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排序方式: 共有441条查询结果,搜索用时 239 毫秒
1.
Nicolò Giovannelli Giuseppe Rao Calogero Vetro 《Rendiconti del Circolo Matematico di Palermo》2005,54(3):443-450
In this paper we consider a definition of essentialK-variation for real functions which gives information on the absolute integrability of its approximate derivate on a measurable
set. 相似文献
2.
Nicolás Andruskiewitsch 《Selecta Mathematica, New Series》2005,11(2):203-246
Quivers over a fixed base set form a monoidal category with tensor product given by pullback. The quantum Yang–Baxter equation,
or more properly the braid equation, is investigated in this setting. A solution of the braid equation in this category is
called a “solution” for short. Results of Etingof–Schedler–Soloviev, Lu–Yan–Zhu and Takeuchi on the set-theoretical quantum
Yang–Baxter equation are generalized to the context of quivers, with groupoids playing the role of groups. The notion of “braided
groupoid” is introduced. Braided groupoids are solutions and are characterized in terms of bijective 1-cocycles. The structure
groupoid of a non-degenerate solution is defined; it is shown that it is a braided groupoid. The reduced structure groupoid
of a non-degenerate solution is also defined. Non-degenerate solutions are classified in terms of representations of matched
pairs of groupoids. By linearization we construct star-triangular face models and realize them as modules over quasitriangular
quantum groupoids introduced in papers by M. Aguiar, S. Natale and the author. 相似文献
3.
The rhetoric surrounding integration of mathematics and science abounds. Professional organizations’ standards and recommendations for reform in mathematics and science education each point out the need to make connections among various disciplines. However, some remain unconvinced, citing a lack of research supporting the assertion that integration improves student achievement. This article examines the current situation, discusses the growing body of related research, and examines the implementation issues related to integrated curriculum projects. The conclusion calls for mathematics and science educators to work collaboratively to address implementation issues surrounding reform of any kind and to explore further the possibilities of integration. 相似文献
4.
Paul Jara Montserrat Justiniani Nicolás Yutronic Isabel Sobrados 《Journal of inclusion phenomena and macrocyclic chemistry》1998,32(1):1-8
We report the syntheses and structural aspects of cyclodextrin host–guest inclusion compounds containing linear secondary alkylamines (dipropyl, dibutyl, dipentyl, dihexyl, and dioctyl) at 25 °C. Elemental analysis, 13C CP-MAS NMR spectroscopy, and powder X-ray diffraction analysis confirm the inclusion process. The basic host structure of the products is similar to that of typical cyclodextrin inclusion systems. 13C MAS NMR experiments show a different resonance pattern for the confined guest molecules with respect to the amine in the liquid phase. The presence of different resonance signals for the homologous carbon atoms of both dialkylamine branches is evidence for the non-symmetric location of the amine in the cyclodextrin channels. 相似文献
5.
Resonance interaction in the deformation (1400 to 1500 cm?1) region of the Raman spectrum of n-C23 H48 and n-C44H90 at high pressures are reported. Implications of these results concerning the interpretation of the corresponding bands of the Raman spectrum of crystalline polyethylene are discussed. 相似文献
6.
Bayó N Jiménez JC Rivas L Nicolás E Albericio F 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(5):1096-1103
An optimized solid-phase strategy for the preparation of the cyclic lipononadepsipeptide [N-Mst(L-Ser1), D-Ser4, L-Thr6, L-Asp8, L-Thr9]syringotoxin is reported. The strategy is based on the use of a mild orthogonal protection scheme and the incorporation of the nonproteinogenic amino acid (Z)-Dhb into the peptide chain as the dipeptide Fmoc-Thr(tBu)-(Z)-Dhb-OH. The didehydrodipeptide was synthesized by a water-soluble carbodiimide-induced beta-elimination of a protected dipeptide containing a residue of Thr with its free hydroxy side chain unprotected. 相似文献
7.
8.
We interpret the results of the preceding paper (I) in terms of partial resummations of the perturbative series for the effective interaction. As an application we sketch how our resummation method leads to a simple summation rule leading to a convergent expansion for the Schwinger functions of the planar
4
4
-theory. 相似文献
9.
Unimolecular (metastable) and collision-induced dissociation of 1,3, 5-trinitrobenzene molecular ion was studied using linked scans and mass-analyzed ion kinetic energy spectrometry on a hybrid instrument of EBEqQ geometry. An unusual ortho effect leading to the loss of OH radical from the parent molecular ion is observed as a unimolecular dissociation process only in the first-field free region between the ion source and the electric sector, although corresponding dissociation in the ion source is of negligible abundance (<0.1%). This unimolecular process is taken over by other dissociation pathways when the parent ion is collisionally activated, suggesting that this dissociation process occurs only in a very narrow energy window with a rate constant of the order of 2 x 10(5) s(-1). Copyright 2000 John Wiley & Sons, Ltd. 相似文献
10.
Bischelate platinum(II) complexes of the type [Pt(H-R(2)-N(2)C(2)S(2))(2)] (H-R(2)-N(2)C(2)S(2)(-) = dialkyl-dithioxamidate) are ditopic receptors which, after coordination of the first Pd(eta(3)-allyl)(+) moiety, induce the orientation of the second palladium-allyl fragment. Thus, a series of trimetallic complexes of formula bis-[(eta(3)-allyl)-palladium(II)](mu-bis-dialkyl-dithioxamidate-platinum(II) kappa-S,S-kappa-S',S'-Pt-kappa-N,N-Pd-kappa-N',N'-Pd') has been prepared in which the allyl fragments are oriented toward the same side of the molecular plane. We have also prepared the trimetallic complex using a dithioxamide obtained from the racemic phenylethylamine. Only two isomers were produced in equimolar ratio: the racemate that has four homochiral alkyl substituents and the mesoform containing the meso-dithioxamide that has homochiral substituents on the same side of molecular plane. Under the effect of the temperature, the trimetallic Pd-Pt-Pd complexes undergo rapid allyl isomerization; the mechanism of the isomerization, which is similar to that found by us in an analogue Pt-Pd bimetallic complex, is discussed. The crystal and molecular structure of bis-[(eta(3)-allyl)-palladium(II)](mu-bis-[S]-phenylethyl-dithioxamidate-platinum(II) kappa-S,S-kappa-S',S'-Pt-kappa-N,N-Pd-kappa-N',N'-Pd') has been reported. 相似文献