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排序方式: 共有5103条查询结果,搜索用时 31 毫秒
11.
YBa2Cu3O7-x (YBCO) bulk is one of the most important high temperature superconducting materials for magnetic levitation applications, because it has a high magnetic irreversibility field Hirr at liquid nitrogen temperature, and can grow into large grains. The levitation force of YBCO bulk is proportional to the critical current density (Jc) and grain radius (r)[1], so higher Jc and r are appreciated for YBCO bulks to achieve higher levitation force. Now single-domain YBCO bulks up to s… 相似文献
12.
13.
设V是一个n维线性空间,V_x~m(G)为V上的张量对称类.A为V的线性算子T的矩阵,K(A)为V_x~m(G)上的诱导线性算子K(T)的矩阵.本文从K(A)的数值半径Υ(K(A))和可分数值半径Υ_x(K(A))定义出发,研究了Υ(K(A))、Υ_x(K(A))与范数||A||_p(1≤p≤2)、广义矩阵函数d_x~G(A)的关系,得到了它们之间的两个不等式. 相似文献
14.
G Padmaja A V Ravi Kumar V Vidyalal P Radhakrishnan V P N Nampoori C P G Vallabhan 《Pramana》1989,32(5):L693-L698
Laser induced plasma emission spectra from highT
c superconducting samples of YBa2Cu3O7 and GdBa2Cu3O7 obtained with 1.06μm radiation from a Q switched Nd:YAG laser beam has been analysed. The results clearly show the presence of diatomic oxides
in addition to ionized species of the constituent metals in the plasma thus produced. 相似文献
15.
原子光谱线增宽的原因 总被引:3,自引:0,他引:3
本文从理论上给出了原子光谱线增宽的几种原因 ,即 :①自然线宽 ,它是原子的内禀特性 (即在跃迁中所涉及到的能级的特性 ) ;②多普勒增宽 ,它是原子无规则热运动的结果 ;③碰撞增宽 ,它是原子间相互作用的结果。并对这几种原因分别给出了数量级上的估算。对原子光谱的测定具有参考意义。 相似文献
16.
Xiao Qi ZHENG Yong Hui WANG Qing Xiang GUO* Li YANG You Cheng LIU Department of Chemistry University of Science Technology of China Hefei National Laboratory of Applied Organic Chemistry Lanzhou University Lanzhou 《中国化学快报》2003,(8)
As artificial enzymes, the binding constants of cyclodextrins (CDs) and their substrates are expected to be high1. For this purpose, many kinds of bridged cyclodextrin dimers2 whose two cyclodextrins are linked by various spacers have been constructed. It was of interest to make the dimers, whose binding constants would exceed 108dm3/mol3. Up to date, the bridged cyclodextrin dimers have been extensively studied as enzyme models and as molecular receptors4-6. Recently, we synthesized a brid… 相似文献
17.
Santwana Mukhopadhyay 《Mechanics Research Communications》2004,31(1):81-89
The present work is concerned with the thermally induced vibration in a homogeneous and isotropic unbounded body with a spherical cavity. The Green and Nagdhi model of thermoelasticity without energy dissipation is employed. The closed form solutions for distributions of displacement, temperature and stresses are obtained. The solutions valid in the case of small frequency are deduced and the results are compared with the corresponding results obtained in other generalized thermoelasticity theories. Numerical results applicable to a copper-like material are also presented graphically and the nature of variations of the physical quantities with radial coordinate and with frequency of vibration is analyzed. 相似文献
18.
Alberto Mariani Simone Bidali Stefano Fiori Marco Sangermano Giulio Malucelli Roberta Bongiovanni Aldo Priola 《Journal of polymer science. Part A, Polymer chemistry》2004,42(9):2066-2072
By combining frontal polymerization and radical‐induced cationic polymerization, it was possible to cure thick samples of an epoxy monomer bleached by UV light. The effect of the relative amounts of cationic photoinitiator and radical initiator was thoroughly investigated and was related to the front's velocity and its maximum temperature. The materials obtained were characterized by quantitative conversion also in the deeper layers, not reached by UV light. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2066–2072, 2004 相似文献
19.
本从第一性原理出发,计算了充磁线圈产生的磁场,脉冲充磁的超导圆盘中的感应电流密度和俘获场分布.以超导体中的电流运动方程为基础,通过磁通动力学方程E=Ec(J/Jc)^n和物质方程B=μ0H表示超导圆盘的超导特性.计算表明第一个脉冲充磁电流的峰值和磁通蠕动指数对于超导圆盘中的感应电流分布非常重要.同时研究了充磁电流的宽度,波形,第二个充磁电流的峰值和充磁线圈的形状对于俘获场的影响.计算表明不断减小脉冲充磁电流峰值的反复充磁可以保持超导圆盘中的感应电流密度的平台在一确定水平. 相似文献
20.
We have presented an investigation of the induced focusing in Kerr media of two laser beams, the pump beam and the probe beam,
which could be either Gaussian or elliptic Gaussian or a combination of the two. We have used variational formalism to derive
relevant beam-width equations. Among several important findings, the finding that a very week probe beam can be guided and
focused when power of both beams are well below their individual threshold for self-focusing, is a noteworthy one. It has
been found that induced focusing is not possible for laser beams of any wavelength and beam radius. In case both beams are
elliptic Gaussian, we have shown that when power of both beams is above a certain threshold value then the effective radius
of both beams collapses and collapse distance depends on power. Moreover, it has been found that induced focusing can be employed
to convert a circular Gaussian beam into an elliptic Gaussian beam. 相似文献