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991.
V.F. Tarasov I.S.M. Saiful Y. Ohba K. Takahashi S. Yamauchi 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2008,69(5):1327
EPR spectra of the excited quartet and doublet molecular states of (tetraphenylporphinato)zinc(II)covalently bounded to 3-(N-nitronyl-notroxide) pyridine stable radical are modeled in terms of the spin-Hamiltonian given by the sum of the contributions from the radical and triplet moieties, and the interaction between them. The later is represented by anisotropic point dipolar and isotropic exchange electron spin–spin interactions. It is shown that the high field (W-band) EPR spectra depend on energy separation between the electronic doublet (D) and quartet (Q) states. This dependence was utilized to estimate the upper limit of the intensity of exchange interaction between the radical and porphyrin moieties. 相似文献
992.
Fresnel zone plates (FZPs) were fabricated in order to evaluate the performance of nonadiabatic photolithography by exploiting
the localized nature of optical near fields. This novel photolithography scheme could realize FZPs with structures smaller
than the wavelength of the light source used for exposure. The FZP for 325-nm-wavelength UV light could focus the incident
light to a spot size of 590 nm. An FZP for focusing soft X-rays was also fabricated and, compared to conventional adiabatic
photolithography, showed higher-contrast zones over the whole area of the FZP. This method exhibits a high dynamic range and
good spatial resolution, and it was free from artifacts due to the interference of the residual propagating exposure light
transmitted through the aperture of the photomask. 相似文献
993.
We study the first positive eigenvalue (p)
1(g) of the Laplacian on p-forms for a connected oriented closed Riemannianmanifold (M, g) of dimension m. We show that for 2 p m – 2 a connected oriented closed manifold M admits three metrics g
i
(i = 1, 2, 3) such that (p)
1(g
1)> (0)
1(g
1),(p)
1(g
2) < (0)
1(g
2) and(p)
1(g
3)= (0)
1(g
3).Furthermore, if (M, g) admits a nontrivial parallel p-form,then (p)
1 (0)
1 always holds. 相似文献
994.
K. Suzuki M. Takahashi M. Takeda T. Kitazawa 《Journal of Radioanalytical and Nuclear Chemistry》2003,255(2):305-309
Four kinds of Dy(III) hexacyanometalates (II or III), DyFe(CN)6·4H2O (1), KDyFe(CN)6·4H2O (2), DyCo(CN)6·4H2O (3), and KDyRu(CN)6·4H2O (4) have been investigated by 161Dy Mössbauer spectroscopy. 161Dy isomer shifts of four compounds fall in the range of +3 ionic compounds. Although all spectra 1-4 show an almost symmetric line, the broadening of the line-width is observed on lowering the temperature due to the paramagnetic relaxation. As a parameter of intermolecular force constant, the M2 value obtained for 161Dy of 1 is slightly larger than that of 2. 相似文献
995.
996.
Takayuki Ban Yutaka Ohya Yasutaka Takahashi 《Journal of Sol-Gel Science and Technology》2003,27(3):363-372
A clear alcoholic solution of titanium alkoxide with an addition of various alkanolamines is suitable for a sol-gel coating of titania films. The reaction of titanium isopropoxide, Ti(OPr
i
)4 (TIP), with alkanolamines, such as triethanolamine (TEAH3), diethanolamine (DEAH2), and N-ethyldiethanolamine (EDEAH2), and an association of the Ti species in the resultant mixtures were examined via liquid-state nuclear magnetic resonance (NMR), infrared spectroscopy (IR), and cryoscopy measurements. Regardless of the kinds of the alkanolamines used, the IR and NMR spectra showed that alcohol exchange reactions occurred between the alcoholic moieties in alkanolamines and the isopropoxy groups in TIP, and that the N atom in the alkanolamines might be datively bonded to Ti. In the DEAH2 and EDEAH2 systems with the molar ratio of amine/TIP = 1, the results of the NMR and cryoscopy measurements showed that an association degree of the formed Ti species increased with an increase in the concentration of TIP, according to the thermodynamical equilibriums of associations between various oligomers. The increase was larger in the DEAH2 system than in the EDEAH2 one, because of the larger equilibrium constants due to the smaller size of the DEA group. In the system of EDEAH2/TIP = 2, the NMR spectra showed that only one kind of oligomer was formed as a Ti species, independent of the concentration of TIP. The oligomer may be a much more stable species than other species. The cryoscopy results showed that the oligomer had a tetrameric structure. 相似文献
997.
Takahashi K Kawakami T Gu ZZ Einaga Y Fujishima A Sato O 《Chemical communications (Cambridge, England)》2003,(18):2374-2375
The first preparation of an Fe(II) spin-crossover complex including a 1,3-dithiole ligand is reported. Crystal analyses of both the low- and the high-temperature phases reveal that short S...S contacts play a key role in an abrupt spin transition. 相似文献
998.
Takahashi S Souma K Hashimoto R Koshino H Nakata T 《The Journal of organic chemistry》2004,69(13):4509-4515
The C(2)-symmetric macrodiolide core 2 of an antiviral agent, macroviracin A (1), was constructed in a single step by the intermolecular macrodimerization of C(22)-hydroxy carboxylic acid 3 with 2-chloro-1,3-dimethylimidazolinium chloride and DMAP in the presence of sodium hydride (NaH). The use of potassium hydride instead of NaH caused the intramolecular cyclization, predominantly providing the corresponding monomer 26. The acid 3 was synthesized through a series of reactions such as the coupling reaction of acetylene 5 and oxirane 6, stereoselective glycosidation with the trichloroacetimidate method, and Jones oxidation. 相似文献
999.
Iwase Y Takahashi M Takemura Y Ju-ichi M Ito C Furukawa H Yano M 《Chemical & pharmaceutical bulletin》2001,49(10):1356-1358
Two new flavanones and one chalcone were isolated from the peel of Citrus kinokuni Hort. ex Tanaka and identified as (2S)-5,6,7,8,4'-pentamethoxyflavanone (1), (2S)-5,6,7,3',4'-pentamethoxyflavanone (2) and 2'-hydroxy-3,4,3',4',6'-pentamethoxychalcone (3). The structures of new compounds were elucidated by spectroscopic analysis. 相似文献
1000.
Shuntaro Mataka Kazufumi Takahashi Masashi Tashiro 《Journal of heterocyclic chemistry》1977,14(6):963-964
The reaction of tetrasulfur tetranitride with alkoxybenzenes such as anisole ( 1a ), o- ( 1b ), m-( 1c ), p-dimethoxybenzenes ( 1d ), and benzyl ether ( 1e ) was investigated. Benzo[1,2-c:3,4-c′ :5,6-c ]-tris[1,2,5]thiadiazole ( 2 ) and benzo[1,2, c:3,4-c′ ]bis[1,2,5]thiadiazoles ( 3a and 3b ) were isolated. J. Chem. Soc., 14, 963 (1977) 相似文献