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31.
32.
The Chebychev polynomials associated to any given moments μn ∞ 0 are formally orthogonal with respect to the formal δ-series $$w(x)= {\sum^\infty_0}(- 1)^{n}\mu_{{n}}\delta^{(n)}(x)/n!.$$ We show that this formal weight can be a true hyperfunctional weight if its Fourier transform is a slowly increasing holomorphic function in some tubular neighborhood of the real line. It provides a unifying treatment of real and complex orthogonality of Chebychev polynomials including all classical examples and characterizes Chebychev polynomials having Bessel type orthogonality. 相似文献
33.
J. J. Engelen S. J. de Jong M. Poletiek J. A. M. Vermaseren 《Zeitschrift fur Physik C Particles and Fields》1988,41(1):173-177
We present cross sections for heavy flavour production through photon gluon fusion in electron proton collisions at HERA energy. The electron photon vertex is taken into account explicitly, and theQ 2 of the exchanged photon ranges from nearly zero (almost real photon) to the kinematically allowed maximum. In our approach the scale is set by the mass of the produced quarks. Our formalism is also applicable to the production of light quarks as long as the invariant mass of the pair is sufficiently high, so we also give cross sections for \(u\bar u,d\bar d\) and \(s\bar s\) production. 相似文献
34.
Three new polyoxygenated briarane-type diterpenoids, briaexcavatolides X-Z (1-3), have been isolated from the gorgonian coral Briareum excavatum. The structures, including the relative configurations of briaranes 1-3, were elucidated by spectroscopic methods, particularly in 1D and 2D NMR experiments. The configuration of briarane 1 was further supported by molecular mechanics calculations. 相似文献
35.
A new class of chiral dienophiles, 5-alkoxy-2(5H)-furanones, has been developed. Both enantiomers of 5-menthyloxy-2(5H)-ftiranone are readily available in enantiomerically pure form, starting from furfural and d- or l-menthol. Excellent diastereoselectivities (d.e. β99%) are obtained in thermal Diels-Alder reactions with several cyclic and acyclic dienes. The use of silyl dienol ethers has resulted in new routes to enantiomerically pure cyclohexanones in a highly regioselective manner. 相似文献
36.
37.
ω-Tetrahydropyran-2-ylsulfanylalkylmagnesium chlorides are prepared as Grignard reagents containing protected mercaptoalkyl chains, which are useful for the direct introduction of ω-mercaptoalkyl chains to electrophiles. In order to prove the usefulness of these reagents, they were reacted with buckminsterfullerene (C60) to give 1-(ω-mercaptoalkyl)-1,2-dihydrobuck minsterfullerenes after the deprotection of THP group with TFA. 相似文献
38.
An analytical method has been developed for determination of dextromethorphan (DMP) and dextrorphan (DRP) in human hair by gas chromatography–mass spectrometry (GC–MS). Hair samples (30 mg) were washed with distilled water and acetone and cut into small fragments (<1 mm) before extraction with methanol. The extracts were evaporated to dryness and then derivatized by use of BSTFA containing 1% TMCS, for preparation of the trimethylsilyl (TMS) derivative of DRP. The extract (1 μL) was then injected into the GC–MS. Recoveries of DMP and DRP at 7.0 and 22.5 ng mg?1 were in the range 90.6–97.2% with intra-assay and inter-assay precision of less than 5.7% and 4.7%, respectively. LOD and LOQ were, respectively, 0.67 and 2.13 ng mg?1 for DMP and 0.14 and 0.47 ng mg?1 for DRP. The responses were linear with correlation coefficients (r > 0.9995) for the drugs studied. The applicability of the method was proven by analysis of authentic hair samples. 相似文献
39.
Tae Oan Ahn Jung Ho Kim Jong Chan Lee Han Mo Jeong Jong-Yoon Park 《Journal of polymer science. Part A, Polymer chemistry》1993,31(2):435-441
A macro-azoinitiator containing polyarylate segment and azo group was prepared by the solution polycondensation of azobiscyanopentanoyl chloride and hydroxy-terminated polyarylates having viscosity-average molecular weights of 6200, 8100, and 12 400. These macro-azoinitiators were used in the radical polymerization of styrene to synthesize polyarylate-polystyrene block copolymers. Thermal properties measured by the differential scanning calorimetry indicated the phase separated morphology of the block copolymers except at low molecular weight of the block constituents. © 1993 John Wiley & Sons, Inc. 相似文献
40.
Kwak WJ Han CK Chang HW Kim HP Kang SS Son KH 《Chemical & pharmaceutical bulletin》2003,51(3):333-335
A new triterpenoid saponin, loniceroside C was isolated from the aerial parts of Lonicera japonica. Its structure was established to be 3-O-beta-D-glucopyranosyl hederagenin 28-O-alpha-L-rhamnopyranosyl (1-->2)-[beta-D-xylopyranosyl(1-->6)]-beta-D-glucopyranosyl ester by spectroscopic techniques and chemical transformations. Loniceroside C showed in vivo antiinflammatory activity against mouse ear edema provoked by croton oil. 相似文献