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排序方式: 共有1387条查询结果,搜索用时 15 毫秒
91.
Masao Sumita Hibeki Abe Hiroyuki Kayaki Keizo Miyasaka 《Journal of Macromolecular Science: Physics》2013,52(1-2):171-184
The electrical conductivities of carbon-black-filled low-density polyethylene (LDPE), poly(methyl methacrylate) (PMMA), and poly(vinyl chloride)-vinyl acetate (PVC/ VAc) copolymer were measured as functions of carbon content and melt viscosity of the matrix at the temperatures at which the composites were prepared. Sharp breaks in the relationship between the carbon filler content and the conductivity of composites were observed in all specimens at some content of the carbon filler. The conductivity jumps as much as 10 orders of magnitude at the break point. This phenomenon has been known as the “percolation threshold”. The critical carbon content corresponding to the break point 相似文献
92.
Masao Hirano Shigetaka Yakabe James H. Clark Hiroyuki Kudo Takashi Morimoto 《合成通讯》2013,43(10):1875-1886
A wide variety of sulphides can be readily converted to the corresponding sulphoxides in good to excellent yields by treatment with a combination of sodium chlorite, (salen)manganese(III) complex, and chromatographic alumina in dichloromethane under mild and neutral conditions. 相似文献
93.
94.
95.
Akagi M Omae D Tamura Y Ueda T Kumashiro T Urata H 《Chemical & pharmaceutical bulletin》2002,50(6):866-868
L-Ribose was synthesized by a simple four-step method with overall yield of 76.3% from a protected L-arabinose derivative, which is a compatible intermediate for the synthesis of L-deoxyribose. The key step of this strategy is the Swern oxidation and subsequent stereoselective reduction accompanied by inversion of the 2-hydroxy group of protected L-arabinose. 相似文献
96.
Kubo K Akemoto M Anderson S Aoki T Araki S Bane KL Blum P Corlett J Dobashi K Emma P Frisch J Fukuda M Guo Z Hasegawa K Hayano H Higo T Higurashi A Honda Y Iimura T Imai T Jobe K Kamada S Karataev P Kashiwagi S Kim E Kobuki T Kotseroglou T Kurihara Y Kuriki M Kuroda R Kuroda S Lee T Luo X McCormick DJ McKee B Mimashi T Minty M Muto T Naito T Naumenko G Nelson J Nguyen MN Oide K Okugi T Omori T Oshima T Pei G Potylitsyn A Qin Q Raubenheimer T Ross M Sakai H Sakai I Schmidt F Slaton T Smith H 《Physical review letters》2002,88(19):194801
Electron beams with the lowest, normalized transverse emittance recorded so far were produced and confirmed in single-bunch-mode operation of the Accelerator Test Facility at KEK. We established a tuning method of the damping ring which achieves a small vertical dispersion and small x-y orbit coupling. The vertical emittance was less than 1% of the horizontal emittance. At the zero-intensity limit, the vertical normalized emittance was less than 2.8 x 10(-8) rad m at beam energy 1.3 GeV. At high intensity, strong effects of intrabeam scattering were observed, which had been expected in view of the extremely high particle density due to the small transverse emittance. 相似文献
97.
7-Ethynylcycloheptatriene (1) cleanly isomerizes to phenylallene in the presence of acid. A mechanism involving the protonation of ethynylnorcaradiene, which is in equilibrium with 1, followed by the cleavage of a three-membered ring to give an arenium ion, is proposed. The rearrangement is accelerated by a factor of 370 by introducing tert-butyl groups on C-2 and C-5, indicating the importance of the equilibrium concentration of the norcaradiene form as a rate-controlling factor. 相似文献
98.
99.
Toshio Motojima Shun-Ichi Ikawa Masao Kimura 《Journal of Quantitative Spectroscopy & Radiative Transfer》1981,25(1):29-33
Infrared absorption intensities of the fundamental vibrations of liquid H2O have been obtained by measuring transmissions at two sample thicknesses (about 9 and 0.9 μ). The effect of multiple internal reflections on the observed absorptions is examined in terms of thin-film optics. It is shown that this simple method yields precise absorption intensities, without corrections for the effects of multiple internal reflections. The resulting intensities are 89.9 × 103 cm/mmol and 5.91 × 103 cm/mmol for the stretching and bending vibrations, respectively. The latter value was estimated after eliminating the absorption of intermolecular vibrations from the 1400–2400 cm-1 region by means of computer simulation. 相似文献
100.
Masao Doi 《Journal of Polymer Science.Polymer Physics》1980,18(5):1005-1020
The primitive chain model of Doi and Edwards is generalized to include the short-time relaxation process. Stress relaxation after a sudden imposition of strain is studied in detail. It is shown that in the linear region (small strain) stress relaxation occurs in two steps, the relaxation of chain segments between the fixed entanglement points, and the relaxation of the entanglement points, in accordance with the conventional picture, whereas in the nonlinear region (large strain) there appears a new relaxation process between the above two. The characteristic time of this process is the Rouse relaxation time which the entire chain would have if there were no entanglements, and increases with the square of the molecular weight. This result is consistent with experimental observations. 相似文献