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Search Results: 1 - 10 of 93879 matches for " 黄维干 "
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中马关联方披露准则比较及启示
,覃红
财会月刊 , 2011,
Abstract:   为提高企业关联交易信息披露的透明度,中马两国都制定了关联方披露准则。本文认为我国可借鉴马来西亚的经验,在会计准则中明确关联方披露的目的,扩大关联方的认定范围,并细化关联方交易要素的披露要求。  【关键词】关联方关联交易信息披露  中国与马来西亚同属发展中国家,在经济发展过程中有不少相似之处,例如,在家族或国家控制的上市公司中普遍存在股权集中、一股独大的现象,关联交易盛行,控股股东或者实际控制人利用不公允关联交易掠夺中小股东的行为时有发生。为规范和监管关联交易,中马两国都建立了对关联交易的信息披露制度,会计准则在其中扮演了重要的角色。在此,笔者拟对我国财政部2006年发布的《企业会计准则第36号——关联方披露》(CAS36)和马来西亚会计准则理事会(MASB)2006年新修订并发布的《财务报告准则第124号——关联方披露》(FRS124)进行比较分析,以期为完善我国关联方披露准则提供借鉴。  一、中马关联方披露准则的内容比较  1.准则的目标和范围。FRS124在第一部分中明确指出“本准则的目标是确保主体的财务报表包含关注这种可能性所必需的披露:即主体的财务状况和损益可能受关联方的存在、关联方交易及其未结算余额影响的可能性”。FRS124还在第二部分以列举的方式详细说明了准则的适用范围:①界定关联方关系和交易;②确定主体与关联方之间的未结算余额;③确定在什么情况下要对以上1项和2项进行披露;④决定对这些项目披露的内容。CAS36没有确指准则的目标,仅在第一章第一条中指出制定本准则是“为了规范关联方及其交易的信息披露”,第二条则以一句“企业财务报表中应该披露所有关联方关系及其交易的相关信息”对准则的适用范围进行总结。可见FRS124对目标和范围的规定更加具体且详细,CAS36的规定则相对笼统而简略。
虚拟现实技术在会计教学中的应用
,锡远
财会月刊 , 2006,
Abstract: 有权威人士断言,虚拟现实技术将是21世纪信息技术的代表。本文简要介绍了虚拟现实技术的概念、特征与分类,阐述了虚拟现实技术在会计教学中的应用及意义。  【关键词】虚拟现实技术课堂教学实践教学远程教学虚拟现实技术或称灵境技术,实际上是一种可创建和体验虚拟世界的计算机系统。此种虚拟世界由计算机生成,既可以是现实世界的再现,也可以是构想中的世界。它是以仿真的方式给用户创造一个实时反映实体对象变化与相互作用的三维虚拟世界,使用者戴上特殊的头盔、数据手套等传感设备或利用键盘、鼠标等输入设备,便可以进入虚拟空间,成为其中的一员,并能够通过语言、头部转动、眼动、手势等自然的方式与虚拟世界进行实时交流,感知和操作虚拟世界中的各种仿真对象。虚拟现实技术综合利用计算机图形学、图像处理技术、智能技术、传感技术、语音处理与音响技术、网络技术等多种信息技术,逼真地模拟人的视觉、听觉、嗅觉、触觉等感官功能,使人能够沉浸在计算机生成的虚拟世界中,形成具有交互效能的多维化的信息环境。
VEGF对白血病树突状细胞抗原提呈能力的影响
张伶,,涂植光,
第三军医大学学报 , 2007,
Abstract: 目的探讨血管内皮生长因子(vascularendothelialcellgrowthfactor,VEGF)对白血病源树突状细胞(dendriticcell,DC)抗原提呈能力的影响及其分子机制。方法K562细胞经5μmol/LVEGF反义寡核苷酸(AS-ODN)处理24h,ELISA和免疫组化检测VEGF蛋白水平。以正常K562细胞诱生的白血病DC作为对照组,利用流式细胞术和混合淋巴细胞反应,观察AS-ODN处理的白血病DC的免疫表型及其刺激T细胞增殖的能力。采用荧光素酶检测系统和RT-PCR分析培养12h时白血病DC内NF-κB转录活性和Flt-1mRNA水平。结果AS-ODN处理使K562细胞VEGF蛋白分泌量较K562细胞组显著下降(P<0.05)。与K562-DC比较,AS-ODN处理的免疫表型(CD40、CD86、CD83、HLA-DR)表达明显上调。在不同DC/T值(1∶10~1∶40)时,MLR实验中AS-K562-DC组刺激指数(SI)明显高于对照组(P<0.05)。此外,培养12h时AS-K562-DCNF-κB转录活性较K562-DC明显增高(P<0.05),而Flt-1mRNA水平未见明显改变。结论反义寡核苷酸可抑制白血病细胞VEGF表达,下调VEGF能够增强白血病DC免疫表型的表达,提高DC抗原提呈能力。
魔芋葡甘寡糖硫酸酯的分离纯化与理化分析
,
食品科学 , 2007,
Abstract: ?制备的魔芋葡甘寡糖硫酸酯经过乙醇二次沉淀、透析、浓缩和真空冷冻干燥,得到粗品;葡聚糖凝胶层析分离纯化其组分,通过硫酸根和糖含量的检测,分别得到硫酸酯化与未硫酸酯化的组分ⅰ、ⅱ;醋酸纤维膜电泳结果为一条单一谱带,说明样品已达到电泳纯;凝胶色谱测定重均相对分子质量1595d,数均相对分子质量1572d,分子量分布pdi(mw/mn)为1.01,表明样品是单分散性分子量分布。
SpCas9结构域相互作用关键氨基酸的动态网络分析
Dynamical Network Analysis of Key Amino Acids for Domain Interactions of SpCas9
 [PDF]

