由此得到一组非平行波导耦合的完美的分析解,依据这些分析解可以优化非平行波导的传输距离、输入/输出端口波导间距和夹角. 相似文献
996.
Vector Ordinal Optimization 总被引:2,自引:0,他引:2
Ordinal optimization is a tool to reduce the computational burden in simulation-based optimization problems. So far, the major effort in this field focuses on single-objective optimization. In this paper, we extend this to multiobjective optimization and develop vector ordinal optimization, which is different from the one introduced in Ref. 1. Alignment probability and ordered performance curve (OPC) are redefined for multiobjective optimization. Our results lead to quantifiable subset selection sizes in the multiobjective case, which supplies guidance in solving practical problems, as demonstrated by the examples in this paper.This paper was supported in part by Army Contract DAAD19-01-1-0610, AFOSR Contract F49620-01-1-0288, and a contract with United Technology Research Center (UTRC). The first author received additional funding from NSF of China Grants 60074012 and 60274011, Ministry of Education (China), and a Tsinghua University (Beijing, China) Fundamental Research Funding Grant, and the NCET program of China.The authors are grateful to and benefited from two rounds of reviews from three anonymous referees. 相似文献
997.
Facile Yb(OTf)3 promoted one-pot synthesis of polyhydroquinoline derivatives through Hantzsch reaction 总被引:1,自引:0,他引:1
Yb(OTf)3 catalyzed efficient Hantzsch reaction via four-component coupling reactions of aldehydes, dimedone, ethyl acetoacetate and ammonium acetate at ambient temperature was described as the preparation of polyhydroquinoline derivatives. The process presented here is operationally simple, environmentally benign and has excellent yield. Furthermore, the catalyst can be recovered conveniently and reused efficiently. 相似文献
998.
Jia Zhen YANG* Ru Bo ZHANG Institute of Rare Scattered Element Chemistry Liaoning University Shenyang 《中国化学快报》2002,13(5)
This paper reports the EMF(electromotive force) measurements of cell (A) without liquid junction at five temperatures from 278.15 to 318.15 K. Pt|H2(101.325kPa)|HCl(m1),GaCl3(m2),H2O|Ag|AgCl (A) The measurements on the system HCl+GaCl3+H2O was carried out in an appropriate concentration of hydrochloric acid when the concentration of hydrochloric acid is not lower than 0.13 mol/kg the hydrolysis of Ga3+ can be avoided or elimited1. The standard association constant, KAS ,… 相似文献
999.
1000.
Fang Jia 《Differential Geometry and its Applications》2007,25(5):433-451
Let be a locally strongly convex hypersurface, given by the graph of a convex function xn+1=f(x1,…,xn) defined in a convex domain Ω⊂Rn. M is called a α-extremal hypersurface, if f is a solution of