气相色谱法分析食用菌中有机磷农药的残留

建立了食用菌中10种农药残留量的气相色谱分析方法.样品用乙酸乙酯-正己烷（体积比1∶1）溶液提取,经HP-5石英毛细管柱分离后,采用GC-FPD同时测定10种农药残留量.10种农药在0.1～5 mg/L范围内,均有良好线性关系.相关系数r大于0.997,样品在3个添加水平时的回收率为82%～110%,相对标准偏差为4.1%～12.9%.检出限为0.02～0.03 mg/kg.方法简便、快速、净化效果较好,可同时满足进、出口食用菌中多种农药残留量的检测需要.     

Urinary Organic Acids Quantitated in a Healthy North Indian Pediatric Population

Human urine gives evidence of the metabolism in the body and contains numerous organic acids and other compounds at a variety of concentration. The concentration of organic acids in urine varies from population to population due to genotype, food habits and other epigenetic and environmental influences. Knowledge of the reference values for urinary organic acids in a healthy pediatric population is very important for critical evaluation. This study was designed to quantify 16 organic acids in a healthy north Indian pediatric population. Early morning urine samples from healthy pediatric subjects of age 1 day to 16 years who did not have symptoms of any disease were analyzed for organic acid content. The children were not on any supplemental vitamins or drugs and were on a free and unrestricted diet. The creatinine concentration of each sample was determined before organic acid analysis. Organic acids were extracted from urine with ethyl acetate, extracted residue was air dried, converted into trimethylsilyl derivatives and analysed by gas chromatography mass spectrometry. Here we reported the age wise mean values and standard deviations for each compound, adjusted for creatinine content (mmol/mol of creatinine). We found the concentration of most of the metabolites are higher in our population in comparison to other populations. Such data may help to provide a basis for diagnosing metabolic abnormalities in patients in a specific ethnicity.     

演马庄矿顶板穿层钻孔的优化设计与实现

焦作矿区原有的底板抽采岩巷预抽措施,必须进行多次石门揭煤,严重制约了区域瓦斯治理进度。为解决这一问题,对该矿区演马庄矿21011运输巷进行顶板穿层钻孔优化,并对钻孔布置方式、孔间距等进行改进。结果表明,施工总量减少,施工进度加快,抽采效率显著提高,有效解决了区域瓦斯防突问题。     

Experimental investigation on the effects of process parameters of GMAW and transient thermal analysis of AISI321 steel

Gas metal arc welding （GMAW） develops an arc by controlling the metal from the wire rod and the input pro- cess parameters. The deposited metal forms a weld bead and the mechanical properties depend upon the quality of the weld bead. Proper control of the process parameters which affect the bead geometry, the microstructures of the weldments and the mechanical properties like hardness, is necessary. This experimental study aims at developing mathematical models for bead height （HB）, bead width （WB） and bead penetration （PB） and investigating the effects of four process parameters viz： welding voltage, welding speed, wire feed rate and gas flow rate on bead geometry, hardness and microstructure of AISI321 steel with 10 mm thickness. The transient thermal analysis shows temperature and residual stress distributions at different conduction and convection conditions.     

新式机械清理机的开发与设计

针对火焰清理机需要消耗大量煤气、氧气、水等介质,以及产生大量废渣、废气的问题,对机械式清理机的开发进行了探讨,并设计了机械清理机的初步机型,为机械式清理机的研发打下了基础。     

真鲷脂肪酸的分析及其营养价值评价

为了解真鲷鱼肉中脂肪酸的组成及其营养价值,采用Bligh-Dyer提取法对样品中脂肪油进行提取,甲酯化后利用气相色谱-质谱联用仪进行分析测定,并对其营养价值进行评价.结果发现从真鲷肉中鉴定出16种脂肪酸,饱和脂肪酸6种,相对百分含量占总检出量的37.68%.不饱和脂肪酸10种,相对百分含量占总检出量的63.32%.真鲷鱼肉的∑PUFAω-3/∑PUFAω-6的比值为6.35,具有较高的营养价值.     

分子有效直径对范德瓦尔斯气体热力学性质的影响

本文首先阐述了范德瓦尔斯气体的理论研究目前待解决的主要问题,在此基础上论述范德瓦尔斯气体常数a和b与分子有效直径的对应关系,探讨了分子有效直径对范德瓦尔斯气体常数a和b的影响途径;分析了范德瓦尔斯气体的内能、熵、热容量随分子直径大小不同的变化规律。     

气排球运动损伤的调查报告

老年人参加气排球运动锻炼,对身心健康有较良好的影响,但是,若违背科学方法进行锻炼,易发生骨折,关节韧带拉伤等运动性伤病,这和老年人日益衰变的运动器官和体质健康状况特点有关。本文旨在研究适合老年人身心特点的锻炼方法,以减少运动损伤的发生,使气排球运动朝着康乐方向顺利地开展。     

高效液相色谱法同时测定溶液中的地克珠利和百球清

采用高效液相色谱法(HPLC),同时测定了溶液中的地克珠利和百球清含量。其测定方法为:色谱柱为BDSC18(5μm,250×4.6mm)或ODSC18(5μm,150×4.6mm),63%乙腈+37%的0.2%磷酸水溶液(体积分数)为流动相,流速1.0mL/min,紫外检测波长为241nm,每次进样量20μL,地克珠利和百球清的色谱峰保留时间分别为6.5和7.7min。该方法既可同时测定溶液中的地克珠利和百球清的含量,也能对二者的混合物产品进行质量控制,还可用于百球清产品的单独检验。     

Three-dimensional transient numerical simulation for gas exchange process in a four-stroke motorcycle engine

INTRODUCTION In-cylinder flow characteristics during fuel in-jection and subsequent interactions with fuel sprays and combustion are important effect on engine per-formance and exhaust emissions of an engine(Floch et al.,1998;Kim et al.,1999).Four key parameters control the flow field in an engine:the mean flow components,the stability of the mean flow,the tem-poral turbulence evolution during the intake and compression strokes,and the mean velocity near the spark gap at the time of ignit…