, 王国栋, 怀聪,
Hans Journal of Computational Biology (HJCB) , 2016, DOI: 10.12677/HJCB.2016.63007
Abstract:
CRISPR-Cas9系统是一种操作简单、灵活性好、识别和切割效率高的基因编辑技术,具有用于基因治疗的潜能。然而,由于该系统的主要组分Streptococcus pyogenes Cas9 (SpCas9)蛋白过大,难于向靶细胞运输,因而亟需构建截短体蛋白,以提高系统的运输效率、扩展其应用前景。前期结构研究表明,SpCas9结构域分界清晰,各结构域功能相对独立又彼此协同,易于通过对各结构域进行分步改造实现蛋白截短优化。但报道的晶体结构缺乏SpCas9的全长结构,及结构域间相互作用的关键信息。针对此问题,本文运用分子动力学(Molecular Dynamics, MD)模拟和动态网络分析方法研究SpCas9-sgRNA-DNA复合物结构。我们首先对已有晶体结构的缺失片段进行补齐,构建了一个包含全长SpCas9及DNA链的三元复合物原子结构。然后对复合物结构进行长时间尺度MD模拟,通过动态网络分析方法分析了SpCas9蛋白各结构域间的相互作用,找出影响SpCas9结构域间相互作用的关键氨基酸。与已有实验结果比较,所识别的位点是SpCas9蛋白正常工作的关键氨基酸。因此,本研究不仅可以加深人们对SpCas9作用机制的了解,也为SpCas9蛋白的优化改造提供理论指导。
CRISPR-Cas9 system is widely used in gene editing because of its simple operation, flexibility, and high recognition and cleavage efficiency, and it also has the potential for usage in gene therapy. However, Streptococcus pyogenes Cas9 (SpCas9), the main component in the powerful system is too large to be transferred to target cells, which limits its application. So it is necessary to shorten the length of SpCas9. Previous studies revealed that SpCas9 executed its functions by several cooperate but relatively independent domains, so it is possible to optimize this protein section by section. Nevertheless, the integrated structure of SpCas9 and the information on domain interacting is still lacking in reported crystal structures. To solve this problem, this study analyzed the structure of SpCas9-sgRNA-DNA complex using molecular dynamics (MD) simulation and dynamical network analysis. Firstly, the missing fragment of the existing crystal structure was completed to construct a ternary complex atomic structure containing full-length SpCas9 and non-complemen- tary DNA strand. And then, after a long time MD simulation of this new structure, the interactions between domains of SpCas9 were analyzed by dynamical network analysis. Finally, we determined the key residues for SpCas9 domains to interact with each other. Compared with previous experimental results, the identified sites are critical amino acids for proper SpCas9 function. Thus, this study not only deepens the understanding of the working mechanisms of the CRIPSR-Cas9 system, but also offers important guidelines for the optimization and improvement of the system.
可并行存取的共享RAM设计方案
,戴大为
自然科学进展 , 2001,
Abstract: 给出一种有广泛适应性的可并行存取的共享RAM设计方案.该方案由数据的无冲突存取存放方法及处理机(或处理单元)与共享RAM之间的互联网络结构两部分组成.详细分析和论证了该方法和该网络的主要特点和性能.并说明了该方案的实现方法与其他方案相比较的优点.
金属银凝固与非晶晶化过程的分子动力学模拟
A Study on Solidification and Amorphous Crystallization of Metal Ag by Molecular Dynamics Simulation
 [PDF]

