从文献数量的变化透视我国服装学科的发展

采用文献计量学方法,对1984年～2004年间我国服装学科研究论文的发表时间、文献分布情况进行了统计分析.通过曲线拟合,建立了文献数量随时间变化的回归方程并进行了有效性验证,从而证明了我国服装学科的文献数量随时间的变化近似符合指数曲线的变化趋势,其曲线与科学发展的初期阶段是相对应的,即我国服装学科正处于学科发展的初始阶段.总的发展趋势是从一般研究到多学科综合理论性研究,从物理性能研究深化到机理性研究,从主观评定转向量化的客观评定,并更强调其实用性、科学性和时代性.     

Insight into a natural Diels-Alder reaction from the structure of macrophomate synthase

The Diels-Alder reaction, which forms a six-membered ring from an alkene (dienophile) and a 1,3-diene, is synthetically very useful for construction of cyclic products with high regio- and stereoselectivity under mild conditions. It has been applied to the synthesis of complex pharmaceutical and biologically active compounds. Although evidence on natural Diels-Alderases has been accumulated in the biosynthesis of secondary metabolites, there has been no report on the structural details of the natural Diels-Alderases. The function and catalytic mechanism of the natural Diels-Alderase are of great interest owing to the diversity of molecular skeletons in natural Diels-Alder adducts. Here we present the 1.70 A resolution crystal structure of the natural Diels-Alderase, fungal macrophomate synthase (MPS), in complex with pyruvate. The active site of the enzyme is large and hydrophobic, contributing amino acid residues that can hydrogen-bond to the substrate 2-pyrone. These data provide information on the catalytic mechanism of MPS, and suggest that the reaction proceeds via a large-scale structural reorganization of the product.     

Insight into steroid scaffold formation from the structure of human oxidosqualene cyclase

In higher organisms the formation of the steroid scaffold is catalysed exclusively by the membrane-bound oxidosqualene cyclase (OSC; lanosterol synthase). In a highly selective cyclization reaction OSC forms lanosterol with seven chiral centres starting from the linear substrate 2,3-oxidosqualene. Valuable data on the mechanism of the complex cyclization cascade have been collected during the past 50 years using suicide inhibitors, mutagenesis studies and homology modelling. Nevertheless it is still not fully understood how the enzyme catalyses the reaction. Because of the decisive role of OSC in cholesterol biosynthesis it represents a target for the discovery of novel anticholesteraemic drugs that could complement the widely used statins. Here we present two crystal structures of the human membrane protein OSC: the target protein with an inhibitor that showed cholesterol lowering in vivo opens the way for the structure-based design of new OSC inhibitors. The complex with the reaction product lanosterol gives a clear picture of the way in which the enzyme achieves product specificity in this highly exothermic cyclization reaction.     

Insight into the covalent grafting of organic films onto carbon steel surfaces for protection

The novel use of p-nitrophenyldiazonium tetrafluoroborate salt(GG salt)as a protectant that is electrochemically grafted onto carbon steel has been investigated in0.05 mol L-1H2SO4and 5 wt%NaCl solutions using various corrosion monitoring techniques,such as electrochemical impedance spectroscopy,potentiodynamic polarisation,infrared spectra and scanning electron microscopy measurements.The electrochemical study reveals that this compound is a mixed inhibitor that predominantly controls the cathodic reaction.The surface-grafted film decreases the double-layer capacitance and obviously increases the charge transfer resistance relative to a bare carbon electrode.The values of inhibition effect remain nearly unchanged with an increase in temperature range of 298–318 K.The aryl diazonium is covalently bonded on the steel surface,causing a slight decrease in the apparent activation energy.Overall,the surface-grafted films exhibit excellent inhibition performance in acid and saline solutions within the studied temperature range.     

邓小平的世界眼光

邓小平观察、分析中国具有独到的世界眼光，这种世界眼光反映了邓小平深厚的马克思主义理论功底和科学的认识方法，主要体现在三个方面：一、邓小平根据对世界发展的趋势和国际格局的判断来确定中国共产党的基本路线、方针和政策，指导社会主义现代化建设；二、邓小平从世界发达国家和发展中国家现代化进程中总结现代化的一般规律、基本经验和教训，创造性地运用于当代中国社会主义现代化，研究中国社会主义现代化的特色。三、邓小平从世界社会主义运动的角度来分析、认识当代中国社会主义现代化的重要意义。     

Ab-initio investigation for the microscopic thermodynamics and kinetics of martensitic transformation

Martensitic transformation(MT) path in Fe-based alloys remains uncertain in spite of decades of research. Lots of relevant works, which mostly focused on the simplest Bain path, have been completed by the state-of-the-art firstprinciples methods based on density functional theory. In this work, the element effects on microscopic thermodynamics and kinetics of the MT are investigated in terms of two different paths, including the well-known shear dominated Bogers-Burgers path and a recently propo...     

热力学的一个相对论广义坐标变换

讨论了一个涉及热力学的广义坐标的相对论变换 ,发现热力学第一定律和理想气体状态方程对广义坐标的相对论变换具有不变性 ,表明广义坐标的相对论变换有其存在的理由 .     

Kinetics of bainite-to-austenite transformation during continuous reheating in low carbon microalloyed steel

A dilatometer was used to study the kinetics of bainite-to-austenite transformation in low carbon microalloyed steel with the initial microstructure of bainite during the continuous reheating process. The bainite-to-austenite transformation was observed to take place in two steps at low heating rate. The first step is the dissolution of bainite, and the second one is the remaining bainite-to-austenite transformation controlled by a dissolution process. The calculation result of the kinetics of austenite formation shows that the two steps occur by diffusion at low heating rate. However, at high heating rate the bainite-to-austenite transformation occurs in a single step, and the process is mainly dominated by shear. The growth rate of austenite reaches the maximum at about 835℃ at different heating rates and the growth rate of austenite as a function of temperature increases with the increase in heating rate.     

