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101.
给出一台脉冲间隔100~1 000 ns、脉冲数2~5个、二极管电压3 MV、引出束流强度2.5 kA的猝发多脉冲电子束源的物理设计及初步调试结果。在设计中,采用感应叠加和阻抗匹配方案获得二极管高电压脉冲;试验中分别采用天鹅绒和大发射面储备式热阴极获得猝发多脉冲电子束。调试结果表明:采用大发射面热阴极可避免阴极等离子体产生,确保二极管在猝发多脉冲状态下稳定运行。初步调试获得大于2.7 MV猝发三脉冲二极管高压,并获得1.6 kA的三脉冲电子束流。 相似文献
102.
103.
M. K. Vemuri 《Proceedings Mathematical Sciences》2008,118(1):115-131
A characterisation of the maximal abelian subalgebras of the bounded operators on Hilbert space that are normalised by the
canonical representation of the Heisenberg group is given. This is used to classify the perfect realizations of the canonical
representation.
Based in part on the author’s doctoral thesis (University of Chicago), written under the direction of Professor Tim Steger. 相似文献
104.
本文研究Retakh's条件(M_0),正则性和弱序列式回缩性之间的关系.对于(LM)-空间,弱序列式回缩性等价于正则性加上一个介于(Q_0)和(M_0)之间的条件对于(LN)-空间,我们获得了更满意的结果,证明了弱序列式回缩性等价于正则性加上条件(M_0),也等价于一个非常弱的正则性条件加上条件(M_0)(见文献[1-28]). 相似文献
105.
《Electroanalysis》2006,18(22):2210-2217
A novel method to immobilize hemoglobin (Hb) in a polymer grown from dopamine (DA) oxidation was proposed. The growth of the polymeric films during DA oxidation at the Prussian blue (PB) modified Au electrode in weak alkaline phosphate buffer (pH 9.18) and the immobilization of Hb into the polymeric films during their growth were traced by the electrochemical quartz crystal impedance analysis (EQCIA) method. A hydrogen peroxide (H2O2) biosensor was thus constructed, and effects of experimental parameters on the sensor performance, including the applied potential, solution pH and electroactive interferents, were examined. At an optimal potential of ?0.25 V vs. SCE, the current response of the biosensor in the selected phosphate buffer (pH 5.29) was linear with the concentration of H2O2 from 0.01 to 4.5 mM, with a lower limit of detection of 0.5 μM (S/N=3), short response time (within 10 s) and good anti‐interferent ability. The Michaelis constant (Kmapp) was estimated to be 3.80 mM. Compared with the separate film of PB or Hb, the composite film of Hb and PB exhibited a higher catalytic activity toward the reduction of H2O2, as a result of the additive effect of the chemical and biological catalyses. 相似文献
106.
Jorge Martínez 《Algebra Universalis》2006,55(1):13-43
One considers the poset of dense, coherent frame quotients of an algebraic frame with the finite intersection property, which
are compact. It is shown that there is a smallest such, the frame of d-elements. However, unless the frame is already compact there is no largest such quotient.
With the additional assumption of disjointification on the frame, one then studies the maximal ideal spaces of these quotients
and the relationship to covers of compact spaces.
Several applications are considered, with considerable attention to the frame quotients defined by extension of ideals of
a commutative ring A to a ring extension; this type of frame quotient is considered both with and without an underlying lattice structure on the
rings.
Received January 8, 2005; accepted in final form August 28, 2005. 相似文献
107.
The dual substituent parameter (DSP) data treatment is a broadly used procedure correlating the reaction energies or other physical quantities with two sets of substituent constants, inductive (σI) and resonance (σR). It was here revised using the most extensive sets of experimental reactivities available in the literature and two sets of reaction energies calculated at the level B3LYP/6‐311+G(d,p): acidities of 4‐substituted benzoic acids and 5‐(E)‐substituted penta‐2,4‐diene‐(E)‐acids with 19 or 15 common substituents. The latter two series enabled us to investigate the substituent effects more systematically than it was ever possible with the experimental data; this means in particular separate treatment of the undissociated acid molecules and of their anions, further separation of donor and acceptor substituents. In addition, the standard statistical treatment was improved when testing the significance of the resonance term. The DSP treatment is not valid generally, this applies both to the standard reference series and to the series commonly investigated. At best, DSP may be considered to hold for donor substituents but the effects of acceptors are much less variable and do not depend on the constants σR nor on any other measure of resonance. The small efficiency of acceptor substituents is due by the fact that the constant functional group (COOH in the standard series) is itself an acceptor. A correct treatment would be to investigate the donor and acceptor substituents separately, donors with an acceptor functional groups, and vice versa; substituents with weak resonance effect should be not included. The popularity and apparent success of the DSP treatment can be attributed to several grounds, most important has been the unbalanced choice of substituents. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
108.
E. G. Sklyarenko 《Mathematical Notes》2005,77(1-2):112-116
The following result is proved in the paper. An Abelian group A is Lw1, w-equivalent to the free Abelian group of countable rank if and only if it is a countably free Abelian group.Translated from Matematicheskie Zametki, vol. 77, no. 1, 2005, pp. 121–126.Original Russian Text Copyright © 2005 by E. G. Sklyarenko.This revised version was published online in April 2005 with a corrected issue number. 相似文献
109.
PRISM is a probabilistic logic programming formalism which allows defining a probability distribution over possible worlds. This paper investigates learning a class of generative PRISM programs known as failure-free. The aim is to learn recursive PRISM programs which can be used to model stochastic processes. These programs generalise dynamic Bayesian networks by defining a halting distribution over the generative process. Dynamic Bayesian networks model infinite stochastic processes. Sampling from infinite process can only be done by specifying the length of sequences that the process generates. In this case, only observations of a fixed length of sequences can be obtained. On the other hand, the recursive PRISM programs considered in this paper are self-terminating upon some halting conditions. Thus, they generate observations of different lengths of sequences. The direction taken by this paper is to combine ideas from inductive logic programming and learning Bayesian networks to learn PRISM programs. It builds upon the inductive logic programming approach of learning from entailment. 相似文献
110.
Kok-Ping Chan 《Tetrahedron letters》2007,48(1):37-41
A convenient approach towards the synthesis of both syn- and anti-2,4,6-chlorotetrahydropyrans has been developed. The electronic and steric influences on the stereochemistry of the Prins cyclized products were investigated based on the substituents of the homoallylic alcohol. 相似文献