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971.
本文用下列解析原子波函数 1s电子:φ1(r)=N1e-μar, 2s电子:φ2(r)=N2[(μr)e-μr-Ne-μar], 2p电子:φ3(r)=N3(μr)cosθe-μr, φ4(r)=N4(μr)sinθeiφ-μr, φ5(r)=N5(μr)sinθe-iφ-μr,推导出入射电子与氮、氧和氖原子之间相互作用的解析势函数,其中包括了交换作用与极化作用。应用这种势函数并用分波法,文中还算出了慢电子在这三种原子的势场中运动的畸变波函数、相移及散射总截面。计算结果与实验值很符合。 相似文献
972.
考虑随机系数自回归模型Yt =Φtyt-1+ ut,其中 Φt为随机系数,ut为随机误差。在允许Φt与ut相依以及Eut无穷的条件下,构造了误差方差的自加权估计,并证明了该估计的渐近正态性。最后通过数值模拟,说明
自加权估计的稳健和有效性。 相似文献
973.
R.?Long T.?Rom W.?H?nsel T. W.?H?nsch J.?ReichelEmail author 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2005,35(1):125-133
We describe a chip-based magnetic conveyor that transports
ultracold atoms with high positioning accuracy over long distances,
into an interaction region which is well separated from the
magneto-optical trap and gives good optical access to the atoms. The
conveyor can work in two different modes, with or without external
bias field. The transport potential is generated by a two-layer
conductor pattern, enabling a significantly smoother transport than
our earlier single-layer conveyor. This is confirmed by numerical
field calculations, using an optimization procedure that minimizes
shape deformations as well as deviations from the linear transport
path. We experimentally demonstrate the use of this conveyor in the
mode with external bias field, transporting a cloud of cold atoms
over a linear distance of 6 cm and a total distance of 24 cm. We
also describe an on-chip quadrupole trap that can be rotated by
π/2. This trap is used to remove design constraints on the
orientation of the laser beams in the surface magneto-optical trap.
The long-distance conveyor is a versatile tool for experiments with
trapped cold atoms, and can achieve sub-micrometric positioning
precision. Possible applications of this tool are discussed. 相似文献
974.
Implementation of a multiple round quantum dense coding using nuclear magnetic resonance 总被引:1,自引:0,他引:1
Zhang?Jingfu?Email author Xie?Jingyi Wang?Chuan Deng?Zhiwei Lu?Zhiheng Long?Guilu 《中国科学G辑(英文版)》2005,48(6):706-715
~~Implementation of a multiple round quantum dense coding using nuclear magnetic resonance1. Bennett, C. H., Wiesner, S. J., Communication via one- and two-particle operators on Einstein-Podolsky-Rosen states, Phys. Rev. Lett., 1992, 69(20): 2881-2884.
2. Mattle, K., Weinfurter, H., Kwiat, P. G. et al., Dense coding in experimental quantum communication, Phys. Rev. Lett., 1996, 76(25): 4656-4659.
3. Fang, X. M., Zhu, X. W., Feng, M. et al., Experimental implementation of dens… 相似文献
975.
[structure: see text] The de novo synthesis of the C9 and C27 sugar subunits (2) and (3), respectively, of the potent antitumor agent, apoptolidin, has been accomplished. A titanium tetrachloride-mediated asymmetric anti glycolate aldol addition was utilized to establish the 4' and 5' stereogenic centers of each of the three monosaccharides. Elaboration of the aldol adducts efficiently provided the three sugar units. A beta-selective glycosidation completed the construction of the C27 disaccharide. 相似文献
976.
Let n be a positive integer and P=diag(−In−κ,Iκ,−In−κ,Iκ) for some integer κ∈[0,n]. In this paper, we prove that for any convex compact smooth hypersurface Σ in R2n with n?2 there always exists at least one closed characteristic on Σ which possesses at least 2n−4κ Floquet multipliers on the unit circle of the complex plane, provided Σ is P-symmetric, i.e., x∈Σ implies Px∈Σ. 相似文献
977.
Pickering AL Seeber G Long DL Cronin L 《Chemical communications (Cambridge, England)》2004,(2):136-137
Isolated polymeric Ag(I) coordination tubes are self-assembled from the rigid triamino ligands cis,cis-1,3,5-triaminocyclohexane (cis-tach) and cis,trans-1,3,5-triaminocyclohexane (trans-tach), forming two topologically equivalent framework motifs. 相似文献
978.
Parenty AD Smith LV Pickering AL Long DL Cronin L 《The Journal of organic chemistry》2004,69(18):5934-5946
A new class of phenanthridinium derivative has been isolated from the reaction of 2-bromoethyl-phenanthridinium bromide with a range of primary amines in excellent yields. The reaction pathway is unprecedented and proceeds via three cascade steps: nucleophilic attack of a primary amine on the iminium moiety of a heteroaromatic ring system and cyclization to form a five-membered ring, followed by hydride loss to yield a rearomatized dihydro-1H-imidazo[1,2-f]phenanthridinium derivative. A range of NMR phase transfer experiments were carried out to elucidate the mechanistic pathway, and the methodology has been further developed by means of a biphasic system using N-bromosuccinimide as a co-oxidizing agent. The method has also been extended to other N-heterocyclic cation derivatives such as quinolinium and quinazolinium. 相似文献
979.
Dang Van Soa Takeo Inami Hoang Ngoc Long 《The European Physical Journal C - Particles and Fields》2004,34(3):285-289
We study the production of bileptons, new gauge bosons of lepton number two, in the minimal 3-3-1 model in high energy
collisions. If the bilepton masses are in the range of 300 GeV the reaction will give observable cross-sections in future colliders.Received: 5 August 2003, Published online: 23 March 2004Dang Van Soa: On leave of absence from Department of Physics, Hanoi University of Education, Hanoi, VietnamHoang Ngoc Long: On leave of absence from Institute of Physics, NCST, P.O. Box 429, Bo Ho, Hanoi 10000, Vietnam 相似文献
980.
Long Jiang~ 《应用数学学报(英文版)》2004,20(3):507-512
It is proved that a probability measure is dominated by g-expectation ε_μ[·] if and only if it can begenerated by Girsanov transformation via a process which is uniformly bounded by μ. 相似文献