铝对焊缝组织与韧性的影响

铝能提高硅、锰的过渡系数和显著地细化焊缝组织,使强度升高,但含铝量过高,焊缝组织中针状铁素体减少,粒状贝氏体增多,甚至形成平行条束状M-A组元,致使焊缝韧性下降,钛、硼可改善含铝焊缝韧性。     

Fe-6.5% Si合金热轧板焊接接头的组织和力学性能

针对Fe-6.5% Si合金热轧板焊接接头易萌生裂纹的问题,研究了不同氩弧焊工艺对焊接接头显微组织和力学性能的影响规律.研究表明:不使用填充焊丝的TIG焊不适合Fe-6.5% Si合金热轧板焊接,因在焊缝内出现大量显微裂纹;使用工业纯铁焊丝的MIG焊实现了Fe-6.5% Si合金热轧板的良好连接,焊缝表面连续、鱼鳞纹均匀,焊缝内无显微裂纹.稀释硅浓度是改善焊缝区组织和力性的有效方法.优化工艺下的焊接接头在500℃拉伸延伸率5.5%,抗拉强度280 MPa,满足Fe-6.5%Si合金板带制造过程中的温轧工艺要求.     

Fabrication of High Quality SiGe Virtual Substrates by Combining Misfit Strain and Point Defect Techniques

High quality strain-relaxed thin SiGe virtual substrates have been achieved by combining the misfit strain technique and the point defect technique.The point defects were first injected into the coherently strained SiGe layer through the "inserted Si layer" by argon ion implantation.After thermal annealing,an intermediate SiGe layer was grown with a strained Si cap layer.The inserted Si layer in the SiGe film serves as the source of the misfit strain and prevents the threading dislocations from propagating into the next epitaxial layer.A strained-Si/SiGe/inserted-Si/SiGe heterostructure was achieved with a threading dislocation density of 1×104cm-2 and a root mean square surface roughness of 0.87 nm.This combined method can effectively fabricate device-quality SiGe virtual substrates with a low threading dislocation density and a smooth surface.     

浅谈我国食品安全监管体系的缺陷和对策

随着《中华人民共和国食品安全法》的颁布和实施，我国食品监管方面有了很大的改善。但与消费者对食品安全的要求还有距离，不安全食品危害事件也时有发生，食品法律法规相互之间的协调性、操作性和对经营者违法惩罚力度等方面还有不足，需进一步完善我国食品安全配套法规、监管方式和运行机制。     

农村学校德育工作的缺失及其对策

由于特定的环境和特殊的受教育者，德育成为了农村教育链条中的最薄弱环节。传统的思想道德教育，无论是从观念、内容上，还是从方法、管理上都存在弊端。若要发挥德育的育人功能，必须调整德育主题目标和内容；加强培训，切实提高德育工作者的自身素质；促使德育走近学生，走人家庭，走向社会；优化德育教育环境。     

抗辐照纳米材料的研究进展

辐照在材料中诱发多种缺陷,使材料的物理、力学及化学性能退化并最终导致材料失效.与传统材料相比,纳米材料具有高密度的晶界、相界等界面,因而展现出更高的抗辐照损伤能力.本文回顾了近年来国内外众多学者有关纳米材料抗辐照性能的研究工作,并针对实验结果做了简要介绍、总结及展望.     

Application of GIS-Based Spatial Filtering Method for Neural Tube Defects Disease Mapping

This study is to assess the prevalence rates spatial pattern of neural tube defects with geographic information system and spatial filtering technique. A total of 80 infants who diagnosed from neural tube defects in the area being studied between 1998 and 2001 were analyzed. Firstly, the geographic information system （GIS） software ArcGIS was used to map the crude prevalence rates. Secondly, the data were smoothed by the method of spatial filtering. We evaluated that the effect of changes in spatial filtering radius size was assessed by creating maps based on various filtering radius sizes. The 3 miles or larger filtering radius gives better section variability than the 2 and 2.5 miles or smaller ones. The maps produced by the spatial filtering technique indicate that prevalence rates in the villages in the southeastern region are to produce higher prevalence than that in the other regions. The smoothed maps based on Heshun County display a more adequate data representation than the raw prevalence rate map.     

民间融资繁荣的背后

阐述了民间融资发展的主要特点,列举了我国银行业九大制度缺陷,指出我国银行业目前存在的制度性缺陷是导致银行业金融服务功能弱化的重要原因,客观上促进了民间融资的繁荣,提出了相应的政策建议。     

跨水域大桥桩基础施工质量评价-案例分析

采用超声波法及取芯法对国内某跨海大桥桩基础施工质量进行评价。超声波法检测时发现波幅及波速存在异常点,进而利用取芯法对取出的芯样进行外观描述及抗压试验,试验结果表明:波幅及波速异常点处的芯样侧面存在微麻面,且抗压强度较低,并判定桩身局部存在离析现象,桩身结构完整性为Ⅱ类。超声波法为实体工程中桩身质量的检测提供了便捷,但其精准性不足,需借助取芯法进行验证。     

环境压力对熔化极气体保护焊焊接过程及焊缝成形的影响

摘要： 在环境压力0.1～1.0 MPa条件下,通过高速摄像和汉诺威分析仪等手段,研究了高压干法熔化极气体保护焊过程及焊缝成形的特点,分析了焊接飞溅和焊缝成形的主要成因.试验表明,随着环境压力的增加,焊接过程逐渐变得不稳定,飞溅增加,焊缝逐渐变窄,焊缝成形变差.