求解y″=f(x,y)的一类多步方法

本文给出求解特殊二阶常微分方程y″=f(x,y)的一类多步方法。我们采用文[1]及[2]中的算子法,推导出该多步方法的系数表达式,它们是容易在计算机上生成的。对于k=2～9,则构造出具体的算法。如果采用文[3]中的生成函数办法,则是难于得到这些结果的。     

长沙市廉租房物业管理现状与对策研究

廉租房是保障性住房体系的重要组成部分,但目前存在重建设、轻管理现象.通过对长沙市四个代表性廉租房项目的实地调查,发现普遍存在配套设施不全、房屋维护不到位、居民成分复杂、管理难度大、服务项目单一、满意度低、管理权责不清、经营困难等诸多问题,提出建立“政府主导、企业运作、多方参与”的廉租房物业管理模式,建立健全相关制度,完善激励机制,鼓励物业企业参与廉租房规划设计、建设和管理的全过程,加强专业培训,开展特色服务和多种经营,提高居民参与意识等一系列对策建议.     

Multilayered feed forward neural network based on particle swarmopti mizer algorithm

1 .INTRODUCTIONNowadays there are many algorithms used to trainand opti mize neural network.BPalgorithm,whichisbased on gradient vectors of nodes ,is the most popu-lar neural network training method. Once gradient in-formation is obtained, kinds of regression technologiesbased on gradient can be adopt to update parameters.However BP algorithm faces some problems :(1) speed of convergence ; (2) local mini ma ; (3)sensitivity of initial value ;(4) dependence on gradi-ent information. For s…     

国内翻译模因论研究综述

模因论在国内是一个新理论,不少学者在翻译学领域从模因论视角提出崭新的观点。通过对近八年(2003-2010年)来有关翻译模因论研究的文章进行统计与分析,总结出目前国内翻译模因论研究的特点,并对模因论在翻译学领域研究三种分类作一综述。     

Quantum computation on gate-defined semiconductor quantum dots

During the past few years, researchers have made significant progress on quantum information processing in gate controlled semiconductor quantum dots. We review the global research efforts, including works by our group, which provides pathways towards applications in quantum computation.     

Cloning of human cytokine signal transduction inhibitor genehumSOCS-2

An EST (gb/AA115239) with high identity to the mouse cytokine signal transduction inhibitor genemmSOCS-2 was selected in GenBank EST database by the homologous screening method. The cDNA with the same sequence of the EST was got in human placenta cDNA library by PCR and a 1011 bp cDNA fragment was selected using above cDNA as probes to perform walking hybridization in placenta cDNA library. The cDNA fragment contains one 594 bp open reading frame (ORF) which encodes 198 amino acid residues. It was proved to be novel after NCBl database screening. Homology comparison showed that this gene has 93% identity tommSOCS-2 at the amino acid level and it has high identities to other related genes in SH₂ domain and SOCS box, so it was namedhumSOCS-2 and the accession number in GenBank is gb/AF020590. The expression analysis showed that the gene is expressed obviously higher in prostate than in other 15 human tissues.     

科学管理源流考

科学管理是20世纪的重要思潮,其产生与美国在建国过程中所形成的博采众长的实用文化——较为纯粹的新教伦理、实用主义科学技术观、以程序保证民主的政治制度和作为科学管理先驱的制度化管理等,不无关联。考察其孕育生态,对于中国兼容并蓄地通过科学管理促进科学发展,不无价值。     

Agonist-independent activation of metabotropic glutamate receptors by the intracellular protein Homer.

G-protein-coupled receptors (GPCRs) transduce signals from extracellular transmitters to the inside of the cell by activating G proteins. Mutation and overexpression of these receptors have revealed that they can reach their active state even in the absence of agonist, as a result of a natural shift in the equilibrium between their inactive and active conformations. Such agonist-independent (constitutive) activity has been observed for the glutamate GPCRs (the metabotropic glutamate receptors mGluR1a and mGluR5) when they are overexpressed in heterologous cells. Here we show that in neurons, the constitutive activity of these receptors is controlled by Homer proteins, which bind directly to the receptors' carboxy-terminal intracellular domains. Disruption of this interaction by mutagenesis or antisense strategies, or expression of endogenous Homer1a (H1a), induces constitutive activity in mGluR1a or mGluR5. Our results show that these glutamate GPCRs can be directly activated by intracellular proteins as well as by agonists.     

具有脉冲的时滞Logistic方程的全局吸引性

考虑具有脉冲的时滞Logistic方程其中τ＞0,r(t)∈C([t0,+∞),R+);-1＜bk≤0;且{tk}满足t0＜t1＜t2＜…＜tk＜…,limtk=+∞,给出了(*)的解是全局吸引的充分条件.     

随机路点运动模型合群特性研究

以随机点过程和Palm积分为数学模型基础,对移动通信系统仿真模型中常用的随机路点(RWP)运动模型的合群特性进行了分析.指出大量服从RWP模型的节点共同运动时,会表现出一种天然的倾向于区域中心的合群特性,而非均匀分布.通过定义合群密度,给出了RWP模型在一般凸区域内的合群密度的计算方法及一维线段和正方形区域上的合群密度显式.通过两个实例仿真验证了分析结论.