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991.
采用密度泛函理论(DFT)中的B3LYP方法, 在LANL2DZ基组水平上, 优化了C19M(M=Cr,Mo,W)团簇的几何结构, 得出了它们的基态构型, 并研究了基态结构的物理化学性能.结果表明: 不同的M原子替换后, C19M的动力学稳定性相差不大, 而热力学稳定性随着M原子序数的增加而逐渐升高; 通过对C19M的前线轨道分析发现, M原子对各个轨道均有一定的贡献, M原子对各个轨道的贡献大致随着M原子序数的增加而增加, C19M中金属原子M(M=Cr,Mo,W)上集中了大量的正电荷; C19M的芳香性随着M原子序数的增加而减弱. 相似文献
992.
Minghua Li Gan HanLei Ding Xiaocui WangYang Liu Chun FengHaicheng Wang Guanghua Yu 《Journal of magnetism and magnetic materials》2012,324(1):1-3
The anisotropic magnetoresistance (AMR) of a Ta (5 nm)/MgO (3 nm)/Ni81Fe19 (10 nm)/MgO (2 nm)/Ta (3 nm) film with MgO-Nano Oxide Layer (NOL) increases dramatically from 1.05% to 3.24% compared with a Ta (5 nm)/Ni81Fe19 (10 nm)/Ta (3 nm) film without the MgO-NOL layer after annealing at 380 °C for 2 h. Although the MgO destroys the NiFe (1 1 1) texture, it enhances the specular electron scattering of the conduction electrons at the NOL interface and suppresses the interface reactions and diffusion at the Ta/NiFe and NiFe/Ta interfaces. The NiFe (1 1 1) texture was formed after the annealing, resulting in a higher AMR ratio. X-ray photoelectron spectroscope results show that Mg and Mg2+ were present in the MgOx films. 相似文献
993.
Nanocomposite of hard (BaFe12O19)/soft ferrite (Ni0.8Zn0.2Fe2O4) have been prepared by the sol–gel process. The nanocomposite ferrite are formed when the calcining temperature is above 800 °C. It is found that the magnetic properties strongly depend on the presintering treatment and calcining temperature. The “bee waist” type hysteresis loops for samples disappear when the presintering temperature is 400 °C and the calcination temperature reaches 1100 °C owing to the exchange-coupling interaction. The remanence of BaFe12O19/Ni0.8Zn0.2Fe2O4 nanocomposite ferrite with the mass ratio of 5:1 is higher than a single phase ferrite. The specific saturation magnetization, remanence magnetization and coercivity are 63 emu/g, 36 emu/g and 2750 G, respectively. The exchange-coupling interaction in the BaFe12O19/Ni0.8Zn0.2Fe2O4 nanocomposite ferrite is discussed. 相似文献
994.
The non-isothermal crystallization kinetics of La2CaB10O19 (LCB) from a La2O3-CaO-B2O3 glass was studied. Differential thermal analysis methods were performed on three glass powders to obtain the kinetic parameters of LCB crystallization mechanism. The activation energies for overall crystallization (E), obtained by the methods of Kissinger and Ozawa, were in the range of 479-569 kJ/mol. Multiple (five) analysis methods were used to estimate the Avrami exponent (n), which could consequently be reduced into the single value of n = 3.1 ± 0.3. The growth morphology index (m) of LCB was corroborated by microscopy (optical and electron) images, which revealed a three dimensional growth. Energy dispersive spectroscopy confirmed that LCB is the crystallizing phase from the glass by an interface controlled mechanism. The parameters of the Johnson-Mehl-Avrami kinetic model for the analysis of LCB crystallization from glass were found to be n = m = 3. 相似文献
995.
We decompose the K-theory space of a Waldhausen category in terms of its Dwyer–Kan simplicial localization. This leads to a criterion for functors to induce equivalences of K-theory spectra that generalizes and explains many of the criteria appearing in the literature. We show that under mild hypotheses, a weakly exact functor that induces an equivalence of homotopy categories induces an equivalence of K-theory spectra. 相似文献
996.
Vladimir Tolstykh 《Journal of Pure and Applied Algebra》2011,215(9):2086-2098
Let F be an infinitely generated free group and let R be a fully invariant subgroup of F such that (a) R is contained in the commutator subgroup F′ of F and (b) the quotient group F/R is residually torsion-free nilpotent. Then the automorphism group of the group F/R′ is complete. In particular, the automorphism group of any infinitely generated free solvable group of derived length at least two is complete.This extends a result by Dyer and Formanek (1977) [7] on finitely generated groups Fn/R′ where Fn is a free group of finite rank n at least two and R a characteristic subgroup of Fn. 相似文献
997.
You Qing Ji 《Linear algebra and its applications》2011,434(10):2149-2157
In this paper, we estimate the stable ranks of a Banach algebra in terms of the stable ranks of its quotient algebra and ideal under the assumption that the quotient map splits. As an application, several results about the Bass and the connected stable ranks of nest algebras are obtained. 相似文献
998.
Jinkui Wan 《Journal of Pure and Applied Algebra》2011,215(7):1569-1581
We formulate a theory of invariants for the spin symmetric group in some suitable modules which involve the polynomial and exterior algebras. We solve the corresponding graded multiplicity problem in terms of specializations of the Schur Q-functions and a shifted q-hook formula. In addition, we provide a bijective proof for a formula of the principal specialization of the Schur Q-functions. 相似文献
999.
M. Bayat 《Linear algebra and its applications》2011,435(11):2936-2941
In this paper, we give a generalization of a determinantal identity posed by Charles R. Johnson about minors of a Toeplitz matrix satisfying a specific matrix identity. These minors are those appear in the Dodgson’s condensation formula. 相似文献
1000.