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71.
Di Zao Li Xian Dao Pan Hong Yan Liu Song Wu 《中国化学快报》2008,19(10):1202-1205
A series of 5-C-alkylating camptothecins have been synthesized by one-step method, and their in vitro antitumor activity was evaluated against six human cancer cell lines. The results showed that all 5-C-alkylates of camptothecins possessed poor cytotoxicity on six human cancer cell lines. 相似文献
72.
A 3-D Metal-organic Framework Mn(Ⅱ)Complex with Ant Net Constructed from 3-Pyridin-4-yl-benzoic Acid
A new coordination polymer, [Mn(3,4-pybz)2]n·3(H2O)(1), has been hydrothermally synthesized from Mn Cl2·4H2O and an unsymmetrical 3-pyridin-4-yl-benzoic acid(3,4-Hpybz), and characterized by IR, elemental analysis, thermogravimetric analysis, and singlecrystal X-ray diffraction. In complex 1, each 3,4-pybz ligand represents a three-connected node to combine with the six-connected Mn(II) ions, generating a 3D binodal(3,6)-connected ant network. In addition, magnetic investigations reveal that complex 1 exhibits an antiferromagnetic behavior. According to the crystal structure, the full-geometrical optimization of complex 1 was carried out by using hybrid DFT methods at the B3LYP/6-31G(d) level. Meantime, the DFT-BS approach was applied to study the magnetic coupling behavior for complex 1, and the result reveals that the calculated exchange coupling constants J were in good agreement with the experimental data. 相似文献
73.
1. IntroductionLet X and Y be p x 1 and q x 1 random vectors, respectively, and let p 5 q. PutCanonica1 correlation analysis focuses on the relationship between the two sets of randomvariables, X.. 1 and Yax 1' We ca1l EFllZl,Zdz Z2l the canonical correlation matrix (CCM).Let pf,',p; (l > Pf 2.' 2 p; 2 0) be the eigenvalues of CCM. Their positive squareroots pl )', pp are the population canonical correlation coefficients. Letbe the sample covaxiance matrix, where U'1,' 5 Wi. ar… 相似文献
74.
75.
Lincheng Zhou Guiying Li Taicheng An Yanfeng Li 《Research on Chemical Intermediates》2010,36(3):277-288
The objective of this work was to prepare novel magnetic Fe3O4/polyurethane foam (Fe3O4/PUF) composites applied to the carriers of immobilized microorganisms for toluene-containing wastewater treatment. The morphology
and structure of Fe3O4/PUF composite were characterized by X-ray diffraction, Fourier transform IR spectroscopy, thermogravimetric analysis, differential
scanning calorimetry, scanning electron microscopy, and magnetic property measurement system. These morphological investigations
revealed that Fe3O4 nano-particles were well dispersed into the matrix of PUF with nano-scale diameter particles. TG experiments indicated that
the initial thermal weight loss temperatures of composite with the content of 2.5 wt% and 7.5% Fe3O4 were increased by 7 and 16 °C, compared with pure PUF. The degradation efficiency of toluene with magnetic PUF composite
was much higher than that of pure PUF carrier, and the reason why the immobilization of microbial biomass of microorganisms
on the magnetic PUF composite was much higher than that of the pure PUF. The prepared magnetic Fe3O4/PUF composite offered excellent thermal stability and medium paramagnetic properties. And this composite could not only increase
the immobilized biomass of the microorganisms, but also enhance the COD removal efficiency of wastewater. 相似文献
76.
Zao Yang Zhizhen Ye Binghui Zhao Xiaolin Zong Ping Wang 《Journal of Sol-Gel Science and Technology》2010,54(3):282-285
ZnO nanobundles were fabricated by Sol–Gel route. The as-prepared ZnO nanobundles were characterized by XRD, FE-SEM, TEM and
PL. ZnO nanobundles structure are composed of many nanorods of about 80 nm in diameter and 0.6 μm in length. It showed weaker
UV emission and stronger green emission. A glucose biosensor was constructed using these ZnO nanobundles as supporting materials
for glucose oxidase (GOX) loading by chitosan-assisted cross-linking technique. The biosensor exhibits a high affinity, high sensitivity, and fast
response for glucose detection. These results demonstrate that zinc oxide nanostructures have potential applications in biosensors. 相似文献
77.
Based on the vectorial Rayleith-Sommerfeld formulae, the nonparaxial propagation properties of the vector hollow Gaussian beams (HGBs) through a circular aperture are studied in detail. We describe the derivation of the integral expressions of the propagation of nonparaxial vector HGBs through a circular aperture. The derived expression is independent the approximation of paraxial and far field, which are valid for either far and near field and for the systems in which aperture radius is comparable to or even smaller than wavelength. And it is also strict integral formula for the light field on the axis. Numerical calculation results indicate that there is no difference between derived formulae and the Collins formulae in the situation of paraxial approximation. Using the formula deduced, we calculate the propagation properties of HGBs. The calculated results indicate that the propagation field of vector hollow Gaussian beams is asymmetric in near field, while the propagation field is symmetric in far field. These research results could well shed light on the further understanding of the vectorial property of HGBs through a circular aperture, and would play a guiding role in the practical application of HGBs. 相似文献
78.
针对手动跟踪设备激光测距机对空中运动目标距离准测率低而难以建立目标航路的问题,提出了一种激光轴同步偏转控制技术。用摄像机摄取目标图像,并由图像处理器求出跟踪误差,控制测距机中的某些小型零部件偏转,同步改变激光发射和接收光轴,有效补偿跟踪误差,以达到提高距离准测率的目的。详述了激光发射和接收光轴变化的原理和计算方法以及激光发射与接收轴同步偏转控制技术的原理和实现方法,分析了使用该技术对跟踪仪性能的影响,介绍了室内台架试验和室外跟踪试验的试验情况,并由试验结果得出了在手动跟踪设备采用本技术后距离准测率可明显得到提高的结论,具有较高的应用和推广价值。 相似文献
79.
考虑Pr-4f及Ni-3d电子间的库仑作用U和交换作用J,采用局域自旋密度近似LSDA(Local spin-density approximation)及LSDA+U(在位库仑势)近似,对Ni4PrB化合物进行结构优化,并计算体系电子结构,能带结构和磁性能. 结果显示,Ni4PrB具备金属半导体性质,存在Pr-Ni铁磁耦合. U的引入对体系磁特性和结构稳定性有关键作用,加U前体系磁性来源为Ni原子磁矩,加U后体系磁性来源为Pr原子,且体系稳定性提高,U值的作用对于修正体系强关联有重要影响,可以合理描述由强关联和自旋排斥引发的排斥效应.
关键词:
密度泛函理论
电子键结构
磁性能
稀土过渡金属间化合物 相似文献
80.
Let (X, Y), (X_1, Y_1),\cdots, (X_n, Y_n) be i. i. d. random vectors taking values in R_d\times R with E(|Y|)<\infinity, To estimate the regression function m(x)=E(Y|X=x), we use the kernel estimate $m_n(x)=[\sum\limits_{i = 1}^n {K(\frac{{{X_i} - x}}{{{h_n}}}){Y_i}/} \sum\limits_{i = 1}^n {K(\frac{{{X_j} - x}}{{{h_n}}})} \]$ where K(x) is a kernel function and h_n a window width. In this paper, we establish the strong consistency of m_n(x) when E(|Y|^p)<\infinity for some p>l or E{exp(t|Y|^\lambda)}<\infinity for some \lambda>0 and t>0. It is remakable that other conditions imposed here are independent of the distribution of (X, Y). 相似文献