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351.
Roussel C Fihi R Ciamala K Vebrel J Zair T Riche C 《Organic & biomolecular chemistry》2003,1(15):2689-2698
Cycloaddition of nitrones 1 with methylene-gamma-butyrolactones 2, 3 and 4 afforded spiroadducts 5, 6 and 7 with high selectivity. Mixtures of diastereoisomers were usually obtained, whose structures were established by 1H and 13C NMR spectroscopies or X-ray crystallography. Treatment of spiroadducts in acidic and alkaline media led to different, unexpected and novel rearrangements. 相似文献
352.
353.
Rachid Hamdi Badr-Eddine Benkelfat Qin Zou Yaneck Gottesman 《Optics Communications》2007,269(1):64-68
We demonstrate that in addition to their role in tuning the wavelength of an N-stage hybrid liquid-crystal Šolc filter, liquid-crystal cells can also be used to vary the transmission bandwidth of such filter around any of the tuned wavelength. This bandwidth tuning is based on the variation of the number of stages by what we call here an “optical cancelling technique”. This is achieved by varying the birefringence of the liquid-crystal cells whose optical path difference switches between two particular values. We show that for a 10-stage filter and at λi = 1.532 μm, the calculated 3-dB bandwidth varies from 2.6 to 11.8 nm when the number of “optically-cancelled” hybrid plates increases from 0 to 8. During the tuning process, the contrast ratio remains equal to that of the equivalent classical Šolc filter. 相似文献
354.
Rachid Essehli Brahim El Bali Mohammed Lachkar Michael Dusek Fejfarova Karla Michael Bolte 《Journal of chemical crystallography》2006,36(10):655-660
(C2N2H10)2Mg(HP2O7)2·2H2O, is a new inorganic organic hybrid structure. It has been synthetized using wet chemistry. Its crystal structure consists of cis- and trans-edge sharing [MgO4(H2O)2] octahedra resulting in chains, which are linked via [HP2O7] units to form [Mg(HP2O7)2(H2O)2]4− layers. The Mg2+ cations and the ethylendiammonium cations are located on centers of inversion. The ethylendiammonium cations are alternately located in the interlayer space. The cohesion of the crystal is well ensured by coulombic interactions between anions and cations and by several hydrogen bonds. The diphosphate anion shows an eclipsed conformation. 相似文献
355.
Chafiq Maryam Chaouiki Abdelkarim Lgaz Hassane Salghi Rachid Bhaskar K. Vijaya Thakur Poorvi Singh Bhat K. Subrahmanya Ali Ismat H. Khan Mohammad I. Chung Ill-Min 《Research on Chemical Intermediates》2020,46(6):2881-2918
Research on Chemical Intermediates - Developing environmentally friendly products is a modern science and an important task for today's chemistry and technology scholars. In the present... 相似文献
356.
Matmour R Joncheray TJ Gnanou Y Duran RS 《Journal of colloid and interface science》2007,311(1):315-321
A novel approach to two-dimensionally crosslink polydienes at the air/water interface is proposed. The acid-catalyzed condensation of the triethoxysilane pendant groups of triethoxysilane-functionalized polybutadiene chains at the air/water interface successfully led to the formation of an insoluble crosslinked material which could be directly removed from the water surface. The efficiency of the cross-linking reaction was demonstrated through surface pressure measurements such as surface pressure-mean molecular area isotherms recorded at different reaction times and isobar experiments for different subphase pH values. The evolution of the monolayer topography during cross-linking was studied by atomic force microscopy imaging of the Langmuir-Blodgett films. 相似文献
357.
Rachid Chaili 《Annali dell'Universita di Ferrara》2014,60(2):339-345
We give a microlocal version of the theorem of the iterates for quasihomogeneous hypoelliptic operators in anisotropic Gevrey spaces. 相似文献
358.
Mhamed El Achhab Andreas Erbe Georg Koschek Rachid Hamouich Klaus Schierbaum 《Applied Physics A: Materials Science & Processing》2014,116(4):2039-2044
The structure and distribution of TiO2 rutile and anatase phases of anodized titanium foil, subjected to a special high-voltage electrochemical preparation technique, are reported. We applied X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy on samples that were oxidized for various times. Combining data from the different techniques led to a model in which the initially formed porous, micrometer-thick TiO2 layer, consisting in a large part of anatase, is transformed into rutile. The result is a porous rutile layer on top of anatase, which is in direct contact with the Ti metal. The first structural model is derived from the evaluated data and the phenomena that occurred during preparation are clarified. 相似文献
359.
360.
This review, divided into three sections, describes the contribution of the chemists' community to the development and application of triple helix strategy by using artificial nucleic acids, particularly for the recognition of DNA sequences incorporating base pair inversions. Firstly, the development of nucleobases that recognise CG inversion is surveyed followed secondly by specific recognition of TA inverted base pair. Finally, we point out in the last section recent perspectives and applications, driven from knowledge in nucleic acids interactions, in the growing field of nanotechnology and supramolecular chemistry at the border area of physics, chemistry and molecular biology. 相似文献