显示条目: 17439-17458 / 166236

    • K(3)Ln OB(OH)(2) (2) HOPO(3) (2) (Ln=Yb, Lu): Layered rare-earth dihydrogen borate monohydrogen phosphates 

      Zhou, Y.; Hoffmann, S.; Huang, Y. X.; Prots, Y.; Schnelle, W.; Menezes, P. W.; Carrillo-Cabrera, W.; Sichelschmidt, J.; Mi, J. X.; Kniep, R.; 宓锦校 (2011-06)
      Two isotypic layered rare-earth borate phosphates, K(3)Ln[OB(OH)(2)](2)[HOPO3](2) (Ln=Yb, Lu), were synthesized hydrothermally and the crystal structures were determined by single-crystal X-ray diffraction (R (3) over bar, ...
    • K-CYCLE RESONANT GRAPHS 

      Guo, X. F.; Zhang, F. J.; 郭晓峰 (1994)
      A connected graph G is said to be k-cycle resonant if, for 1 less than or equal to t less than or equal to k, any t disjoint cycles in G are mutually resonant, that is, there is a perfect matching M of G such that each of ...
    • k-means型软子空间聚类算法 

      张燕萍; 姜青山 (2010)
      软子空间聚类是聚类研究领域的一个重要分支和研究热点。高维空间聚类以数据分布稀疏和“维度效应“现象等问题而成为难点。在分析现有软子空间聚类算法不足的基础上,引入子空间差异的概念;在此基础上,结合簇内紧凑度的信息来设计新的目标优化函数;提出了一种新的k-MEAnS型软子空间聚类算法,该算法在聚类过程中无需设置额外的参数。理论分析与实验结果表明,相对于其他的软子空间算法,该算法具有更好的聚类精度。
    • K-Nearest neighbors relevance annotation model for distance education 

      Ke, Xiao; Li, Shaozi; Cao, Donglin; 李绍滋; 曹冬林 (IGI Publishing, 2011 Janua)
      With the rapid development of Internet technologies, distance education has become a popular educational mode. In this paper, the authors propose an online image automatic annotation distance education system, which could ...
    • K-P-Means: A Clustering Algorithm of K "Purified" Means for Hyperspectral Endmember Estimation 

      Xu, Linlin; Li, Jonathan; Wong, Alexander; Peng, Junhuan; 李军 (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2014 OCT)
      This letter presents K-P-Means, a novel approach for hyperspectral endmember estimation. Spectral unmixing is formulated as a clustering problem, with the goal of K-P-Means to obtain a set of "purified" hyperspectral pixels ...
    • K-P-means: A clustering algorithm of K 'purified' means for hyperspectral endmember estimation 

      Xu, Linlin; Li, Jonathan; Wong, Alexander; Peng, Junhuan; 李军 (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2014 Octob)
      This letter presents K-P-Means, a novel approach for hyperspectral endmember estimation. Spectral unmixing is formulated as a clustering problem, with the goal of K-P-Means to obtain a set of 'purified' hyperspectral pixels ...
    • k-Resonance in Benzenoid Systems, Open-ended Carbon Nanotubes, Toroidal Polyhexes; and k-Cycle Resonant Graphs 

      Guo, Xiaofeng; 郭晓峰 (2006)
      Let G be either a benzenoid system (hexagonal system) or an open-ended carbon nanotube (tubule) or a toroidal polyhex. G is said to be k-resonant if, for 1 <= t <= k, any t disjoint hexagons of G are mutually resonant, ...
    • k-resonance of open-ended carbon nanotubes 

      Zhang, FJ; Wang, LS; 张福基 (2004-02)
      An open-ended carbon nanotube or a tubule is a part of some regular hexagonal tessellation of a cylinder. A tubule T is said to be k-resonant if for every k ( or fewer) pairwise disjoint hexagons, the subgraph obtained ...
    • k-resonant benzenoid systems and k-cycle resonant graphs 

      Guo, XF; Zhang, FJ; 张福基 (2001-MAY-J)
      A benzenoid system (or hexagonal system) H is said to be k-resonant if, for 1 less than or equal to t less than or equal to k, any t disjoint hexagons of H are mutually resonant; that is, there is a Kekule structure (or ...
    • K-前缀树全文搜索方法及其应用 

      陈金桥 (2009-11-26)
      在科学技术高速发展和信息爆炸式膨胀的时代,如何快速和有效的从海量信息中获取有用信息是信息检索技术主要的研究课题。当前应用广泛的后缀树和后缀数组全文搜索方法在搜索速度和计算空间方面各有特点和局限,本文正是针对此问题提出了K-前缀树全文搜索方法。 K-前缀树全文搜索方法是一种基于前缀树且能够对内容长度不大于K的字串进行搜索的文本全文搜索方法,其主要特点是使用K子串来构建前缀树,使得最大空间复杂度为O(Zk+1),并具有折中后缀数和后缀数组在 ...
    • k-悬挂边的树的Wiener指标研究 

      洪荣辉 (2009-11-20)
      一个连通图的Wiener指标是图中所有无序顶点对之间的距离之和。这个概念是由化学家Wiener于1947年首次提出的。Wiener指标在理论化学和通讯网络中有大量的应用。自二十世纪七十年代以来,Wiener指标已得到广泛的研究,并得到了许多新的结果。其中,给定k-悬挂边的树的Wiener指标的极值问题的研究尤其受到关注。近年来,Entringer得到了下面的结论[2]:如果T是阶数为n,k-悬挂边的树,2kn,那么W(S(n,k))W( ...
    • K17在翼状胬肉中表达及调控机制的相关研究 

