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本文研究加权Bergman空间A(p,α)(B)(p>1)上Toeplitz与Hankel算子的紧性.证明了符号属于L∞(B)的Toeplitz与Hankel算子的紧性与作用空间Ap,α(B)无关 相似文献
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本文讨论了单位圆中Hardy空间H∞到p-Bloch空间βp的复合算子T1,φ加权复合算子Tψ,φ的有界性,也讨论了H∞到小p-Bloch空间β0p的复合算子T1,φ的有界性问题;另外还讨论了小p-Bloch空间到H∞空间的点乘子及小p-Bloch空间上复合算子的紧性等. 相似文献
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本文讨论了θ(t)型和(log,θ)型Calderón-Zygmund算子在加权Hardy型空间HAwp上的有界性,θ(t)型Calderón-Zygmund算子在Hardy型加权块空间上的有界性,以及广义的w-Calderón-Zygmund算子是HApw到HAp上的有界算子. 相似文献
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设 T 是一个 θ 型 Calder′on–Zygmund 算子. 本文利用Sharp极大函数估计的方法,借助交换子[b,T]在 Lp 空间上的有界性, 证明当权函数 ω 满足一定条件时,[b,T] 在加权Morrey 空间上的有界性质, 其中 b 属于 Lipschitz空间和加权Lipschitz空间. 相似文献
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本文讨论了δ-Calderon-Zygmund算子以及θ(t)-Calderon-Zygmund算子在Hardy型空间CHpq上的有界性. 相似文献
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该文在Cn中单位球上讨论了Zygmund 型空间(小Zygmund 型空间)之间的加权Cesàro 算子Tg 的有界性和紧性特征, 得到了以下的结果: (1) Tg 是Zp 到Zq的有界算子或紧算子的充要条件; (2) Tg 是 Zp0 到Zq0 的有界算子或紧算子的充要条件. 相似文献
9.
《数学物理学报(A辑)》2009,29(6):1634-1641
设φ 是Cn的开单位多圆盘上的全纯自映射,α > 0. 该文主要研究了多圆盘上的H∞与广义加权Bloch空间Bαlog(Un)之间的复合算子Cφ的有界性与紧性. 相似文献
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关于广义Calderon-Zygmund算子 总被引:2,自引:1,他引:1
本文讨论了θ(t)型和(log,θ)型Calderon-Zygmund算子在加权Hardy型空间HA^Pw上的有界性,θ(t)型Calderon-Zygmund算子在Hardy型加权块空间Bp,w上的有界性,以及广义的w-Calderon-Zygmund算子是H^p上的有界算子。 相似文献
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Xiangyi Zhang Jingwu Zhang Fuxiang Zhang Wen Yu Duanwei He Liming Cao Jianhua Zhao Riping Liu Yingfan Xu Wenkui Wang 《中国科学A辑(英文版)》1999,42(4):407-413
The formation of nanocrystalline Fe73.5 Cu1Nb3Si13.5 B9 alloy by annealing an amorphous Fe73.5Cu1Nb3Si13.5B9 alloy at a temperature of 823 K under pressures in the range of 1–5 GPa is investigated by using X-ray diffraction, electron
diffraction, and transmission electron microscopy. The high pressure experiments are carried out in belt-type pressure apparatus.
Experimental results show that the initial crystalline phase in these annealed alloys is a-Fe solid solution (named a-Fe phase
below), and high pressure has a great influence on the crystallization process of the a-Fe phase. The grain size of the a-Fe
phase decreases with the increase of pressure (P). The volume fraction of the a-Fe phase increases with increasing the pressure
as the pressure is below 2 GPa, and then decreases (Pδ2 GPa). The mechanism for the effects of the high pressure on the crystallization
process of amorphous Fe73.5Cu1Nb3Si13.5B9 alloy is discussed
Project supported by the National Natural Science Foundation of China (Grant No. 19674070) and the Natural Science Foundation
of Hebei Province. 相似文献
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Yang Li Guohui Cao Ruifei Duan Guangcan Che Zhongxian Zhao J. A. Larrea J E. M. Baggio-Saitovitch 《中国科学A辑(英文版)》2000,43(4):400-406
119Sn M?ssbauer research is carried out on (La1-xSrx),Cu1-xSnxO4(x = 0.075 and 0.110) superconductors which are designed under a new concept. The M?ssbauer spectra results show that Sn occupies
Cu position in Sn4+ state, and there is no Sn2+ ion occupying La position. The local lattice deformation near Sn4+ site is small, but displays an increasing tendency with Sn doping. For La2CuO4 matrix, the simultaneous dopings of Sr/Sn induce holes and electrons on CuO2 layer in a new mechanism which influences superconductivity. Under a new mechanism of extra oxygen, the extra oxygen effect
of Sn-doping on superconductivity is discussed 相似文献
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Duanwei He Fuxiang Zhang Xiangyi Zhang Ming Zhang Riping Liu Yingfan Xu Wenkui Wang 《中国科学A辑(英文版)》1998,41(4):405-410
C3N4 crystals with the size of several micrometers have been synthesized from C3N4H4 in the presence of nickel-based alloy or cobalt as catalyst under high pressure of 7 GPa and temperature of about 1400°C
for 10 min. Scanning electron microscopy, energy-disperse X-ray analysis, and X-ray diffraction were used to examine the grown
crystals. The general rule on selecting the starting materials for synthesis of carbon nitride crystals at high pressures
and high temperatures is suggested. 相似文献
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Jialin Zhu Liangchen Chen Richeng Yu Fengying Li Jing Liu Changqing Jin 《中国科学A辑(英文版)》2002,45(7):900-905
In situ high pressure energy dispersive X-ray diffraction measurements on the layered perovskite-like manganate Ca3Mn2O7 powder under pressures were performed by using the diamond anvil cell with synchrotron radiation. The results show that the
