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关键词： 樟脑   薄荷脑   冰片   含量测定   医疗器械,贴敷类   色谱法,气相  

摘要： 目的建立测定贴敷类医疗器械中樟脑、薄荷脑、冰片含量的气相色谱法。方法采用Alltech EC-WAX(30 m×0.53 mm,1.2μm)毛细管柱,以氮气为载气,氢火焰离子化检测器(FID),采用程序升温,初始柱温85℃,保持1 min,以10℃.min-1速率升至140℃,保持13 min,再以50℃.min-1速率升至210℃,保持3 min,进样口温度250℃,检测器温度280℃。结果樟脑、薄荷脑、冰片分别在8.7～4 355.0μ***-1(r=0.999 9),9.9～4 956.0μ***-1(r=0.999 9),10.0～4 998.0μ***-1(r=0.999 8)范围内线性关系良好,樟脑、薄荷脑、冰片的平均回收率分别为104.1%(RSD=2.7%),100.6%(RSD=2.4%),99.8%(RSD=2.6%)。结论该方法简便、灵敏、准确、快速,可用于贴敷类医疗器械中樟脑、薄荷脑和冰片的含量测定。

关键词： 形态学算子   虹膜定位   脉冲神经网络   边缘提取   最小二乘法  

摘要： 运用形态学算子对人眼图像进行睫毛除噪,引入并行性脉冲神经网络提取虹膜的内外边缘。对获取的虹膜内边缘进行连通量标记,求出内边缘上的点坐标从而求得内边界圆各参数;避开运算量大,占运行内存的Hough变换,利用先验知识提取虹膜外边界的有效弧长,通过最小二乘法拟合外边界圆。实验表明,该算法在睫毛,眼睑以及眼球转向的干扰下都能得到较准确的虹膜定位,并且算法在GPU平台上运行速度快。

关键词： 基于内容的图像检索(CBIR)   脉冲耦合神经网络(PCNN)   交叉皮层模型(ICM)   特征提取  

摘要： 为提高基于内容的图像检索系统(CBIR)中纹理特征提取的有效性,进一步提升CBIR系统的整体性能。提出了一种基于脉冲耦合神经网络的纹理图像检索方法。脉冲耦合神经网络(PCNN)是新一代的人工神经网络,在数据处理上具有很多优势。特征提取时具有平移、旋转、尺度、扭曲等不变性,以及很好的抗噪性,而这一点非常适合于图像检索系统。利用PCNN及简化模型ICM得到对应于不同灰度值的二值图像序列,计算序列中每幅图像的熵序列,其一维的特征矢量作为纹理特征。采用Eu-clidean距离进行相似度计算,建立了一套基于示例查询图像的纹理图像检索系统。实验结果表明,与小波包等特征提取方法相比,该方法不仅对噪声具有较强的鲁棒性,同时能降低特征向量维数,具有尺度、平移和旋转不变性,而且能取得更高的检索率。

关键词： 损伤检测   短时傅立叶变换   脉冲耦合神经网络   熵序列   特征提取  

摘要： 机械结构的损伤发展到一定程度,会对其功能产生严重影响,所以及早检测出损伤非常必要。针对机械结构在损伤发生时其内部能量分布会发生变化的情况,对加速度计测得的结构振动信号进行短时傅立叶变换,获得可以反映能量分布的时频谱图。使用脉冲耦合神经网络提取时频谱图的熵序列特征,很好地识别了结构的损伤。使用上述方法对简支梁的损伤进行了实验研究,验证了其有效性和实用性。

摘要： The work of this thesis is devoted to the development of an original and general numerical method for solving the elliptic equation in an arbitrary domain (described by a level-set function) with general boundary conditions (Dirichlet, Neumann, Robin,...) using Cartesian grids. It can be then considered an immersed boundary method, and the scheme we use is based on a finite-difference ghost-cell technique. The entire problem is solved by an effective multigrid solver, whose components have been suitably constructed in order to be applied to the scheme. The method is extended to the more challenging case of discontinuous coefficients, and the multigrid is suitable modified in order to attain the optimal convergence factor of the whole iteration procedure. The development of the multigrid is an important feature of this thesis, since multigrid solvers for discontinuous coefficients maintaining the optimal convergence factor without depending on the jump in the coefficient and on the problem size is recently studied in literature. The method is second order accurate in the solution and its gradient. A convergence proof for the first order scheme is provided, while second order is confirmed by several numerical tests.

