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171.
Julien Ferrari Christian Terreaux Tibor Kurtn Attila Szikszai‐Kiss Sndor Antus JeromeD. Msonthi Kurt Hostettmann 《Helvetica chimica acta》2003,86(8):2768-2778
Investigation of the methanol extract of the roots of Gnidia involucrata (Thymelaeaceae) led to the isolation and characterization of two new 3,8″‐biflavonoid diastereoisomers, named GB‐4 ( 6a ) and GB‐4a ( 6b ). Their absolute configurations were determined in mixture by on‐line LC/CD measurements, which also allowed the revision of absolute configurations of the biflavanoids GB‐1 and GB‐2, and the configurational assignment of GB‐3. 相似文献
172.
A model is developed for the analysis of factors influencing organizational and technological changes associated with CAD and CAD/CAM (computer-aided design/computer-aided manufacture). Different pressures for adoption and the sociopolitical environment of the organization and related to managerial strategies and their impact on skills, tasks, training, and changes in work organization. Opportunities are illustrated through the experiences of seven British engineering companies implementing the technologies. Six of the companies are in manufacturing and one is an engineering services organization. Four of the companies are of small to medium size (under 500 employees) and the other three are large, multisite organizations. Key elements of the technological change are identified, and the position of the seven companies in relation to these elements is summarized and discussed 相似文献
173.
174.
Stuart P. RomerilVictor Lee Jack E. Baldwin Timothy D.W. ClaridgeBarbara Odell 《Tetrahedron letters》2003,44(42):7757-7761
The absolute configuration of the marine sponge alkaloid pyrinodemin A is established by organic synthesis. 相似文献
175.
176.
Aiqing Zhang Xiangdan Li Changwoon Nah Keejun Hwang Myong‐Hoon Lee 《Journal of polymer science. Part A, Polymer chemistry》2003,41(1):22-29
A soluble aromatic polyimide was chloromethylated via a reaction with chloromethyl methyl ether in the presence of tin(IV) chloride to produce a new starting material for the modification of aromatic polyimides. The chemical structure of the resulting polymer was confirmed by 1H NMR and Fourier transform infrared spectroscopy. The maximum number of chloromethyl groups per repeat unit was 1.81. The chloromethylated polyimide was stable up to 250 °C and soluble in both chloroform and tetrahydrofuran. So that its utilization for further modification could be demonstrated, cinnamic acid was reacted with the formed polyimide, and it produced a new photosensitive polyimide with a cinnamoyl side chain. The photosensitivity of the resulting polyimide was investigated with ultraviolet spectroscopic methods. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 22–29, 2003 相似文献
177.
The goal of the paper is to analyse properties of solutions for linear thermoelastic systems of type III in one space variable. Our approach does not use energy methods, it bases on a special diagonalization procedure which is different in different parts of the phase space. This procedure allows to derive explicit representations of solutions. These representations help to prove results for well‐posedness of the Cauchy problem, LP–Lq decay estimates on the conjugate line and results for propagation of singularities. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
178.
The original article to which this Erratum refers was published in Journal of Graph Theory 47:129–146,2004 . 相似文献
179.
Jenn‐Long Liu 《国际流体数值方法杂志》2004,44(12):1299-1315
This paper presents a relaxation algorithm, which is based on the overset grid technology, an unsteady three‐dimensional Navier–Stokes flow solver, and an inner‐ and outer‐relaxation method, for simulation of the unsteady flows of moving high‐speed trains. The flow solutions on the overlapped grids can be accurately updated by introducing a grid tracking technique and the inner‐ and outer‐relaxation method. To evaluate the capability and solution accuracy of the present algorithm, the computational static pressure distribution of a single stationary TGV high‐speed train inside a long tunnel is investigated numerically, and is compared with the experimental data from low‐speed wind tunnel test. Further, the unsteady flows of two TGV high‐speed trains passing by each other inside a long tunnel and at the tunnel entrance are simulated. A series of time histories of pressure distributions and aerodynamic loads acting on the train and tunnel surfaces are depicted for detailed discussions. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
180.
A least‐squares meshfree method based on the first‐order velocity–pressure–vorticity formulation for two‐dimensional incompressible Navier–Stokes problem is presented. The convective term is linearized by successive substitution or Newton's method. The discretization of all governing equations is implemented by the least‐squares method. Equal‐order moving least‐squares approximation is employed with Gauss quadrature in the background cells. The boundary conditions are enforced by the penalty method. The matrix‐free element‐by‐element Jacobi preconditioned conjugate method is applied to solve the discretized linear systems. Cavity flow for steady Navier–Stokes problem and the flow over a square obstacle for time‐dependent Navier–Stokes problem are investigated for the presented least‐squares meshfree method. The effects of inaccurate integration on the accuracy of the solution are investigated. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献