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981.
Peter Mikuš Lucia Veizerová Juraj Piešťanský Katarína Maráková Emil Havránek 《Electrophoresis》2013,34(8):1223-1231
An analytical method, based on a column coupling capillary ITP and CZE in a hydrodynamically closed separation mode hyphenated with the detection in the modular arrangement, was developed in this work. Analytical possibilities of this approach are demonstrated on the direct and ultrasensitive quantitative determination of quinine (QUI) in diluted real multicomponent ionic matrices (beverages, urine). The detection cell interface, with the rectangular arrangement of the optical channels inside, connected the separation capillary with the LIF detector via optical fibers in the on‐column detection arrangement. ITP enabled the direct large volume (30 μL) injections of the diluted real matrices with an on‐line sample pretreatment (preseparation, preconcentration) so that no external sample preparation (except for the dilution) was necessary for the separation of the analyte in the multicomponent ionic matrices. Due to the ITP sample preconcentration and intrinsic sensitivity of the LIF detection, very low concentration LOD (as low as 77 pg/mL), were reached at the same time. This was ca. two orders lower than the corresponding LOD achieved by the same 2D separation system with UV absorbance detection. Compared to the single column CE‐LIF methods applied for this model analyte and matrix, this method was found to be superior in terms of concentration LOD, with acceptable selectivity and benefits of the on‐line sample preparation. A food control and bioanalytical application clearly illustrates great practical possibilities and routine use of the proposed modular ITP–CZE–LIF technique. 相似文献
982.
If H is an isotype knice subgroup of a global Warfield group G, we introduce the notion of a k-subgroup to obtain various necessary and sufficient conditions on the quotient group G/H in order for H itself to be a global Warfield group. Our main theorem is that H is a global Warfield group if and only if G/H possesses an H(ℵ0)-family of almost strongly separable k-subgroups. By an H(ℵ0)-family we mean an Axiom 3 family in the strong sense of P. Hill. As a corollary to the main theorem, we are able to characterize
those global k-groups of sequentially pure projective dimension ⩽ 1. 相似文献
983.
984.
985.
Based on the closed orbit theory framework together with the quantum defect theory and time-independent scattering matrices
theory, we calculate the recurrence spectra of diamagnetic Cs atoms at several different scaled energies near the second ionization
threshold. It is revealed that the new extra peaks in spectra are attributed to the combination recurrences of semiclassical
closed orbits arising from core-scattered events. This method considers the dynamic states of the Rydberg electron in the
core region and long-range region and can be analytically resumed to include all orders of core-scattering automatically.
With this approach a convergent recurrence spectrum can be reasonably achieved. It is found that the spectral complexity depends
highly sensitively on the scaled energy. With the increase of the scaled energy, the spectral structure changes from simple
to complicate and the dynamic feature from regular to chaotic. The comparison of the recurrence spectra with Dando’s result
under the same conditions demonstrates that there exist some similarities and differences between them, and furthermore, the
feasibility of the scattering matrix method is explained.
Supported by the National Natural Science Foundation of China (Grant Nos. 10774093 and 10374061) 相似文献
986.
唐矛宁 《应用数学与计算数学学报》2008,(2)
本文研究了标的资产价格服从连续时间It过程模型的金融市场的完备性问题。在允许有摩擦的金融市场中,当可允许投资策略取值于一个非空凸闭集时,给出了金融市场在内蕴完备条件下广义不完备的充分必要条件. 相似文献
987.
Gosper算法与一类组合和是否有闭形式的问题 总被引:2,自引:0,他引:2
本文由Gosper算法研究了一类形如f_(p,r,x)(n)=∑_(k=0)~(rn)((?))x~k的组合和是否有闭形式的问题。 相似文献
988.
P.A. Cojuhari 《Journal of Mathematical Analysis and Applications》2007,326(2):1394-1409
Based on the direct methods of the perturbation theory, sufficient conditions for the finiteness of the discrete spectrum of linear pencils of the form L(λ)=B−λA, where A and B are bounded self-adjoint operators, are established. An estimate formula for the discrete spectrum is also presented. As applications, we study the spectrum of the characteristic equation of radiation energy transfer. 相似文献
989.
Eric Beutner 《Mathematical Methods of Operations Research》2007,65(3):539-557
The paper proposes a new approach to the mean–variance-hedging problem under transaction costs. This approach is based on
the idea of dividing the gain functional into two parts. One part representing the gains resulting from a pure buying strategy,
and the other part representing the gains resulting from a pure selling strategy. The problem will be studied in a general
incomplete market in discrete time. Some technical assumptions such as the RAS condition are excluded.
相似文献
990.
We investigate how to modify a simple graph G combinatorially to obtain a sequentially Cohen-Macaulay graph. We focus on adding configurations of whiskers to G, where to add a whisker one adds a new vertex and an edge connecting this vertex to an existing vertex of G. We give various sufficient conditions and necessary conditions on a subset S of the vertices of G so that the graph G∪W(S), obtained from G by adding a whisker to each vertex in S, is a sequentially Cohen-Macaulay graph. For instance, we show that if S is a vertex cover of G, then G∪W(S) is a sequentially Cohen-Macaulay graph. On the other hand, we show that if G?S is not sequentially Cohen-Macaulay, then G∪W(S) is not a sequentially Cohen-Macaulay graph. Our work is inspired by and generalizes a result of Villarreal on the use of whiskers to get Cohen-Macaulay graphs. 相似文献