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Search Results: 1 - 10 of 13610 matches for " Yuanhong Fan "
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Titanium-mediated reductive cross-coupling reactions of imines with terminal alkynes: An efficient route for the synthesis of stereodefined allylic amines
Kebin Mao,Guoqin Fan,Yuanhong Liu,Shi Li
Beilstein Journal of Organic Chemistry , 2013, DOI: 10.3762/bjoc.9.69
Abstract: Low-valency titanium species, generated in situ by using Ti(OiPr)4/2 c-C5H9MgCl reagent, react with imines to give a titanium-imine complex that can couple with terminal alkynes to provide azatitanacyclopentenes with excellent regioselectivity. Stereodefined allylic amines are obtained in good yields after hydrolysis or iodonolysis of the corresponding azatitanacyclopentenes. When ethynylcyclopropane is used as the coupling partner to react with imines in this reaction, the initially generated allylic amine undergoes an unexpected 1,3-amino migration on silica gel during the column chromatography.
Asymptotic Stability of Impulsive Cellular Neural Networks with Infinite Delays via Fixed Point Theory
Yutian Zhang,Yuanhong Guan
Abstract and Applied Analysis , 2013, DOI: 10.1155/2013/427827
Abstract:
Accelerated Kernel CCA plus SVDD: A Three-stage Process for Improving Face Recognition
Ming Li,Yuanhong Hao
Journal of Computers , 2008, DOI: 10.4304/jcp.3.10.94-100
Abstract: Kernel canonical correlation analysis (KCCA) is a recently addressed supervised machine learning methods, which shows to be a powerful approach of extracting nonlinear features for face classification and other applications. However, the standard KCCA algorithm may suffer from computational problem as the training set increase. To overcome the drawback, we propose a three-stage method to improve the performance of KCCA. Firstly, a scheme based on geometrical consideration is proposed to enhance the extraction efficiency. The algorithm can select a subset of samples whose projections in feature space (Hilbert space) are sufficient to represent all of the data in feature space. Subsequently, an improved algorithm inspired by principal component analysis (PCA) is developed. The algorithm can select the most contributive eigenvectors for training and classification instead of considering all the ones. Finally, a multi-class classification method based on support vectors data description (SVDD) is employed to further enhance the recognition performance as it can avoid the repeated use of training data. The theoretical analysis and the experiment results demonstrate the effectiveness of improvements.
Three-Dimensional Planar Metallic Lenses Based on Concentric Rings with Modulated Subwavelength Width  [PDF]
Di Feng, Chunxi Zhang, Lishuang Feng, Yuanhong Yang
Journal of Electromagnetic Analysis and Applications (JEMAA) , 2012, DOI: 10.4236/jemaa.2012.412068
Abstract: A kind of Subwavelength Planar Metallic Lenses (SPMLs) is proposed to realize far-field optical focusing in the visible range based on concentric rings with modulated width in a silver film. The width of each metallic ring is mutative so that the radiation fields of surface plasmon polaritons can be controlled and the relevant phase retardations can be modulated to make a beam focus at the desired position. For comparison, the Subwavelength Planar Dielectric Lenses (SPDLs) structured on silica glass with the same concentric ring shapes as SPMLs are analyzed, although without opaque metal coating on SPDLs, the computational results show that SPMLs can support higher intensity focal spot, narrower full-width half-maximum beam width, and longer depth of focus at the focal region under certain lens thickness due to the coupling of surface plasomon polaritons, diffracted evanescent waves and propagated electromagnetic waves.
Antimicrobial Resistance and Genotype Analysis of Extended-Spectrum-β-Lactamase-Producing Proteus Mirabilis  [PDF]
Ying Huang, Yuanhong Xu, Zhongxin Wang, Xianghong Lin
Open Journal of Clinical Diagnostics (OJCD) , 2014, DOI: 10.4236/ojcd.2014.41011
Abstract: To analyse the genotypes of clinical isolates of Extended-Spectrum-β-Lactamase-Producing (ESBL-producing) Proteus mirabilis (P. mirabilis) and the mechanisms of antimicrobial resistance, to guide reasonable use of antibiotics and to avoid nosocomial outbreak infections by ESBL-producing P. mirabilis. 125 clinical isolates of P. mirabilis were collected from the Drug-Resistant Bacteria Surveillance Center of Anhui Province (from Jan 2009 to May 2010). Searching for the genotypes of ESBLs was perfomed by PCR amplification and DNA sequencing, and performed conjugation test simultaneously. Among ESBL-producing strains, CTX-M was the major genotype (3 CTX-M-13 and 1 CTX-M-3). TEM-1b spectrum β-lactamase was also prevalence in P. mirabilis. The diversity of β-lactamases in P. mirabilis and the emergency of multi-drug-resistance clinical strains will present serious threat to clinical therapy and even will lead to outbreak of nosocomial infections. Our study emphasizes the need for enhanced supervision of ESBL-producing P. mirabilis. Timely and reasonable drug-resistance data are indispensable to clinical therapy.
On the periodic solutions of a type of differential-iterative equations
Weigao Ge,Zhengrong Liu,Yuanhong Yu
Chinese Science Bulletin , 1998, DOI: 10.1007/BF02898911
Abstract: Sufficient conditions for the existence of periodic solutions to a type of nonautonomous differential-iterative equations are given.
Poincare Mapping and Periodic Solution for the Nonlinear Differential System
非线性微分系统的Poincare映射与周期解

Zhou Zhengxin,Yu Yuanhong,
周正新

系统科学与数学 , 2006,
Abstract: In this paper, we use a quite new method-reflective function, establish Poincare mapping for the nonautonomous nonlinear systems, and set up the necessary and sufficient conditions of existence of the periodic solution and stability for these systems.
On the periodic solutions of a type of differential-iterative equations

