关于雀科四种鸟的核型分析与探讨

鸟类染色体研究是一个新兴的研究领域。最近几年大约有六百多种鸟类的核型被报道,但是同科鸟之间核型的比较分析所见报道较少。本实验以雀形目中的四种鸟为实验材料,通过核型之间的比较和分析,探讨了鸟类染色体的多态性和四种鸟的亲缘关系及进化趋势。同时还探讨了PHA对鸟类核型影响。     

矩阵方程AXB=C的一种新解法

给出了矩阵方程AXB=C的一种新解法及有关结论的一种新证明.     

永磁轴向多极场的获得

本文描述了永磁非对称轴向二极场的结构和形态,这种磁场用于替代同轴线圈提供微波ECR等离子体CVD系统所需的磁场;简要分析了磁场对等离子体特性的影响。     

航空机载软件适航性审定标准DO-178C与软件管理标准GJB5000A的比较分析

 航空机载软件适航性审定是验证软件安全性是否满足飞行要求的重要手段，审定依据的标准DO-178C是航空企业软件设计所必须遵循的规范要求，但在软件管理领域，还存在着重要的能力成熟度集成模型标准GJB5000A。比较分析了DO-178C与GJB5000A的异同，得出机载软件适航性审定在对软件开发过程的管理方面存在不足，提出需要加强企业在项目监控、过程测量与分析和风险管理方面的要求，并按照DO-178C标准的形式要求，给出了参考的改进方案。     

The functions of mucosal T cells in containing the indigenous commensal flora of the intestine

There is an immense load of non-pathogenic commensal bacteria in the distal small intestine and the colon of mammals. The physical barrier that prevents penetration (translocation) of these organisms into the body is a simple epithelium comprised of the single enterocyte/colonocyte cell layer with its overlying mucus. In this review, we discuss the roles of intestinal T cells in initiating and regulating innate and adaptive mucosal immune responses of the mucosal immune system that avoid or limit penetration of the commensal intestinal bacteria. Received 9 August 2002; accepted 9 September 2002 RID="*" ID="*"Corresponding author.     

A critical role for the protein tyrosine phosphatase receptor type Z in functional recovery from demyelinating lesions

Several lines of evidence suggest that tyrosine phosphorylation is a key element in myelin formation, differentiation of oligodendrocytes and Schwann cells, and recovery from demyelinating lesions. Multiple sclerosis is a demyelinating disease of the human central nervous system, and studies of experimental demyelination indicate that remyelination in vivo requires the local generation, migration or maturation of new oligodendrocytes, or some combination of these. Failure of remyelination in multiple sclerosis could result from the failure of any of these processes or from the death of oligodendrocytes. Ptprz encodes protein tyrosine phosphatase receptor type Z (Ptpz, also designated Rptpbeta), which is expressed primarily in the nervous system but also in oligodendrocytes, astrocytes and neurons. Here we examine the susceptibility of mice deficient in Ptprz to experimental autoimmune encephalomyelitis (EAE), a model of multiple sclerosis. We observe that mice deficient in Ptprz show impaired recovery from EAE induced by myelin oligodendrocyte glycoprotein (MOG) peptide. This sustained paralysis is associated with increased apoptosis of mature oligodendrocytes in the spinal cords of mutant mice at the peak of inflammation. We further demonstrate that expression of PTPRZ1, the human homolog of Ptprz, is induced in multiple sclerosis lesions and that the gene is specifically expressed in remyelinating oligodendrocytes in these lesions. These results support a role for Ptprz in oligodendrocyte survival and in recovery from demyelinating disease.     

Annexin II light chain regulates sensory neuron-specific sodium channel expression

The tetrodotoxin-resistant sodium channel Na(V)1.8/SNS is expressed exclusively in sensory neurons and appears to have an important role in pain pathways. Unlike other sodium channels, Na(V)1.8 is poorly expressed in cell lines even in the presence of accessory beta-subunits. Here we identify annexin II light chain (p11) as a regulatory factor that facilitates the expression of Na(V)1.8. p11 binds directly to the amino terminus of Na(V)1.8 and promotes the translocation of Na(V)1.8 to the plasma membrane, producing functional channels. The endogenous Na(V)1.8 current in sensory neurons is inhibited by antisense downregulation of p11 expression. Because direct association with p11 is required for functional expression of Na(V)1.8, disrupting this interaction may be a useful new approach to downregulating Na(V)1.8 and effecting analgesia.     

旋风预热器预热过程数值模拟试验研究

本文通过"三传一反"基本原理,建立了四级旋风预热器系统的预热过程气体平衡、物料平衡、热量平衡与流体、传热动动力学过程耦合的数学模型,并确立了其求解方法,通过对某厂实例的具体分析计算,表明该方法计算结果能较好地反应实际情况,为设计和优化预热器系统提供了一条有效的途径和方法.     

中日铁路项目国民经济评价方法比较与分析

以日本《铁路费用效益分析手册 (99版 )》和中国《铁路建设项目经济评价办法 (第 2版 )》为参照 ,通过对比分析中日铁路项目国民经济评价方法的差异 ,提出日本铁路费用效益分析方法中的可借鉴之处 :借鉴日本评价方法分 3类界定受益群体的思路 ,解决我国现行方法存在的效益重复计算问题 ;以福利经济学和“有无对比法”作为项目评价的基本指导原则 ,解决我国由于评价原则模糊导致的同一项目不同评价结论的问题等     

Analysis and design of DSP-based dual-loop controlled UPS inverters

This paper presents a novel digital dual-loop control scheme of the PWM(PUlse width modulate)inverter. Deadbeat control technique are employed to enhance the performance. Half switching period delayed sampling and control timing strategy is used to improve the system dynamic response. Simulation and experimental results presented in the paper verified the validity of the proposed control scheme.