N,N''-取代邻苯二胺的合成

通过2-取代苯并咪唑盐的还原开环反应制备了8个N,N′-不同取代的邻苯二胺,并经1HNMR、IR、MS及元素分析表征,其中5个未见文献报道.这是一条由邻苯二胺和羧酸经2.取代苯并咪唑制取该类化合物的简洁合成路线.     

烯烃聚合单活性中心非茂催化剂的最新研究进展

综述了近几年来烯烃聚合用单活性中心非茂催化剂的研究进展。简要介绍了 2 3种由前、后过渡金属组成的配位化合物催化剂的结构与性能     

Structure and properties of CE/CTBN/EP blends: II. Effect of EP on the mechanical properties and thermostability of the CE/CTBN system

Carboxyl‐terminated butadiene‐acrylonitrile rubber (CTBN) has often been used to improve the toughness of cyanate ester (CE) resin while sacrificing modulus and thermostability. In this paper, the addition of the appropriate amount of epoxy resin (EP) to the CE/CTBN system is shown to not only increase the modulus and thermostability of the blend, but also improve the toughness. The values of impact strength showed a maximum for the CE/CTBN/EP 100/5/5 blend. The temperature of 10 % weight loss (T₁₀) improves from 376 °C for CE/CTBN 100/5 to 407 °C for the CE/CTBN/EP 100/5/2.5 blend. It is proposed that addition of the appropriate amount of EP can decrease the mobility and increase the stability of CTBN via the reaction between the terminal carboxyl group of CTBN and the hydroxyl group of EP. But a very high EP concentration will decrease the crosslinking density of CE, consequently reducing the mechanical properties and thermostability of the blends. Copyright © 2004 Society of Chemical Industry     

一种以太网兼容的综合话音/数据传输协议

本文提出一种与现有以太网兼容的综合话音/数据协议.描述了协议模型及实现方法.并用PASCAL语言在IBM-PC机上模拟研究了该协议的性能.模拟结果表明,该协议能满足话音的实时要求,性能良好,且数据传输性能没有明显下降.协议克服了以太网传输话音延迟不确定的缺点.     

Implementing total quality management at the U.S. Department of Defense

This paper examines Total Quality Management (TQM) as defined by Dr. W. Edwards Deming including Deming's fourteen points and explains how the United States' Department of Defense (DOD) defines TQM and why TQM is necessary. It also covers how the DOD is planning on implementing TQM and the policy that has been established as guidance in the implementation process.     

A micromechanical model for cleavage-crack reinitiation

A crack-tip screening analysis of cleavage fracture of steel is developed. The analysis incorporates evidence that reinitiation of an arrested cleavage crack requires less stress intensity than cleavage initiation from a fatigue precrack. Fractographic evidence as well as metallographic sectioning of arrested cracks have previously shown that the mechanism of rapid crack propagation by cleavage is affected strongly by partial crack-plane deflection which leaves unbroken ligaments in its wake. The tearing of these ligaments by dimple rupture is the dominant energy-absorbing mechanism. Earlier etch-pit experiments using an Fe-Si alloy showed that the crack-tip stress intensity based on plastic zone size is extremely low. These observations are incorporated into a model in which cleavage crack reinitiation is analyzed using a sharp crack that is shielded by a distribution of pinching forces along its faces. During reloading of the arrested crack, the ligaments restrict crack-tip blunting, leading to higher local stresses. As a result, lower stress intensities are needed for reinitiation than for initiation from a fatigue precrack.     

Model reactions on roast aroma formation

Summary From model roastings of mixtures containing serine, threonine and sucrose about 350 volatile compounds were separated and identified by GC/MS. Among them there were more than 100 monocyclic furans, 13 furanones and 8 bicyclic furans, the mass spectra and retention indices of which are recorded. The most important mass spectrometric fragmentation pathways are described. Spectra obtained from roasting coffee under identical conditions are compared with the spectra from model roastings.

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Modell-Reaktionen zur Röstaroma-BildungII. Die massenspektrometrische Identifizierung von Furanen und Furanonen aus der Reaktion von Serin und Threonin mit Saccharose unter den Bedingungen der Kaffeeröstung

Zusammenfassung Aus Modellröstungen von Gemischen aus Serin, Threonin und Saccharose unter den Bedingungen der Kaffeeröstung wurden etwa 350 flüchtige Verbindungen mittels GC/MS getrennt und identifiziert. Unter ihnen befanden sich über 100 monocyclische Furane und 13 Furanone sowie 8 bicyclische Furane, deren Massenspektren und Retentions-indices angegeben werden. Die wichtigsten massenspektrometrischen Fragmentierungswege werden beschrieben. -Die aus einer gleich behandelten Röstung von Rohkaffee erhaltenen Spektren werden mit denen der Modellröstungen verglichen.

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Dissertation Gloria Bochmann, TU Berlin 1984     

Optimal algorithms for adjacent side routing

We consider the switchbox routing problem of two-terminal nets in the case when all thek nets lie on two adjacent sides of the rectangle. Our routing model is the standard two-layer model. We develop an optimal algorithm that routes all the nets whenever a routing exists. The routing obtained uses the fewest possible number of vias. A more general version of this problem (adjacent staircase) is also optimally solved.This research was supported in part by NSA Contract No. MDA-904-85H-0015, NSF Grant No. DCR-86-00378, and by NSF Engineering Research Centers Program NSFD CDR 88003012.     

一个用户接口管理系统

本文介绍了一个用户接口管理系统NUUIMS的设计和实现.重点叙述了该系统基于规范化目标用户接口模型的设计思想,系统组成及描述方法.文章也讨论了使用NUUIMS设计而成的用户接口的特点.     

Edge-to-edge interfaces in Ti?Al modeled with the embedded atom method

The atomistic structure and energies of high-index interphase boundaries are explored using a combination of molecular statics and dynamics simulations with embedded atom potentials. We investigate planar boundaries between the α₂ and γ phases in the Ti−Al system. The class of boundaries considered has a high-index boundary orientation; the orientation relationship between the α₂ and γ phases also is high index, and a set of planes from each phase meet edge to edge at the boundary plane. For the particular case of a boundary that is commensurate in one direction and coincides with a moiré plane given by the so-called “Δg” diffraction condition, the boundary is not structurally singular, but it is energetically stable and does not appear to dissociate into other low-energy configurations. Misfit compensating defects are not observed; misfit in directions other than the commensurate one appears to be distributed uniformly. The boundary energy is evaluated as a function of the orientation of the boundary plane, and the edge-to-edge (moiré) boundary is found to lie in an energy cusp. This article is based on a presentation made in the “Hume-Rothery Symposium on Structure and Diffusional Growth Mechanisms of Irrational Interphase Boundaries,” which occurred during the TMS Winter meeting, March 15–17, 2004, in Charlotte, NC, under the auspices of the TMS Alloy Phases Committee and the co-sponsorship of the TMS-ASM Phase Transformations Committee.