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91.
《Journal of Pure and Applied Algebra》2022,226(4):106862
We investigate how to characterize subcategories of abelian categories in terms of intrinsic axioms. In particular, we find axioms which characterize generating cogenerating functorially finite subcategories, precluster tilting subcategories, and cluster tilting subcategories of abelian categories. As a consequence we prove that any d-abelian category is equivalent to a d-cluster tilting subcategory of an abelian category, without any assumption on the categories being projectively generated. 相似文献
92.
作为Hom-Leibniz代数胚的代数类比, 本文引入Hom-Leibniz-Rinehart代数的概念. 证明了分裂的正则Hom-Leibniz-Rinehart代数$L$写成$L=U+\sum_{\gamma}I_\gamma$, 其中$U$为极大交换子代数$H$的子空间和$I_\gamma$为$L$的理想, 若$[\gamma]\neq[d]$, 满足$[I_\gamma, I_d]=0$. 随后分别发展了分裂Hom-Leibniz-Rinehart代数的根和权的连通技术.最后研究了紧致的正则Hom-Leibniz-Rinehart代数的结构. 相似文献
93.
Photoproducts of pyridoxal-5-P, i.e., 4-pyridoxic-5-P and bis-pyridoxal-5-P, have been studied by spectroscopic methods. The spectroscopic properties of bis-pyridoxal-5-P (bis-PLP) resemble those of pyridoxal-5-P (PLP) under similar experimental conditions. The coupling of methylen hydrogens to the phosphorus atom has been shown by NMR spectroscopy. The singlet in the31P-NMR spectra and the triplet in1H-undecoupled experiments confirm the presence of the phosphate group in the 5 position of the structure of the vitamin. The effect of pH and solvent composition on the relative distribution of species of bis-pyridoxine-5-P (bis-PNP) has been investigated by absorption and fluorescence spectroscopy. The acid-base dissociation of the phosphate group is easily detected by emission spectroscopy. Bis-PNP and bis-PLP bind to the enzyme RNase A and they behave as competitive inhibitors with respect to the substrate cytidine-2-3-cyclic phosphate. The natural forms of vitamin B6, pyridoxine, and pyridoxine-5-P have no effect on the catalytic activity of the protein. Experimental evidence derived from fluorescence and inhibition experiments is consistent with the hypothesis that bis-PNP recognizes the catalytic site of RNase A. 相似文献
94.
R. N. Ball 《Algebra Universalis》1996,35(1):85-112
Any lattice-ordered group (l-group for short) is essentially extended by its lexicographic product with a totally ordered group. That is, anl-homomorphism (i.e., a group and lattice homomorphism) on the extension which is injective on thel-group must be injective on the extension as well. Thus nol-group has a maximal essential extension in the categoryIGp ofl-groups withl-homomorphisms. However, anl-group is a distributive lattice, and so has a maximal essential extension in the categoryD of distributive lattices with lattice homomorphisms. Adistinguished extension of onel-group by another is one which is essential inD. We characterize such extensions, and show that everyl-groupG has a maximal distinguished extensionE(G) which is unique up to anl-isomorphism overG.E(G) contains most other known completions in whichG is order dense, and has mostl-group completeness properties as a result. Finally, we show that ifG is projectable then E(G) is the -completion of the projectable hull ofG.Presented by M. Henriksen. 相似文献
95.
A. Salam 《Numerical Algorithms》1996,11(1):327-337
The vector -algorithm is obtained from the scalar -algorithm by taking the pseudo-inverse of a vector instead of the inverse of a scalar. Thus the vector -algorithm is known only through its rules contrarily to the scalar -algorithm and some other extrapolation algorithms.The aim of this paper is to provide an algebraic approach to the vector -algorithm. 相似文献
96.
Mark Curtis Wilson 《Proceedings of the American Mathematical Society》1996,124(2):383-387
We show that a primeness criterion for enveloping algebras of Lie superalgebras discovered by Bell is applicable to the Cartan type Lie superalgebras , even. Other algebras are considered but there are no definitive answers in these cases.
97.
Two Fraenkel-Mostowski models are constructed in which the Boolean Prime Ideal Theorem is true. In both models, AC for countable sets is true, but AC for sets of cardinality 2 and the 2m = m principle are both false. The Principle of Dependent Choices is true in the first model, but false in the second. Mathematics Subject Classification: 03E25, 03E35, 04A25. 相似文献
98.
Fang Jie 《数学学报(英文版)》1996,12(3):249-253
In this paper we introduce an algebraic concept of the product of Ockham algebras called the Braided product. We show that ifL
i
MS(i=1, 2, ,n) then the Braided product ofL
i(i=1, 2, ,n) exists if and only ifL
1, ,L
n have isomorphic skeletons. 相似文献
99.
A.K. Tashmukhamedova I.A. Stempnevskaya 《Journal of inclusion phenomena and macrocyclic chemistry》1998,30(2):91-98
The effect of the nature of the substituent in the monosubstituted derivatives of dibenzo-18-crown-6 on the reactivity and direction of the electrophilic substitution reaction of the unsubstituted benzene ring has been determined. This transfer is carried out via the macrocycle and therefore is called transannular transmission. The possible mechanism of this transmission is discussed. 相似文献
100.
K. Bogdanowicz-Szwed M. Krasodomska M. Lipowska B. Rys A. Skonecka 《Monatshefte für Chemie / Chemical Monthly》1993,124(6-7):721-731
Summary The tandem Michael addition-cyclization of 2-oxo-cycloalkane carbothioic acid anilides1–3 to benzylidenemalononitrile4 yielded spiroannulated pyridines5–7. Reaction of acrylonitrile with2 and3 gave 2,2-disubstituted Michael adducts14,15, whereas with1 led to 2,2,5-tri(2-cyanoethyl)-cyclopentanone11.
Synthese von Pyridinderivaten durch Reaktionen von ,-ungesättigten Nitrilen mit 2-Oxo-cycloalkano-thiokohlensäure-aniliden
Zusammenfassung Die Michael Tandem-Addition-Cyclisierung von 2-Oxo-cycloalkano-thiokohlensäure-aniliden1–3 mit Benzylidenmalononitril4 ergab die spiroannelierten Pyridine5–7. Reaktion von Acrylnitril mit2 und3 ergab die 2,2-disubstituierten Michael-Addukte14,15, wohingegen mit1 2,2,5-Tri(2-cyanethyl)-cyclopentanon11 erhalten wurde.相似文献