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排序方式: 共有110条查询结果,搜索用时 15 毫秒
1.
A. Ikegami Y. Kimura H. Suzuki T. Sato T. Tanigaki O. Kido M. Kurumada Y. Saito C. Kaito 《Surface science》2003,540(2-3):395-400
Titanium carbide formation by the solid–solid reaction on the surface of Ti nanoparticles was studied in situ using a high-resolution transmission electron microscope with a heating stage. The cross-sectional image of the Ti surface was clearly observed. Vacuum-deposited carbon covered the whole the surface of Ti nanoparticles in spite of the partly evaporation on the nanoparticle surface. The diffusion of the carbon atoms inside the Ti nanoparticles depended on the size of the nanoparticles. When the Ti nanoparticle diameter was less than 30 nm, carbon atoms diffused into the Ti nanoparticle and formed TiC. The superstructure of the Ti nanoparticles was observed, which revealed the growth process of TiC to be the diffusion of carbon atoms. For Ti nanoparticles with diameter larger than 30 nm it was observed that diffusion of Ti atoms into the carbon layer was dominant, which resulted in formation of TiC in the carbon layer at the surface of Ti nanoparticles. 相似文献
2.
Anionic cycloaddition of methyl isocyanoacetate to diethoxyacetonitrile afforded methyl 5-diethoxymethylimidazole-4-carboxylate, a useful imidazole nucleus with two different functional groups. 相似文献
3.
Abstract— The chromophore of the visual pigment of the fruit fly Drosophila melanogaster was studied by high-pressure liquid chromatography (HPLC). Oxime derivatives of the chromophore were successfully analyzed with a more polar solvent than has been used for retinaloximes. A preceding monochromatic irradiation resulted in reversible interchanges in the amount among geometric isomers of the oximes that reflected the photointerconversion of rhodopsin and metarhodopsin of the peripheral photoreceptors (Rl-R6). Authentic all- trans -3-h-ydroxyretinal was used to identify the chromophore from metarhodopsin. Results demonstrated that the chromophore of the visual pigment in Drosophila is 3-h-ydroxyretinal as was proposed in larger flies. 相似文献
4.
T. Minamisono S. Fukuda T. Ohtsubo M. Tanigaki A. Kitagawa M. Fukuda K. Matsuta Y. Nojiri S. Takeda 《Hyperfine Interactions》1993,78(1-4):191-194
Quadrupole effects in -NMR spectra of41Sc(I
=7/2–,T
1/2=0.596 s) implanted in a TiO2 single crystal were detected by use of a modified -NMR technique. Using the field gradient in the crystal determined by the pulsed-Fourier-transformed NMR of45Sc in TiO2, the quadrupole moment of41Sc has been determined as |Q(41Sc; 7/2–)|=166±8 mb. 相似文献
5.
Denning MS Watts ID Moussa SM Durand P Rosseinsky MJ Tanigaki K 《Journal of the American Chemical Society》2002,124(19):5570-5580
The high symmetry and resulting electronic degeneracy of the C(60)(3)(-) anion is viewed as the key molecular feature in the high superconducting transition temperatures of fulleride and oxidized fullerene systems. The experimental evaluation of this hypothesis requires the synthesis of face-centered cubic (fcc) trivalent fulleride anion salts derived from higher fullerenes such as C(70), which have thus far proved elusive with only stable A(1)C(70), A(4)C(70), and A(6)C(70) phases known. In this paper, we report the synthesis of fcc A(3)C(70) phases stabilized by size-matching the tetrahedral site with the sodium cation. The structures are strongly dependent on the cooling protocol due to the existence of metastable partially or completely orientationally disordered phases. EPR data indicate that the phases are metallic but not superconducting. The densities of states at the Fermi level appear too low to give superconductivity at above 5 K, consistent with recent observations that four electrons per C(70) anion are required for superconductivity. Size-matching on both the octahedral and tetrahedral sites is required for A(3)C(70) stability - K(2)CsC(70) is only stable at elevated temperature and Na(2)C(70) is unstable, the composition corresponding to C(70) and a sodium-rich trigonal phase. 相似文献
6.
