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排序方式: 共有300条查询结果,搜索用时 15 毫秒
81.
Zn0.93Co0.07O thin films infiltrated with nitrogen and aluminum were prepared by means of magneton sputtering. The structural and magnetic
properties of the films were studied systematically. The materials were single phase (wurtzite structure) with surfaces showing
signs of homogeneous growth. The films were ferromagnetic at room temperature, and magnetic domains could be clearly observed
on the surfaces. In the case of Al infiltration, saturated magnetization increased with Al concentration increasing; whereas
in the case of N infiltration, saturated magnetization decreased with the increase in N concentration. The results show that
ferromagnetic interactions in Co-doped ZnO diluted magnetic semiconductor may be transferred by electrons.
Supported by the National Natural Science Foundation of China (Grant No. 10674059) and the Major Project of National Basic
Research Program of China (Grant No. 2005CB623605) 相似文献
82.
83.
W. Zhong W. Chen H.Y. Jiang X.S. Liu C.T. Au Y.W. Du 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,30(3):331-337
Polycrystalline two-layered perovskite La2.5-xK0.5+xMn2O
7 + δ
(0 <
x
< 0.5) samples have been prepared by a modified sol-gel method and their magnetoresistance and magnetocaloric effects have been
studied. A large deviation between the metal-insulator (MI) transition temperature (T
ρ
) and the magnetic transition temperature (TC) is observed. Large magnetoresistance (MR) effects with Δρ/ρ
of ∼40% at 12 kOe are obtained in wide temperature ranges. The maximum of the magnetic entropy change peaks at its Curie temperature
(TC), far above its MI transition temperature (T
ρ
). The large magnetic entropy change (∼1.4 J/kg.K) is obtained in the sample La2.5-xK0.5+xMn2O
7 + δ
(x
= 0.35) upon 10 kOe applied magnetic field.
Received 2 May 2002 / Received in final form 1st October 2002 Published online 19 December 2002
RID="a"
ID="a"e-mail: wzhong@ufp.nju.edu.cn 相似文献
84.
Kelly T. Au 《Mathematical Programming》1996,72(3):259-272
For optimization problems with computationally demanding objective functions and subgradients, inexact subgradient methods
(IXS) have been introduced by using successive approximation schemes within subgradient optimization methods (Au et al., 1994).
In this paper, we develop alternative solution procedures when the primal-dual information of IXS is utilized. This approach
is especially useful when the projection operation onto the feasible set is difficult. We also demonstrate its applicability
to stochastic linear programs. 相似文献
85.
86.
Synthesis,Characterization, Self‐Assembly,Gelation, Morphology and Computational Studies of Alkynylgold(III) Complexes of 2,6‐Bis(benzimidazol‐2′‐yl)pyridine Derivatives 下载免费PDF全文
King‐Chin Yim Elizabeth Suk‐Hang Lam Dr. Keith Man‐Chung Wong Dr. Vonika Ka‐Man Au Dr. Chi‐Chiu Ko Dr. Wai Han Lam Prof. Dr. Vivian Wing‐Wah Yam 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(32):9930-9939
A novel class of alkynylgold(III) complexes of the dianionic ligands derived from 2,6‐bis(benzimidazol‐2′‐yl)pyridine (H2bzimpy) derivatives has been synthesized and characterized. The structure of one of the complexes has also been determined by X‐ray crystallography. Electronic absorption studies showed low‐energy absorption bands at 378–466 nm, which are tentatively assigned as metal‐perturbed π–π* intraligand transitions of the bzimpy2? ligands. A computational study has been performed to provide further insights into the nature of the electronic transitions for this class of complexes. One of the complexes has been found to show gelation properties, driven by π–π and hydrophobic–hydrophobic interactions. This complex exhibited concentration‐ and temperature‐dependent 1H NMR spectra. The morphology of the gel has been characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). 相似文献
87.
Giedrė Kesiūnaitė Aušra Linkevičiūtė Evaldas Naujalis Audrius Padarauskas 《Chromatographia》2009,70(11-12):1691-1695
A new method involving matrix solid-phase dispersion (MSPD) extraction and UPLC in conjunction with photodiode array detection was developed for the rapid and simple determination of Sudan dyes in chili powder. Separation of Sudan I, Sudan II, Sudan III, and Sudan IV was achieved within 2 min on the 1.7 μm Acquity UPLC BEH C18 column by using gradient elution with a mobile phase consisting of acetonitrile–water at a flow rate of 0.5 mL min?1. Optimization of MSPD extraction parameters, such as type of solid sorbent and elution solvent were carried out. Optimal conditions selected for MSPD extraction were 0.25 g of sample, 0.5 g of silica gel as solid sorbent, and 7 mL of acetonitrile–methanol (9:1, v/v) as eluting solvent. Limits of detection ranged between 0.25 and 0.30 mg kg?1 depending on the dye involved. All analytes provided average recoveries from spiked (at 1, 1.5, and 2 mg kg?1) chili powder samples ranging from 81 to 106%. The method was applied to the analysis of chili powder samples obtained from different countries. 相似文献
88.
Qian Shu Li Feng Long Gu Au Chin Tang 《International journal of quantum chemistry》1994,50(3):173-179
The structure of B14, B, and B14H in octahedral symmetry has been investigated by ab initio calculations at the STO-3G and 4–31G levels. The relationship of molecular orbitals among them has been analyzed and it can be found that the number of valence bonding orbitals of high borane obeys the Wade rule. The similarities and difference between boron clusters and carbon clusters are also discussed. © 1994 John Wiley & Sons, Inc. 相似文献
89.
90.
By employing electrostatic interaction as driving force, an organic/inorganic composite with positively charged dimethyl dialkyl‐chain ammonium surfactants encapsulating negatively charged (NH4)12[Mo36(NO)4O108(H2O)16]. 33H2O polyoxoanion was prepared. The structure of the novel organic/inorganic hybrid particle with hydrophilic core and hydrophobic shell in a defined stoichiometric ratio was confirmed by element analysis, 1H NMR and FT‐IR spectra. The property of the polyoxoanion was changed due to the encapsulation and it can be dissolved in organic solvent such as chloroform, benzene and toluene, but not dissolved in water. 相似文献