关键词： 椒盐噪声   高斯噪声   灰度极限   脉冲耦合神经网络   均值滤波   可变步长  

摘要： 针对图像中同时存在椒盐噪声和高斯噪声,提出一种基于灰度极限和脉冲耦合神经网络(PCNN)滤除混合噪声的新方法。首先,根据灰度极值定位出椒盐噪声点;其次,在滤波窗口中对椒盐噪声点进行均值滤波;然后,利用PCNN赋时矩阵定位出高斯噪声点;最后,自适应调整可变灰度步长,选择不同滤波方法滤除高斯噪声。实验结果表明提出的算法较常见的混合噪声滤波方法在主观滤波效果和客观评价指标峰值信噪比(PSNR)及信噪比改善因子(ISNR)两方面均有明显的优势。

关键词： 双向联想记忆神经网络   全局指数稳定性   脉冲   时滞  

摘要： 本文研究了当脉冲不太频繁易受大的脉冲影响下的时滞BAM神经网络具有唯一的指数稳定的平衡点.分析采用一个推广的比较原理和M-矩阵理论,得到一些关于唯一平衡点的收敛性的简单可行的充分条件.所得结果推广和改进了已有文献的结果.

关键词： Antigens, CD55/metabolism   Antigens, CD55/metabolism   Caco-2 Cells   Clathrin/metabolism*   Endocytosis*   Endosomes/virology   Enterovirus/pathogenicity*   Epithelial Cells/physiology*   Epithelial Cells/virology*   Humans   Protein Binding   rab GTP-Binding Proteins/metabolism*   rab5 GTP-Binding Proteins/metabolism   Virus Internalization*  

摘要： Enteroviruses invade the host by crossing the intestinal mucosa, which is lined by polarized epithelium. A number of enteroviruses, including echoviruses (EV) and group B coxsackieviruses (CVB), initiate infection by attaching to decay-accelerating factor (DAF), a molecule that is highly expressed on the apical surface of polarized epithelial cells. We previously observed that entry of DAF-binding CVB3 into polarized intestinal epithelial cells occurs by an unusual endocytic mechanism that requires caveolin but does not involve clathrin or dynamin. Here we examined the entry of a DAF-binding echovirus, EV7. We found that drugs, small interfering RNAs (siRNAs), and dominant negative mutants that target factors required for clathrin-mediated endocytosis, including clathrin and dynamin, inhibited both EV7 infection and internalization of virions from the cell surface. Once virus had entered the cell, it colocalized with markers of early endosomes (EEA1) and then late endosomes (LAMP-2). Inhibition of endosomal maturation-with siRNAs or dominant negative mutants targeting Rab5 and Rab7-inhibited infection and prevented release of viral RNA into the cell. These results indicate that EV7 is internalized by clathrin-mediated endocytosis and then moves to early and late endosomes before releasing its RNA. Trafficking through endosomes is known to be important for viruses that depend on low pH or endosomal cathepsin proteases to complete the entry process. However, we found that EV7 infection required neither low pH nor cathepsins. IMPORTANCE The results demonstrate that echovirus 7 (EV7), after binding to decay-accelerating factor (DAF) on the cell surface, enters cells by clathrin-mediated endocytosis;this entry mechanism differs markedly from that of another DAF-binding enterovirus, coxsackievirus B3 (CVB3). Thus, after attachment to the same cell surface receptor, these closely related viruses enter the same cells by different mechanisms. The cellular cues required for r

关键词： GC-MS   贴敷类医疗器械   樟脑   薄荷脑   冰片  

摘要： 目的:利用气相色谱-质谱联用仪(GC-MS)建立贴敷类医疗器械中樟脑、薄荷脑、冰片的定性和定量分析方法。方法:采用Agilent HP-INNOWax(30 m×0.25 mm,0.25μm)毛细管色谱柱;以氦气为载气,流量为1.0 ml·min^(-1);柱温80℃维持2 min,以10℃·min^(-1)的升温速率升至120℃,维持12 min,再以30℃·min^(-1)的升温速率升至200℃,维持3 min;离子源为电子轰击电离(EI)源,采集模式为全扫描/选择离子检测。结果:能检测出样品中是否添加樟脑、薄荷脑、冰片,并对其进行定量。3种化合物的线性范围分别为1.742～2.177×10~3(r=0.998 9),1.982～2.478×10~3(r=0.998 9),1.999～2.499×10~3μg·ml^(-1)(r=0.999 8),线性关系均良好;平均回收率分别为93.3%,98.8%,94.9%(n=9)。结论:方法简便、灵敏、准确、快速,可用于贴敷类医疗器械中樟脑、薄荷脑、冰片的定性和定量检测。