      许可 (2011-11-24)
      翼状胬肉(Pterygium)是一种常见的眼表疾病,以睑裂区增生肥厚的球结膜及其下的纤维组织血管横跨角膜缘呈三角形长入角膜为主要特征,可伴有炎症、新生血管、色素沉着等改变。可能发病于单眼或者双眼,鼻侧多见,但也可见到颞侧甚至双侧发病的患者。一般早期不引起患者明显的自觉症状,仅有轻度异物感、眼红或干涩感,病变侵及瞳孔区时则会引起失明。临床上一般通过手术进行治疗,并可联合自体结膜移植、角膜缘干细胞移植、羊膜移植、局部使用丝裂霉素等方法减少术 ...
    • K2CO3-Catalyzed Synthesis of Chromones and 4-Quinolones through the Cleavage of Aromatic C-O Bonds 

      Zhao, Jie; Zhao, Yufen; 赵玉芬; Fu, Hua (AMER CHEMICAL SOC, 2012-06-01)
      Phenol-derived electrophiles are favorable substrates because phenols are naturally abundant or can be readily prepared from other aromatic compounds. However, the cleavage of aromatic C-O bonds Is a great challenge because ...
    • K2Fe [H(HPO4)2] F2 

      Mi, J. X.; Wang, C. X.; Wei, Z. B.; Chen, F. J.; Xu, C. Y.; Mao, S. Y.; 宓锦校 (2005-08)
      The crystal structure of dipotassium iron(III) {hydrogen bis[hydrogenphosphate(V)]} difluoride, K2Fe[H(HPO4)(2)]F-2, obtained by hydrothermal synthesis, was determined from single-crystal X-ray diffraction data. The structure ...
    • K48泛素化甘露糖受体在尼古丁增强树突状细胞交叉提呈中的作用研究 

      胡纯芳 (2018-04-09)
      树突状细胞(Dendriticcells,DCs)作为适应性免疫应答的始动者,其所诱生的CD8+T细胞应答是机体抗胞内病原微生物感染和抗肿瘤的主要效应细胞。其中,DCs对外源性抗原的交叉提呈是启动CD8+T细胞应答的必要条件,而甘露糖受体(Mannosereceptor,MR)介导的抗原内体转位及内体对p97、Sec61的招募是DCs交叉提呈的关键环节。我们的前期研究发现,微量的尼古丁能通过上调MR表达并进而促进MR介导的抗原内体转位及 ...
    • K5[W4O8(H2BO4)(HPO4)(2)(PO4)(2)]·0.5H(2)O: A Tungsten Borophosphate with a Novel Sandwich-like Layered structure 

      Shao-Yu Mao; You-Jun Kang; Wei Liu; Jin-Xiao Mi; 宓锦校; Jing-Tai Zhao (2006-06-05)
      The first tungsten borophosphate compound, K-5[W4O8-(H2BO4)(HPO4)(2)(PO4)(2)] center dot 0.5H(2)O, has been synthesized under mild hydrothermal conditions, and the crystal structure with a new stoichiometry (B:P ratio 1:4) ...
    • K_2O-Fe_2O_3系催化剂的穆斯堡尔谱研究 

      祝以湘; 陈荣钦; 封雷; 王军 (1999)
      利用穆斯堡尔谱在k2 O fE2 O3催化剂中检出了α fE2 O3(大晶粒及微晶 )、kfEO2 、k1+ XfE11O17、α fEOOH和γ fEOOH等物相 ,它们的相对含量取决于催化剂的含钾量及煅烧温度 ,相对含量的改变导致样品的穆斯堡尔谱图出现了复杂的变化 .与Xrd相比 ,穆斯堡尔谱可对钾与氧化铁的相互作用进行更有效的表征 ,穆斯堡尔谱和TPr研究都表明钾可延缓催化剂中fE(III)的被还原 .
    • Kaehler流形上的超全纯理论和Clfford分析 

      汤冬梅 (2008-12-05)
      多复变函数论和单复变函数论在本质上有许多不同。例如在多复变数中有著名的Hartogs现象,在单复变数中却没有;著名的Riemann映射基本定理在多复变数空间中却不成立;单复变数中在单叶连通区域上只有一个Cauchy公式,在多复变数中互不等价的区域上却有不同的积分表示;在单变数中Borel--Pompeiu公式由于它的核是全纯的,所以可以直接用来解-方程,但在多复变数中相应于Borel--Pompeiu公式的Bochner-Martine ...
    • Kahler流形上的Bochner技巧 

      易广招 (1985-04-13)
    • KAI1基因与肿瘤转移 

      陈玉强; 张鸣青; 吴乔 (中山医科大学肿瘤防治中心, 2001-12)
      肿瘤转移在肿瘤发展进程中具有十分重要的作用。恶性肿瘤患者很少死于原发癌,绝大多数死于肿瘤转移。目前对于肿瘤转移的机理了解甚少,也缺乏有效的控制和治疗手段。1995年Dong犤1犦首次发现的肿瘤转移抑制基因KAI1以及近年来对其机理的研究取得了新进展,研究表明该基因只对肿瘤转移产生抑制作用,而对肿瘤形成没有影响。本文拟就KAI1基因与肿瘤转移抑制的相关性作一综述。1KAI1基因的发现与定位前列腺癌在美国的死亡率较高,其发病率更是高得惊人。 ...