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991.
Chiral recognition and resolution of methanobenzazocines was investigated by HPLC using polysaccharide, Pirkle-type, native and derivatized β-cyclodextrin chiral stationary phases. Enantioseparation of phenyl substituted 2,6-methanobenzazocines was achieved with multiple chiral stationary phases throughout the classes described. Chiral resolution of the enantiomers of 1,5-methano-3-methyl-6-oxo-1,2,3,4,5,6-hexahydro-3-benzazocine was produced on both polysaccharide and Pirkle-type phases. In the case of 1,5-methano-3-methyl-6-phenyl-1,2,3,4,5,6-hexahydro-3-benzazocine only a dinitrophenyl substituted β-cyclodextrin produced a separation of enantiomers. 相似文献
992.
简要介绍了手性Schiff碱及其类似物和配合物在催化、医药、功能材料中的应用研究进展,为同类课题的进一步研究奠定了基础。 相似文献
993.
An efficient synthesis of ferrocenyl imidazolines starting from ferrocenyl carboxylic acids has been developed. Bis(triphenyl)oxodiphosphonium trifluoromethanesulfonate was used to convert smoothly ferrocenyl carboxylic amides bearing an amine side chain, derived from ferrocenyl carboxylic acids and 1,2-diamines, to their corresponding ferrocenyl imidazolines. 相似文献
994.
Chiral recognition of phenylalanine (Phe) was achieved in the gas phase by electrospray ionization Q-TOF tandem mass spectrometry.
In this method, two central ions, i.e. proton and divalent copper, were used and chiral crown ether, (+)-2,3,11,12-tetracarboxylic
acid-18-crown-6 (18-C-6-TCA), was used as a chiral host. Dimeric complexes were readily formed by electrospray ionization
of a methanol/water (50/50, V/V) solution containing central ions, Phe and 18-C-6-TCA. The dimeric complex included proton-bound (18-C-6-TCA)(Phe)H+ and
copper-bound deprotonated [Cu2+(18-C-6-TCA)(Phe)-H]+ ions were mass selected and then collided with Ar in the CID experiments. The chiral recognition capability of these complexes
was evaluated using the relative abundance of daughter ion to parent ion. A higher degree of chiral recognition ability was
observed with Cu2+ compared to that of H+. Different central ions exhibited distinctive dissociation pathways and unique chiral recognition characteristics. The chiral
recognition mechanism was also discussed in detail with the help of the structure of copper-bound complex predicted by theoretical
calculation. 相似文献
995.
MIAO Ru XU ZhenXiang HUANG ZhiTang & CHEN ChuanFeng Beijing National Laboratory for Molecular Science 《中国科学B辑(英文版)》2009,52(4):505-512
A series of novel N,O-type chiral ligands derived from enantiopure inherently chiral calix[4]arenes containing quinolin-2-yl-methanol moiety in
the cone or partial-cone conformation have been synthesized and characterized. Moreover, they have been applied to the catalytic
asymmetric addition of diethylzinc to benzaldehyde, which represents the first example that the inherently chiral calixarene
can be used as the chiral ligands for the catalytic asymmetric synthesis.
Supported by the National Natural Science Foundation of China (Grant Nos. 20625206 & 20372064), the National Basic Research
Project (Grant Nos. 2007CB808000 & 2008CB617501), and the Chinese Academy of Sciences 相似文献
996.
997.
Jorge San Martín Loredana Smaranda Tako Takahashi 《Journal of Computational and Applied Mathematics》2009,230(2):521-545
We consider the approximation of the unsteady Stokes equations in a time dependent domain when the motion of the domain is given. More precisely, we apply the finite element method to an Arbitrary Lagrangian Eulerian (ALE) formulation of the system. Our main results state the convergence of the solutions of the semi-discretized (with respect to the space variable) and of the fully-discrete problems towards the solutions of the Stokes system. 相似文献
998.
A. Ghose Choudhury Partha Guha Barun Khanra 《Journal of Mathematical Analysis and Applications》2009,360(2):45-664
We use a formula derived almost seventy years ago by Madhav Rao connecting the Jacobi Last Multiplier of a second-order ordinary differential equation and its Lagrangian and determine the Lagrangians of the Painlevé equations. Indeed this method yields the Lagrangians of many of the equations of the Painlevé–Gambier classification. Using the standard Legendre transformation we deduce the corresponding Hamiltonian functions. While such Hamiltonians are generally of non-standard form, they are found to be constants of motion. On the other hand for second-order equations of the Liénard class we employ a novel transformation to deduce their corresponding Lagrangians. We illustrate some particular cases and determine the conserved quantity (first integral) resulting from the associated Noetherian symmetry. Finally we consider a few systems of second-order ordinary differential equations and deduce their Lagrangians by exploiting again the relation between the Jacobi Last Multiplier and the Lagrangian. 相似文献
999.
We study chiral solitons in a quantum potential using a dimensional reduction of the problem for (2+1)-dimensional anyons. We show that the integrable version of the model is described by a family of the resonant derivative nonlinear Schrödinger equations. For a quantum potential strength s > 1, we show that the chiral soliton interaction has a resonance. We investigate the semiclassical quantization procedure for solitons. 相似文献
1000.
M. C. Nucci 《Theoretical and Mathematical Physics》2009,160(1):1014-1021
It is well known that for any second-order ordinary differential equation (ODE), a Lagrangian always exists, and the key to its construction is the Jacobi last multiplier. Is it possible to find Lagrangians for first-order systems of ODEs or for higher-order ODEs? We show that the Jacobi last multiplier can also play a major role in this case. 相似文献