网络安全隔离GAP技术研究

GAP技术是从物理隔离技术之上发展起来的一种新型网络安全技术，其核心是在物理隔离的基础上实现数据安全传输和资源共享。对物理隔离的功能和安全性，GAP的工作原理与解决方案进行了详细的分析，对物理隔离网闸、物理隔离网卡和防火墙进行了比较，并展望了GAP技术的应用前景。     

基于GAP技术的电子商务安全管理方案

结合技术研究和实际产品设计经验,探讨了第四代物理隔离技术-GAP技术的安全隔离与信息交换系统的实现原理和设计方案,分析和总结了该系统的改进之处和其发展趋势,用通俗事例说明了GAP在电子商务中的具体应用.     

网络隔离技术(GAP)及其应用研究

目前,网络安全问题十分严峻,采用GAP技术可以实现两个物理层断开网络间的信息摆渡,很好地解决了安全隔离下的信息可控交换等问题。本文介绍了隔离技术的发展历程,网络隔离技术(GAP)的概念、原理和特点,论述了网络隔离技术(GAP)在未来靶场的实现方法。     

安全数据交换管理系统的研究与实现

在分析了物理连接逻辑隔离的网络所存在的安全隐患以及传统的物理隔离解决方案的缺陷的基础上，提出了逻辑连接物理隔离的网络安全解决方案，进而开发了安全数据交换管理系统．该系统采用物理隔离技术、强身份认证技术安全审计技术、实现内外网的物理隔离，适用于需要安全隔离计算机网络的单位，特别是企事业单位和政府机关。     

物理隔离技术及其数据安全转发模型

在对保护内部网络安全的物理隔离技术进行分析的基础上,针对物理隔离环境下数据转发存在的问题,提出一种基于物理隔离技术的数据安全转发模型,并就其技术途径、实现方法、可能出现的安全隐患进行分析,探讨了安全策略和安全措施,从而达到保护内部网络安全的目的.     

以太网物理隔离控制器的设计与实现

以太网物理隔离系统由物理隔离控制器和用户终端组成,物理隔离控制器基于MCF5271设计,舍用户身份识别和用户网络切换两个主要功能,可通过FPGA芯片控制8片KS8995,支持8个通道的物理隔离。由于采用嵌入式以太网技术,该设计具有无附加网络干扰和支持三层网络控制等优点,可作为物理隔离技术的实验研究平台。测试表明：物理隔离控制器能够与用户终端稳定的交互信息,并实现网络切换的功能。     

网络物理隔离技术的应用

物理隔离是一种有效的网络安全防护措施,应用物理隔离技术可以很好地满足政府、军队、军工、金融、电信、科研、企业等单位在保证内部数据安全的同时又能方便获取外网信息的双重要求。本文介绍了网络物理隔离的基本技术,根据实际需求提出了单布线双网物理隔离解决方案。     

利用物理隔离技术解决涉密网与非涉密网信息交换的安全问题

当前电子政务建设中一般都对网络按照安全级别进行了安全域的划分，这在一定程度上保证了信息的安全，但同时也带来了网络和信息互联互通难，资源共享难，信息交换难的问题，本文试利用物理隔离技术对这一难题进行破解。     

基于物理隔离技术的企业防信息泄露解决方案

伴随网络的普及,安全问题日益成为影响网络效能的瓶颈,而企业的网络安全存在漏洞的状况也是众所周知的。物理隔离技术是一种比较彻底、安全的防范技术,解决了目前网络安全存在的根本问题。本文将介绍物理隔离技术以及某金融公司物理隔离技术解决方案。     

多网安全隔离交换系统的设计与实现

以隔离网闸技术为基础,设计并实现了一个多网安全隔离交换系统.系统采用了多线程、ARP缓存、网络地址转换等技术,使多个外网能够并行接入系统,对内网进行安全访问;采用了零拷贝技术,并优化了规则匹配算法以提高处理性能.经验证,设计实现的多网安全隔离交换系统能够对内外网络进行物理隔离,并对网络数据进行深度内容检查和安全控制,且具有较高的网络处理性能.     

