矩阵的若干性质对其伴随矩阵的传递性

用对比的方法讨论了矩阵与其伴随矩阵的若干关联性质,说明了伴随矩阵对矩阵的若干性质有很好的继承性．     

关于坡上矩阵的秩

对交换坡上矩阵A的行秩、列秩、Schein秩及其性质进行了探讨,证明了在已知矩阵行秩ρr(A)=r的情况下,A的传递闭包t(A)=∑rk=1Ak,以及有关矩阵幂收敛和伴随矩阵的一些定理.     

关于坡上矩阵的秩

对交换坡上矩阵A的行秩、列秩、Schein秩及其性质进行了探讨,证明了在已知矩阵行秩pi（A）=r的情况下,A的传递闭包t（A）=r↑∑↓k=1Ak,以及有关矩阵幂收敛和伴随矩阵的一些定理．     

矩阵式电力变换器的仿真研究

与其它矩阵变换器的控制策略相比,矩阵式电力变换器的双电压控制策略具有电压增益大,抗扰动性能好的优点。文章对矩阵式电力变换器进行了Simulink仿真研究,建立了详细的仿真模型,对基波频率为50Hz、75Hz时的矩阵式电力变换器输入端电流、输出端电压的波形进行了分析。仿真分析结果验证了矩阵式电力变换器的众多优点及矩阵式电路变换器用于工程实际的可行性。     

Light-evoked changes in the interphotoreceptor matrix

The normal function of vertebrate photoreceptor cells depends on multiple interactions and transfer of substances between the photoreceptors and the retinal pigment epithelium (RPE), but the mechanisms of these interactions are poorly understood. Many are thought to be mediated by the interphotoreceptor matrix (IPM), a complex extracellular matrix that surrounds the photoreceptors and lies between them and the RPE. Histochemical, immunocytochemical, and lectin probes for several IPM constituents revealed that components of the IPM in the rat undergo a major shift in distribution or molecular conformation after the transition between light and dark. In the light, various IPM constituents concentrated in bands at the apical and basal regions of the outer segment zone; in the dark, they distributed much more uniformly throughout the zone. The change in IPM distribution was triggered by the light-dark transition; it was not a circadian event, and it was not driven by a systemic factor. The light-evoked change in IPM distribution may facilitate the transfer of substances between the photoreceptors and the RPE.     

昆虫围食膜的研究进展

围食膜是昆虫中肠的特有构造,具有多种重要功能.近几年这一领域的研究取得了突破性进展.本文从围食膜的形成机制,围食膜的组成及特性,新的围食膜模型等方面进行了综述.围食膜的形成机制研究表明,Ⅰ型围食膜昆虫的围食膜在胚胎期即存在;Ⅱ型围食膜是由前胃的特化的囊泡分泌产生的,分泌物先分泌到中肠微绒毛膜表面,最终形成围食膜.根据围食膜蛋白分离的难易程度,将蛋白分为四类,第三类蛋白是一类在强的变性剂作用下才能从围食膜中分离的成分,统称为围食膜因子(Peritrophin);目前已鉴定的有peritrophin-44, peritrophin-48, peritrophin-95, peritrophin-15, Ag-per1, IIM(Invertebrate intestinal mucin),其中一些已经进行了序列测定和功能研究.在此基础上,提出了新的围食膜结构模型.     

弹状病毒基质蛋白(Matrix protein)的研究进展

弹状病毒的基因组由1段线性单股不分节的负链RNA组成,主要编码5个结构蛋白,分别为核蛋白(Nucleoprotein,N)、磷蛋白(Phosphoprotein,P)、基质蛋白(Mattix protein,M)、糖蛋白(Glycoprotein,G)和RNA聚合酶(RNA polymerase,L).其中,基质蛋白(...     

基质金属蛋白酶生物合成与活性的调节

基质金属蛋白酶酶原生物合成基因转录水平的调节,分泌酶原的活化,活化酶的特异性抑制作用及金属蛋白酶的组织抑制物对酶原自发裂解的阻止作用是基质金属蛋白酶生物合成与活性调节的几个关键环节.     

