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排序方式: 共有216条查询结果,搜索用时 31 毫秒
51.
Shirai J Ohmoto T Abe K Amako K Arai Y Arima T Asano Y Chiba M Chiba Y Daigo M Fukawa M Fukushima Y Haba J Hanai H Hemmi Y Higuchi M Hinode F Hirose T Homma Y Hosoda N Ishihara N Iwata Y Kanda N Kanematsu N Kanzaki J Kikuchi R Kondo T Korhonen TT Krüger AE Kurashige H MacNaughton J Matsuda EK Matsui T Miura M Miyake K Mori S Nagashima Y Nakagawa Y Nakamura T Nakano I Odaka S Ogawa K Ohama T Ohsugi T Ohyama H Okamoto A Ono A Oyama T Sakamoto H Sakuda M Sato M Sato N Shioden M Shirakata M 《Physical review letters》1994,72(21):3313-3316
52.
Osamu Haba Isao Itakura Mitsuru Ueda Shigeki Kuze 《Journal of polymer science. Part A, Polymer chemistry》1999,37(13):2087-2093
A novel nonphosgene process for producing bisphenol-A polycarbonate (PC) was developed through a transesterification between bisphenol-A (BPA) and dimethyl carbonate (DMC) and a melt-polycondensation of the resulting bisphenol-A bismethylcarbonate (1). The transesterification was carried out by heating bisphenol A in dimethylcarbonate in the presence of Lewis acid catalysts, removing the by-producing methanol using molecular shieves 4A. Among various catalysts, a combination of (Bu2SnCl)2O and dimethylaminopyridine gave the best results to produce 1 in 22% yield for 48 h. Using a larger amount of the molecular sieves further improved the yield to 80% in 120 h. The resulting 1 was heated under reduced pressure in the presence of titanium catalysts to produce PC in good yields. The resulting PC had high weight average molecular weight (Mw) of 75,000. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2087–2093, 1999 相似文献
53.
Satoru Amou Kazuhiko Takeuchi Michihiko Asai Kouichi Niizeki Takashi Okada Makoto Seino Osamu Haba Mitsuru Ueda 《Journal of polymer science. Part A, Polymer chemistry》1999,37(19):3702-3709
Regiocontrolled polymer (2) having 2-naphthol unit was prepared by oxidative coupling polymerization of bis(2-naphthol) (1). Polymerizations were conducted in dichloromethane in the presence of [di-μ-hydroxo-bis(N,N,N′,N′-tetramethylethylenediamine)copper(II)] chloride [CuCl(OH)TMEDA] under air at room temperature, producing polymers with number-average molecular weights up to 12,000. The structure of polymer 2 was characterized by 270 MHz 1H–NMR and 68.5 MHz 13C–NMR spectroscopies and was estimated to consist almost completely of 1,1′-linkage. The polymer was readily soluble in polar aprotic solvents and tetrahydrofuran at room temperature. Thermogravimetric analysis of polymer 2 showed 10% weight loss at 450°C in nitrogen. The model reactions were studied to clarify the applicability of CuCl(OH)TMEDA for coupling of naphthol derivatives. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3702–3709, 1999 相似文献
54.
Recent neutrino experiments suggest strong evidence of tiny neutrino masses and the lepton-flavor mixing. Neutrino-oscillation
solutions for the atmospheric neutrino anomaly and the solar neutrino deficit can determine the texture of the neutrino mass
matrix according to the neutrino mass hierarchies as Type A: , Type B: , and Type C: , where is the i-th generation neutrino mass. In this paper we study the stability of the lepton-flavor mixing matrix against quantum corrections
for all three types of mass hierarchy in the minimal supersymmetric Standard Model with an effective dimension-five operator
which gives the Majorana masses of neutrinos. The relative sign assignments of neutrino masses in each type play crucial role
for the stability against quantum corrections. We find that the lepton-flavor mixing matrix of Type A is stable against quantum
corrections, and that of Type B with the same (opposite) signs of and are unstable (stable). For Type C, the lepton-flavor-mixing matrix approaches the definite unitary matrix according to the
relative sign assignments of the neutrino mass eigenvalues as the effects of quantum corrections become large enough to neglect
the squared mass differences of neutrinos.
Received: 24 June 1999 / Revised version: 23 December 1999 / Published online: 17 March 2000 相似文献
55.
N. Haba Y. Matsui N. Okamura 《The European Physical Journal C - Particles and Fields》2000,17(3):513-520
Neutrino-oscillation solutions for the atmospheric neutrino anomaly and the solar neutrino deficit can determine the texture
of the neutrino mass matrix according to three types of neutrino mass hierarchy: Type A: , Type B: , and Type C: , where is the absolute mass of the ith generation neutrino. The relative sign assignments of the neutrino masses in each type of mass hierarchy play crucial roles
in the stability against quantum corrections. Actually, two physical Majorana phases in the lepton flavor mixing matrix connect
the relative sign assignments of the neutrino masses. Therefore, in this paper we analyze the stability of the mixing angles
against quantum corrections according to three types of neutrino mass hierarchy (Type A, B, C) and two Majorana phases. The
two phases play crucial roles in the stability of the mixing angles against quantum corrections.
