从RC5到RC6

论文详细描述并分析了从RC5到RC6的演化设计过程,在详细研究了RC6性能的同时,指出了应该如何从一个旧的密码设计出好的新密码。最后对RC6和Rijndael作了一些比较,指出各自在性能上的优缺点。     

NMDA Receptor Modulation of Incidental Learning in Pavlovian Context Conditioning.

Rats exposed to a footshock show conditional fear when reexposed to the shock context. Immediate presentation of shock after placement in the context significantly reduces this fear. Preexposure to the context in the absence of shock, coupled with a minimum preshock interval during training, overcomes this immediate shock deficit. Because rats learn about the context during preexposure and express that learning after being reinforced, the context preexposure effect is an aversive analogue of latent learning. The authors examined the effect of the N-methyl-D-aspartate (NMDA) receptor antagonist D,L-2-amino-5-phosphovalerate (APV) on the facilitatory effect of context preexposure. Rats were preexposed to a chamber after APV administration. The next day they were placed in the same chamber without drug and received shock 35 s later. APV blocked the facilitatory effect of preexposure. Therefore NMDA receptors are important for contextual latent learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cd-ZSM-5沸石催化剂的制备、表征和芳构化催化性能

采用离子交换、浸渍和混合三种方法制备镉改性ZSM-5沸石催化剂,考察了改性方法和镉含量对催化剂的表面酸性和Cd状态以及芳构化性能的影响。结果表明,加入镉降低了B酸性,Cd~(2+)与沸石结合形成了L_(1612)酸中心,其生成量取决于改性方法和Cd含量,并与芳构化活性提高有直接关系。     

故县大坝坝基泥化性F_5断层的化学灌浆防渗加固处理

泥化软化性F_5断层是故县大坝坝基范围内最大的一条断层,位于左岸,对左坝肩的稳定极为不利,采用水泥灌浆处理无效,故改用化学灌浆处理。选用EAA化学浆材,采用“优选组合配方综合施灌”的创新施工工艺,效果良好,为今后低渗透性复杂的泥化软化性断层的防渗加固处理,提供了新的依据和途径。     

冲裁模CAD／CAM结构库之原型法

本文首先给出了一种新的2.5D 实体表示法,然后在此基础上提出了“原型”的概念。原型法的思想运用在结构库的管理中主要体现在它将模具结构与构成这种结构的零件之间的强联系变成弱联系,结构库面向的对象是一个具有整体性和可运算性的结构原型。这样的原型结构库基本上达到了通用性与开放性的要求。     

A STUDY ON ACIDITY AND CATALYTIC PROPERTY OF [B] ZSM-5 CATALYST MODIFIED WITH SILICON COMPOUND BY CHEMICAL SURFACE DEPOSITION OF LIQUID-PHASE TECHNIQUE

The boron heteroatom zeolite catalyst has been modified with silicon compound by Chemical Surface Deposition of Liquid-phase (CLD) technique and the catalytic property of the modified catalyst is studied. Meanwhile, the acidity of the modified zeolite catalysts is characterized through TPD and IR technique, and the fluid adsorption method is used to determine its pore structure. The relationship between the catalytic property of the zeolite catalyst and its pore structure, its acidity has been found. The results of toluene-ethylene alkylation reaction indicate that the selectivity of p-ethyltoluene on the modified zeolite catalyst is higher than that on the zeolite catalyst before silanizated, reaching 94.14%.     

Morphology and properties of poly[2‐methoxy‐5‐(2′‐ethyl‐hexyloxy)‐para‐phenylene vinylene]/silica nanoparticle hybrid films

Poly[2‐methoxy‐5‐(2′‐ethyl‐hexyloxy)‐para‐phenylene vinylene] (MEH‐PPV)/silica nanoparticle hybrid films were prepared and characterised. Three kinds of materials were compared: parent MEH‐PPV, MEH‐PPV/silica (hybrid A films), and MEH‐PPV/coupling agent MSMA/silica (hybrid B films), in which MSMA is 3‐(trimethoxysilyl) propyl methacrylate. It was found that the hybrid B films could significantly prevent macrophase separation, as evidenced by scanning electron and fluorescence microscopy. Furthermore, the thermal characteristics of the hybrid films were largely improved in comparison with the parent MEH‐PPV. The UV‐visible absorption spectra suggested that the incorporation of MSMA‐modified silica into MEH‐PPV could confine the polymer chain between nanoparticles and thus increase the conjugation length. The photoluminescence (PL) studies also indicated enhancement of the PL intensity and quantum efficiency by incorporating just 2 wt% of MSMA‐modified silica into MEH‐PPV. However, hybrid A films did not show such enhancement of optoelectronic properties as the hybrid B films. The present study suggests the importance of the interface between the luminescent organic polymers and the inorganic silica on morphology and optoelectronic properties. Copyright © 2004 Society of Chemical Industry     

基于双因子认证技术的网络身份识别

本文提出了一种基于动态双因子认证技术的网络身份识别方法,用户每次登录的口令是利用系统时间和用户ID通过MD5加密算法计算得到,其通过MD5加密后生成的登录口令是随机的,这将进一步提高开放网络环境下身份识别的可靠性和安全性。同时,本文还提出网络身份识别技术可以应用到各类网站的服务器上,用来完成对用户身份的识别,以提高网络系统的安全性。     

High Temperature Oxidation Behavior of La2O3-MosSi3/MoSi2 Composites

The oxidation behavior of 0. 8% La2O3- Mo5Si3/MoSi2 composites at 1200℃ in air was investigated. The results reveal that the oxidation resistance of the material with 0. 8% La2O3 and Mo5Si3 is impaired. The oxidation resistance is decreased with increasing Mo5Si3 content. The mass loss follows a linear law in the initial oxidation. With oxidation time prolonging, a continuous and dense oxidation scale prevents oxygen from diffusing increasing when and leads to mass change a Mo5Si3 content is less than 30%. However, the composite shows ＂PEST＂ with the addition of 40% Mo5Si3. With increasing Mo5Si3 content, the oxidation resistance of 0.8% La2O3- Mo5Si3/MoSi2 decreases. This attributes to the poor oxidation resistance of M05Si3 and the relative density decreasing of 0. 8% La2O3-Mo5Si3/MoSi2 composite.     

Influence of CYP3A5 polymorphism on tacrolimus blood concentrations in renal transplant patients

Objective Tacrolimus is an immunosuppressive drug with narrow therapeutic range and wide interindividual variation in its pharmacokinetics. Tacrolimus is a substrate of cytochrome P450(CYP)3A5. The aim of this study was to evaluate whether the A6986G polymorphism is associated with tacrolimus concentration /dose ratio. Methods Fifty-two Chinese renal transplant patients were enrolled in this study. Their body weight, dosage and concentration of tacrolimus were observed. CYP3A5 genotype was determined by polymerase chain reaction followed by restriction fragment length polymorphism analysis. Results A significant association was found between tacrolimus levels per dose/kg/d and CYP3A5 gene A6986G polymorphism (P<0.001). The CYP3A5 * 3 * 3 patients have a significantly higher tacrolimus level/dose than CYP3A5 * 1 * 1 and CYP3A5 * 1 * 3. Conclusions CYP3A5 gene A6986G polymorphism is associated with tacrolimus pharmacokinetics and dose requirements. Pharmacogenetic methods could be employed prospectively to help the dose selection and to individualize immunosuppressive therapy according to the result. Foundation item: Project (03GZ3072) supported by the Science and Technology Department of Hunan Province; project (2004035206) supported by the China Postdoctoral Foundation and project (30300383) supported by the National Natural Sciences Foundation of China