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991.
We study the semi-classical ground states of the nonlinear Maxwell–Dirac system: $$\begin{aligned} \left\{ \begin{array}{l} \alpha \cdot \left( i\hbar \nabla + q(x)\mathbf{A }(x)\right) w-a\beta w -\omega w - q(x)\phi (x) w = P(x)g(\left| w\right| ) w\\ -\Delta \phi =q(x)\left| w\right| ^2\\ -\Delta {A_k}=q(x)(\alpha _k w)\cdot \bar{w}\ \ \ \ k=1,2,3 \end{array} \right. \end{aligned}$$ for \(x\in \mathbb{R }^3\) , where \(\mathbf{A }\) is the magnetic field, \(\phi \) is the electron field and \(q\) describes the changing pointwise charge distribution. We develop a variational method to establish the existence of least energy solutions for \(\hbar \) small. We also describe the concentration behavior of the solutions as \(\hbar \rightarrow 0\) . 相似文献
992.
为判别决策单元在随机DEA期望值模型下的随机有效性,首次提出了随机期望无效、随机期望弱有效、随机期望有效以及随机期望超有效的概念.并给出了三个命题用于判别不同显著性水平下随机期望效率与期望效率的关系.在此基础上,得到了两个重要的性质:(1)当期望效率保持不变时,随机期望效率为显著性水平的增函数;(2)当显著性水平保持不变时,随机期望效率为期望效率的增函数.最后,利用随机模拟和一个算例对上述结论进行了验证. 相似文献
993.
Bernstein Polynomial Estimation in the Partially Linear Model under Monotonicity Constraints
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In this paper, a Bernstein-polynomial-based likelihood
method is proposed for the partially linear model under monotonicity constraints.
Monotone Bernstein polynomials are employed to approximate the monotone
nonparametric function in the model. The estimator of the regression parameter
is shown to be asymptotically normal and efficient, and the rate of convergence
of the estimator of the nonparametric component is established, which could be
the optimal under the smooth assumptions. A simulation study and a real data
analysis are conducted to evaluate the finite sample performance of the proposed
method. 相似文献
994.
浙江杜鹃花属植物的研究 总被引:3,自引:0,他引:3
本文报道了浙江产杜鹃花属植物16 种及 1 变型其中白花满山红为新变型,丁香杜 鹃和江西杜码为浙江分布新记录.根据最新分类系统,本属分为 5 个亚属,在浙江都有 它们的代表,说明浙江的杜鹃花属植物在该属系统研究中的地位,此外,文中还附有分种 检 索表和种类列举 ( 分布、用途 ) 相似文献
995.
定光桂 《数学物理学报(B辑英文版)》2002,22(4)
In this paper, some results concerning the relationship between the bounded-ness of some spheres and the local boundedness of the F*-space are presented. Moreover, some results about the compactness are also given. 相似文献
996.
A high optical quality erbium doped Lu2SiO5 single crystal has been grown by the Czochralski method. The distribution coefficient of Er3+ was measured to be ∼0.926. The absorption and emission spectra as well as the fluorescence decay curve of the excited state 4I13/2 were measured at room temperature. The spectroscopic parameters were calculated using the Judd–Ofelt theory, and the J–O parameters Ω2, Ω4 and Ω6 were found to be 4.451×10-20, 1.614×10-20 and 1.158×10-20 cm2, respectively. The room-temperature fluorescence lifetime of the Er3+4I13/2→4I15/2 transition was measured to be 7.74 ms. The absorption and emission cross-section as well as the gain cross-section in the eye-safe regime of 1400–1700 nm were also determined and discussed. 相似文献
997.
998.
Derong Ding 《Tetrahedron letters》2010,51(9):1322-6795
2-Amino-8-oxo-tetrahydro-4H-chromene-3-carbonitriles were synthesized for the first time from a tandem Michael addition-cyclization reaction between cyclohexane-1,2-dione and benzylidenemalononitriles. An enantioselective synthesis of these compounds was achieved in moderate ee values (up to 63% ee) by using a cinchona alkaloid-derived thiourea catalyst. 相似文献
999.
J. H. Liu L. P. Wang Q. M. Xiao Z. Yao H. Ding 《Plasma Chemistry and Plasma Processing》2010,30(3):349-361
This work reports laser ionization combined with Time-Of-Flight (TOF) mass spectrometry investigation on intermediate species
in the hydrocarbon plasma of atmospheric-pressure fast-flow pulsed dc-discharge. All neutral intermediate species including
transient radicals from benzene/Ar discharge have been characterized by a molecular beam sampling combined with TOF mass spectrometry.
This shows that with a hydrocarbon gas mixture of 0.3% C6H6 in Ar discharge the intermediate species consist of simple radicals (such as C2, C5H5, C7H7) and polycyclic organic molecules (C10H8, C13H10, C14H10). Theoretical studies on total energies and ionization potentials of the intermediate species have been carried out using
the hybrid density functional theory. Effect of the ionization potential on mass spectral intensity has been discussed. Based
on the observed data, the possible major neutral reaction channels of the plasma chemistry have been discussed. The developed
experimental method has implications in volatile organic compounds removing and impurities diagnosis in Tokamak edge-plasma. 相似文献
1000.