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411.
Modal analysis of nonproportionally damped linear dynamic systems is considered. Dynamic response of such systems can be expressed by a modal series in terms of complex modes. Normally state-space based methods or approximate perturbation methods are necessary for the computation of complex modes. In this paper, an iterative method to calculate complex modes from classical normal modes for general linear systems is proposed. A simple numerical algorithm is developed to implement the iterative method. The new method is illustrated using a numerical example.  相似文献   
412.
Canarene (1), a triterpene with an unprecedented carbon backbone, was isolated from Canarium schweinfurthii . It is the first member of a new class of triterpenoids, for which the name "canarane' is proposed. 1 showed weak α-glucosidase inhibitory activity, and its structure was unambiguously deduced by single-crystal X-ray diffraction.  相似文献   
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A series of ethyl 7-({2-[(substituted)carbonyl]hydrazino}carbonyl)-2,3-dihydrothieno [3,4-b][1,4]dioxine-5-carboxylates (5–13) and ethyl 7-{[({2-[(substituted)carbonyl]hydra-zino}carbonothioyl)amino]carbonyl}-2,3-dihydrothieno[3,4-b][1,4]dioxine-5-carboxy-lates (15–20) were synthesized in good yield by condensing ethyl-7-(chlorocarbonyl)-2,3-dihydrothieno[3,4-b][1,4]dioxine-5-carboxylate (4) with suitable hydrazides. The newly synthesized compounds were characterized using FTIR, 1H NMR, 13C NMR, mass spectroscopy, and elemental analyses. The anticonvulsant activity of all the title compounds was investigated against maximal electroshock-induced seizures (MES) and pentylenetetrazole (PTZ)-induced convulsion models. None of the compounds showed toxicity at the maximum dose of 2000 mg/kg. Almost all the compounds showed protection in flexion and extension stage against induced convulsion. Among them, naphthyloxy-substituted derivatives exhibited very good response against induced seizures.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.  相似文献   
416.
Journal of Nanoparticle Research - CdSe nanocrystalline thin films have been synthesized on indium tin oxide (ITO) substrates by an electrodeposition technique. A Schottky junction device in the...  相似文献   
417.
The front cover artwork is provided by the groups of Prof. Dr. Hans-Peter Steinrück and Prof. Dr. Norbert Jux at the Friedrich-Alexander-Universität (FAU) Erlangen-Nürnberg. The image shows a mixture of six 2H-tetrakis-(3, 5-di-tert-butyl-phenyl)(x)benzoporphyrins (2H-diTTBP(x)BPs, x = 0, 1, 2-cis, 2-trans, 3, or 4) molecules forming a porous square structure on Ag(111) as observed in scanning tunneling microscopy (STM) at room temperature. Read the full text of the Research Article at 10.1002/cphc.202300355 .  相似文献   
418.
Proper monomer design is the key to enhancing the strength of noncovalent interactions between the molecules toward the efficient formation of supramolecular polymers (SPs). We have designed and synthesized 1,n′-disubstituted ferrocene-azobenzene-long alkyl chains, Fc(CONH-Azo-TDP)2, to afford SPs with a high probability. The design exploits the ‘‘molecular ball-bearing’’ property of the ferrocene core, which allows two azobenzene arms to rotate in the planes of cyclopentadienyl rings, generating the most suitable molecular conformation required for SP formation. This ferrocene monomer formed a supergel consisting of SPs supported by strong intermolecular (H-bonding and π-π stacking) interactions and higher enthalpy gain than the reference molecules, where the central ferrocene core was replaced by flexible aliphatic as well as rigid benzene linkers. The molecular conformation involved in SPs, the strength of noncovalent interactions, and the process of supramolecular polymerization were investigated through NMR, UV-Vis, XRD and TEM studies. The results demonstrate that ferrocene may act as a good modulator for constructing efficient SPs.  相似文献   
419.
Using different microscopic techniques, we investigate the morphology and the micro-deformation processes in two entirely different classes of polymer based composites: natural biocomposites and synthetic polymer composites. The emphasis has been put on the comparison of the micromechanical properties of those composite materials. In the natural layered composites exemplified by human cortical bone, analogous to the synthetic glassy polymers, craze-like deformation zones were formed. A strong dependence of deformation mechanisms (such as transition from formation of single crazes to multiple crazing behaviour) on the layer dimension was observed in the layered composites made up of different amorphous polymers.  相似文献   
420.
The correlation between the morphology and the deformation mechanism in styrene/butadiene block copolymers having modified architecture and in blends with homopolymer polystyrene (hPS) was studied. It was demonstrated that the morphology formation in the block copolymers is highly coupled with their molecular architecture. In particular, the micromechanical behaviour of a star block copolymer and its blends with polystyrene was investigated by using electron microscopy and tensile testing. A homogeneous plastic flow of polystyrene lamellae (thin layer yielding) was observed if the lamella thickness was in the range of 20 nm. The deformation micromechanism switched to the formation of craze-like deformation zones when the average PS lamella thickness changed to about 30 nm and more.  相似文献   
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