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Search Results: 1 - 10 of 126971 matches for " Yongfang Li "
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Thoughts on Course Construction of “New Energy Vehicle Lightweight Technology”  [PDF]
Yongfang Li, Yali Yang
Open Access Library Journal (OALib Journal) , 2019, DOI: 10.4236/oalib.1105597
Abstract:
Based on the current situation that the course “New Energy Vehicle Light-weight Technology” is a new professional course, this paper expounds the construction objectives, theoretical teaching content and practical teaching content of the course, and also puts forward some teaching methods and means to improve the teaching effect of the course.
New Developments and Challenge of Task Dissociation in Implicit Memory
内隐记忆任务分离范式的新进展和挑战

Li Dezhong,Liu Yongfang,
李德忠
,刘永芳

心理科学进展 , 1999,
Abstract: 间接测验和直接测验的系统比较促进了对两种测验内在机制的认识。加工说坚持“认知经济”的原则,指出当代心理学的中心任务是阐明各种记忆任务的编码、贮存和提取加工。多重记忆系统说主张在加工观点中加入某些结构限制,强调探讨不同记忆系统的操作特点及系统间的相互作用。两种观点的融合成为一种趋势。视触通道可能具有共享表征以及新的信息加工模型的提出向任务分离范式提出了挑战。
LARGE DEFORMATION ANALYSIS OF A RUBBER WEDGE CONTACTING WITH A RIGID NOTCH
橡胶楔体与刚性缺口接触大变形分析

Chen Shaohua,Li Yongfang,
陈少华
,李咏芳

力学学报 , 2000,
Abstract: problem is very complex, especially, the contact problem oflarge deformation. When the contact surface contains vertex, the problemmust be solved by large strain theory. As for the large strain theory,the most important thing is to put out a reasonable and applicableconstitutive relation. In 1973, Knowles and Sternberg gave a kind ofconstitutive relation for non-linear elasticity large deformation andanalyzed the elastic crack tip field. In this paper, one kind of typicalproblem that is a rubber wedge contacting with a rigid notch isconsidered. Using the constitutive relation given by Knowles andSternberg in 1973 and proper mapping functions between before and afterdeformation, the problem is solved and the theoretical analysis is given.The results show that there is no expanding sector or shrinking sectornear the rubber wedge tip, not like the crack tip field in rubber-likematerial; When the rubber wedge is compressed into the rigid notch, thepoints on the same radius before deformation distribute evenly; Thedeformation in the direction of radius possesses singularity and thesingular exponent depends on the ratio of the rubber wedge angle to thenotch angle; The non-vanishing components of stress,τrr andτθθ, near the wedge tip possess the same singularity,r-2(n+1), and both componentsare independent of the angle after deformation. Furthermore, finiteelement program of large deformation is made and the contact boundaryconditions are added to the program, numerical calculation is done tothe typical contact problem. The numerical results are consistent wellwith those of the theoretical analysis.
Case report of nonalcoholic fatty liver cirrhosis complicated with esophageal and gastric variceal bleeding
LIU Yongfang
Journal of Clinical Hepatology , 2013,
Abstract:
Fluorescence and sensitization performance of phenylene-vinylene-substituted polythiophene
JinMao Chen,JianHui Hou,YongFang Li,XiaoWen Zhou,JingBo Zhang,XuePing Li,XuRui Xiao,Yuan Lin
Chinese Science Bulletin , 2009, DOI: 10.1007/s11434-009-0209-0
Abstract: A new kind of polythiophene derivative, Poly(3-{2-[4-(2-ethylhexyloxy)-phenyl]-vinyl}-2,2′-bithiophene) (PTh), was applied in dye-sensitized solar cell to extend the light response of nanocrystalline TiO2 electrode. UV-vis absorption and fluorescence spectra were employed to investigate the interaction of PTh with nanocrystalline TiO2. The absorption coefficient of the PTh was high in visible part of spectrum, and the fluorescence emission of the PTh can be efficiently quenched by TiO2 nanoparticles owing to charge injection from the excited singlet state of PTh to the conduction band of the TiO2 particles. Cyclic voltammetry measurements were performed to study the dye regeneration reaction at the nanocrystalline TiO2/electrolyte interface. The solar cell sensitized with PTh exhibited a short-circuit photocurrent (I sc) of 3.08 mA/cm2, an open circuit voltage (V oc) of 511 mV and an overall efficiency of 0.9% under the illumination of 100 mW/cm2 (AM 1.5).
Study on the Question Processing of Farmer-oriented Question Answering System
面向农民的问答系统问句处理研究*

Jia Junzhi Wang Yongfang Li Ting,
贾君枝
,王永芳,李婷

现代图书情报技术 , 2010,
Abstract: In order to improve the convenience of farmers’ access to information, this paper is focused on developing the farmer-oriented question answering system and proposes that the system is composed of four modules: knowledge base construction, question processing, information retrieval, answer extraction, in which question processing is the research priority. On the basis of concluding the characteristics of farmers’ questions, it proposes the question classification method based on interrogatives and phrases. During the question processing, methods are adopted to classify the questions and extract the keywords effectively, such as removing polite words, establishing special rule table for informal interrogatives and no interrogative and so on. While, the authors take advantage of the synonym extended table to expand keywords, and set different weight benchmarks. The research can lay the foundation for the processing of the information retrieval module.
High efficient light-emitting diodes using polystyrene as matrix
HE Gufeng,LIU Jie,YANG Yang,Li Yongfang,
HEGufeng
,LIUJie,YANGYang,LIYongfang

