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51.
52.
在辽宁省辽河流域水生态功能三级区与河流水生态野外调查基础上,以辽河流域的清河、汎河两条典型一级支流为研究对象,采用主成分分析与相关性分析方法筛选水生态系统健康评价指标,构建了由总磷(TP)、总氮(TN)、化学需氧量(CODCr)、五日生化需氧量(BOD5)、溶解氧(DO)、藻类香农多样性指数(DAA)、底栖动物完整性指数(B-IBI)、鱼类完整性指数(F-IBI)、生境指数、水文指数10个指标构成的水生态系统健康综合评价指标体系,体现了河流水生态系统的物理完整性、化学完整性和生物完整性特征。研究结果表明,清河与汎河流域11个水生态功能三级区中,水生态健康等级1个(Ⅳ-5-4),亚健康等级6个(Ⅳ-5-1、Ⅳ-5-2、Ⅳ-5-3、Ⅳ-5-9、Ⅳ-5-10、Ⅳ-5-11),一般健康等级3个(Ⅳ-5-12、Ⅳ-5-13、Ⅳ-5-14),较差健康等级1个(Ⅳ-5-8)。清河与汎河流域水生态系统总体健康状态从其上游河流源头至下游入辽河干流汇入口呈现逐渐恶化的空间分布特征,且与流域人类活动强度具有密切关系。 相似文献
53.
本文利用一包含湿过程的简单热带大气滤波模式,通过引入辐合反馈机制和下垫面的蒸发效应对凝结潜热释放的贡献的物理过程,研究了下垫面热状况对热带大气季节内尺度低频振荡的作用过程。结果表明:下垫面性质特别是暖洋面的存在主要是减小低频振荡东传相速度和增大振幅,其中 Kelvin-Rossby 相互作用模在调制相速度和振幅的变化中起重要作用,因此,下垫面热状况是形成观测到的热带大气低频振荡局地特征的主要条件。 相似文献
54.
Data mining has been successfully applied in many fields to find useful information stored in vast databases.Market segmentation,which segments data into homogenous clusters by using cluster analysis,is among the most important of the applications in data mining.In this study,we propose a clustering system which integrates particle swarm optimization and honey bee mating optimization methods (PSHBMO).Simulations for a benchmark test function show that our proposed method is better equipped to find the global optimum than other well-known clustering algorithms.Finally,the proposed clustering system is applied to a real-world consumer electronic company to perform market segmentation via the RFM model. 相似文献
55.
为解决现有算法速度慢、 集成度低的问题, 提出了改进的算法。利用图像分割算法Grabcut对图片的前景进行分割; 高效地生成三分图, 并以此作为基于三分图的抠图算法Shared Matting的输入; 综合处理抠图结果。针对该系统的特点, 使用下采样技术对Grabcut算法进行优化, 加快分割速度, 并对三分图生成算法和Shared Matting抠图算法进行并行性加速。仿真实验结果表明, 该系统适用性较强, 可用性较好, 并能在短时间内利用较少的交互量取得较理想的抠图效果。 相似文献
56.
Pallid (pa) is 1 of 13 platelet storage pool deficiency (SPD) mouse mutants. pa animals suffer from prolonged bleeding time, pigment dilution, kidney lysosomal enzyme elevation, serum alpha1-antitrypsin activity deficiency and abnormal otolith formation. As with other mouse mutants of this class, characterization of pa mice suggests a defect in organelle biosynthesis. Here we describe the physical mapping, positional cloning, and mutational and functional analysis of the gene that is defective in pa mice. It encodes a ubiquitously expressed, highly charged 172-amino-acid protein (termed pallidin) with no homology to known proteins. We detected a nonsense mutation at codon 69 of this gene in the pallid mutant. In a yeast two-hybrid screen, we discovered that pallidin interacts with syntaxin 13, a t-SNARE protein that mediates vesicle-docking and fusion. We confirmed this interaction by co-immunoprecipitation assay. Immunofluorescence studies corroborate that the cellular distribution of pallidin overlaps that of syntaxin 13. Whereas the mocha and pearl SPD mutants have defects in Ap-3, our findings suggest that pa SPD mutants are defective in a more downstream event of vesicle-trafficking: namely, vesicle-docking and fusion. 相似文献
57.
