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101.
Two tunneling frequencies were identified for methyl groups in hexamethylbenzene from 4.2 up to 30.9 K by means of the N.M.R. field cycling method. The frequencies were 9.6 ±- 0.4 MHz (A) and 7.9 ±- 0.4 MHz (B) at 4.2 K. The frequency A was almost independent of the temperature whereas the frequency B decreased as the temperature increased, the decrease being a linear function of T3. These facts indicate that the six methyl groups in hexamethylbenzene molecule are not independent but are coupled to one another rather strongly. 相似文献
102.
Aldehydes and ketones can be converted into γ,δ-unsaturated-β-ketoesters by reaction with the dianion from phosphine oxide . 相似文献
103.
104.
Nakamichi S Kawaguchi Y Fukuda H Enami S Hashimoto S Kawasaki M Umekawa T Morino I Suto H Inoue G 《Physical chemistry chemical physics : PCCP》2006,8(3):364-368
Buffer-gas pressure broadening for the (3 0(0) 1)(III)<--(0 0 0) band of CO(2) in the 1600 nm region was investigated with continuous wave cavity ring-down spectroscopy within the temperature range 263-326 K. The measured absorption profiles were analyzed with Voigt functions. Pressure broadening coefficient, gamma(gas), and the temperature dependent parameter (broadening exponent), n, were determined for a variety of buffer gases: N(2), O(2), He, Ne, Ar, Kr and Xe. gamma(air) values estimated subsequently are 0.096(2) for R(0), 0.085(5) for P(8), 0.075(2) for P(16), 0.070(4) for P(26), and 0.069(2) for P(38) in units of cm(-1) atm(-1), where numbers in parentheses are one standard deviation in units of the last digits quoted. n(air) values are 0.77(4) for R(0), and 0.73(11) for P(8). 相似文献
105.
106.
Lei Wang Yanpeng Qi Dongliang Wang Xianping Zhang Zhaoshun Gao Zhiyu Zhang Yanwei Ma Satoshi Awaji Gen Nishijima Kazuo Watanabe 《Physica C: Superconductivity and its Applications》2010,470(2):183-186
We report the achievement of transport critical currents in Sr0.6K0.4Fe2As2 wires and tapes with a Tc = 34 K. The wires and tapes were fabricated through an in situ powder-in-tube process. Silver was used as a chemical addition as well as a sheath material. All the wire and tape samples have shown the ability to transport superconducting current. Critical current density Jc was enhanced upon silver addition, and at 4.2 K, a largest Jc of ~1200 A/cm2 (Ic = 9 A) was achieved for 20% silver added tapes, which is the highest in iron-based wires and tapes so far. The Jc is almost field independent between 1 T and 10 T, exhibiting a strong vortex pinning. Such a high transport critical current density is attributed to the weak reaction between the silver sheath and the superconducting core, as well as an improved connectivity between grains. We also identify a weak-link behavior from the apparent drop of Jc at low fields and a hysteretic phenomenon. Finally, we found that compared to Fe, Ta and Nb tubes, Ag was the best sheath material for the fabrication of high-performance 122 type pnictide wires and tapes. 相似文献
107.
This study proposes and construct a primitive quantum arithmetic logic unit (qALU) based on the quantum Fourier transform (QFT). The qALU is capable of performing arithmetic ADD (addition) and logic NAND gate operations. It designs a scalable quantum circuit and presents the circuits for driving ADD and NAND operations on two-input and four-input quantum channels, respectively. By comparing the required number of quantum gates for serial and parallel architectures in executing arithmetic addition, it evaluates the performance. It also execute the proposed quantum Fourier transform-based qALU design on real quantum processor hardware provided by IBM. The results demonstrate that the proposed circuit can perform arithmetic and logic operations with a high success rate. Furthermore, it discusses in detail the potential implementations of the qALU circuit in the field of computer science, highlighting the possibility of constructing a soft-core processor on a quantum processing unit. 相似文献
108.
Konstantin Chernyshov Dmitry Gen Yuri Shemouratov Kirill Prokhorov Gulnara Nikolaeva Elena Sagitova Pavel Pashinin Anton Kovalchuk Alla Klyamkina Polina Nedorezova Boris Shklyaruk Valery Optov 《Macromolecular Symposia》2010,296(1):505-516
Nascent form of random copolymers of propylene with ethylene, 1-butene, 1-hexene, 1-octene, and 4-methyl-1-pentene was studied by Raman spectroscopy. The most significant spectral alterations with a change in propylene content were observed in two lines at 809 and 841 cm−1. The first line corresponds to vibrations of polypropylene helical chains in the crystalline phase, while the second one is associated with vibrations of polypropylene helical chains having isomeric defects. Raman data confirm that conformational composition and phase state of copolymer macromolecules strongly depend on the comonomer content as well as on the size of the comonomer units. 相似文献
109.
The inference for the parameters in a semiparametric regression model is studied by using the wavelet and the bootstrap methods. The bootstrap statistics are constructed by using Efron's resampling technique, and the strong uniform convergence of the bootstrap approximation is proved. Our results can be used to construct the large sample confidence intervals for the parameters of interest. A simulation study is conducted to evaluate the finite-sample performance of the bootstrap method and to compare it with the normal approximation-based method. 相似文献
110.
In this paper, using an equivalent characterization of the Besov space by its wavelet coefficients and the discretization technique due to Maiorov, we determine the asymptotic degree of the Bernstein n-widths of the compact embeddings Bq0s+t(Lp0(Ω))→Bq1s(Lp1(Ω)), t〉max{d(1/p0-1/p1), 0}, 1 ≤ p0, p1, q0, q1 ≤∞,where Bq0s+t(Lp0(Ω)) is a Besov space defined on the bounded Lipschitz domain Ω ? Rd. The results we obtained here are just dual to the known results of Kolmogorov widths on the related classes of functions. 相似文献