BN(110)弛豫表面电子结构的理论研究

本文利用形式散射理论的格林函数方法，采用考虑最紧邻的sp^3s^*模型描述体带，计算了BN（110）面的电子结构，分别给出了理想表面和驰豫表面的投影带结构和波矢分辨的层态密度，并进行了较详细的讨论。结果表明：BN（110）DM面的电子结构与大多数Ⅲ-Ⅴ族和Ⅱ-Ⅵ族半导体的（110）面的电子结构定性上是类似的，但在各表面态的能级位置、色散特性和轨道特性等方面均有较大的差别。这与它的反常弛豫有一定的关系。     

Ⅲ-Ⅴ族半导体化合物(311)A表面的电子结构特征

在考虑最近邻、次近邻相互作用的SP3模型基础上,采用形式散射理论的格林函数方法计算了Ⅲ-Ⅴ族半导体化合物GaAs、InSb、InAs和GaP的(311)A表面的电子结构,给出了以上半导体材料体能带的表面投影能带结构,并给出了GaAs的(311)A表面的层态密度函数,分析了各表面态沿表面布里渊区高对称线的色散特性和(311)A表面的共同电子结构特征,计算结果与实验结果基本一致.     

利用Zeeman效应测定原子能级的量子数和朗德g因子

本文阐述了通过Ｚｅｅｍａｎ效应来测定原子能级的量子数以及朗德ｇ因子的方法，理论分析并实验测定，切实可行．     

影响运动技能学习的外部因素研究

运用问卷调查法、数理统计法等研究方法，对影响运动技能学习的外部因素进行定性定量研究．经研究得出结论为：影响运动技能学习主要的外部因素按其影响作用大小排序依次为：动作难度、教师影响、场地器材、教学评价、学校中的人际关系、家庭环境，旨在提高运动技能学习效率，改善体育教学质量，充实我国的体育学习理论。     

Selection of a human chromosome 21 enriched YAC sub-library using a chromosome-specific composite probe.

The subdivision of total genomic human yeast artificial chromosome (YAC) libraries into specific chromosome clone collections will greatly facilitate the construction of an integrated genetic, physical and transcriptional map of the genome. We report the isolation of 388 YAC clones from a human library with an average insert size of 620 kilobases (kb) by the hybridization of a composite chromosome 21 probe to a high-density array of YAC clones. Roughly half of these clones hybridize to chromosome 21 by fluorescence in situ hybridization. These clones represent a twofold coverage of the chromosome. The technique offers the potential of sub-dividing whole genomic YAC libraries into their chromosomal elements to produce high-resolution tools for genome mapping.     

Biosynthesis of isoprenoids via the non-mevalonate pathway

The mevalonate pathway for the biosynthesis of the universal terpenoid precursors, isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP), is known in considerable detail. Only recently, the existence of a second mevalonate-independent pathway for the biosynthesis of IPP and DMAPP was detected in plants and certain eubacteria. Experiments with ¹³C and/or ²H-labelled precursors were crucial in the elucidation of this novel route. The pathway is essential in plants, many eubacteria and apicomplexan parasites, but not in archaea and animals. The genes, enzymes and intermediates of this pathway were rapidly unravelled over the past few years. Detailed knowledge about the mechanisms of this novel route may benefit the development of novel antibiotics, antimalarials and herbicides.Received 7 October 2003; received after revision 23 December 2003; accepted 21 January 2004     

SL(3,pn)(p≥7)的第一Cartan不变量

一般性地计算了ｐ≥７时李型有限群ＳＬ（３,ｐｎ）的第一Ｃａｒｔａｎ不变量Ｃ（ｎ）００以及射影不可分解模Ｕｎ（０）的维数ｄｉｍＵｎ（０）。     

VEGF is a modifier of amyotrophic lateral sclerosis in mice and humans and protects motoneurons against ischemic death

Amyotrophic lateral sclerosis (ALS) is an incurable degenerative disorder of motoneurons. We recently reported that reduced expression of Vegfa causes ALS-like motoneuron degeneration in Vegfa(delta/delta) mice. In a meta-analysis of over 900 individuals from Sweden and over 1,000 individuals from Belgium and England, we now report that subjects homozygous with respect to the haplotypes -2,578A/-1,154A/-634G or -2,578A/-1,154G/-634G in the VEGF promoter/leader sequence had a 1.8 times greater risk of ALS (P = 0.00004). These 'at-risk' haplotypes lowered circulating VEGF levels in vivo and reduced VEGF gene transcription, IRES-mediated VEGF expression and translation of a novel large-VEGF isoform (L-VEGF) in vivo. Moreover, SOD1(G93A) mice crossbred with Vegfa(delta/delta) mice died earlier due to more severe motoneuron degeneration. Vegfa(delta/delta) mice were unusually susceptible to persistent paralysis after spinal cord ischemia, and treatment with Vegfa protected mice against ischemic motoneuron death. These findings indicate that VEGF is a modifier of motoneuron degeneration in human ALS and unveil a therapeutic potential of Vegfa for stressed motoneurons in mice.     

视频帧内运动目标复制-粘贴篡改检测算法

摘要： 提出了一种基于Lucas_Kanade(LK)光流及运动目标预检机制的视频帧内运动目标复制 粘贴篡改检测算法.该算法分为运动目标检测与跟踪、运动序列筛选和空间域匹配3个阶段.运动目标检测与跟踪利用背景建模算法和卡尔曼滤波器进行检测和跟踪;运动序列的筛选采用LK方法得到各运动序列的光流值,并计算其相关性来选择可能存在篡改的视频帧序列;空间域匹配利用尺度不变特征变换算法对上一阶段得到的对应运动序列逐帧进行匹配,过滤正常的视频序列.实验结果表明,本文算法能有效检测同源视频中针对运动目标的多帧复制 粘贴篡改.     

协作WSN路由算法的能耗及其影响因素研究

研究了一般拓扑意义下的无线传感器网络协作路由算法的能耗情况及其影响因素.在Amir协作链路费用模型的基础上,从理论上证明了协作路由传递一定会带来能量节省.同时,从实践的角度研究了节点收发电路能耗对路由算法节能效果的影响.仿真结果表明:在自由空间模型下,能量节省值与收发电路能耗成反比,其极限值为收发电路能耗值为零时的能量节省值;协作路由的能量节省值还与参与协作的节点数量、网络中的节点总数呈正相关的关系.