关于惠斯登电桥测电阻倍率与检流计灵敏度关系的研究

在相同的设备条件下，电桥临近平衡时灵敏度最高的最佳倍率是：组成倍率的两个电阻的数量级与待测电阻数量级相等，且比值为1的倍率。     

A structured light-based system for human heads

The 3-D modeling of heads by using optical triangulation techniques is of great interest in the context of virtual reality, telecommunication and computer animation. This paper presents a structured light-based system mainly for human heads. It is named “3-D Laser Color Scanner” (3DLCS). A 3-D model is obtained with a cylindrical scan. The laser beam is switched on and off using a “light valve” and two successive CCD frames are captured, one with the laser line showing and one without. We can simplify the laser line extracting by subtracting these two images.In this system, two CCD cameras are used to avoid occlusion problems. Color information is read from the CCD when the laser light is absent. Since traditional laser scanner will miss the range data in the low-reflectance areas such as the hair area of human head, a shape from silhouette algorithm is presented to overcome this problem. Finally, we give some results using our system. The resulting model is suitable for many applications.     

核磁共振法测定高聚物的结构—核磁共振二维谱

介绍了核磁共振(NMR)波谱,尤其是核磁共振二维谱(2D NMR)在最近几年内的进展。内容包括怎样用NMR测定高聚物的序列分布、共聚物结构、聚合物的混溶性、聚合物液晶的取向度、分子量、短链度和长链支化度、凝聚态高聚物的多相结构等。     

生物柴油及1,3-丙二醇联产工艺产业化进展

生物柴油作为可再生的清洁能源,已在美国、欧盟等多个国家和地区推行使用。在生物柴油的生产过程中,最高可得到约10%的副产物甘油,副产物甘油的去向将成为生物柴油大规模产业化发展所面临的严峻问题。1,3-丙二醇是一种重要的化工原料,作为合成新型聚酯PTT的原料,1,3-丙二醇已引起人们的广泛关注。以生物柴油副产物甘油为原料耦合生产1,3-丙二醇,不仅解决了生物柴油副产物甘油的出路问题,同时降低了1,3-丙二醇的生产成本。本文详细介绍了生物柴油及1,3-丙二醇生产技术及联产工艺的研究进展,并对其应用前景进行了展望。     

Recent Progress in Direct Partial Oxidation of Methane to Methanol

The direct conversion of methane to methanol has attracted a great deal of attention for nearly a century since it was first found possible in 1902, and it is still a challenging task. This review article describes recent advancements in the direct partial oxidation of methane to methanol. The history of direct oxidation of methane and the difficulties encountered in the partial oxidation of methane to methanol are briefly summarized. Recently reported developments in gas-phase homogeneous oxidation, heterogeneous catalytic oxidation and liquid phase homogeneous catalytic oxidation of methane axe reviewed.     

聚(丁二酸丁二酯-co-丁二酸丙二酯)的等温结晶行为研究

以1,4-丁二酸、1,4-丁二醇和1,3-丙二醇为原料通过直接熔融缩聚法合成了聚丁二酸丁二酯(PBS),聚丁二酸丙二酯(PPS)和聚(丁二酸丁二酯-co-丁二酸丙二酯)(PBSPS)等脂肪族聚酯.利用1H-NMR,WAXD,DSC和POM等研究了聚酯的结晶结构和结晶动力学过程等结晶行为.PBSPS的结晶晶型与PBS一致,说明只有丁二酸丁二酯(BS)单元结晶而丁二酸丙二酯(PS)单元处于无定形区.聚酯等温结晶后,在升温熔融过程中出现了多重熔融峰.分析表明多重熔融峰主要来自于聚酯升温过程中的熔融-重结晶行为.利用Avrami方程分析了聚酯的等温结晶动力学,Avrami指数n为2.2~2.8,说明聚酯等温结晶时主要以异相成核的三维生长方式进行;随着PS单元的增多,聚酯的表观结晶活化能升高,也就是说BS单元的结晶变得困难.POM观察到聚酯等温结晶时都出现了环带球晶现象,球晶形态会随着结晶温度和化学结构差异而改变.     

不同分子筛载体对CO加氢产物分布的影响

研究了几种小孔分子筛ＺＳＭ－５，ＨＹ，ＮａＹ及β担载ＺｒＯ２对Ｃ加氢反应的催化作用，并就产物的分布情况与担载ＺｒＯ２的硅铝中孔分子筛进行了对比研究。其中中孔分子筛分别用季铵盐和一级胺为模板剂，在水热条件和常温常压下合成；并用ＢＥＴ，ＸＲＤ，ＳＥＭ等手段表征了它们的孔道和骨架结构。另外，考察了碱金属Ｋ＾２＋，Ｎａ＾２＋对催化剂催化性能的影响。     

高效液相色谱法测定水产品中的恶喹酸

建立了高效液相色谱法测定水产品中恶喹酸残留量的方法。样品用二氯甲烷提取后，除去溶剂，用稀盐酸和正己烷处理，去除残渣中的脂肪，再用二氯甲烷萃取，浓缩至干后用甲醇定容。以0.002mol/L磷酸溶液－乙腈－四氢呋喃（体积比为65：20：15）为流动相，在ODS反相色谱柱上分离后，用荧光检测器测定，外标法定量。方法的线性范围为5－5000ng/mL，线性回归方程为A＝9.426c-2.123，相关系数r=0.9988，检出限为1μg/kg，回收率为93.0%-96.0%，相对标准偏差为3.7%-6.2%。     

生物柴油及1,3-丙二醇联产工艺产业化进展

生物柴油作为可再生的清洁能源,已在美国、欧盟等多个国家和地区推行使用.在生物柴油的生产过程中,最高可得到约10%的副产物甘油,副产物甘油的去向将成为生物柴油大规模产业化发展所面临的严峻问题.1,3-丙二醇是一种重要的化工原料,作为合成新型聚酯PTT的原料,1,3-丙二醇已引起人们的广泛关注.以生物柴油副产物甘油为原料耦合生产1,3-丙二醇,不仅解决了生物柴油副产物甘油的出路问题,同时降低了1,3-丙二醇的生产成本.本文详细介绍了生物柴油及1,3-丙二醇生产技术及联产工艺的研究进展,并对其应用前景进行了展望.     

Novel WS2/Fe0.95S1.05 Hierarchical Nanosphere as a Highly Efficient Electrocatalyst for Hydrogen Evolution Reaction

Fe_0.95S_1.05 with high reactivity and stability was incorporated into WS₂ nanosheets via a one-step solvothermal method for the first time. The resulted hybrid catalyst has much higher catalytic activity than WS₂ and Fe_0.95S_1.05 alone, and the optimal WS₂/Fe_0.95S_1.05 hybrid catalyst was found by adjusting the feed ratio. The addition of Fe_0.95S_1.05 was proven to be able to enhance the hydrogen evolution reaction (HER) activity of WS₂, and vice versa. At the same time, it was found that the catalytic effect of the hybrid catalyst was the best when the feed ratio was W : Fe=2 : 1. In other words, we confirmed that there is a synergistic effect between W- and Fe-based sulfide hybrid catalysts, and validated that the reason for the improved HER performance is the strong interaction between the two in the middle sulfur. WS₂/Fe_0.95S_1.05-2 hybrid catalyst leads to enhanced HER activity, which shows a low overpotential of ∼0.172 V at 10 mA cm⁻², low Tafel slope of ∼53.47 mV/decade. This study supplies innovative synthesis of a highly active WS₂/Fe_0.95S_1.05 hybrid catalyst for HER.