有机质谱仪测量同位素峰丰度的精密度和准确度

本文探讨了利用带光点记录器的有机质谱仪同时测量有机分子全部同位素峰丰度的可能性,并对测量的准确度和精密度进行了讨论.     

Postponement in Mass Customization: A Literature Review

Mass customization (MC) is emerging as a competitive advantage of firms with the intensified competition and economic globalization. As a key feature of MC, postponement strategy postpones activities in the supply chain until customer orders are received. This article provides a review of the literature on postponement from perspectives of research content and methodology. Taking postponement as a supply chain concept, this article specifically reclassifies the postponement applications according to the positioning of the customer order decoupling point (CODP) in the supply chain. Future directions for postponement research are also suggested in this article.     

Role of Ferrel cell in daily variability of Northern Hemisphere Annular Mode

The Northern Hemisphere Annular Mode(NAM) represents the zonally symmetric planetary-scale atmospheric mass fluctuations between middle and high latitudes, whose variations have shown a large impact on other components of the climate system. Previous studies have indicated that the NAM is correlated with the Ferrel cell in their monthly or longer timescale variability.However, there have been few studies investigating their connections at daily timescale, though daily variability of NAM has been suggested to be an important component and has significant implication for weather forecast. The results from this study demonstrate that variability of the Ferrel cell leads that of the NAM by about 1–2 days. This statistically identified temporal phase difference between NAM and Ferrel cell variability can be elucidated by meridional mass redistribution. Intensified(weakened)Ferrel cell causes anomalously smaller(larger) poleward mass transport from the middle to the high latitudes,resulting in an increase(a decrease) in mass in the middle latitudes and a decrease(an increase) in the high latitudes.As a consequence, anomalously higher(lower) poleward pressure gradient forms and the NAM subsequently shifts to a positive(negative) phase at a time lag of 1–2 days. The findings here would augment the existing knowledge for better understanding the connection between the Ferrel Cell and the NAM, and may provide skillful information for improving NAM as well as daily scale weather prediction.     

海河特大桥承台大体积混凝土施工

结合海河大桥承台施工实例,介绍承台大体积混凝土浇筑施工方案,包括热工计算,浇筑工艺设计,温度控制方案,及温控检洲实施等。从浇筑完成体积为2492m。的38#,36#承台看。施工方案正确。合理。施工质量良好。     

分散固相萃取-超高效液相色谱串联质谱法测定茶叶中的7种农药残留

以分散固相萃取技术为前处理手段,结合超高效液相色谱串联质谱法,建立一种快速检测茶叶中7种农药残留的方法.茶叶样品经前处理后,采用UPLC-MS/MS法检测分析.用空白样品提取液配制基质工作曲线,外标法定量.结果表明,多菌灵、丁醚脲、喹螨醚在0.1~2.0、灭多威在1.0~20.0、噻虫嗪、吡虫啉、噻螨酮在2.0~40.0 ng·m L-1的范围内具有良好的线性关系,其检出限为0.10~5.00μg·kg-1.平均加标回收率为75.9%~116.8%,相对标准偏差为2.6%~6.1%.该方法简便、可靠、稳定,可用于茶叶中多种农药残留的快速检测与确证.     

稀有气体小团簇研究

原子团簇是几个至上千个原子组成的相对稳定的聚集体,其性质与单个原子、分子和大块固体均不相同,例如幻数和壳层结构、热力学效应等．正为物理、化学和材料科学共同关注。介绍形成团簇的实验质谱技术,结合MonteCartt,方法模拟部分IJ团簇的结构,分析稀有气体团簇幻数规律和特性。     

红芪组织培养中次生代谢产物的研究Ⅰ.红芪愈伤组织异柠檬酸裂解酶活性的变化

在红芪不同生长状态的愈伤组织中,异柠檬酸裂解酶（ＩＣＬ）活性差异很大,其中以分化愈伤组织中活性最高．与此相平行在红芪不同培养时期的愈伤组织中,不饱和脂肪酸含量降低,多糖含量升高．由此可以肯定异柠檬酸裂解酶为红芪次生代谢产生多糖过程中的一个重要酶．同时在无菌苗中异柠檬酸裂解酶活性也很高,而多糖没有检测到,说明异柠檬酸裂解酶也参加了植物细胞的初级代谢．我们认为初级和次级代谢过程中某些重要的甚至关键的酶是相同的,只是随着细胞的发育过程其活性发生了变化．     

超声速飞行底部排气弹三维湍流流场数值模拟

该文采用有限体积法数值离散雷诺时均Navier-Stokes方程,模拟了超声速飞行的圆柱体外部流场.其中两种湍流模式,即Spalart-Allmaras湍流模型和RNG k-ε湍流模型分别应用于该问题的求解.文中给出了数学模型和计算结果,并与实验数据进行了比较.结果表明:采用Spalart-Allmaras湍流模型能很好地描述高速运动体复杂的外部流场.利用上述模型对超声速飞行的底部排气弹三维流场进行数值研究,计算结果揭示了流场的物理现象和基本规律,以期对底部排气弹设计提供理论指导.     

基于FLOWMASTER软件的引气系统仿真分析

为准确模拟飞机导管引气系统在各工况下的运行状态,在研究飞机引气系统结构及流体网络算法原理的基础上,基于一维流体仿真技术建立了引气系统计算模型,根据实际工况对系统进行了稳态和瞬态分析。重点考察了系统中各主要元件的运行情况及节点的压力、温度等关键参数的变化规律。仿真结果表明,系统及各主要元件均满足设计与控制要求,可为我国民用客机导管系统的优化设计提供一定的理论参考。     

轨道交通干式变压器安装工艺研究

本文介绍了深圳轨道交通3号线二期工程供电系统中牵引变压器和降压变压器设置情况．分析了干式电力变压器的特点及城市轨道交通变电场所相对窄小等情况,研究了干式变压器的安装工艺,来保证工期的顺利完成。