, 梁工英
Applied Physics (APP) , 2013, DOI: 10.12677/APP.2013.36021
Abstract:

文章采用分子动力学方法,以金属银为对象,模拟了面心立方金属的凝固和非晶化过程,借助于体系的内能变化、径向分布函数(RDF)、公共近邻分析(CNA)、原子可视化技术对凝固和晶化形核过程中的结构演变细节进行了描述。模拟结果表明,液态金属中就存在11% bcc结构的短程有序集团,随着液态金属不断过冷,bcc集团逐渐增加,在凝固前达到最高的31%,在非晶形成时,bcc集团大约有24%。当最近邻原子距离相同时,bcc结构单位原子所占体积大于fcc结构,有利于在液态金属和非晶中存在。这些bcc结构作为结晶时的非自发形核的核心,与周围的无序原子一起迅速转变为fcc结构和少量的hcp结构。在过冷液体和非晶系统中并没有发现fcc和hcp的结构,fcc结构为凝固和非晶晶化的很短周期中迅速转变而成。

The melting and solidification of Ag was simulated by molecular dynamics method. The structural transfor- mation of Ag during the metal solidification and amorphous crystallization was analyzed based on the variations of the internal energy, radial distribution function (RDF), common neighbor analysis (CNA), and atomic visualization technique. The simulation results showed that the embryonic crystals similar to body-centered cubic (bcc-like) structure (about 11%) already exist in the liquid metal, the content of bcc increases with cooling and it is up to 31% near the solidifying. About 24% bcc structure has in the amorphous structure. The volume per atom of bcc is larger than that of fcc, which is beneficial in the cooling liquid metal and amorphous structure. In the nucleation process, bcc-like embryonic crystals can be used as the nucleus with disorder atoms near the bcc to transform fcc crystal. There is no fcc and hcp structure in the cooling melt and amorphous structure. They are formed in the solidification directly.

 

Ag-Cu共晶合金非晶转变及晶化的分子动力学模拟
A Molecular Dynamics Study on Amorphous Formation and Crystallization of Ag-Cu Eutectic Alloys
 [PDF]

, 梁工英
Applied Physics (APP) , 2013, DOI: 10.12677/APP.2013.38028
Abstract:

本文采用分子动力学方法研究了Ag-Cu共晶合金的结晶过程。依靠体系内能变化、公共近邻分析和原子可视化技术对Ag-Cu共晶合金的结构演变进行了分析。模拟结果表明,在10%~40%Cu范围内,随着Cu含量的增加,合金形成非晶结构的临界冷却速度减小,玻璃化转变温度增加。公共近邻分析的结果表明,在非晶晶化前的阶段,表征非晶结构的1551、1541和1431键对占据主要部分,但也存在少量的bcc和fcc晶核团簇。其中,表征正二十面体团簇的1551键对,随着Cu含量的增加而增加,表征缺陷二十面体团簇的1541和1431键对则相应减少,这表明,随着Cu含量的增加非晶体系的稳定性增加。与此同时,表征晶体相结构的键对随Cu含量的增加都有所减少,其中,bcc晶核的数量减少较小,但fcc晶核的数量却有较大的下降,从而使非晶晶化的形核核心减少,这也从结构上解释了非晶合金的玻璃化转变温度随成分增加而增加的现象。在非晶晶化以后,虽然体系以fcc结构为主,但仍存在一些无序的非晶态结构,这些结构存在于共晶两相界面,随Cu含量的增加而增加。利用可视化技术,我们可以发现,随着Cu含量的增加,Ag-Cu合金的共晶组织存在从固溶体形、网状共晶到层状共晶的演变。
The crystallization of Ag-Cu alloys was studied by molecular dynamics method (MD) with embedded atom potential (EAM). The structural developments of Ag-Cu alloys were analyzed based on the variations of internal energy, common neighbor analysis (CNA), and atomic visualization technique. The simulation results showed that with the increase in Cu composition, the critical cooling rate of amorphous formation decreased and the glass-transition temperature of amorphous increased under the same heating rate. The results of CNA showed that the amorphous structure is main, and a few crystal clusters (bcc and fcc) are in it. Among the amorphous bond pairs, the pairs 1551 increases with the increase in Cu composition, which is the character of regular icosahedrons cluster. Meanwhile, the pairs 1541 and 1431, which are the character of defect icosahedrons clusters, reduce correspondingly. These show that the stability of amorphous increases. With the increase in Cu composition, the pairs 1441, 1661 and 1421 are all reduced, the 1441 and 1661 decrease little and the 1421 decreases great, which implies that the nuclei reduce during the crystallization of amorphous and the glass-transition temperature increases. After crystallization, the fcc structure is dominant but there are a few defect icosahedrons clusters between the eutectic boundaries. Moreover, the eutectic structure of Ag-Cu alloys can be transformed from solid solution, net-like into the lamellar morphologies with composition during the solidification and crystallization.

