目的:通过Meta分析评价前庭康复训练联合药物疗法治疗持续性姿势-知觉性头晕(PPPD)的疗效。方法:制定检索策略,检索Cochrane Library、Pubmed、Web of Science、维普数据库(VIP)、中国期刊全文数据库(CNKI)、万方数据库(Wangfang)建库到...目的:通过Meta分析评价前庭康复训练联合药物疗法治疗持续性姿势-知觉性头晕(PPPD)的疗效。方法:制定检索策略,检索Cochrane Library、Pubmed、Web of Science、维普数据库(VIP)、中国期刊全文数据库(CNKI)、万方数据库(Wangfang)建库到2021年3月关于前庭康复训练联合药物治疗PPPD的临床随机对照试验,由2名研究人员严格按照纳入排除标准独立筛选文献、提取数据、评价文献质量,运用Review Manager 5.3软件进行质量评价及Meta分析。结果:筛选后最终得到10篇文献,均为随机对照实验,共计904例PPPD患者。Meta分析结果显示,与常规药物治疗相比,前庭康复训练联合药物治疗能有效缓解头晕症状[MD=-7.19,95%CI(-9.52,-4.86),P<0.01],缓解焦虑情绪[MD=-2.45,95%CI(-4.39,-0.51),P<0.01]及抑郁情绪[MD=-3.59,95%CI(-6.10,-1.09),P<0.01],提高有效率[OR=2.46,95%CI(1.43,4.21),P<0.01]。结论:前庭康复训练联合药物治疗PPPD与常规药物治疗相比,能有效改善患者主观头晕症状,并且缓解焦虑抑郁情绪。展开更多
为指导高强高韧Q420qE桥梁钢实际焊接工艺,采用Gleeble-3500热模拟试验机建立了试验钢的SHCCT曲线;针对各模拟样品,采用光学显微镜和透射显微镜观察了显微组织,测定了维氏硬度HV10,并利用Rykalin 2D模型根据冷速反推大致对应的焊接热输...为指导高强高韧Q420qE桥梁钢实际焊接工艺,采用Gleeble-3500热模拟试验机建立了试验钢的SHCCT曲线;针对各模拟样品,采用光学显微镜和透射显微镜观察了显微组织,测定了维氏硬度HV10,并利用Rykalin 2D模型根据冷速反推大致对应的焊接热输入并进行不同线能量焊接工艺模拟。结果表明:试验钢SHCCT冷速为1~10℃/s时,组织类型主要以粒状贝氏体为主,当冷速超过10℃/s时,开始出现板条贝氏体,并且随冷速的增加,相变开始和终了温度降低,贝氏体铁素体基体晶粒尺寸细化,由块状逐渐变为条状,维氏硬度增加。根据组织和硬度变化规律,初步推断高强高韧Q420qE钢适合焊接的热输入范围在45 k J/cm以下。展开更多
Using TEM (transmisson electron microscopy), electron diffraction, EDX (energy dispersive X-ray) analysis and physicochemical phase analysis, the morphology, crystal structure, size distribution and chemical compo...Using TEM (transmisson electron microscopy), electron diffraction, EDX (energy dispersive X-ray) analysis and physicochemical phase analysis, the morphology, crystal structure, size distribution and chemical composition of precipitates in the microstructure of high strength Nb-microalloyed Xl00 pipeline steel were investigated, and the strengthening effect of precipitation was quantitatively calculated with Ashhy-Orowan correction model. The precipitates obtained in X100 pipeline steel can be divided into two kinds: "complex" and "single" particles by morphology. The EDX analysis of "single" precipitates reveals that the chemical composition matches well with particle dimensions, especially the Nb to Ti ratio regularly decreases with the increase of particle size. The yield strength increments in the way of precipitation strengthening of X100 pipeline steel reached about 52 MPa, suggesting that the precipitation strengthening is not the dominative strengthening mechanism for X100 pipeline steel.展开更多
文摘为指导高强高韧Q420qE桥梁钢实际焊接工艺,采用Gleeble-3500热模拟试验机建立了试验钢的SHCCT曲线;针对各模拟样品,采用光学显微镜和透射显微镜观察了显微组织,测定了维氏硬度HV10,并利用Rykalin 2D模型根据冷速反推大致对应的焊接热输入并进行不同线能量焊接工艺模拟。结果表明:试验钢SHCCT冷速为1~10℃/s时,组织类型主要以粒状贝氏体为主,当冷速超过10℃/s时,开始出现板条贝氏体,并且随冷速的增加,相变开始和终了温度降低,贝氏体铁素体基体晶粒尺寸细化,由块状逐渐变为条状,维氏硬度增加。根据组织和硬度变化规律,初步推断高强高韧Q420qE钢适合焊接的热输入范围在45 k J/cm以下。
文摘Using TEM (transmisson electron microscopy), electron diffraction, EDX (energy dispersive X-ray) analysis and physicochemical phase analysis, the morphology, crystal structure, size distribution and chemical composition of precipitates in the microstructure of high strength Nb-microalloyed Xl00 pipeline steel were investigated, and the strengthening effect of precipitation was quantitatively calculated with Ashhy-Orowan correction model. The precipitates obtained in X100 pipeline steel can be divided into two kinds: "complex" and "single" particles by morphology. The EDX analysis of "single" precipitates reveals that the chemical composition matches well with particle dimensions, especially the Nb to Ti ratio regularly decreases with the increase of particle size. The yield strength increments in the way of precipitation strengthening of X100 pipeline steel reached about 52 MPa, suggesting that the precipitation strengthening is not the dominative strengthening mechanism for X100 pipeline steel.