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81.
V. N. Listvan V. V. Listvan A. N. Shekel' 《Chemistry of Heterocyclic Compounds》2002,38(12):1480-1483
The reaction of cholesteryl triphenylphosphonioacetate chloride with heterocyclic aldehydes and hetaroyloxyarenecarbaldehydes in the presence of base gave the corresponding cholesteryl esters of substituted propenoic acids possessing liquid crystal properties. 相似文献
82.
魏健文 《西南师范大学学报(自然科学版)》2002,27(3):333-337
借助于原子的矢量模型,利用“l-L”旋进带来的价电子动能增量与其相应的相互作用能的关系,给出了估算两价电子原子“l-L”旋进快慢的一般表示式。 相似文献
83.
Aida Moreira Da Silva José Empis José J.c. Teixeira-Dias 《Journal of inclusion phenomena and macrocyclic chemistry》1999,33(1):81-97
In aqueous solution, the apparent association constant at room temperature for the 1 : 1 inclusion of S-(+)-carvone in - cyclodextrin is double of that for R-(-)-carvone, whereas, at 45 °C, both enantiomers have association constants two orders of magnitude smaller, with the S-(+) inclusion being then slightly weaker than the R-(-) encapsulation. Calculations carried out at the molecular mechanics, AM1 and STO-3G levels confirm the preferential inclusion of the S-enantiomer and provide important clues for understanding chiral discrimination by -cyclodextrin. 相似文献
84.
Roy Joshua 《K-Theory》1999,17(1):1-35
Let G denote a complex linear algebraic group. In this paper we establish several forms of equivariant Riemann–Roch valid for the category of Gquasiprojective complex varieties. The main application is to the operation of convolution that appears in the construction of modules over convolution algebras, for example the Hecke algebras associated to a complex reductive group as well as in the representation theory of quantum groups. The paper concludes with a discussion of some of these applications. The results in this paper hold mostly at the level of Grothendieck groups. The second part of this paper will discuss the extension to higher Ktheory in detail. 相似文献
85.
The multiplicities a of simple modules L in the composition series of Kac modules V lambda for the Lie superalgebra
(m/n ) were described by Serganova, leading to her solution of the character problem for
(m/n ). In Serganova's algorithm all with nonzero a are determined for a given this algorithm, turns out to be rather complicated. In this Letter, a simple rule is conjectured to find all nonzero a for any given weight . In particular, we claim that for an r-fold atypical weight there are 2r distinct weights such that a = 1, and a = 0 for all other weights . Some related properties on the multiplicities a are proved, and arguments in favour of our main conjecture are given. Finally, an extension of the conjecture describing the inverse of the matrix of Kazhdan–Lusztig polynomials is discussed. 相似文献
86.
Lars Kadison 《Algebras and Representation Theory》1999,2(4):397-414
This paper begins with an introduction to -Frobenius structure on a finite-dimensional Hopf subalgebra pair. In Section 2 a study is made of a generalization of Frobenius bimodules and -Frobenius extensions. Also a special type of twisted Frobenius bimodule which gives an endomorphism ring theorem and converse is studied. Section 3 brings together material on separable bimodules, the dual definitions of split and separable extension, and a theorem of Sugano on endomorphism rings of separable bimodules. In Section 4, separable twisted Frobenius bimodules are characterized in terms of data that generalizes a Frobenius homomorphism and a dual base. In the style of duality, two corollaries characterizing split -Frobenius and separable -Frobenius extensions are proven. Sugano"s theorem is extended to -Frobenius extensions and their endomorphism rings. In Section 5, the problem of when separable extensions are Frobenius extensions is discussed. A Hopf algebra example and a matrix example are given of finite rank free separable -Frobenius extensions which are not Frobenius in the ordinary sense. 相似文献
87.
Summary Synthesis of MBAMT (3-methyl-4-benzylideneamino-5-mercapto-1,2,4-triazole) and its IR and NMR spectral data are reported. The high stability of the characteristically coloured chelates with Cu(II), Co(II), Ni(II), Pd(II), Pt(IV) and Rh(III) has been made the basis for their efficient ascending TLC separations on silica gel G layers, when present together. Results of four different solvent systems are included to assess efficient resolution of the chelates along with their limits of identification and separation. TLC separations, followed by the ring colorimetric determination of the six metal ions (as ternary mixtures) are tabulated.MBAMT=3-methyl-4-benzylideneamino-5-mercapto-1,2,4-triazole. 相似文献
88.
A. Jiménez-lópez P. Maireles-Torres P. Olivera-Pastor E. Rodriguez-Castellón M. J. Hudson P. Sylvester 《Journal of inclusion phenomena and macrocyclic chemistry》1990,9(3):207-217
The intercalation of amines into -tin(IV) hydrogen phosphate, -Sn(HP04)2·H20, (-SnP) can occur to give mono- or bilayers of the guest molecule. The distribution and orientation of the amines is influenced by geometrical factors, acidity of the guest molecule and moreover, the degree of charge localisation of the guest organic cations. Regarding the monolayer formation, there are two possibilities. The first is that aromatic amines form monolayers with parallel orientation of the amine with respect to the phosphate layer, when the charge is delocalised over the aromatic ring. Monolayer formation with perpendicular orientation occurs when the positive charge is localised in opposite parts of the aromatic ring molecule. Bilayer formation occurs when the positive charge is localised in one part of the molecule and simultaneous interaction with two adjacent layers is not possible. 相似文献
89.
Gunnar Karlström 《Theoretical chemistry accounts》1977,44(2):165-169
A new method to perform variational CI calculations on systems containing non-interacting molecules is presented. 相似文献
90.
Eberhard?ReimannEmail author Christian?Ettmayr 《Monatshefte für Chemie / Chemical Monthly》2004,135(8):959-972
Summary. N-Alkylation of certain angularly substituted heterocycles by C2- and C3-units provided appropriate precursors to construct stereoselectively the erythrinanone and several erythrinanone type analogues by intramolecular Friedel-Crafts acylation. The resulting aromatic ketones were catalytically reduced affording the corresponding parent frameworks including the hitherto unknown tetracyclus A-norschelhammerane. On the other hand, the stereoselective reduction of the carbonyl moiety offered a convenient approach to 11-hydroxylated erythrinanes with the natural occurring -configuration. The structures and the stereochemistry of the target compounds were proved by NMR spectroscopy.Part of PhD thesis, LMU München, D 相似文献