甲醇氧化酯化反应的Mo－Sb－O催化剂研究

探讨了采用Ｍｏ－Ｓｂ－Ｏ复合氧化物催化剂，由甲醇的氧化酯化反应合成甲酸甲酯。文中考察了反应温度、催化剂晶格、接触时间对甲醇转化率的影响，测试了催化剂性能，扼要探讨了该催化反应的机理。     

稳定工艺条件解决氮肥生产中的亏氨问题

介绍了解决氮肥厂亏氨问题的８点经验：提高合成放空气中的甲烷含量，不随放氨带放气，选好放空点，保持冰机出口压力和氨贮槽压力，严格控制各级氨冷温度，用好催化剂，消除跑、冒、滴漏，搞好三气氨回收。     

拱肋间距对喷混凝土拱肋加固效应的影响研究

喷混凝土拱肋是加固软弱围岩的一种有效支护形式,其间距主要根据经验确定,可能偏大或偏小。为了揭示拱肋间距对加筋拱肋加固效应的影响,采用基于有限差分法的FLAC3D软件对施工期某地下厂房交通洞软弱围岩在拱肋间距分别在1.0―5.0m之间变化情况下变形、应力和屈服区等分布规律进行了对比仿真模拟。仿真结果表明:拱肋间距越大,围岩变形、顶拱最大主压应力和塑性屈服区越大,拱肋承受荷载越大;且拱肋间距介于2.0―3.0m时,能充分发挥围岩自承作用和拱肋支护潜力,围岩变形稳定满足要求,支护成本最低。本文的研究成果为确定喷混凝土拱肋合理间距提供了重要参考。     

铝盐沉淀法制备低堆比假一水软铝石的研究

研究了铝盐沉淀法制备假-水软铝石过程中各因素对水合产物物性的影响规律。提出了制备低堆比的高纯假-水软铝石的方法。用NH4HCO3或(NH4)2CO3溶液做洗涤介质有效降低了假-水软铝石中的杂质含量。采用加入晶种的方法制备了低堆比、含有大孔的假-水软铝石。     

聚醚多元醇中环状齐聚物的去除(续)

(接上期第 2 3页 )3　膜分离Doraietal[16] 通过超滤除去低相对分子质量级份 ,使聚醚多元醇 ,尤其是聚四氢呋喃多元醇 ,具有较窄的分布 (Mw∶Mn=1 .2～ 1 .8)。该方法通过对多分散的熔融聚合物实施物理分级 ,达到降低相对分子质量分布的目的 ,可使最终产物的相对分子质量为 40 0～ 40 0 0 ,分散度为 1 .2～ 1 .8。该方法首先需要准备 1套交叉流动的膜分离系统 ,采用渗透膜或半渗透膜 ,膜的一边是滞留物 ,另一边是超滤液。然后 ,在起始聚合物的熔点以上 ,分解温度以下 ,且温度不大于膜的熔融和分解温度 ,将起始聚合物熔融 ,并流入该系统中…     

α,β,γ,δ-四-(4-吡啶)卟啉分光光度法测定瓷餐具铜溶出量

本文提出用α，β，γ，δ-四-（4-吡啶）卟啉为显色剂，分光光度法测定瓷餐具铜的溶出量，该方法灵敏度高，选择性好，可以不经分离，直接对试样进行测定，操作简便，结果满意。     

Liquid-phase oxidation of toluene by molecular oxygen over copper manganese oxides

Copper manganese oxides (Cu–Mn oxides) were prepared by coprecipitation method and characterized by several techniques, such as X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and Temperature-programmed reduction (TPR). Catalytic activities of the Cu–Mn oxides were tested by the oxidation of toluene with molecular oxygen in liquid phase and solvent-free conditions. The molar ratio of Cu:Mn in catalyst was optimized to be 1:1 and thus the corresponding crystalline material was designated as Cu_1.5Mn_1.5O₄.     

Experimental Study on Phase Transformation Between MgB2 and MgB4

Using X-ray diffraction (XRD), scanning electron microscope (SEM), and differential scanning calorimetry (DSC), we have investigated the reaction between MgB₄ and Mg in its solid, liquid, and gas physical states. The XRD results indicate that the reaction of MgB₄+Mg=2MgB₂ always occurs independently of the different states of Mg. DSC measurements show that the solid–solid reaction MgB₄( s )+Mg( s )=2MgB₂( s ), the Mg melting Mg( s )→Mg( l ), and the Mg volatilization occur in turn with increasing temperature for mixed (MgB₄+Mg) powder with a nominal stoichiometry of MgB₂. SEM observations indicate that the resulting synthesized MgB₂ samples, obtained from the MgB₄+Mg mixtures, have a denser microstructure than those obtained directly from Mg+B mixtures. On the basis of XRD, DSC, and SEM results, a kinetic model for the reaction between MgB₄ and Mg is proposed.     

Response of the seated human body to whole-body vertical vibration: biodynamic responses to sinusoidal and random vibration

The dependence of biodynamic responses of the seated human body on the frequency, magnitude and waveform of vertical vibration has been studied in 20 males and 20 females. With sinusoidal vibration (13 frequencies from 1 to 16 Hz) at five magnitudes (0.1–1.6 ms^? 2 r.m.s.) and with random vibration (1–16 Hz) at the same magnitudes, the apparent mass of the body was similar with random and sinusoidal vibration of the same overall magnitude. With increasing magnitude of vibration, the stiffness and damping of a model fitted to the apparent mass reduced and the resonance frequency decreased (from 6.5 to 4.5 Hz). Male and female subjects had similar apparent mass (after adjusting for subject weight) and a similar principal resonance frequency with both random and sinusoidal vibration. The change in biodynamic response with increasing vibration magnitude depends on the frequency of the vibration excitation, but is similar with sinusoidal and random excitation.