105 resultados para H 301.14 R454r

em Chinese Academy of Sciences Institutional Repositories Grid Portal


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利用表面机械研磨处理技术,在301奥氏体不锈钢中得到晶粒尺度呈梯度分布的变形表层,进行了压缩试验和微观组织观察。结果表明,变形表层中晶粒可细化至100nm。相比原始态的屈服强度236MPa,具有变形梯度表层后屈服强度增加到436MPa,变形后的加工硬化指数为0.31,经400和700℃的退火后分别增加到0.32和0.35。另外,随着应变速率的增加,流变应力增大而加工硬化能力降低.

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hspace="8" width="100" height="153" align="left" />Adiabatic shear localization is a mode of failure that occurs in dynamic loading. It is characterized by thermal softening occurring over a very narrow region of a material and is usually a precursor to ductile fracture and catastrophic failure. This reference source is the first detailed study of the mechanics and modes of adiabatic shear localization in solids, and provides a systematic description of a number of aspects of adiabatic shear banding. The inclusion of the appendices which provide a quick reference section and a comprehensive collection of thermomechanical data allows rapid access and understanding of the subject and its phenomena. The concepts and techniques described in this work can usefully be applied to solve a multitude of problems encountered by those investigating fracture and damage in materials, impact dynamics, metal working and other areas. This reference book has come about in response to the pressing demand of mechanical and metallurgical engineers for a high quality summary of the knowledge gained over the last twenty years. While fulfilling this requirement, the book is also of great interest to academics and researchers into materials performance.
<h3 id="yui_3_7_3_1_1356267270901_1326">Table of Contentsh3>
h="20%">1h="70%">Introductionh="10%" align="right">1
h="20%">1.1h="70%">What is an Adiabatic Shear Band?h="10%" align="right">1
h="20%">1.2h="70%">The Importance of Adiabatic Shear Bandsh="10%" align="right">6
h="20%">1.3h="70%">Where Adiabatic Shear Bands Occurh="10%" align="right">10
h="20%">1.4h="70%">Historical Aspects of Shear Bandsh="10%" align="right">11
h="20%">1.5h="70%">Adiabatic Shear Bands and Fracture Mapsh="10%" align="right">14
h="20%">1.6h="70%">Scope of the Bookh="10%" align="right">20
h="20%">2h="70%">Characteristic Aspects of Adiabatic Shear Bandsh="10%" align="right">24
h="20%">2.1h="70%">General Featuresh="10%" align="right">24
h="20%">2.2h="70%">Deformed Bandsh="10%" align="right">27
h="20%">2.3h="70%">Transformed Bandsh="10%" align="right">28
h="20%">2.4h="70%">Variables Relevant to Adiabatic Shear Bandingh="10%" align="right">35
h="20%">2.5h="70%">Adiabatic Shear Bands in Non-Metalsh="10%" align="right">44
h="20%">3h="70%">Fracture and Damage Related to Adiabatic Shear Bandsh="10%" align="right">54
h="20%">3.1h="70%">Adiabatic Shear Band Induced Fractureh="10%" align="right">54
h="20%">3.2h="70%">Microscopic Damage in Adiabatic Shear Bandsh="10%" align="right">57
h="20%">3.3h="70%">Metallurgical Implicationsh="10%" align="right">69
h="20%">3.4h="70%">Effects of Stress Stateh="10%" align="right">73
h="20%">4h="70%">Testing Methodsh="10%" align="right">76
h="20%">4.1h="70%">General Requirements and Remarksh="10%" align="right">76
h="20%">4.2h="70%">Dynamic Torsion Testsh="10%" align="right">80
h="20%">4.3h="70%">Dynamic Compression Testsh="10%" align="right">91
h="20%">4.4h="70%">Contained Cylinder Testsh="10%" align="right">95
h="20%">4.5h="70%">Transient Measurementsh="10%" align="right">98
h="20%">5h="70%">Constitutive Equationsh="10%" align="right">104
h="20%">5.1h="70%">Effect of Strain Rate on Stress-Strain Behaviourh="10%" align="right">104
h="20%">5.2h="70%">Strain-Rate History Effectsh="10%" align="right">110
h="20%">5.3h="70%">Effect of Temperature on Stress-Strain Behaviourh="10%" align="right">114
h="20%">5.4h="70%">Constitutive Equations for Non-Metalsh="10%" align="right">124
h="20%">6h="70%">Occurrence of Adiabatic Shear Bandsh="10%" align="right">125
h="20%">6.1h="70%">Empirical Criteriah="10%" align="right">125
h="20%">6.2h="70%">One-Dimensional Equations and Linear Instability Analysish="10%" align="right">134
h="20%">6.3h="70%">Localization Analysish="10%" align="right">140
h="20%">6.4h="70%">Experimental Verificationh="10%" align="right">146
h="20%">7h="70%">Formation and Evolution of Shear Bandsh="10%" align="right">155
h="20%">7.1h="70%">Post-Instability Phenomenah="10%" align="right">156
h="20%">7.2h="70%">Scaling and Approximationsh="10%" align="right">162
h="20%">7.3h="70%">Wave Trapping and Viscous Dissipationh="10%" align="right">167
h="20%">7.4h="70%">The Intermediate Stage and the Formation of Adiabatic Shear Bandsh="10%" align="right">171
h="20%">7.5h="70%">Late Stage Behaviour and Post-Mortem Morphologyh="10%" align="right">179
h="20%">7.6h="70%">Adiabatic Shear Bands in Multi-Dimensional Stress Statesh="10%" align="right">187
h="20%">8h="70%">Numerical Studies of Adiabatic Shear Bandsh="10%" align="right">194
h="20%">8.1h="70%">Objects, Problems and Techniques Involved in Numerical Simulationsh="10%" align="right">194
h="20%">8.2h="70%">One-Dimensional Simulation of Adiabatic Shear Bandingh="10%" align="right">199
h="20%">8.3h="70%">Simulation with Adaptive Finite Element Methodsh="10%" align="right">213
h="20%">8.4h="70%">Adiabatic Shear Bands in the Plane Strain Stress Stateh="10%" align="right">218
h="20%">9h="70%">Selected Topics in Impact Dynamicsh="10%" align="right">229
h="20%">9.1h="70%">Planar Impacth="10%" align="right">230
h="20%">9.2h="70%">Fragmentationh="10%" align="right">237
h="20%">9.3h="70%">Penetrationh="10%" align="right">244
h="20%">9.4h="70%">Erosionh="10%" align="right">255
h="20%">9.5h="70%">Ignition of Explosivesh="10%" align="right">261
h="20%">9.6h="70%">Explosive Weldingh="10%" align="right">268
h="20%">10h="70%">Selected Topics in Metalworkingh="10%" align="right">273
h="20%">10.1h="70%">Classification of Processesh="10%" align="right">273
h="20%">10.2h="70%">Upsettingh="10%" align="right">276
h="20%">10.3h="70%">Metalcuttingh="10%" align="right">286
h="20%">10.4h="70%">Blankingh="10%" align="right">293
h="20%"> h="70%">Appendicesh="10%" align="right">297
h="20%">Ah="70%">Quick Referenceh="10%" align="right">298
h="20%">Bh="70%">Specific Heat and Thermal Conductivityh="10%" align="right">301
h="20%">Ch="70%">Thermal Softening and Related Temperature Dependenceh="10%" align="right">312
h="20%">Dh="70%">Materials Showing Adiabatic Shear Bandsh="10%" align="right">335
h="20%">Eh="70%">Specification of Selected Materials Showing Adiabatic Shear Bandsh="10%" align="right">341
h="20%">Fh="70%">Conversion Factorsh="10%" align="right">357
h="20%"> h="70%">Referencesh="10%" align="right">358
h="20%"> h="70%">Author Indexh="10%" align="right">369
h="20%"> h="70%">Subject Indexh="10%" align="right">375