Dr. Yoshikazu Ito Dr. Yoichi Tanabe Dr. H.‐J. Qiu Dr. Katsuaki Sugawara Dr. Satoshi Heguri Dr. Ngoc Han Tu Dr. Khuong Kim Huynh Dr. Takeshi Fujita Prof. Takashi Takahashi Prof. Katsumi Tanigaki Prof. Mingwei Chen 《Angewandte Chemie (International ed. in English)》2014,53(19):4822-4826
We report three‐dimensional (3D) nanoporous graphene with preserved 2D electronic properties, tunable pore sizes, and high electron mobility for electronic applications. The complex 3D network comprised of interconnected graphene retains a 2D coherent electron system of massless Dirac fermions. The transport properties of the nanoporous graphene show a semiconducting behavior and strong pore‐size dependence, together with unique angular independence. The free‐standing, large‐scale nanoporous graphene with 2D electronic properties and high electron mobility holds great promise for practical applications in 3D electronic devices. 相似文献
7.
8.
Silicon clathrate with an f-electron system 总被引:1,自引:0,他引:1
A novel crystal of Ba6Ce2Au4Si42 with Ba and Ce encapsulated into silicon-polyhedral clusters is self-assembled from the state of elemental mixture. Each atom in the crystal is arranged in its well-defined position with a nanoscale period, causing unique interactions between the conduction and the magnetic electrons originating from the independent sources of Ba and Ce, respectively. In this system, the long-distant magnetic f electrons can interact with each other through nanoscale spacing with isotropic three dimensionality, leading to the occurrence of a unique spontaneous spin ordering at 6.5 K. 相似文献
9.
Yasuaki Tokudome Kazuki Nakanishi Kazuyoshi Kanamori Koji Fujita Hirofumi Akamatsu Teiichi Hanada 《Journal of colloid and interface science》2009,338(2):506-513
Detailed nanostructures have been investigated for hierarchically porous alumina aerogels and xerogels prepared from ionic precursors via sol–gel reaction. Starting from AlCl3·6H2O and poly(ethylene oxide) (PEO) dissolved in a H2O/EtOH mixed solvent, monolithic wet gels were synthesized using propylene oxide (PO) as a gelation initiator. Hierarchically porous alumina xerogels and aerogels were obtained after evaporative drying and supercritical drying, respectively. Macroporous structures are formed as a result of phase separation, while interstices between the secondary particles in the micrometer-sized gel skeletons work as mesoporous structures. Alumina xerogels exhibit considerable shrinkage during the evaporative drying process, resulting in relatively small mesopores (from 5.4 to 6.2 nm) regardless of the starting composition. For shrinkage-free alumina aerogels, on the other hand, the median mesopore size changes from 13.9 to 33.1 nm depending on the starting composition; the increases in PEO content and H2O/EtOH volume ratio both contribute to producing smaller mesopores. Small-angle X-ray scattering (SAXS) analysis reveals that variation of median mesopore size can be ascribed to the change in agglomeration state of primary particles. As PEO content and H2O/EtOH ratio increase, secondary particles become small, which results in relatively small mesopores. The results indicate that the agglomeration state of alumina primary particles is influenced by the presence of weakly interacting phase separation inducers such as PEO. 相似文献
10.
Kenzo Inoue Hisanori Kaku Hirokazu Hayashi Teiichi Tanigaki 《Journal of polymer science. Part A, Polymer chemistry》1989,27(13):4231-4239
The copolymerization of 4-hydroxy-4′-vinylbiphenyl (HVB) with α-chloromaleic anhydride (CMAn) was investigated in THF, 1,4-dioxane, and acetonitrile. The formation of the 1:1 charge transfer complex between HVB and CMAn was confirmed spectroscopically, and the corresponding equilibrium constant (Keq) was determined as follows: Keq = 0.19, 0.11, and 0.058 mol/L in THF, 1,4-dioxane, and CH3CN, respectively. The copolymer composition is affected by the solvent, i.e., the content of HVB in the copolymer obtained in THF or 1,4-dioxane is lower than 50 mol % whereas the copolymer obtained in CH3CN has excess of HVB units. The maximum rate of copolymerization was observed at a 1:1 initial comonomer mole ratio, irrespective of the solvent polarity. Plots of Rp/[HVB] vs. [HVB] gave a straight line with a slope and an intercept for the copolymerization in THF whereas a straight line in CH3CN has no slope. On the basis of these results and 13C-NMR spectra of the copolymers, the mechanism of the predominant formation of alternating copolymers is discussed. 相似文献