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111.
Petrásková L Charvátová A Prikrylová V Kristová V Rauvolfová J Martínková L Jiménez-Barbero J Aboitiz N Petrus L Kren V 《Journal of chromatography. A》2006,1127(1-2):126-136
A new separation method based on the combination of exclusion and ion exchange chromatography in borate buffer was developed. It allows semi-preparatory and preparatory separation of isobaric N-acylhexosamines (C-2 epimers) and corresponding methyl glycosides (anomers and tautomers). Three types of polyolic gels were tested for these separations. Ion-exchange HPLC was used as a rapid and reliable method for the quantification of the respective analytes. NMR studies of the interactions of N-acetylhexosamines with borate confirmed the importance of a proper stereochemical arrangement of acetamido sugars for their interactions with borate anions. 相似文献
112.
The group index dispersion and birefringence of guided modes supported by straight photonic crystal (PhC) waveguides are theoretically and experimentally investigated as a function of the waveguide width within various reduced frequency domains. Within the photonic gap and far from the Brillouin zone edges, strongly confined modes supported by narrow PhC guides exhibit both a group index and a birefringence larger than those of a deep ridge. These two results evidence the contribution of the photonic gap to the guiding mechanism in the refractivelike domain. 相似文献
113.
Ladislav Nebeský 《Czechoslovak Mathematical Journal》2006,56(2):659-675
In this paper, by a travel groupoid is meant an ordered pair (V, *) such that V is a nonempty set and * is a binary operation on V satisfying the following two conditions for all u, v ∈ V:
. Let (V, *) be a travel groupoid. It is easy to show that if x, y ∈ V, then x * y = y if and only if y * x = x. We say that (V, *) is on a (finite or infinite) graph G if V (G) = V and
. Clearly, every travel groupoid is on exactly one graph. In this paper, some properties of travel groupoids on graphs are
studied. 相似文献
114.
In [HOLá, Ľ.—HOLY, D.: Pointwise convergence of quasicontinuous mappings and Baire spaces, Rocky Mountain J. Math.] a complete answer is given, for a Baire space X, to the question of when the pointwise limit of a sequence of real-valued quasicontinuous functions defined on X is quasicontinuous. In [HOLá, Ľ.—HOLY, D.: Minimal USCO maps, densely continuous forms and upper semicontinuous functions, Rocky Mountain J. Math. 39 (2009), 545–562], a characterization of minimal USCO maps by quasicontinuous and subcontinuous selections is proved. Continuing
these results, we study closed and compact subsets of the space of quasicontinuous functions and minimal USCO maps equipped
with the topology of pointwise convergence. We also study conditions under which the closure of the graph of a set-valued
mapping which is the pointwise limit of a net of set-valued mappings, is a minimal USCO map. 相似文献
115.
Let
be an abstract class (closed under isomorpic copies) of left R-modules. In the first part of the paper some sufficient conditions under which
is a precover class are given. The next section studies the
-precovers which are
-covers. In the final part the results obtained are applied to the hereditary torsion theories on the category on left R-modules. Especially, several sufficient conditions for the existence of -torsionfree and -torsionfree -injective covers are presented. 相似文献
116.
Let
be a hereditary torsion theory for the category
-mod of unital left
-modules over an associative ring
with an identity element. The purpose of this note is to prove that if the associated Gabriel filter
consists of finitely presented left ideals, then every module has a
-injective cover and if
contains a cofinal subset of finitely presented left ideals, then every module has a
-torsionfree
-injective cover. The methods used working with pure submodules contained in ``large" submodules also allow to unify the proofs of some previously known results. 相似文献
117.
Ladislav Adamec 《Applications of Mathematics》1998,43(2):111-117
The paper gives the answer to the question of the number and qualitative character of stationary points of an autonomous detailed balanced kinetical system. 相似文献
118.
An analogue for composite moduli of the Wilson quotient is studied. Various congruences are derived, and the question of when these quotients are divisible by is investigated; such an will be called a ``Wilson number". It is shown that numbers in certain infinite classes cannot be Wilson numbers. Eight new Wilson numbers up to 500 million were found.
119.
Presented by H. P. Gumm. 相似文献
120.
The E. Coli K12 UDP-Gal mutase inhibitor 1 was prepared from d-glucose in 5 steps (42% overall yield). The 4-azido galactose derivative 11, leading to 1, was formed by treatment of galactose dithioacetal 7 with mercuric oxide and mercuric chloride in acetone. To obtain 7, acetal 3 was tosylated or triflated and treated with NaN3. 相似文献