科学通报(英文版) , 2003,
Abstract: High efficient polymer light-emitting diodes (PLEDs) were obtained by using a blend of conjugated polymer G-PF, a copolymer of fluorene and thiophene, and polystyrene (PS). The maximum electroluminescent (EL) efficiency of the device is 12 cd/A when G-PF/PS weight ratio is at 80/20, while that of pure G-PF device is 6.5 cd/A. Studies on photoluminescence and electroluminescence of the blends indicate that inter-chain interactions were tremendously suppressed due to the dilution effect. However, after PS concentration exceeds 20% the EL efficiency of the devices decreases with further increase of PS concentration. This may be due to the decrease of the recombination probability of electrons and holes with the excessive addition of PS insulator.
Population genetics of foxtail millet and its wild ancestor
Chunfang Wang, Jinfeng Chen, Hui Zhi, Lu Yang, Wei Li, Yongfang Wang, Haiquan Li, Baohua Zhao, Mingsheng Chen, Xianmin Diao
BMC Genetics , 2010, DOI: 10.1186/1471-2156-11-90
Abstract: In this study, we surveyed DNA sequence for nine loci across 50 accessions of cultivated foxtail millet and 34 of its wild progenitor. We found a low level of genetic diversity in wild green foxtail (θ = 0.0059), θ means Watterson's estimator of θ. Despite of a 55% loss of its wild diversity, foxtail millet still harbored a considerable level of diversity (θ = 0.0027) when compared to rice and sorghum (θ = 0.0024 and 0.0034, respectively). The level of LD in the domesticated foxtail millet extends to 1 kb, while it decayed rapidly to a negligible level within 150 bp in wild green foxtail. Using coalescent simulation, we estimated the bottleneck severity at k = 0.6095 when ρ/θ = 1. These results indicated that the domestication bottleneck of foxtail millet was more severe than that of maize but slightly less pronounced than that of rice.The results in this study establish a general framework for the domestication history of foxtail millet. The low level of genetic diversity and the increased level of LD in foxtail millet are mainly caused by a population bottleneck, although gene flow from foxtail millet to green foxtail is another factor that may have shaped the pattern of genetic diversity of these two related gene pools. The knowledge provided in this study will benefit future population based studies in foxtail millet.Plant domestication, which began approximately 10,000 years ago, is the most crucial development in human history [1]. Domesticated crops provide most of our food today, and provide the foundation for human civilization. Yet, only a small fraction of flowering plants were actually domesticated. It will be of great benefit for future crop breeding and improvement if we have a better understanding of the domestication process.The evolutionary footprints left by domestication at the population level are dispersed throughout the genome. Due to population bottlenecks, a large proportion of genetic diversity is typically lost during the domestication proc
Fluorescence and sensitization performance of phenylene-vinylene-substituted polythiophene

JinMao Chen,JianHui Hou,YongFang Li,XiaoWen Zhou,JingBo Zhang,XuePing Li,XuRui Xiao,Yuan Lin,

科学通报(英文版) , 2009,
Abstract: A new kind of polythiophene derivative, Poly(3-{2-4-(2-ethylhexyloxy)-phenyl]-vinyl}-2,2′-bithiophene) (PTh), was applied in dye-sensitized solar cell to extend the light response of nanocrystalline TiO2 electrode. UV-vis absorption and fluorescence spectra were employed to investigate the interaction of PTh with nanocrystalline TiO2. The absorption coefficient of the PTh was high in visible part of spectrum, and the fluorescence emission of the PTh can be efficiently quenched by TiO2 nanoparticles owing to charge injection from the excited singlet state of PTh to the conduction band of the TiO2 particles. Cyclic voltammetry measurements were performed to study the dye regeneration reaction at the nanocrystalline TiO2/electrolyte interface. The solar cell sensitized with PTh exhibited a short-circuit photocurrent (I sc) of 3.08 mA/cm2, an open circuit voltage (V oc) of 511 mV and an overall efficiency of 0.9% under the illumination of 100 mW/cm2 (AM 1.5). Supported by the Major State Basic Research Development Program of China (Grant No. 2006CB202605), High-Tech Research and Development of China Program (Grant No. 2007AA05Z439), National Natural Science Foundation of China (Grant No. 50221201), and Innovative Foundation of the Center for Molecular Science, Chinese Academy of Sciences (Grant No. CMS-CX200718)
White organic light-emitting devices using Zn(BTZ)2 doped with Rubrene as emitting layer
Jiajin Zheng,Yulin Hua,Shougen Yin,Xiulan Feng,Xiaoming Wu,Yuanyuan Sun,Yongfang Li,Chunhe Yang,Zhigang Shuai
Chinese Science Bulletin , 2005, DOI: 10.1007/BF02897473
Abstract: Zn(BTZ)2 was synthesized from the complex reaction between zinc acetate dihydrate and 2-(2-hydroxyphenyl) benzothiazolate. Then Zn(BTZ)2 was used as main light-emitting material doped with different amounts of fluorescent dye Rubrene and fabricated a series of white organic light emitting devices. The configurations were as follows: ITO/PVK:TPD/Zn(BTZ)2:Rubrene/Al. The doping concentration of Rubrene in Zn(BTZ)2 was 1.2%, 0.12%, 0.08% and 0.05% respectively. According to the EL spectra and CIE coordinates of the above devices, the optimum doping concentration (0.05% weight percent) had been determined. The steady and bright white light emitting of the device with 0.05% doping concentration had been obtained, and the white emission covered a wide range of driving voltage (10–22.5 V). The CIE coordinates were (x=0.341,y=0.334) at the driving voltage of 20 V, which was very close to the equi-energy point (x=0.333,y=0.333), and the corresponding luminance and external quantum efficiency were 4048 Cd/m2 and 0.63% (4.05 Cd/A), respectively. Lastly, we also discussed the emitting mechanisms of the material and the devices.
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