镇源县发现山羊斯氏多头蚴病

镇源县发现山羊斯氏多头蚴病李建国，徐世山，黄文忠，田保平（云南省思茅地区畜牧兽医站）１９９４年秋冬季，在云南省镇源县黄草岭畜牧场先后发现１３只山羊长有核桃至鸡蛋大、个别可达拳头大的皮下囊包。多数患畜２～３个，个别可达６～７个。患畜均系１岁以上成年母羊...

P-糖蛋白的研究进展

P-糖蛋白是一类能量依赖性的转运蛋白,能将许多结构不同的化合物逆向转运出细胞。P-糖蛋白的过表达与肿瘤细胞的多药耐药性(Multidrug Resistance,MDR)密切相关,是导致肿瘤化疗失败的主要原因。随着对MDR机制认识的深入,已针对P-糖蛋白的结构设计出多种形式的MDR逆转药物。近年研究发现,P-糖蛋白广泛存在于正常的组织和器官,参与药物和内、外源毒素的吸收、分布和排泄,行使解毒和防御保护的功能。因此,通过转植P-糖蛋白基因可有效地降低经济鱼类、虾等水产品和经济作物中有毒污染物的积累,对保护人

Narrow line-width resonant cavity enhanced photodetectors operating at 1.55 mu m

A method for fabrication of long-wavelength narrow line-width InGaAs resonant cavity enhanced (RCE) photodetectors in a silicon substrate operating at the wavelength range of 1.3-1.6 mu m has been developed. A full width at half maximum (FWHM) of 0.7 nm and a peak responsivity of 0. 16 A/W at the resonance wavelength of 1.55 mu m have been accomplished by using a thick InP layer as part of the resonant cavity. The effects of roughness and tilt of the InP layer surface, and its free carrier absorption, as well as the thickness deviation of the mirror pair on the resonance wavelength shift and the peak quantum efficiency of the RCE photodetectors are analyzed in detail, and approaches for minimizing them toward superior performance are suggested. (C) 2007 Elsevier B.V. All rights reserved.

Preparation and electrical properties of new oxide ion conductors Ce6-xDyxMoO15-delta (0.0 <= x <= 1.8)

Ce6-xDyxMoO15-delta (0.0 <= x <= 1.8) were synthesized by modified sol-gel method. Structural and electrical properties were investigated by means of X-ray diffraction (XRD), Raman, X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS). The XRD patterns showed that the materials were single phase with a cubic fluorite structure. Impedance spectroscopy measurement in the temperature range between 350 degrees C and 800 degrees C indicated a sharp increase in conductivity for the system containing small amount of Dy2O3. The Ce5.6Dy0.4MoO15-delta detected to be the best conducting phase with the highest conductivity (sigma(t) = 8.93 x 10(-3) S cm(-1)) is higher than that of Ce5.6Sm0.4MoO15-delta (sigma(t) = 2.93 x 10(-3) S cm(-1)) at 800 degrees C, and the corresponding activation energy of Ce5.6Dy0.4MoO15-delta (0.994 eV) is lower than that of Ce5.6Sm0.4MoO15-delta (1.002 eV).

Effect of pretreatment of black carbon on electrocatalytic activity of Pt/C catalyst for methanol oxidation

Direct methanol fuel cell (DMFC) has attracted wide attention due to its many advantages. However, its practical application is limited by the low electrocatalytic activity of the anodic Pt/C catalyst usually used for the methanol oxidation. In this paper, in order to increase the electrocatalytic performance of the Pt/C catalyst for the methanol oxidation, the black carbon, usually used as the supporter, was pretreated with CO2, air, HNO3 or H2O2. The cyclic voltarnmetric results indicated that the current densities of the anodic peak of methanol oxidation at the Pt/C catalysts with the black carbon pretreated with CO2,air, HN03, H202 and untreated black carbon were 39, 33, 32, 20 and 18 mA center dot cm(-2), respectively, illustrating that among the above five kinds of the Pt/C catalysts, the Pt/C catalyst with the black carbon pretreated with CO2 shows the best electrocatalytic activity and stability for the methanol oxidation. Its main reason is that the CO2 pretreatment could reduce the content of the oxygen-containing groups on the surface of the black carbon and increase the content of graphite in the black carbon, leading to the low resistance of the black carbon and the increase in the dispersion extent of the Pt particles in the Pt/C catalyst.

碳黑预处理对Pt/C催化剂对甲醇氧化电催化活性的影响

直接甲醇燃料电池(DMFC)由于具有较多的优点而受到广泛的关注.但是碳载Pt(Pt/C)阳极催化剂电催化活性低是限制其应用的一个主要问题.为了提高Pt/C催化剂对甲醇氧化的电催化性能,分别用CO2,空气,H2O2或HNO3对常用作为载体的VulcanXC-72碳黑进行预处理.结果表明,在用CO2,空气,HNO3,H2O2处理的及未处理的碳黑作载体制得的Pt/C催化剂电极上,甲醇氧化峰的峰电流密度顺序为39,33,32,20和18mA?cm-2,表明用CO2处理的碳载体制备的Pt/C催化剂对甲醇氧化有最好的电催化活性和稳定性.其主要原因是用CO2处理能减少碳黑表面的含氧基团和增加石墨化程度,而使碳黑的电阻降低及Pt粒子在碳黑上的分散性变好.

中性载体ETH1117推动H~+通过水/硝基苯界面传递的电化学研究

用循环伏安法研究中性载体ETH1117推动H~+通过水/硝基苯界面的转移。通过络合使H~+穿过水/硝基苯界面转移,是受扩散控制的可逆过程,ETH1117与H~+在硝基苯相的配合比为1:1,配合物的稳定常数β_0为2.9×10~7,扩散系数D为4.2×10~(-6)cm~2/s。

时序推理的现状

本文概述了时序推理的代表理论以及它们对本学科的未来研究，尤其是对ＡＩ的影响。

红原泥炭苔草的碳同位素组成与全新世季风变化

从红原泥炭中挑选出的单一植物残体——苔草纤维素的δ^13C时间序列是印度洋夏季风强度变化的敏感代用指标，它不仅请楚地指示了过去12000年印度洋夏季风数千年尺度上的变化历史，而义记录下了9次明显的季风突然减弱事件，它们可以与同时期北大西洋发生的冰川漂移碎屑沉积物事件一一对比。红原泥炭混合纤维素δ^13C时间序列也同样请楚地记录了过去12000年印度洋夏季风数千年尺度上的变化历史，对全球大范围的主要气候突然变化事件也有很好的响应。因此，泥炭混合纤维素δ^13C时间序列乃是一种很有实用价值的古气候代用记录。