矩阵特征根的性质及几个矩阵秩的不等式证明

全面讨论了矩阵特征根的性质,并利用矩阵的初等变换证明了矩阵秩的常用不等式。     

A rubberlike stretchable active matrix using elastic conductors

By using an ionic liquid of 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, we uniformly dispersed single-walled carbon nanotubes (SWNTs) as chemically stable dopants in a vinylidene fluoride-hexafluoropropylene copolymer matrix to form a composite film. We found that the SWNT content can be increased up to 20 weight percent without reducing the mechanical flexibility or softness of the copolymer. The SWNT composite film was coated with dimethyl-siloxane-based rubber, which exhibited a conductivity of 57 siemens per centimeter and a stretchability of 134%. Further, the elastic conductor was integrated with printed organic transistors to fabricate a rubberlike active matrix with an effective area of 20 by 20 square centimeters. The active matrix sheet can be uniaxially and biaxially stretched by 70% without mechanical or electrical damage. The elastic conductor allows for the construction of electronic integrated circuits, which can be mounted anywhere, including arbitrary curved surfaces and movable parts, such as the joints of a robot's arm.     

红锥容器育苗基质选择试验

将沤制松树皮、炭化松树皮、珍珠岩和黄心土 4种材料按不同比例配制成 6种基质配方，开展红锥育苗试验，通过不同基质理化性质与生长指标的相关分析，应用主成分分析对其育苗效果进行综合评价，旨在筛选出适宜红锥育苗生长的基质。结果表明：基质持水量与苗高、地上部分生物量和总生物量及苗木出圃率呈显著或极显著负相关，是影响红锥苗木生长的关键因素；各基质育苗效果综合评价得分值的大小顺序为T3、T4、T5、T6、T2、T1，以T3基质育苗效果最好，其次T4，T1基质育苗效果最差。建议生产上采用T3(沤制松树皮60% +珍珠岩20% +黄心土20% ) 基质作为红锥的育苗基质。     

Echinoid skeleton: absence of a collagenous matrix

Lack of hydroxyproline and proline in the calcified distal spines and Aristotle's lantern of the echinoderm Strongylocentrotus indicated the absence of a collagenous matrix. The fact that the small amount of collagen present in the base of the spines and in the test with sutures was removed by bacterial collagenase indicates that this collagen was not calcified.     

叶片传统特征和距离矩阵与角点矩阵相结合的树种识别算法

针对基于叶片特征进行树种识别的问题,本文在结合叶片纹理、不变矩以及传统形状共25维传统特征的基础上,自定义了叶尖角、边角均值等2个叶片轮廓特征,并以相似多边形定义及其推论作为理论依据,提出了一种基于叶片轮廓构建距离矩阵与角点矩阵进行树种识别的分类方法。该方法首先对树木叶片图像进行预处理,提取出归一化的叶片特征向量,然后利用KNN最近邻分类器筛选出相似度最高的前20个结果集(Top 20),然后构建距离矩阵和角点矩阵进行更为精确的识别匹配。在图像预处理阶段,为获取更为准确的叶片轮廓特征,利用叶片在HSV颜色空间中饱和度特征以及色度特征方面的显著差异性,设计了一种消除叶片阴影的图像预处理算法。在识别匹配阶段,利用Douglas Peucker approximation算法提取叶片轮廓的近似多边形,定义了距离矩阵、角点矩阵、矩阵中元素间相似度、矩阵相似度以及综合相似度计算方法,设计了全局匹配与局部匹配相结合的算法。该算法在Android系统的手机平台上进行了实现和运行验证,结果表明:在Flavia数据集中,对32种共1 907个正常叶片样本的识别准确率为99.61%,对32种共851个残叶样本的准确率为94.92%;在Leafsnap数据集中,对185种共23 147个Lab样本前5个结果集(Top 5)的识别准确率为98.26%。相对其他算法,该算法识别准确率更高,对叶片外形描述能力更强,对残叶、扭曲叶、阴影叶具有更好的鲁棒性,算法的实用性和适应性更强。      

核基质结合区与转基因植物的基因表达

核基质结合区(matrixattachmentregions,MARs)是真核细胞染色质中能与核基质结合的一段DNA序列.当MARs位于外源基因两侧时,能够使转基因植株高效、稳定表达,说明MARs是消除植物转基因沉默的一条可行途径.本文综述了MARs的研究进展,认为MARs的研究与利用对获得高效、稳定的转基因禾谷类作物具有重要的意义.