Chin K de Solorzano CO Knowles D Jones A Chou W Rodriguez EG Kuo WL Ljung BM Chew K Myambo K Miranda M Krig S Garbe J Stampfer M Yaswen P Gray JW Lockett SJ 《Nature genetics》2004,36(9):984-988
Transition through telomere crisis is thought to be a crucial event in the development of most breast carcinomas. Our goal in this study was to determine where this occurs in the context of histologically defined breast cancer progression. To this end, we assessed genome instability (using fluorescence in situ hybridization) and other features associated with telomere crisis in normal ductal epithelium, usual ductal hyperplasia, ductal carcinoma in situ and invasive cancer. We modeled this process in vitro by measuring these same features in human mammary epithelial cell cultures during ZNF217-mediated transition through telomere crisis and immortalization. Taken together, the data suggest that transition through telomere crisis and immortalization in breast cancer occurs during progression from usual ductal hyperplasia to ductal carcinoma in situ. 相似文献
58.
Effect of NaNO<Subscript>3</Subscript> concentration on anodic electrochemical behavior on the Sb surface in NaOH solution 下载免费PDF全文
Yun-long He Rui-dong Xu Shi-wei He Han-sen Chen Kuo Li Yun Zhu Qing-feng Shen 《矿物冶金与材料学报》2018,25(3):288-299
The effect of NaNO3 concentration on the anodic electrochemical behavior of antimony in 4 M NaOH solution was investigated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) analyses. The mechanism of NO3- concentration effect on the anodic electrochemical behavior of antimony was proposed, and its availability was confirmed by experimental results. The effect of NaNO3 on the anodic behavior of antimony in NaOH solution can be interpreted as a stepwise formation of different antimony compounds with different NaNO3 concentrations. Metallic antimony is apt to be oxidized into Sb2O3 within the NaNO3 concentration range of 0-0.48 M. NaSbO3 can be found on the antimony surface when the NaNO3 concentration increases gradually. Insoluable NaSbO3 inhibits the anodic oxidation of antimony due to its shielding effect on the mass transport of the reactants and products. Surface morphology and composition were analyzed by X-ray photoelectron spectroscopy (XPS), scanning electronic microscopy (SEM), and electron dispersion spectroscopy (EDS) analyses. Results indicate that the anodic oxidation layer is composed of Sb2O3, NaSbO3, and Sb. The atomic proportion of antimony in the form of NaSbO3 increases with increasing NaNO3 concentration due to the powerful oxidizing property of NaNO3. 相似文献
59.
Two new susceptibility loci for Kawasaki disease identified through genome-wide association analysis
Lee YC Kuo HC Chang JS Chang LY Huang LM Chen MR Liang CD Chi H Huang FY Lee ML Huang YC Hwang B Chiu NC Hwang KP Lee PC Chang LC Liu YM Chen YJ Chen CH;Taiwan Pediatric ID Alliance Chen YT Tsai FJ Wu JY 《Nature genetics》2012,44(5):522-525
To find new candidate loci predisposing individuals to Kawasaki disease, an acute vasculitis that affects children, we conducted a genome-wide association study in 622 individuals with Kawasaki disease (cases) and 1,107 controls in a Han Chinese population residing in Taiwan, with replication in an independent Han Chinese sample of 261 cases and 550 controls. We report two new loci, one at BLK (encoding B-lymphoid tyrosine kinase) and one at CD40, that are associated with Kawasaki disease at genome-wide significance (P < 5 × 10(-8)). Our findings may lead to a better understanding of the role of immune activation and inflammation in Kawasaki disease pathogenesis. 相似文献
60.
Yeung TM Chia LA Kosinski CM Kuo CJ 《Cellular and molecular life sciences : CMLS》2011,68(15):2513-2523
The gastrointestinal epithelium is a highly organised tissue that is constantly being renewed. In order to maintain homeostasis,
the balance between intestinal stem cell (ISC) self-renewal and differentiation must be carefully regulated. In this review,
we describe how the intestinal stem cell niche provides a unique environment to regulate self-renewal and differentiation
of ISCs. It has traditionally been believed that the mesenchymal myofibroblasts play an important role in the crosstalk between
ISCs and the niche. However, recent evidence in Drosophila and in vertebrates suggests that epithelial cells also contribute to the niche. We discuss the multiple signalling pathways
that are utilised to regulate stemness within the niche, including members of the Wnt, BMP and Hedgehog pathways, and how
aberrations in these signals lead to disruption of the normal crypt–villus axis. Finally, we also discuss how CDX1 and inhibition
of the Notch pathway are important in specifying enterocyte and goblet cell differentiation respectively. 相似文献