structure of layered perovskite-like manganate Ca3Mn2O7 is unstable under pressure due to the easy compression of NaCl-type blocks. The structure of Ca3Mn2O7 underwent two phase transitions under pressures in the range of 0–35 GPa. One was at about 1.3 GPa with the crystal structure
changing from tetragonal to orthorhombic. The other was at about 9.5 GPa with the crystal structure changing from orthorhombic
back to another tetragonal. 相似文献
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Ulyanova T. M. Basalyga I. I. Paemurd E. S. Krut'ko N. P. 《Mechanics of Composite Materials》2002,38(2):163-168
The interaction between a fibrous alumina filler and a hydrated zirconia matrix during the fabrication of ceramic composites is studied. The influence of the crystal structure and porosity of the filler on the properties of the ZrO2-Al2O3 composite material is investigated. It is found that, as a result of addition of alumina fibers of cubic and monoclinic structures (- and -phases), the ZrO2 hydrogel interacts with fibers and solid ZrO2 solutions of tetragonal structure are formed. These solutions exist over the range of 600 to 1200°C and, at annealing above 1200°C, due to crystallographic transitions the of - and -phases, they break down, namely Al2O3 transforms into -corundum and ZrO2 into a monoclinic modification. However, the material does not fail and a stable porous ceramic composite is formed. To manufacture a composite with improved mechanical characteristics, fibrous alumina fillers with the structure of -corundum must be used. 相似文献
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Caoshui Xiong Li Pi Yeqing Tang Hong Zhu Denggang Zong Junfeng Zhang Yunfei Deng Jingsheng Zhu Yuheng Zhang 《中国科学A辑(英文版)》1999,42(1):106-112
The La0,67Sr0.33Mn03 +δ/Pr0.7Cao.3Mn03+δ/La0.67Sr0.33Mn03+δ(LPL) trilayered films on (100)LaA-1O3 substrates are prepared by using direct current (DC) magnetron sputtering method. The results obtained by means of X-ray
powder diffractometer show that all films are the high quality epitaxial films. The results gained by SQUID magnetometer indicate
that there is a magnetic coupling in the LPL trilayered films. The resistivities of LSMO, PC-MO and LPL films are measured
using standard four-probe method and analyzed logp-1/T curve. From the results it is concluded that the middle-layered PCMO which is ferromagnetic may play a role of intra-magnetic
field, which weakens the paramagnetism of LSMO film, lowersp
max and enlargesT
p
which is the transition temperature from metal to insulator, just as the applied magnetic field does. And the middle-layered
PCMO may induce the change of the density of states in the LSMO’s gap. The two reasons above make the resistivity andT
p
of the samples in zero field change with the thickness of PCMO layers.
Project supported by the Chinese Academy of Sciences and the Foundation of State Science and Technology Commission of China. 相似文献
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Riping Liu Jianhua Zhao Xiangyi Zhang Duanwei He Zhicheng Qin Yingfan Xu Wenkui Wang 《中国科学A辑(英文版)》1999,42(1):74-79
The microstructure of Pd77.5Au6Si16.5alloy solidified both on board a Chinese Retrievable Satellite and on the earth is studied. Postmortem analyses of microstructure
presented that the same types of phases, primary phase (Pd3Si) and eutectics (Pd3Si + Pd solid solution) were formed in both cases. But the phase morphologies were quite different. It was dendritic for the
primary phase and lamellar for the eutectics under normal gravity condition. However, under microgravity condition the primary
phase was granular and the eutectic was peculiar network. Detailed analysis showed that the differences in morphologies of
the microstructure were due to the existence of gravity-induced buoyancy convection on the earth which increased the mass
transport abilities and decreased the thickness of the solute boundary in front of the solid-liquid interface during solidification
under normal gravity condition. 相似文献
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本文首先讨论空间l1(Xn)中的弱收敛性,然后给出了l1(Xn)中弱紧性的几种等价刻画,同时对lp(Xn)(1<p<∞)中的弱紧性也得到了类似的结果. 相似文献
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Cocalibrated G2-manifolds are seven-dimensional Riemannian manifolds with a distinguished 3-form which is coclosed. For such a manifold M, S. Salamon in Riemannian Geometry and Holonomy Groups (Longman, 1989) defined a differential complex
related with the G2-structure of M.In this paper we study the cohomology
of this complex;it is treated as an analogue of a Dolbeault cohomologyof complex manifolds. For compact G2-manifoldswhose holonomy group is a subgroup of G2 special propertiesare proved. The cohomology
of any cocalibrated G2-nilmanifold \K is also studied. 相似文献