Discretization and resolution of the (<Emphasis Type="Italic">r</Emphasis>|<Emphasis Type="Italic">X</Emphasis><Subscript><Emphasis Type="Italic">p</Emphasis></Subscript>)-medianoid problem involving quality criteria

In this paper an extension of the (r|X _p )-medianoid on networks introduced by Hakimi (1983) is studied. In this extension the customer considers not only the distance but some characteristics of the facilities such as store size, quality of service and parking space. A new firm wants to establishr new facilities which have to compete with thep facilities that already exist in the market. The entry firm wants to find their locations and characteristics to maximize profits. Three different customer choice rules (binary, partially binary and proportional preferences) are considered. Some discretization results are obtained and a resolution procedure is proposed. The problem is solved combining a global search algorithm based on a branch and bound procedure with some combinatorial heuristics (greedy, interchange, and tabu search). Some computational experiences are presented. Partially supported by Ministerio de Ciencia y Tecnología (Spain) and FEDER, grant BFM2002-04525-C02-01.     

现代教育技术在物理教学中的应用

现代教育技术与课程教学的整合,是我国面向21世纪基础教育教学改革的新视点。笔者就物理教学中应用现代教育技术的实践作初步探讨。     

镧掺杂水滑石材料的热分解过程研究

采用共沉淀法制备了系列La掺杂改性的含Cu类水滑石,高温焙烧得到其衍生混合氧化物材料,并用XRD,TG-DSC,FT-IR等对材料进行表征.结果表明,前驱物XRD图谱呈典型的水滑石衍射特征且颗粒结晶良好;经800℃焙烧后,掺杂La2O3含量为5.1%的样品仅有Mg1-xFexO晶相出现,说明La的掺杂提高了材料的高温稳定性,混合氧化物中的Cu离子呈高分散状态.     

信息技术与物理课程整合的几个层面

《基础教育课程改革纲要》要求 :要“大力推进信息技术在教学过程中的普遍应用 ,促进信息技术与学科课程的整合 ,逐步实现教学内容的呈现方式、学生的学习方式、教师的教学方式和师生互动方式的变革 ,充分发挥信息的优势 ,为学生的学习和发展提供丰富多彩的教育环境和有力的学习工具 .”可见 :信息技术与其它课程的整合是课程教学中把信息技术、信息资源、信息方法和课程内容有机结合 ,是一种新型的教学方式 .下面讨论几个具体层面上的问题 :1　信息技术与物理教学目标和内容的整合面对新世纪 ,信息处理的技能、学习能力、问题解决能力、与…     

Synthesis of some chiral liquid crystals and study of the effect of intramolecular hydrogen bonding on the phase behaviour

The synthesis of three new series of chiral Schiff's bases containing benzilideneaniline and 2-hydroxybenzilideneaniline moieties as mesogenic cores is presented. Differential scanning calorimetry, optical polarizing microscopy and X-ray diffraction measurements were used to study the phase transition temperatures and behaviour. The results reveal that most of these materials show chiral smectic mesomorphism.     

Role of Na(+)-Ca2+ exchange system in the pathogenesis of myocardial ischemia-reperfusion damage

Results from a systematic experiment on isolated perfused rat heart and isolated myocytes of adult rat showed that the mechanism of calcium influx during myocardial ischemia-reperfusion is due to the development of intracellular sodium overload during ischemic period; on reperfusion, the high intracellular Na+ content activated the reverse direction of Na(+)-Ca2+ exchange over myocardial sarcolemma (SL), thus a large quantity of extracellular Ca2+ fluxed over the SL to the intracellular space, forming a condition of intracellular Ca2+ overload, which leads to irreversible damage of the myocardium.     

用于光学神经网络硬件系统误差纠正的虚拟神经网络

提出了一种用于修正光学神经网络硬件系统误差的虚拟神经网络模型，光学实验结果表明该网络能够有效地消除硬件系统误差对实验结果的影响。     

Weighted Sobolev embedding with unbounded and decaying radial potentials

We prove embedding results of weighted W1,p(RN) spaces of radially symmetric functions. The results then are used to obtain ground and bound state solutions of quasilinear equations with unbounded or decaying radial potentials.     

Studies on the chemical constituents of the South China Sea sponge Phacellia fusca

Three pyrrololactam alkaloids have been isolated from the marine sponge Phacellia fusca Schmidt collected from the South China Sea, and their structures were determined as 1–3 , on the grounds of spectral data. This is the first report of these compounds from this sponge. The structure of 1 was confirmed by X-ray analysis.     

Controllable synthesis of ZnS/PMMA nanocomposite hybrids generated from functionalized ZnS quantum dots nanocrystals

We reported controllable synthesis of ZnS nanocrystal-polymer transparent hybrids by using polymethylmethacrylate (PMMA) as a polymer matrix. In a typical run, the appropriate amounts of zinc chloride (ZnCl₂) and sodium sulfide (Na₂S) in the presence of 2-mercaptoethanol (ME) as the organic ligand were well dispersed in H₂O/dimethylformamide solution without any aggregation. In addition, the Mn-doped ZnS nanocrystals (NCs) were synthesized with similar method. Then, ZnS-PMMA hybrids were obtained via free radical polymerization in situ by using ZnS NCs functionalized with methacryloxypropyltrimethoxysilane (MPS). FT-IR characterization indicates the formation of robust bonding between ZnS NCs and the organic ligand. The TEM images show that ZnS NCs are well dispersed in PMMA matrix, and particle size of as-prepared ZnS NCs is about 2.6 nm, in agreement with the computing results of Brus’s model and Debye–Scherrer formula. The photoluminescence measurements present that ZnS NCs, Mn-doped ZnS NCs, and ZnS/PMMA hybrid show good optical properties.