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油菜甾醇类物质(Brassinosteroids, BRs)是植物生长发育必需的一类植物激素。在拟南芥中,BR可直接结合在位于细胞膜表面的受体激酶BRI1去激活BR的信号转导从而调节细胞核内的基因表达来调控植物的生长发育。为更好的了解水稻中BR信号的转导机理,我们利用反向遗传学研究了OsBZR1的功能并鉴定了一些与OsBZR1有相互作用的蛋白。利用RNAi干涉降低植物体内OsBZR1的表达可导致植株矮小,叶片直立,BR敏感性降低并改变一些BR响应基因的表达水平。此外我们利用酵母双杂交发现14-3-3蛋白可与OsBZR1发生相互作用,而去除推定的14-3-3结合位点的OsBZR1则不能与14-3-3蛋白在酵母和植物体内发生相互作用。去除14-3-3结合位点的OsBZR1转入拟南芥bri1-5突变体中可部分恢复bri1-5的表型而转野生的OsBZR1则对bri1-5的表型没有明显的影响。同时我们发现去除OsBZR1的14-3-3结合位点可影响OsBZR1在细胞内的分布,能增加OsBZR1在细胞核内的分布,这表明14-3-3蛋白至少可通过降低OsBZR1核内的分布来抑制OsBZR1的功能。这些结果有力的证明了OsBZR1和14-3-3蛋白在水稻BR信号转导中的重要功能。

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14-3-3蛋白家族结构非常保守,被认为广泛存在于所有真核生物的各组织器官中。已有研究表明,14-3-3蛋白可以和上百种蛋白进行相互作用,作为许多细胞进程的重要调节因子参与植物生长发育、细胞周期调节、细胞凋亡和信号转导等多个调控网络。植物14-3-3蛋白家族包括两大类:Epsilon group和Non-epsilon group。我们对这两类蛋白序列进行了进一步的分析,发现这两类蛋白有明显的更小亚类分布,并且不同的亚类包含有不同的模体。从对水稻和拟南芥中的14-3-3基因的分析结果来看,这两类基因在染色体上的分布以及外显子数目明显不同,我们认为这两类蛋白有着不同的进化历史。达尔文正选择在蛋白进化过程中起着很重要的作用,我们对两类蛋白受到的正选择进行分析,分别发现了一些受到正选择的位点,这些位点可能在两类蛋白的进化过程中起着关键作用。水稻是最主要的粮食作物之一,水稻14-3-3基因包含8个成员:GF14a、GF14b、GF14c、GF14d、GF14e、GF14f、GF14g和GF14h。我们选取其中的OsGF14c作为研究对象,对水稻14-3-3的功能做一定探讨。OsGF14c基因位于水稻8号染色体上,cDNA全长1154bp,编码256个氨基酸。序列分析表明该基因与酵母同源基因BMH2有71%的同源性,我们将OsGF14c转入BMH2缺陷型酵母中,发现可以互补酵母14-3-3缺陷的表型。同时对OsGF14c所做的酵母双杂交实验表明,蛋白本身在体外可以形成同源二聚体。GFP融合基因稳定表达结果显示,OsGF14c定位在细胞质中。为了更好的研究该基因的功能,我们通过构建的过表达载体异源转化拟南芥,得到纯合体后我们进行了一系列的胁迫和激素处理。激素、PEG8000、LiCl和甘露醇处理的植株均未表现出明显的表型,而NaCl、KCl处理后的植株表现出盐敏感的表型。