钛合金自由锻“脊骨”型零件机加变形控制

根据"脊骨"型钛合金零件的数字化加工工艺,对该类型零件的结构及工艺性进行了分析,对数控加工该类型零件的走刀方式及切削参数进行了实践探索,并进行了数据记载,可为同类型零件的加工提供参考。

大跨径混凝土双塔双索面部分斜拉桥概念设计

大跨径混凝土双塔双索面部分斜拉桥设计的关键是双索面布置的箱型主梁构造及其可靠的传力构造。以部分斜拉桥力学性能分析为依据确定结构总体布置。通过概念设计提出了具有稳定三角边室的主梁截面构造,以适应斜拉索锚固力的局部作用。主墩区域变高度主梁采用“脊骨”型纵向立面构造,以达到线形的平顺及美观。为满足主梁整体受力及局部传力,提出了多向预应力尤其是“弓形”预应力束的布置方案,并优化分析确定了在有索区主梁三角边室内设置加劲肋以替代整体横隔板的横向传力构造。

Time Course of Changes in Trabecular Bone Microstructure in Rats with Spinal Cord Injury

The study aimed to examine changes in trabecular bone microstructure （TBMS） during the period of 5 weeks after the injury in a rat model of spinal cord injury （SCI）. Eight-week-old male Wistar rats underwent surgical transection of the lower thoracic spinal cord （SCI, n = 16） or sham operation （SHAM, n = 14）. TBMS （tissue volume, bone volume, bone volume fraction, trabecular thickness, width, number, separation, connectivity density, and trabecular bone pattern factor）, assessed using a micro-computed tomography, was deteriorated 1, 3 and 5 weeks after SCI. In addition, both bone mass and serum biochemical parameters were determined. Dry bone weight, ash weight, bone mineral content （BMC）, and BMC/tissue-volume were significantly lower in the SCI group than in the SHAM group throughout the experimental period. Serum inorganic phosphate and alkaline phosphatase levels were significantly lower in the SCI group than in the SHAM group 1 week after the surgery. SCI resulted in rapid deterioration of both bone mass and microstructure. These changes appeared as early as 1 week after SCI. Based on the authors＇ results, it should be noted that in SCI patients, interventions for preventing bone loss should start as soon as possible after the injury.

肌萎缩侧索硬化与脊髓型颈椎病的鉴别诊断

目的 探讨肌萎缩侧索硬化 (ALS)与脊髓型颈椎病 (CSM )早期临床鉴别诊断方法。方法 回顾性对临床确诊的 36例ALS和 2 2例CSM主要症状 /体征、辅助检查异常率进行比较。结果 除肌无力为两病共同的常见症状和体征外 ,肌萎缩、肌束震颤、感觉异常、病理征阳性率皆有显著性差别 ;ALS不存在客观感觉障碍 ,CSM不存在构音 /吞咽障碍和掌颏反射阳性。运动单位减少 ,波幅增高 ,时限增宽 ,纤颤电位增多 ,感觉传导速度和体感诱发电位正常 ,胸锁乳突肌EMG异常均利于ALS诊断。结论 在临床早期 ,通过识别关键性的症状、体征 ,结合电生理等实验室检查 。