对氨基苯酚的生产方法评述

纳本文介绍了对氨基苯酚生产的主要方法,指出了各种方法的优缺点.重点介绍了硝基苯催化加氢还原合成对氨基苯酚的机理、研究现状,以及中试工业化研究情况.     

高密度聚乙烯的研究及应用

综述了近年来我国高密度聚乙烯(HDPE)的最新研究现状,并介绍了高密度聚乙烯的特点及其应用,最后指出了我国高密度聚乙烯的发展方向。     

电力负荷动态模型综述

概括介绍了基于统计综合法和总体辨识法建立的各种负荷动态模型,分析了它们的优缺点和适用范围;提出了一种考虑综合负荷中配电网络的影响和感应电动机所占比重,通过大量仿真计算,对结果进行拟合从而建立负荷动态模型的新思路.     

一种生长延缓剂对早熟巨峰生长的调控作用

以早熟巨峰为试材,采用南开大学研制的一种生长延缓剂,于花前10 d和花后10 d进行2种浓度的处理,测定主梢和副梢生长量及果实品质,发现该制剂能够抑制葡萄新梢生长,对副梢的抑制作用强于主梢,并且随处理浓度的增加,抑制作用增强。0.5 mL/L浓度处理后的副梢长度、质量及节数分别比对照减少41.84%、54.90%、36.22%,节间长度和粗度分别比对照减少32.77%和19.28%;各处理对14节以下主梢节间长度没有明显抑制作用,对上部节位节间抑制减少2.4%～5.5%。0.25 mL/L和0.5 mL/L浓度处理分别使穗重比对照增加了20.79%和52.53%,使果实可滴定糖含量分别比对照增加3.1 g/L和5.4 g/L;高浓度处理增加了果实可滴定酸含量,降低了花青素含量,但差异不显著。各处理显著增加了枝条中的束缚水/自由水,降低了游离氨基酸含量,但对枝条的可溶性糖和淀粉含量没有显著影响。     

激光准直仪的光学系统设计

本文介绍了一种用于转动传动系统轴间准直的激光准直仪和它的光学系统设计考虑.所研制的准直仪由激光器及准直系统、反射棱镜、四象限探测器和微处理器组成,可实时显示指导性调节量.其光学系统精度达5μm.     

Microstructural studies of PMMA impregnated mortars

Studies on cement concrete microstructures are carried out to explain experimentally observed phenomenon and for modeling of concrete at the macroscopic level. In this article, the preparation of polymer impregnated mortar (PIC) is carried out by partially or fully replacing the pores in the cement mortars (OPC) by PMMA. The effect of this polymer impregnation on density and morphology of the cement matrix is studied. The microstructural changes in the mortar, on exposure of these specimens to hydrochloric acid and sea water for 7 and 28 days, are also investigated in this article. The above studies indicated that the polymer addition decreased the voids in the mortar thereby preventing leaching of water soluble salts present in the OPC. It was observed that the polymer also prevented the external chemical media from permeating into the cement matrix and undergoing interactions with it. It is concluded that the durability and chemical resistance properties of the PIC are better compared with OPC. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

一则电梯冲顶导致安全钳动作的事故分析

九江市某公司一台载货电梯冲顶越层近300mm,轿厢内被困司机1人（已被解救）,限速器和安全钳动作。现就本案例,对可能造成电梯轿厢;中顶及安全钳动作的原因,逐一进行分析。     

水泥浆固化体的浸出行为

本文概述了用于水力压裂处置的水泥浆固化体在去离子水和处置现场近域地下水中的浸出行为。浸出试验分别采用国际标准化组织(ISO)颁布的长期浸出试验方法和美国能源部材料特征化中心(MCC)曾采用过的静态浸出试验法。用长期浸出试验方法(浸出剂为去离子水)得到192天时的三种浸出试样(Ⅰ、Ⅱ、Ⅲ)中~(137)Cs 和~(90)Sr 的浸出分数、累积浸出分数、递增浸出率和扩散系数见下表。     

Mechanism of enhancement in magnetoresistance properties of manganite perovskite ceramics by current annealing

Studies on spintronics have provided solid evidence that the grain boundaries (GBs) in polycrystalline manganite can produce a strong extrinsic magnetoresistance (MR). This type of MR, called Low-field MR (LFMR), is larger than the intrinsic MR and can be triggered over a wide range of temperature. However, the existence of more GBs would bring about the weakening of magnetism and decrease the magnitude of MR simultaneously. Here we show that during annealing the application of electric-current to a representative ferromagnetic manganite perovskite, polycrystalline La_2/3Sr_1/3MnO₃ (LSMO), can produce more GBs and improve low-field magnetization, which leads to enhanced MR effect and field-response sensitivity as compared to the traditional-annealed sample. By using static micromagnetic models combined with the theories of spin-polarized intergrain tunneling and charge carrier hopping across domain wall, the observed enhancement of magnetoresistive response in current-annealed LSMO can be well explained.