基于仿真分析的网闸系统强壮性设计

基于网闸的原理和信号完整性设计方法,提供了网闸系统仿真设计方案,并保证了系统设计的强壮性.其稳定的性能使之成为新一代网络安全控制模块有价值的候选者.     

MIPS千兆网闸系统实现及其信号完整性设计

描述了网闸技术原理和实际采用的技术路线，提供了一套千兆网闸的架构设计方案及其隔离设备的设计方法．给出了基于仿真分析的印刷线路板（PCB）信号完整性设计方法，通过对重要时钟信号网络两次布线前的仿真分析，调整了时钟芯片及其他接收芯片的布局，保证了整个系统的强壮性．而且系统的精确度和稳定性得到了改善，并以其优良的性能使之成为新一代网络安全控制模块有价值的候选者．     

Suppression of c-ras transformation by GTPase-activating protein

The ras genes are required for normal cell growth and mediate transformation by oncogenes encoding protein tyrosine kinases. Normal ras can transform cells in vitro and in vivo, but mutationally activated ras does so much more efficiently, and highly transforming mutant versions of ras have been isolated from a variety of human and animal tumours. The ras genes encode membrane-associated, guanine nucleotide-binding proteins that are active when GTP is bound and inactive when GDP is bound. The slow intrinsic GTPase activity of normal mammalian Ras proteins can be greatly accelerated by the GTPase-activating protein (GAP), which is predominantly cytoplasmic. This activity of GAP, which can increase with cell density in contact-inhibited cells, suggests that it functions as a negative, upstream regulator of ras. Other studies, however, show that GAP interacts with a region of ras-encoded protein implicated in ras effector function, which raises the possibility that GAP might also be a downstream target of ras. Mutationally activated ras-encoded proteins also interact with GAP, although they are resistant to its catalytic activity. In an attempt to define the role of GAP in ras-mediated transformation, we examined the effects on transformation of normal or mutant ras when cells overexpress GAP. We found that GAP suppresses transformation of NIH 3T3 cells by normal Ha-ras (c-ras) but does not inhibit transformation by activated Ha-ras (v-ras). These results support the hypothesis that GAP functions as a negative regulator of normal ras and make it unlikely that GAP alone is the ras target.     

GAP改性单基球形药的热分解性能研究

采用热重-微热重(TG-DTG)和差示扫描量热(DSC)实验,研究了纯单基球(NC)、聚叠氮缩水甘油醚(GAP)以及GAP改性的单基球形药的热分解性能,探索了球药中主要组分NC和GAP之间的相互作用. 实验结果表明:GAP质量分数分别为20%和30%的改性单基球形药在发生热分解时,存在GAP的热分解过程,且其主链的热分解峰值温度较纯,GAP相应的峰值温度分别提前3.5℃和8.4℃. DSC测试显示,NC的热分解产物和热量使GAP质量分数为20%和30%的改性单基球中—N₃基团的放热峰分别降低8.18℃和7.70℃,即发现在GAP改性的单基球中,NC的存在对GAP的热分解具有一定的促进作用.      

贵州药用植物种质资源的调查和可持续利用研究(英文)

采用“贵州药用植物资源调查与鉴定→资源保护与开发利用的偶合关系→资源利用与种苗扩繁技术及途径→GAP基地示范和中药材及其产品分级开发体系论证→综合评价与结论”的技术路线和实验研究方法进行调查研究 ,鉴于贵州 6 1.9%的喀斯特地质地貌因水土流失和石漠化现象而造成的生态环境恶化致使一些生态脆弱的珍稀和特有药用植物种类趋于濒危 ,广布种也逐渐稀少等问题。提出了在对贵州药用植物种质资源实行有效保护和确保植物体药用质量的前提下 ,合理高效的开发利用和大面积规范化种植栽培 ,走资源节约型、产品高科技的中药现代化发展路子     

Aberrant regulation of ras proteins in malignant tumour cells from type 1 neurofibromatosis patients.

