试论我国非公有经济的存在和发展

我国非公有经济经历了过渡时期和改革开放以来两个不同的发展阶段。实践证明非公有经济对促进国民经济发展，增加就业，满足人们不同的需要方面发挥了重要作用，是社会主义市场经济的重要组成部分。     

与排队系统G／G／1有关的一些结果

Ｎ．Ｕ．Ｐｒａｂｈｕ在文献［１］中利用随机游动研究Ｇ／Ｇ／１系统得到一些有趣的结果，但文献［１］Ｐ．３３定理１４的陈述不准确。本文对该定理提出修正意见，即对于Ｍ／Ｍ／１系统，Ｎ与Ｉ＝－ＳＮ仅在条件概率空间（Ω，Ｆ，Ｐ［Ｎ＜∞］）上是独立的。此外对Ｇ／Ｍ／１系统给出计算ｐ＝Ｐ［Ｎ＜∞］的公式，并且证明Ｎ与ＳＮ在（Ω，Ｆ，Ｐ［Ｎ＜∞］）上独立     

Increasing urea-N efficiency for transplanted lowland rice by pneumatic injection: Yield and economics at the farm level

To increase the fertilizer-N efficiency in lowland rice (Oryza sativa L.) cultivation, new management practices are needed. Main cause of the present low efficiency is the low N recovery by plants, as a considerable part of the N applied is lost; deep placement techniques improve the recovery. A pneumatic injector, with which urea prills can be point-placed at a depth of 5–10 cm in paddy soils, was tested in 38 on-farm trials in 1989/90, mostly during the wet season. The experiments, located in Africa and Asia, focussed on differences in grain yield between conventional methods of broadcasting urea and injection by the pneumatic injector, at recommended N-rates. The study shows that the pneumatic injector is effective as a tool to improve the N fertilizer efficiency. The average yield increases per region, resulting from the use of the injector, ranged from about 250 to 1300 kg grain ha^–1. The value of the yield increase would allow most farmers to recover the costs of the injector within one season, even if labour was hired to carry out the injections. The average labour requirement of the injector was 40 hours ha^–1. In Indonesia, injection of prilled urea gave yields similar to those obtained with urea briquettes.     

Texaco煤气化装置长周期运行影响因素分析

介绍了Texaco煤气化工艺流程,从原料煤种、水煤浆浓度、操作工艺、关键设备等几个方面讨论了影响装置长周期运行的因素,提出了延长气化装置运行周期的措施。     

Use of rosemary extract in preventing oxidation during deep-fat frying of potato chips

The effect of using a rosemary extract on the stability of oil used for frying potato chips has been evaluated. Sliced potatoes were fried intermittently in soybean oil containing a natural extract from rosemary. The conditions used for frying were 185°C for 90 s. Two separate experiments, with and without replenishment of oil, were carried out. Oil samples were taken each day, not only from the frying pans but also by extraction with hexane from the chips. Changes in the induction period of the oil samples (Rancimat method) were determined. The induction period decreased as frying progressed. The reduction in the induction period was higher in the oil free of rosemary extract, and the chips were much darker in color. The oil containing the extract showed greater antioxidant activity, and reduced darkening and rancidity of the oil. Potato chips fried in the oil with added rosemary extract were more acceptable than chips fried in oil containing no extract until the last frying. The free radical scavenging activity of rosemary extract in comparison to other natural antioxidants was also determined by the reduction of O₂ ^.- in a hypoxanthine/xanthine oxidase system.     

影响濮城油田潜油电泵井检泵周期的因素分析及对策

潜油电泵采油已成为濮城油田的重要采油手段之一。本文系统地分析了影响濮城油田潜油电泵井检泵周期的各种因素 ,并提出了相应的技术对策和措施。检泵周期的延长是一个系统问题 ,只有将提高机组质量、优化选井选泵、强化生产管理有机地结合起来 ,才能实现检泵周期的延长。     

STRESSES IN VISCOELASTIC PLATE DRIED CONVECTIVELY

ABSTRACT

The deformations and drying-induced stresses in a saturated porous plate insulated on one side and dried convectively on the others were analysedPlate material is assumed to be elastic and viscoelastic. A rigorous solution of the problem is presented using Laplace transformations and the method of variable separation. The results are presented in the form of a series resulting from the solution of a Sturm-Liouville problem. The shrinkage stresses in the plate are caused by non-uniform distribution of the moisture content. The thermal stresses are not included as the consideration were confined to only constant rate drying period.     

钢基体中温酸性化学镀的研究

选择合适的络合刺及促进剂是进行中温酸性化学镀镍的关键?对钢基体中温酸性化学镀镍的络合剂与促进剂做了进一步研究，得到最佳复合络合剂为乳酸 一种无机酸、最佳促进剂为一种有机酸。其适宜添加量分别为20mL／L、g/L。讨论了镀液pH值及操作温度对镀速的影响，得到其适宜pH值及操作温度范围分别为4．8～5．2、65～90℃。周期实验研究结果表明，添加剂浓缩液不同的添加量对镀液寿命、镀层综合性能有较大影响。当其添加比例为15％时，镀液寿命大于10个周期，稳定性常数大于97%，镀速高，镀层镀态硬度达到480HV、热处理后达到1346HV，耐硝酸变色时间大于70s，磷质量分数大部分为11％～12％，外观平整、光亮，SEM照片显示其镀层表面微观结构致密、均匀。     

我国玻璃纤维复合材料新时期的特点与对策

本文综合论证了玻璃纤维及其主要用途的复合材料工业概况,指出我国玻璃纤维复合材料工业已经进入一个新的发展时期.过去是以发展速度为主要特征,现在则以产品应用、质量提高为重要标志.本文对新时期我国玻璃纤维复合材料的技术方向和行业管理提出建议.