圆柱体涡激振动缩尺实验的相似关系研究
Study on the Similarity Relation of Model Test of Vortex-Induced Vibration on Circular Cylinders
 [PDF]

周阳,
International Journal of Fluid Dynamics (IJFD) , 2014, DOI: 10.12677/IJFD.2014.23004
Abstract:
提出了一种基于雷诺相似的圆柱体涡激振动(VIV)实验方法。涡旋的泄放模式与雷诺数Re密切相关,目前圆柱体涡激振动的研究中,缩尺模型实验往往基于弗汝德相似而雷诺数不相似,因此,模型与原型的涡泄模式不同,由此可以推断,模型的涡激振动响应与原型不相似。这就意味着基于弗汝德相似准则的模型实验结果不能准确地预测原型的涡激振动响应。对基于雷诺数相似的模型与原型的涡激振动实验相似关系进行了推导,采用CFD方法对原型和3种不同相似准则条件下的缩尺模型进行了涡激振动仿真计算, 同时引入实验进行对比。数模结果表明,仅满足雷诺数相似的模型与原型的涡泄模式相似,这个结果与弗汝德数和雷诺数均相似的结果一致,而仅弗汝德数相似条件下,模型与原型之间的涡泄模式和尾流场完全不同。实验结果表明,仅满足雷诺数相似时,模型与原型涡泄周期满足相应缩尺比,而仅满足傅汝德数相似时,模型与原型涡泄周期不满足相应缩尺比。因此,缩尺实验中仅满足傅汝德数相似模型的涡激振动特性不可能与原型相似,应采用雷诺相似准则。
An experimental method, based on Reynolds number similarity, of the vortex-induced vibration (VIV) of circle cylinders is proposed to achieve VIV similarity between prototype and tested model. The VIV response of a circle cylinder is closely related to Reynolds number because the mode of vortex shedding highly depends on Re. However, the scaled model test of circle cylinder’s VIV is designed based on Froude number similarity but Reynolds number is not similar under the same fluid for both model and prototype. Therefore, the VIV response of tested model is not similar to that of the prototype because they have different vortex shedding modes. It means that the test results can not be used to predict the VIV response of the prototype according to the scaling law based on Froude number similarity. The prototype and three scaled models with different simi-larity schemes have been simulated using CFD to validate the method and at the same time, expe-riments are compared. The numerical results show that the similarity between prototype and model is satisfying by Reynolds number similarity, and it is in accordance with both Froude number and Reynolds number similarity. But the similarity between prototype and model is not satisfying by Froude number similarity. The experimental results show that the similarity of period of the vortex shedding is satisfying by Reynolds number similarity but not satisfying by Froude number similarity. As a result, Reynolds number similarity should be used in the scale model test instead of Froude number similarity when studying the characteristics of VIV.
GMT熔融浸渍中熔体在玻纤毡中的流动
李铭,,
复合材料学报 , 2000,
Abstract:  通过改装毛细管流变仪建立了专门的实验装置,研究高温高压下熔体在纤维床层中的流动行为。采用一维恒压流动实验分别测量了不饱和及饱和流动状况下玻纤毡厚度方向聚丙烯熔体的渗透率,考察了玻纤毡空隙率、单丝直径、针刺等几何结构对渗透率的影响。根据实验结果进一步讨论了GMT片材熔融浸渍过程中的气泡形成以及浸渍工艺参数的选择。
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