热压/热变形Nd2Fe14B/α-Fe纳米双相永磁体的研究

为了制备各向异性块状Nd2Fe14B／α—Fe纳米双相永磁体，研究了热压／热变形工艺参数与样品微观组织结构、磁性能之间的关系。结果表明，饱和磁化强度Js随模压温度的升高而提高；而剩磁Jr、内禀矫顽力Hcj和最大磁能积(BH)max开始都随模压温度的升高而上升，但超过一定温度后反而降低；同时提高热压压力会使磁性能增加，而热变形温度对磁性能影响很小。热变形后样品垂直于压力方向的磁性能略高于平行于压力方向，呈现出轻微的各向异性。Nd2Fe14B／α—Fe纳米双相永磁材料在热压／热变形后没有产生晶粒的择优长大，在晶体学上仍然是各向同性的。     

Hydrogen Absorption and Release Behavior in Hydrogen Decrepitation Process of Nd-Fe-B Alloys

The behavior of hydrogen absorption and release in hydrogen decrepitation (HD) process of Nd-Fe-B alloys were investigated. The results reveal that the reactivity and the amount of hydrogen absorption in HD process are related to the surface activity of the alloy so that the fresh and active surface has a higher efficiency. The presence of Nd-rich phase at the grain boundary is an essential factor of the HD activity of the alloy at room temperature. On degassing, hydrogen is released from the HD powder continuously with increasing temperature. And the residual hydrogen is as low as 0.0015% at 1073K, which shows that the hydrogen is almost exhaused. It is feasible to remove the hydrogen from the HD powder by heating treatment at the temperature of 523-723K for 1h prior to the magnetic field forming in order to decrease the harmful effect of hydrogen on the easy axis alignment of HD magnet.     

商品混凝土收缩性能研究

商品混凝土以其施工进度快、质量好、劳力省、消耗低、技术先进等诸多优点而越来越受到人们的欢迎，已作为国家建设部的重点推广项目列入了“十五”发展规划。然而，由于商品混凝土使用要求流动性大、配合比中水泥和细骨料比例偏大、粗骨料比例偏小．而使得其材料本身在收缩过程中易产生裂缝，因而如何控制收缩裂缝便成了有待解决的突出问题。本文谨就此作一些探讨。     

采用直接探测技术的相对测量法降低非均匀光束给传输信息带来的影响

激光光束质量(均匀性)直接影响着激光传输光束空间分布的特性,也严重影响激光在传输应用领域(激光通讯、激光指令式制导、激光模拟训练技术等)的使用性能。 解决此问题的方法很多,例如用激光物理和物理光学方法改善激光器输出的光束质量、用光学耦合或积分法提高传输光束空间分布的质量等。这些技术措施虽然可行,但是造成系统结构复杂化,增大了体积和重量,同时也降低了激光输出的效率和功率。 本文采用激光直接探测技术的相对测量方法,将同一接收孔径接收到的光功率分为两路信号进行光电转换,信号处理后再进行两路信号的差、和、比计算,从而大大降低了因光束质量和大气抖动、     

新课程标准下的小学低年级语文教学

新课程标准的实施,促进了小学语文教学的改革与发展。就小学低年级学生来说,良好的学习习惯正尚未形成,生性活泼好动,学习全凭兴趣取舍,教师课堂教学一味的填鸭式满堂灌,让学生死记硬背,枯燥无味的死学,必然导致学生的厌学,学生的怕学,学生的拒学。教师一定注重教材的研究,实施恰当的教学方法,让低年级的课堂教学生动而有情趣,让学生喜欢学习语文,愿意学习语文。本文对新课程标准下的小学低年级语文教学进行了阐述。     

Texture of Nanocomposite Nd2Fe14B/α-Fe Melt Spun Ribbons

Highly textured nanocomposite Nd9Fe84.5Nb0.5B6 ribbons were obtained by rapid solidification at wheel speeds from 15 to 20 m·s-1.X-ray diffraction(XRD)shows that these ribbons are preferentially orientated with the c axis of Nd2Fe14B phase perpendicular to the surface of the ribbons.The texture of Nd2Fe14B phase on the free surface is stronger than that on the contact surface and decreases with increase of wheel speed.The texture of Nd2Fe14B phase seems to be caused by the preferential growth of the crystal nuclei favorable orientation with their c-axes along the temperature gradient during rapid solidification,which can be explained by a growth circular cone(GCC).The intensity of the anisotropy can be expressed by the magnitude of the cone generating angle.The supercooling velocity and wheel speed will influence the cone generating angle,which in turn influences the anisotropy.The remanence and maximum energy product in the direction perpendicular to the ribbon surface is much higher than that in the direction parallel with the ribbon surface.High remanence and maximum energy product can be obtained in the direction perpendicular to the ribbon surface.The texture of Nd2Fe14B phase decreases gradually after annealing above 600 ℃,which is mainly attributed to the precipitation of new α-Fe from Nd2Fe14B phase with super-saturated Fe.Decreasing the annealing temperature or reducing the annealing time is beneficial for preserving the anisotropy of Nd2Fe14B phase after annealing.     

用脲基聚合物生产聚脲基润滑脂

以脲基聚合物做稠化剂生产聚脲基润滑脂，该脂具有优良的抗氧化安定剂，耐高温性能及良好的胶体安定性、抗水淋性。可适用于各行业高温、重荷、潮湿、中高转速等环境。     

青州造纸产浆超10万吨

截至2004年12月23日，青州造纸有限责任公司共生产本色浆板10．51万吨，完成年度生产经营计划的100．12％，全年完成销量11．3万吨，完成工业总产值3．6亿元，实现销售收入3．83万元。     

浅谈近视眼的物理疗法暨小孔眼镜

目前,治疗近视眼的方法很多,现仅以国内文献记述的一些物理疗法作一介绍: 一、平(直)流电疗法:电疗器有两线为一阳极,一阴极。手捏阳极,阴极置眼部。电力为40～100安培,每眼放五分钟,经临床研究证明其作用在大脑皮层而不在眼的局部。它的疗效机转是,微弱电流对大脑皮层的视觉细胞有兴奋作用,使视功能增强,视力获得提高。但疗效维