Weigao Ge,Zhengrong Liu,Yuanhong Yu,

科学通报(英文版) , 1998,
Abstract: Sufficient conditions for the existence of periodic solutions to a type of nonautonomous differential-iterative equations are given.
Permanence and Almost Periodic Solution for an Enterprise Cluster Model Based on Ecology Theory with Feedback Controls on Time Scales
Yuanhong Zhi,Zunling Ding,Yongkun Li
Discrete Dynamics in Nature and Society , 2013, DOI: 10.1155/2013/639138
Abstract: We present a model with feedback controls based on ecology theory, which effectively describes the competition and cooperation of enterprise cluster in real economic environments. Applying the comparison theorem of dynamic equations on time scales and constructing a suitable Lyapunov functional, sufficient conditions which guarantee the permanence and the existence of uniformly asymptotically stable almost periodic solution of the system are obtained. 1. Introduction In recent years, a few researchers have presented some models about enterprise clusters based on ecology theory, which arouse growing interest in applying the methods of ecology and dynamic system theory to study enterprise clusters, for example [1–9] and references cited therein. In [1], two models from biology were given and explained by economic view, and sufficient conditions were obtained to guarantee the coexistence and stability of enterprise clusters. In [3], the developing strategy of enterprise clusters was analyzed based on the logistic model, and the suggestions of constructing cooperative relation and choosing generalization or specialization tactics for commodity were put forward. In addition, based on the theoretical model of ecological population science, Wang and Pan [6] made a detailed analysis to the equilibrium mechanism of enterprise clusters, including net model and center halfback model and drew a conclusion that the relationship of pierce competition and beneficial cooperation among enterprise clusters was the crucial factor for them to keep stability. More related research about enterprises cluster one can refer to the literatures [10–13]. Recently, the literature [5] considered the competition and cooperation system of two enterprises based on ecosystem: where , represent the output of enterprises and , , are the intrinsic growth rate, denotes the carrying capacity of market under nature unlimited conditions, , are the competitive coefficients of two enterprises, , are the initial production of two enterprises. Accordingly, we consider now the equation with nonconstant coefficients, which can be obtained as a modified system (1) with variable coefficients (Letting , , , in system (1)): In real world, the situation of enterprises is often distributed by unpredictable forces which can result in changes in enterprises' parameters such as intrinsic growth rates. So it is necessary to study models with control variables which are so-called disturbance functions [14–17]. As well known, both continuous and discrete systems are very important in implementation and
Dosimetric Comparison of Volumetric Modulated Arc Therapy (VMAT), 5F Intensity Modulated Radiotherapy (IMRT) and 3D Conformal Radiotherapy (3DCRT) in Rectal Carcinoma Receiving Neoadjuvant Chemoradiotherapy  [PDF]
Ge Wen, Jinshan Zhang, Feng Chi, Li Chen, Sijuan Huang, Shaoqing Niu, Yuanhong Gao, Bixiu Wen, Yujing Zhang
International Journal of Medical Physics,Clinical Engineering and Radiation Oncology (IJMPCERO) , 2015, DOI: 10.4236/ijmpcero.2015.41008
Abstract:
Objective: To investigate better dosimetric distribution of volumetric modulated arc therapy (VMAT) vs. 5F intensity modulated radiotherapy (IMRT) and 3D conformal radiotherapy (3DCRT) in patients with locally advanced rectal cancer (LARC) when treated with neoadjuvant chemoradiotherapy. Methods: 3D-CRT, 5F-IMRT and VMAT plans for preoperative radiotherapy were 66011designed in 12 patients with locally advanced rectal cancer. The conformity index (CI) and homogeneity index (HI) in target volume, and the dose and volume of the organs at risk (OAR) irradiated including small bowel, bladder and bilatera1 femoral heads were compared among the three plans. Results: The CI for planning target volume (PTV) 2 and HI for PTV1 of VMRT and 5F-IMRT were superior to 3D-CRT. The CI of VMAT, 5F-IMRT and 3D-CRT plans were 0.71, 0.69 and 0.62 (p = 0.011 and p = 0.019, respectively). The HI of the VMAT and 5F-IMRT plans were both 1.04 and 3D-CRT planning was 1.06 (p = 0.022 and p = 0.006, respectively). The V35 - V45 of small bowel in VMAT were significantly less than in 5F-IMRT and 3D-CRT. V35 was 47.0, 56.4, and 72.8 cm3 for VMAT, 5F-IMRT, and 3D-CRT (p = 0.021 and p = 0.034, respectively), while V40 was 30.5, 35.5, 45.1 cm3 (p = 0.024 and p = 0.032, respectively) and V45 was 15.1, 18.1, 30.0 cm3 (p = 0.033 and p = 0.032, respectively). The D5, V30 and V50 of bladder in 3D-CRT were less than in VMAT and 5F-IMRT planning (p = 0.034, 0.004, 0.002 and p = 0.027, 0.003, 0.002, respectively). The Dmean of left femoral head in VMAT and 5F-IMRT were less than in 3D-CRT planning (p = 0.028 and p = 0.022, respectively) and the Dmean, V30 of right femoral head in VMAT and 5F-IMRT were better than in 3D-CRT planning (p = 0.044, 0.036 and p = 0.023, 0.028, respectively). Conclusions: Dosimetric analyses demonstrated that IMRT is superior to 3D-CRT in the conformity and homogeneity of dose distribution to the target volume, and provide a better protection to OARs sparing in patients with locally advanced rectal cancer for preoperative radiotherapy. With similar target coverage, VMRT is superior to 5F-IMRT in normal tissue sparing.
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