Received: 9 May 2000 / Revised version: 23 May 2000 / Published online: 8 September 2000 相似文献
56.
Y. Chikira N. Haba Y. Mimura 《The European Physical Journal C - Particles and Fields》2000,16(4):701-705
We evaluate the one-loop fermion self-energy for the gauged Thirring model in (2+1) dimensions, with one massive fermion
flavor. We do this in the framework of the causal perturbation theory. In contrast to QED, the corresponding two-point function turns out to be infrared finite on the mass shell. Then, by means of a Ward identity,
we derive the on-shell vertex correction and discuss the role played by causality for non-renormalizable theories.
Received: 5 May 1999 / Published online: 27 January 2000 相似文献
57.
K. Masumoto T. Ohtsuki Y. Miyamoto J. H. Zaidi A. Kajikawa H. Haba K. Sakamoto 《Journal of Radioanalytical and Nuclear Chemistry》1999,239(3):495-500
Iodine, thallium and uranium were determined by photon activation analysis. Two electron linear accelerators were used for
the analysis of several kinds of environmental, biological and geochemical reference materials under different irradiation
conditions. Both analytical results for iodine were in good agreement with each other but not with literature values in the
case of environmental samples. The results of thallium and uranium agreed well with their reference values. The detectable
concentration levels of iodine, thallium and uranium were almost 0.3μg/g. 相似文献
58.
E. Segal Y. Haba M. Narkis A. Siegmann 《Journal of Polymer Science.Polymer Physics》2001,39(5):611-621
This article describes electrically conductive polymer blends containing polyaniline‐dodecyl benzene sulfonic acid (PANI‐DBSA) dispersed in a polystyrene (PS) matrix or in crosslinked polystyrene (XPS). Melt blending of previously mixed, coagulated, and dried aqueous dispersions of PANI‐DBSA and PS latices lead to high conductivities at extremely low PANI‐DBSA concentrations (∼0.5 wt % PANI‐DBSA). In these blends, the very small size of the PANI‐DBSA particles and the surface properties (with surfactants used) of both the PANI and polymer particles play a major role in the PANI‐DBSA particle structuring process. The PANI‐DBSA behavior is characteristic of a unique colloidal polymeric filler with an extremely high surface area and a strong interaction with the matrix, evidenced by a significantly higher glass‐transition temperature of the matrix. The effect of the shear level on the conductivity and morphology of the PS/PANI‐DBSA blends was studied by the production of capillary rheometer filaments at various shear rates. An outstanding result was found for XPS/PANI‐DBSA blends prepared by the blending of aqueous XPS and PANI‐DBSA dispersions. Some of these blends were insulating at low shear levels; however, above a certain shear level, smooth surface filaments were generated, with dramatically increased and stable conductivities. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 611–621, 2001 相似文献
59.
We construct a pointwise solution for the time dependent Schrödinger equation on Rd with potentials and initial conditions which can grow exponentially at infinity and belong to the class of smooth Laplace transforms of complex measures on Rd. The methods used are both analytic and probabilistic and the result can be looked upon as an extension of rigorously defined Feynman path integrals to the case of potentials which can strongly grow at infinity. An appendix with the calculation of some Wiener integrals is also presented. 相似文献
60.
H. Haba T. Akiyama D. Kaji H. Kikunaga T. Kuribayashi K. Morimoto K. Morita K. Ooe N. Sato A. Shinohara T. Takabe Y. Tashiro A. Toyoshima A. Yoneda T. Yoshimura 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,45(1):81-86
A review is given on the startup of the superheavy element (SHE) chemistry
at RIKEN. A gas-jet transport system for the SHE chemistry has been coupled
to the gas-filled recoil ion separator GARIS at the RIKEN Linear
Accelerator. The performance of the system was appraised using 206Fr
and 245Fm produced in the 169Tm (40Ar, 3n) 206Fr and
208Pb (40Ar, 3n) 245Fm reactions, respectively. The α
particles of 206Fr and 245Fm separated with GARIS and transported
by the gas-jet were identified with a rotating wheel system for α
spectrometry under desired low background condition. The high gas-jet
efficiencies over 80% were independent of the beam intensities up to 2
particle μA. A gas-jet coupled target system for the production of SHEs
was also installed on the beam line of the RIKEN K70 AVF cyclotron. The
gas-jet transport of 255No and 261Rf produced in the
238U (22Ne, 5n) 255No and 248Cm (18O, 5n) 261Rf
reactions, respectively, was conducted for the future chemical studies of
265Sg via the 248Cm (22Ne, 5n) 265Sg reaction. 相似文献