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排序方式: 共有329条查询结果,搜索用时 31 毫秒
321.
322.
Bis(trifluoromethyl)-2,2′-bipyridines have been synthesized in moderate yields by nickel or palladium catalysed homocoupling of 2-chloro(trifluoromethyl) pyridines. 相似文献
323.
We exploit theoretically the occurrence and tunability of photonic Bloch oscillations (PBOs) in one-dimensional photonic crystals (PCs) containing nonlinear composites. Because of the enhanced third-order nonlinearity (Kerr-type nonlinearity) of composites, photons undergo oscillations inside tilted photonic bands, which are achieved by the application of graded external-pump electric fields on such PCs, varying along the direction perpendicular to the surface of layers. The tunability of PBOs (including amplitude and period) is readily achieved by changing the field gradient. With an appropriate graded pump ac or dc electric field, terahertz PBOs can appear and cover a terahertz band in an electromagnetic spectrum. 相似文献
324.
We study the optical response of strongly coupled metal nanoparticle chains using rigorous multiple scattering calculations. The collective resonant frequency of silver nanosphere chains and the coupling between chains are considered. The coupling between silver nanoparticle chains are understood by the transmission and reflection calculations of 2D periodic arrays of nanospheres. The results are in agreement with recent experiments. The splitting of plasmon resonance modes for different polarizations of the incident light are explored. Our results show that the transverse mode resonant wavelength is very sensitive to the inter-chain distance. Results on the effect of disorder are also presented. 相似文献
325.
Baosong Li Shoaib Anwer Xinhua Huang Shaohong Luo Jing Fu Kin Liao 《Journal of Energy Chemistry》2021,(4):202-210
Controllable synthesis of insertion-type anode materials with beneficial micro-and nanostructures is a promising approach for the synthesis of sodium-ion storage devices with high-reactivity and excellent electrochemical performance.In this study,we developed a sacrificial-templating route to synthesize TiO2@N-doped carbon nanotubes(TiO2@NC-NTs)with excellent electrochemical performance.The asprepared mesoporous TiO2@NC-NTs with tiny nanocrystals of anatase TiO2 wrapped in N-doped carbon layers showed a well-defined tube structure with a large specific surface area of 198 m2 g-1 and a large pore size of~5 nm.The TiO2@NC-NTs delivered high reversible capacities of 158 m A h g-1 at 2 C(1 C=335 m A g-1)for 2200 cycles and 146 m A h g-1 at 5 C for 4000 cycles,as well as an ultrahigh rate capability of up to 40 C with a capacity of 98 m A h g-1.Even at a high current density of 10 C,a capacity of 138 m A h g-1 could be delivered over 10,000 cycles.Thus,the synthesis of mesoporous TiO2@NC-NTs was demonstrated to be an efficient approach for developing electrode materials with high sodium storage and long cycle life. 相似文献
326.
Zhao Jing Zhu Yajuan Wong Pak Kin Li Wenfeng Yang Zhixin Li Panshuo Song Chonghui 《Nonlinear dynamics》2023,111(9):8275-8291
Nonlinear Dynamics - The vehicle active suspension has attracted considerable attention owing to its great contributions to the vertical dynamics of vehicle. This paper investigates the non-fragile... 相似文献
327.
Suk Hang Chan Lillian Sze Man Lam Wing Tak Wong Wai Kin Chan 《Macromolecular rapid communications》2000,21(15):1075-1080
We report the synthesis of a polymer that contains the diaza‐18‐crown‐6 moiety on the polymer main chain. Metal containing polymers were obtained when the respective barium or strontium complexes were used as monomers. These polymers emitted greenish blue light in solution, and the metal had little influence on absorption and emission energies. In the solid state, the position of the emission peaks was different probably due to a different degree of aggregation. 相似文献
328.
A series of novel aromatic polyamides containing 2,2′-bipyridine moiety were synthesized by polycondensation of 2,2′-bipyridine-5,5′-dicarboxylic acid ( 2 ) with various aromatic diamines in hexamethylphosphoramide (HMPA) containing lithium chloride. The resulting polyamide solutions in 98% sulfuric acid and in HMPA-LiCl exhibited lyotropic liquid crystal phases. The phase transition behaviors were studied by polarizing microscopy and X-ray diffraction. The polyamides also formed metal complexes with cis-dichlorobis(bipyridine)ruthenium dihydrate [cis-Ru(bpy)2Cl2 · 2H2O] which was supported by changes in electronic spectra. 相似文献
329.
Kin‐ya Akiba Shiro Matsukawa Kazumasa Kajiyama Masaaki Nakamoto Satoshi Kojima Yohsuke Yamamoto 《Heteroatom Chemistry》2002,13(5):390-396
By freezing Berry pseudorotation of spirophosphoranes with recourse to the rigidity of the Martin bidentate ligand, we successfully prepared configurationally stable enantiomeric pairs of optically active phosphoranes, and could isolate “anti‐apicophilic” C‐apical O‐equatorial (O‐cis) phosphoranes. The effect of σ*P O orbital of the O‐cis phosphorane was investigated both experimentally and theoretically. O‐cis phosphoranes were revealed to be much more electrophilic at the phosphorus atom than O‐trans isomers by experimental studies. The acidity of the α‐proton of an O‐cis benzylphosphorane was found to be higher than that of the corresponding O‐trans isomer. By the reaction of the α‐carbanion of an O‐cis benzylphosphorane with PhCHO, we succeeded in the first isolation and full structural characterization of a 12‐P‐6 phosphate bearing an oxaphosphetane ring, the intermediate in the Wittig type reaction using a 10‐P‐5 phosphorane. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:390–396, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/hc.10072 相似文献