Defects in the NF1 gene have been implicated in the inherited disorder neurofibromatosis type 1, which is characterized by several developmental abnormalities including an increased frequency of benign and malignant tumours of neural crest origin (neurofibromas and neurofibrosarcomas respectively). The NF1 gene encodes a ubiquitous protein homologous to p120GAP, the GTPase-activating protein (GAP) for the products of the ras protooncogenes. When expressed in non-mammalian systems, the region of the NF1 gene homologous to p120GAP produces a protein with GAP-like activity. Here we present evidence that the ras proteins in malignant tumour cell lines from patients with type 1 neurofibromatosis are in a constitutively activated state, as judged by the guanine nucleotide bound to them, and are necessary for cellular proliferation. These cells contain p21ras and p120GAP that are both functionally wild type, but barely any functional NF1 protein. Our results show that the NF1 protein is normally essential for correct negative regulation of ras proteins in the cell, even in the presence of normal p120GAP, and they support the hypothesis that NF1 is a tumour-suppressor gene whose product acts upstream of ras.     

求解广义分配问题的拉格朗日蝙蝠算法

基于广义分配问题(GAP)自身的特点,将拉格朗日松弛算法(LR)和蝙蝠算法(BA)相结合,提出了一种高效的拉格朗日蝙蝠算法(LR-DBA)。首先,基于GAP的数学模型,在BA算法的基本框架上,重新定义了蝙蝠速度、位置以及局部更新公式,得出全新的求解GAP的离散蝙蝠算法(DBA)。其次,将其与LR相结合,设计出求解GAP的LR-DBA算法。最后,经过大量算例测试表明,对比DBA算法,LR-DBA混合算法在求解GAP时具有明显优势。     

Cloning of bovine GAP and its interaction with oncogenic ras p21

The plasma membrane-bound mammalian ras proteins of relative molecular mass 21,000 (ras p21) share biochemical and structural properties with other guanine nucleotide-binding regulatory proteins (G-proteins). Oncogenic ras p21 variants result from amino acid substitutions at specific positions that cause p21 to occur predominantly complexed to GTP in vivo. Recently, a GTPase activating protein (GAP) with cytosolic activity has been discovered that stimulates the GTPase activity of normal but not of oncogenic ras p21. GAP might be either a negative regulatory agent which acts further upstream in the regulatory pathway or the downstream target of ras p21. We have identified a protein from bovine brain with apparent relative molecular mass 125,000 that has GAP activity. Here, using pure GAP in a kinetic competition assay, we show that GAP interacts preferentially with the active GTP complexes of both normal and oncogenic Harvey (Ha) ras p21 compared with the inactive GDP complexes. We also report the cloning and sequencing of the complementary DNA for bovine GAP. Regions of GAP share amino acid similarity with the noncatalytic domain of adenylate cyclase from the yeast Saccharomyces cerevisiae and with regions conserved between phospholipase C-148, the crk oncogene product and the nonreceptor tyrosine kinases.     

PDGF induction of tyrosine phosphorylation of GTPase activating protein

The cascade of biochemical events triggered by growth factors and their receptors is central to understanding normal cell-growth regulation and its subversion in cancer. Ras proteins (p21ras) have been implicated in signal transduction pathways used by several growth factors, including platelet-derived growth factor (PDGF). These guanine nucleotide-binding Ras proteins specifically interact with a cellular GTPase-activating protein (GAP). Here we report that in intact quiescent fibroblasts, both AA and BB homodimers of PDGF rapidly induce tyrosine phosphorylation of GAP under conditions in which insulin and basic fibroblast growth factor (bFGF) are ineffective. Although GAP is located predominantly in the cytosol, most tyrosine-phosphorylated GAP is associated with the cell membrane, the site of p21ras biological activity. These results provide a direct biochemical link between activated PDGF-receptor tyrosine kinases and the p21ras-GAP mitogenic signalling system.