石家庄地铁1号线北宋站钢支撑轴力变化规律分析

基坑的整体稳定性及基坑周边地下管线、周边建筑物的稳定非常重要。介绍石家庄地铁1号线北宋站钢支撑施工中出现轴力频率读数仪数值变化的情况,从外部环境、基坑开挖支护以及主体工程的施工等方面分析数值波动原因。主要结论如下： 1）温度越高,钢支撑所受的轴力越大;温度越低,钢支撑所受的轴力越小。2）临近钢支撑施加轴力会减小已施加轴力的钢支撑所受轴力。3）未施工完成结构主体,只要强度达到设计混凝土强度要求,可以替代钢支撑,作为基坑支护的一部分。     

桥梁基础温度裂缝产生的原因及预防措施

大体积混凝土桥梁基础的裂缝主要是有温度变化引起的。由于混凝土是热的不良导体,散热很慢,混凝土浇筑后,由于大量水泥发生水化反应,产生大量水化热,混凝土内部温度远较外部高,形成较高的温差,造成内部膨胀而外部收缩,使表面产生较大的拉应力,最终导致混凝土开裂。     

Comparative study on ghrelin level change and its related factors in hypertensive elders with psychological distress

Objective To investigate the change of plasma ghrelin level and explore the related factors of ghrelin alteration in elderly hypertensive patients with psychological distress. Methods A total of 300 elders, who were screened with Hamilton Anxiety Scale (HAMA), Hamilton Rating Scale for Depression (HAMD), and the Symptom Checklist-90 (SCL-90) for psychological stress and somato-psychological manifestations respectively, were divided into hypertension group (n=148) and non-hypertension group (n=152). Their blood samples were collected to measure the plasma level of ghrelin and total cortisol on the same day. Results The incidences of anxiety and depression were 27.7% and 11.7%, respectively, in all the enrolled elders. However, the rates of psychological distress, particularly anxiety, were significantly higher in the hypertensive elders than in the non-hypertensive ones (43.2% vs. 12.5%). Anxiety was positively related to the cortisol level but negatively related to the plasma ghrelin level, and the latter two were negatively correlated with each other. Conclusion Chronic increase of plasma cortisol induced by long-term anxiety can lead to the reduction of ghrelin level, which then adversely affects blood pressure in elders with psychological distress. Therefore, ghrelin might be a selective antihypertensive medicine for hypertensive elders with anxiety.     

Inhibitory action of docetaxel on the proliferation of HeLa and SiHa cells

Objective To study the inhibitory action of docetaxel (DOC) on the proliferation of HeLa and SiHa cells. Methods Cell morphological changes were observed with inverted phase contrast microscope. MTT was adopted to test and calculate the cell inhibition ratio. Flow cytometry was used to detect cell cycle. Results DOC had an obvious concentration-dependent inhibitory effect on the proliferation of both HeLa and SiHa cells. The inhibition ratio of DOC on SiHa was significantly higher than that on HeLa (P<0.05). DOC blocked HeLa at G2/M phase. Under the effect of DOC, the cell cycle of SiHa was not changed much. Conclusion DOC has an obvious inhibitory action on both HeLa and SiHa cells, which shows a promising prospect of DOC in clinical treatment of cervical cancer.     

交通与全球环境变化

在美国,交通部门、交通出行所带来的二氧化碳排放,占全部经济部门、经济活动所排放空气污染的1／4。交通与二氧化碳排放、二氧化碳排放与全球环境变化,全球环境变化对交通的影响、交通对全球环境的影响等等是一系列密不可分的问题。最新一期的美国交通研究会TRNews杂志,对上述问题中的交通与全球环境变化进行了高屋建瓴的讨论,有兴趣的读者,可以在以下网址免费阅读：     

车速变化对车辆操纵稳定性的影响(英文)

为了降低车速变化对车辆操纵稳定性的影响,建立了考虑车速变化的动态车辆转向运动模型,分析了描述模型的微分方程组所有系数都是随车速变化而时变的特性,通过变参数动态仿真,定量研究了车速变化对车辆操纵稳定性的影响.研究结果表明:减速时正的纵向车辆惯性力使后轴负荷向前轴转移,导致前轴侧偏刚度变大,后轴侧偏刚度变小,进而使车辆的横摆角速度增益增大,即车辆操纵稳定性变差;初始车速越高,减速度越大,车辆横摆角速度增益增大越快;加速时负的纵向车辆惯性力使前轴负荷向后轴转移,导致前轴侧偏刚度变小,后轴侧偏刚度变大,进而使车辆的横摆角速度增益减小.可见,减小车辆减速度、降低车身质心高度及增大轴距是弱化减速导致车辆操纵稳定性急剧变差的有效方法.     

上海银行业面临四类主要风险

上海银监局局长认为,当前上海银行业面临四类主要风险：企业和个人的信用风险增加：房地产开发企业资金趋紧,潜在信用风险加剧;市场变化难测。全球利率和汇率波动加大,银行市场风险管理难度加大;受经济金融下行趋势影响,银行操作风险不可忽视。案件防控难度加大。     

胶砂试件抗硫酸盐侵蚀试验研究

以掺粉煤灰的胶砂试件为研究对象,探讨水泥胶砂试件抗硫酸盐侵蚀试验方法及其评价指标。通过胶砂试件成型压力变化、标准砂粒径变化及粉煤灰掺量变化的试验得出：抗蚀系数随粉煤灰掺量的增大而逐渐变大,但随着掺量的加大而变化逐渐变得平缓;在砂的粒径区间不重叠的情况下,在一定范围内增大粒径可起到加速试验的目的;胶砂试件在成型压力达到一定值并侵蚀较长时间后,抗蚀系数才会变化更大。     

工程车辆柴油机转速控制研究

引言 工程车辆作业工况复杂,为了保证柴油机在负荷变化幅度较大的情况下以稳定的速度作业,通常柴油机都安装全程式调速器。当外负载发生变化时,柴油机的输出扭矩会发生变化,转速也相应地发生改变,然而柴油机转速的变化会引起燃油消耗量增加,使柴油机出现失速、闷车和燃油经济性能下降等现象。因此,研究柴油机转速控制具有重要的意义。     

非完整约束系统的广义能量守恒律

本文研究双面理想非完整约束系统在约束不是定常且主动力不是有势时的广义能量守恒律。建立系统的能量变化方程,给出存在广义能量守恒律的充分必要条件。分析有广义能量守恒律的12种情况．最后给出说明性算例。