邻—(4—乙基苯甲酰基)苯甲酸的研究

本文阐述了通过Friedel-Crafts反应合成邻-(4-乙基苯甲酰基)苯甲酸的方法.研究了影响产物质量的因素,提出了适宜的工艺条件.     

Trends and variations in neonatal length of in-hospital stay in Canada

The objectives of this study were to evaluate the possible mechanisms involved in prolongation of bleeding time in pre-eclamptic patients receiving a magnesium sulfate infusion to prevent convulsions. Eighteen pre-eclamptic patients near term or at term (4 cases 33 to 35 weeks; the remainder > 36 weeks) were studied. Fifteen of them received magnesium sulfate infusion; 3 did not and served as controls. Bleeding time (modified Ivy method with Surgicutt), platelet count, platelet aggregation pattern, as well as serum arachidonic acid metabolites [thromboxane B2 (TxB2) and 6-Keto-prostaglandin F1 alpha (6-Keto-PGF1 alpha)] werde done on admission to the labor floor (before magnesium infusion) and repeated at discontinuation of the infusion, 12-24 hours postpartum; the controls received the second test 24 hours postpartum. Thirteen of 15 patients receiving magnesium sulfate had an increase in bleeding time from an average of 6 minutes 31 seconds to 11 minutes 56 seconds, an 82% rise (p < 0.004). In 2 there was a decrease. Among the 3 controls the averages were 6 minutes 38 seconds and 6 minutes 3 seconds. The total magnesium given ranged from 52.5 to 145 grams. Platelet counts averaged 251,000/mm3 (range 145,000-519,000). Platelet aggregation pattern done in 11 patients and was normal and unchanged after magnesium in 10 of the patients with increased bleeding time and one control. TxB2 and 6-Keto-PGF1 alpha levels did not change significantly either after magnesium administration (688 and 135 pgm/ml, to 654 and 117) or in controls (695 and 230 pgm/ml, to 445 and 225). Likewise, the ratio of these 2 substances did not change in either group (6.3 to 6.6, and 4.2 to 2.2). There was no correlation between duration of infusion or total magnesium given and directions of small changes observed. This study confirms a prior preliminary observation that magnesium sulfate infusion, as currently used to prevent eclamptic convulsions, induces a significant prolongation of bleeding time. This effect is mediated neither by changes in platelets count or aggregation pattern, nor by changing the level or ratios of serum arachidonic acid metabolites (TxB2 and 6-Keto-PGF1 alpha). Further studies are needed to clarify the mechanism of this clinically important observation of increased bleeding following magnesium sulfate infusion.     

提高柴油机缸盖内腔铸造质量的工艺措施

缸盖是柴油机上的重要零件之一。铸造毛坯不可避免地存在劈缝、内腔粘砂、粗糙、局部不通等内腔质量问题 ,从而影响缸盖串水冷却效果。本文介绍了一些工艺措施 ,较好地解决了这个问题。     

H.248协议在UMTS核心网中的应用

描述了H.248协议的连接模型和消息结构,分析了H.248协议在UMTS核心网中的实现方案,并给出了一个应用实例,最后探讨了实现中可能面对的问题和解决方案。     

二维谐振子与二维氢原子的能量及波函数

借助于ＳＵ(１,１)代数,找出了二维谐振子与二维氢原子的能量及波函数间的关系．     

Si衬底上Ta-N/Cu薄膜性能研究

对Si衬底上Ta-N/Cu薄膜进行了电学和热学分析，结果发现500℃以下薄膜电随几乎不变，600-690℃下的退火引起的电阻率降低是由于Ta-N电阻的热氧化和Cu熔化扩散引起的，而690℃以上的电阻率增加是由于Cu引线传输能力减弱所致，为0.18μm以下的超大规模集成电路中的Cu引线和电阻薄膜的制作提供了有益的借鉴。     

基于CDMA智能网平台的增值业务--"位置服务"

本主要介绍基于CDMA智能网平台的一种增值业务——“位置服务”，阐述这个业务的网络结构、涉及到的技术问题和解决方案，并将这个整体思路投入到开发业务中去。     

Adaptive motion control using neural network approximations

In this paper, we present a new adaptive technique for tracking control of mechanical systems in the presence of friction and periodic disturbances. Radial Basis Functions (RBFs) are used to compensate for the effects of nonlinearly occurring parameters in the friction and periodic disturbance model. Theoretical analysis, such as stability and transient performance, is provided. Furthermore, the performance of the adaptive RBF controller and its non-adaptive counterpart are compared.     

江西省抚州市水利工程产权制度改革的调查与思考

介绍了江西省抚州市水利产权改革前的基本情况和改革的措施，总结了水利产权制度的经验。     

抽水蓄能电站运行方式和电网经济效益分析

用计算机模拟法建立模拟模型，对选定的系统进行生产模拟，统计计算出电网系统投入不同抽水蓄能容量时所发生的系统运行总燃料费用（包括抽水蓄能电站的抽水费）和系统的负荷缺电力时间概率（LOLP）等指标。通过对计算结果的分析，得出不同系统在投入不同容量抽水蓄能机组和采取不同运行方式的情况下，其运行总燃料费用的边际成本和LOLP的边际值的变化规律，并且对电网的经济效益进行合理分析。从而为抽水蓄能电站的规划和投资建设提供理论依据，推动抽水蓄能电站的发展，促使我国电源结构趋向合理。