活性碳,碳黑,石墨与金刚石晶种的生长

介绍了活性碳、碳黑与石墨在过剩压驱动下金刚石晶种的生长．对两种无定形碳以及石墨在触媒中的分散溶解输运与再结晶进行了观察，对活性碳、碳黑在金刚石晶种生长中的机理作了探索性的讨论．三种碳片上的晶种均有明显长大，无定形碳作晶种生长的碳源是可行的     

探究英汉复句的省略

本文以Halliday提出的小句的信息功能的相关理论为理论支持,试图从语言功能的角度来解释英汉复句省略手法上的差异。具体分析是借助邱述德的语篇原则,通过探求说话人的交流意图和表达心理,细致地探究了英汉复句的省略手法的选择机制。     

Al对高碳钢连续冷却转变行为的影响

通过热处理试验结合热力学与动力学计算,研究连续缓慢冷却过程中Al元素对高碳钢组织转变的影响。结果表明,未添加Al的高碳钢中,显微组织由马氏体及残余奥氏体组成,含1.37%Al的高碳钢中出现了体积分数为5.1%的珠光体组织,且宏观硬度降低了约0.8HRC,这是由于Al的加入能使高碳钢的共析点向高温高碳方向移动,提高了珠光体转变的临界冷却速度及相变开始温度,加速了珠光体组织的形成。     

试论二语听力的可教性

从认知语言学角度出发．二语听者在自下而上及自上而下信息处理方面存在着各种困难。教师应针对这些困难,采取培养听者自下而上及自上而下两种信息处理能力的教学方式。在课堂教学上应有意识地培养学生话语感知,单词识别及策略使用的能力以体现二语听力的可教性。二语听力“可教性”的观点认为听力课堂的功能不应仅体现在丰富真实的听力内容与活泼生动的教学形式上,也不能仅止于提供机会让学生练习听力。二语听力课堂的功能应更深层次地体现在培养学生对自己听力能力的责任意识及驾驭能力上。     

胸腺嘧啶二醇脱氧核苷单分子糖苷键断裂的理论研究

采用理论计算方法对c is-(5S,6R)胸腺嘧啶二醇脱氧核苷(dTg)单分子糖苷键断裂的热力学和动力学性质进行了研究.在气相中,所有稳定点的几何构型都采用B3LYP/6-31+G(d,p)方法进行全优化,并利用导电极化连续模型对气相优化构型进行单点计算确定水的溶剂效应,作者主要考虑了直接断裂和抽氢断裂两条路径.计算结果表明:两条反应机理均涉及较高的活化能,从而说明单分子分解并不能促进糖苷键的断裂,该研究为生物体内这一重要反应提供了更多有用的信息.     

宋代皇权与相权关系再审视

自钱穆先生发表论文以来,皇权与相权关系问题成为学界讨论的热点。有学者以皇权多受宰相限制而得出相权加强的结论,未免有失公允。表面上皇权确实受相权限制,但只要深入考察,就会发现真正限制皇权的是宋代的士大夫群体、祖宗家法、儒家礼法以及统治者自身的统治理念。宋代之相权较唐代而言,确有削弱之势,且一直持续至明、清,这与皇权不断加强的大趋势相一致。而南宋权相的出现,一是皇权的主动授予,二是皇权的被迫让渡,即权相所行使的并非实际的相权,而是部分皇权。因此,南宋相权增强乃是一种假象,且这种假象给后世学者研究这一问题增加了很大的障碍。     

团簇Fe3Cr3异构转化热力学与动力学研究

依据密度泛函理论,在B3LYP/Lan12dz水平下运用Gaussian09程序,对团簇Fe_3Cr_3初始构型作优化计算,共得到8种三重态优化构型.先后从热力学和动力学角度对根据过渡态理论所得4种异构化反应展开研究.结果表明,基础构型的能量越低即构型越稳定则易于转化,而能量越高即越不稳定则越不易转化.此外,研究预测团簇Fe_3Cr_3三重态构型所能发生异构化反应的平衡常数K值范围为26.84～1.78×10~(52);由构型的热力学函数变化量结合范特荷夫方程,可对常温下未知异构化反应的热力学函数变化量及反应在不同温度下发生时的限度进行预测.     

从继承性看基础理论化学的发展及"空洞"

基础理论化学的继承性围绕着提出经验问题和解决实际问题而展开.继承性发展既体现着科学理论的前因后果又表明科学发展的一脉性及与时俱进性.化学家总是在理论与现实的“空洞“间寻找继承发展的切入点,“空洞“的最终便是继承性发展,进而产生更完善的理论来指导科学实践活动.     

Insight into the 2004 Sumatra-Andaman earthquake from GPS measurements in southeast Asia

Data collected at approximately 60 Global Positioning System (GPS) sites in southeast Asia show the crustal deformation caused by the 26 December 2004 Sumatra-Andaman earthquake at an unprecedented large scale. Small but significant co-seismic jumps are clearly detected more than 3,000 km from the earthquake epicentre. The nearest sites, still more than 400 km away, show displacements of 10 cm or more. Here we show that the rupture plane for this earthquake must have been at least 1,000 km long and that non-homogeneous slip is required to fit the large displacement gradients revealed by the GPS measurements. Our kinematic analysis of the GPS recordings indicates that the centroid of released deformation is located at least 200 km north of the seismological epicentre. It also provides evidence that the rupture propagated northward sufficiently fast for stations in northern Thailand to have reached their final positions less than 10 min after the earthquake, hence ruling out the hypothesis of a silent slow aseismic rupture.