Design of a microprocessor-controlled PABX

A complete design of a small ‘private automatic branch exchange’ (PABX) system serving 32 subscribers is introduced, using the simplest and most direct design procedures. The system uses space division analogue switching concepts and allows four internal and two external calls at the same time. A logical design is first carried out to give the evolution of the state of a subscriber during call processing, followed by a complete design of the microprocessor circuits. All external circuits responsible for counting and storing dialled digits, generating telephone tones and interfacing are described. All programs and subroutines are discussed and several flowcharts are given to describe the controlling program. Finally the advantages, disadvantages and the system limitations are discussed. The design uses an Intel 8080 microprocessor with 2 kbyte of EPROM and 256 byte of RAM.     

QuEChERS-高效液相色谱-串联质谱法快速测定牛奶中18种糖皮质激素类药物残留

通过Qu ECh ERS前处理方法,结合高效液相色谱-串联质谱多反应监测模式下的定性和定量分析,实现牛奶中18种糖皮质激素的同时检测。牛奶样品加入酸化乙腈溶剂提取后,加入氯化钠和无水硫酸镁进行盐析,经PSA、C_(18)吸附剂净化后,取上清液进行高效液相色谱-串联质谱分析。方法的基质效应影响在0.81~0.96之间,方法检出限在0.1~0.3μg/kg之间,定量限在0.3~1.1μg/kg之间,在0.5~100 ng/m L范围内呈线性关系,目标物线性相关系数(R~2)均大于0.993 6,3个水平加标回收率在73.7%~98.6%之间,精密度(n=5)在4.9%~12.9%之间。该方法简单快捷、准确可靠,适合于大批量牛奶样品中糖皮质激素的快速检测。     

青稞麦绿素粉冷冻干燥制备工艺优化

以干燥速率、总黄酮保留量和SOD保留量为指标,对真空冷冻干燥青稞麦绿素粉的影响因素进行分析,确定青稞麦绿素粉冷冻干燥的最佳工艺条件：预冻温度－40℃、预冻时间4h、装填厚度5mm、工作压力60Pa、升华温度40℃、解析温度50℃。在此最优工艺条件下制备的青稞麦绿素粉中总黄酮保留量69.3%、SOD保留量20.1%,且色泽鲜绿,气味保留了青草香味。结果表明,冷冻干燥法是制备高品质青稞麦绿素粉的有效方法。     

山药-蛹虫草双向发酵的抗氧化活性增效性

本实验研究山药-蛹虫草(Cordyceps militaris)双向发酵的抗氧化活性增效性.以超氧阴离子自由基清除率、2,2-二苯基-1-苦基肼自由基清除率和羟自由基清除率为指标,比较分析山药-蛹虫草菌质和山药基质的抗氧化活性.通过抗氧化活性成分含量测定以及高效液相色谱指纹图谱、扫描电子显微镜和傅里叶变换红外光谱分析,...     

北方寒冷地区桥面防水层施工工艺研究

结合内蒙古通辽-下洼高速公路教来河大桥桥面铺装实体工程,简要介绍了桥面防水层的施工概况,总结了涂膜类防水材料的施工工艺,为北方寒冷地区公路桥面防水层施工提供一定的参考依据。     

Regulation of adenylyl cyclase activity in human peripheral blood mononuclear cells: effects of protein kinase inhibitors and of a calcium ionophore

In a previous paper we presented evidence for a negative regulation of adenylyl cyclase activity by tyrosine protein kinase(s) in the human leukemic T cell line Jurkat. In order to examine this point in non malignant cells, we conducted the present study in human peripheral blood mononuclear cells (PBMC). In these cells, staurosporine, a broad spectrum protein kinase inhibitor, enhanced not only the receptor-mediated, induced by prostaglandin E2 (PGE2), but also the direct (forskolin-induced) stimulation of adenylyl cyclase activity. Herbimycin A, a specific protein tyrosine kinase inhibitor, reproduced only in part the effect of staurosporine, whereas bisindolylmaleimide, the most specific protein kinase C (PKC) inhibitor known at present time, was ineffective. All these observations were made both in the absence and presence of isobutylmethylxanthine, a phosphodiesterase inhibitor, indicating that the effects of staurosporine and herbimycin A on cAMP accumulation were not due to phosphodiesterase inhibition. The calcium ionophore A 23187 also enhanced the PGE2-induced cAMP accumulation, and this effect was not additive to that of staurosporine, but additive to that of herbimycin A. These results confirm and extend those obtained in Jurkat cells. Taken together, they indicate that in human PBMC the adenylyl cyclase activity is negatively regulated by tyrosine kinase(s) and not by PKC, and positively regulated by Ca2+. They also suggest that the major enhancement by staurosporine of the PGE2-induced cAMP accumulation, although chiefly mediated by protein tyrosine kinase inhibition, also depends on another, presently undetermined, effect of the drug simulating that of Ca2+.     

Sixty years of EHL

It is now 60 years since Ertel produced the first solution to the elastohydrodynamic lubrication (EHL) problem. There has been enormous progress since then, both in numerical modelling and in experimental research on EHL. The moving, rough surface EHL problem can now be solved on laptop‐level computers, while maps of film thickness, pressure and temperature can be obtained experimentally from within rolling/sliding contacts. However, there remain some important questions that have not been fully resolved. One of the most contentious is how to describe the rheological properties of lubricants under the very severe conditions present in thin film EHL contacts. A second is how to model mixed lubricated contact, where the fluid film can break down at asperity conjunctions. But perhaps the greatest challenge to researchers in EHL is to produce useful design equations for predicting the performance of machine components operating in EHL and thereby ensure that EHL theory becomes an integral part of the design process. Copyright © 2006 John Wiley & Sons, Ltd.     

电子影像图在既有建筑普查中的应用

电子影像图是既有建筑普查工作实施的基础,对城市建设数字化以及城市管网改造与规划都具有重要意义,论述了获取电子影像图的方法,及其在既有建筑普查工作中的应用情况。     

世茂深坑酒店钢结构设计

系统介绍了世茂深坑酒店的钢结构设计,着重阐述了该结构的关键节点设计,对酒店钢结构框架进行了施工过程分析.结果表明:结构上端有很强的约束,刚度较大,宜选取延性较好的钢框架-支撑结构;楼板刚度对结构构件受力有显著影响,构件设计时须取不同楼板刚度计算模型下的包络结果;采用带肋钢铺板组合楼板可有效解决混凝土板受拉问题.     

铝双层板结构超高速正撞击后板弹坑分布

利用二级轻气炮发射2017-T4铝合金球形弹丸,对铝合金双层板结构进行超高速正撞击试验研究,从而模拟空间碎片对航天器防护结构的撞击作用.弹丸直径为2.00～6.35 mm,弹丸撞击速度为1.50～6.98 km/s,撞击角度为0°,试验得到不同撞击速度区间内的铝合金双层板结构后板弹坑分布模式.分析铝合金双层板结构后板弹坑分布特性,建立预测铝合金球形弹丸超高速正撞击铝合金双层板结构后板弹坑分布的经验公式.结果表明,在正撞击条件下,铝合金双层板结构的后板弹坑呈圆形区域分布,后板弹坑分布区域随弹丸直径、撞击速度和前后板间距的增加而增大,弹丸的撞击破碎临界速度将影响后板的弹坑分布模式.