动生电动势的几何意义

根据动生电动势中包含的矢量混合积,分析动生电动势的几何意义.在此基础上,对导体在磁场中运动产生的动生电动势用动生电动势的定义和求体积的方法进行求解,并从几何意义上对导体在磁场中运动时不产生动生电动势的情况进行说明.     

广东地区儿童全血铅、锰、锌、铜、铁参考区间的调查分析

微量元素检测受到多种因素的影响,其正常参考区问的建立也显得非常复杂。为建也广东地区儿童全血铅、锰、锌、铜、铁的参考区间,通过规范化的样本采集、检测过程中严格的质量控制、科学的统计方法,对来自广东地区的4968份样本进行了调查分析。分析结果表明,除全血铁外,儿童全血铅、锰、锌、铜的值呈偏态分布;广东地区绝大部分儿童全血铅水平仍处在相对安全的水平;全血锰参考值范围与大多数文献不一致,可能与工业污染有关;实验室的全血锌参考区间整体低于一般实验室,可能与使用去除了微量元素的专用采样管有关。     

Recognition algorithm of internal defect images of thermal battery北大核心CSCD

针对目前热电池内部装配缺陷检测效率低、准确度不高的问题,研究了一种可精准分割内部电池堆图像并能够准确识别缺陷种类的方法。首先采用水平、垂直积分投影法对目标电池堆边缘特征进行提取,利用局部自适应对比度增强算法对局部不清晰部分进行细节纹理增强;然后研究了缺陷结构的灰度特性,计算提取出缺陷特征参数;最后使用BP（back propagation）神经网络和CART（classification and regression tree）决策树对特征参数分类识别,并根据分类准确度进行权重分配,将加权融合后的结果作为检测的最终判据。实验结果表明:该方法对2 000个样本的检测准确度达98.9%,为热电池的X射线缺陷检测提供了有效的途径。     

On the Blow-up for Quasilinear Parabolic Equations

This article is concerned with the position of blow-up points, blow up rate and an isoperimetric problem for the equation u_t = Δu^m + u^p(p > m ≥ 1) in a convex bounded domain.     

Dirac分布的幂

本文结合发散积分的正则化方法及复阶导数概念,在基础空间D(Rⁿ)的某些子空间上,给出了Dirac分布的一些幂δ^α(x)及δ(x)ln δ(x)的确定意义。     

鲁米诺—溴酸钠—羟基化学发光体系测定痕量钌的研究和应用

本文详细地研究了应用鲁米诺－ＮａＢｒＯ３－ＯＨ＾－化学发光体系流动测定痕量钌的最佳反应条件，探讨了该化学发光反应的机理，合理地解释了一些实验现象，建立了测定痕量钌的新方法，并有很好的选择性。方法已用于测定铬铁矿和镍铜锍扣中钌的测定，获得了满意的结果，其检出限达到０．８ｎｇ／ｍｌ，相对标准偏差为３％－７％，回收率在９４％－１０７％之间。     

Explicit ion, implicit water solvation for molecular dynamics of nucleic acids and highly charged molecules

An explicit ion, implicit water solvent model for molecular dynamics was developed and tested with DNA and RNA simulations. The implicit water model uses the finite difference Poisson (FDP) model with the smooth permittivity method implemented in the OpenEye ZAP libraries. Explicit counter-ions, co-ions, and nucleic acid were treated with a Langevin dynamics molecular dynamics algorithm. Ion electrostatics is treated within the FDP model when close to the solute, and by the Coulombic model when far from the solute. The two zone model reduces computation time, but retains an accurate treatment of the ion atmosphere electrostatics near the solute. Ion compositions can be set to reproduce specific ionic strengths. The entire ion/water treatment is interfaced with the molecular dynamics package CHARMM. Using the CHARMM-ZAPI software combination, the implicit solvent model was tested on A and B form duplex DNA, and tetraloop RNA, producing stable simulations with structures remaining close to experiment. The model also reproduced the A to B duplex DNA transition. The effect of ionic strength, and the structure of the counterion atmosphere around B form duplex DNA were also examined.     

Template‐Free Synthesis of Nanorod‐Assembled Hierarchical Zn1−xMnxS Hollow Nanostructures with Enhanced Pseudocapacitive Properties

Mixed‐metal sulfide Zn_1?xMn_xS nanorod‐assembled hierarchical hollow spheres were synthesized by a template‐free solvothermal process based on Ostwald ripening. In the reaction system, glycerol plays a key role in the formation of Zn_xMn_1?xS hierarchical hollow structures by a quasi‐microemulsion‐template mechanism. When applied as capacitor electrode material, the hierarchical Zn_1?xMn_xS hollow spheres show excellent electrochemical performance. Specifically, Zn_0.25Mn_0.75S hollow spheres can deliver a high specific capacitance of 664 F g^?1 at a current rate of 1 A g^?1, which is almost five times of that of MnS under the same conditions and higher than those of previously reported single Mn‐based compounds.