Based on the structural characteristics of the high-speed loading tester,a four-point bending test device was designed to carry out the four-point bending strength test of glass under the action of static load and dif...Based on the structural characteristics of the high-speed loading tester,a four-point bending test device was designed to carry out the four-point bending strength test of glass under the action of static load and different impact velocities,and the formulae for calculating the maximum dynamic stress and strain rate of glass specimens under the action of impact loads were derived.The experimental results show that the bending strength values of the glass under dynamic impact loading are all higher than those under static loading.With the increase of impact speed,the bending strength value of glass specimens generally tends to increase,and the bending strength value increases more obviously when the impact speed exceeds 0.5 m/s or higher.By increasing the impact velocity,higher tensile strain rate of glass specimens can be obtained because the load action time becomes shorter.The bending strength of the glass material increases with its tensile strain rate,and when the tensile strain rate is between 0 and 2 s^(-1),the bending strength of the glass specimen grows more obviously with the strain rate,indicating that the glass bending strength is particularly sensitive to the tensile strain rate in this interval.As the strain rate increases,the number of cracks formed after glass breakage increases significantly,thus requiring more energy to drive the crack formation and expansion,and showing the strain rate effect of bending strength at the macroscopic level.The results of the study can provide a reference for the load bearing and structural design of glass materials under dynamic loading.展开更多
目的了解老年女性骨质疏松性骨折患者手术后应用双膦酸盐的临床反应,分析常见不良反应的相关特点。方法收集苏州大学附属第二医院骨科151例老年女性骨质疏松性骨折术后初次静脉应用双膦酸盐治疗病例,记录患者年龄、体质量、体质量指数(b...目的了解老年女性骨质疏松性骨折患者手术后应用双膦酸盐的临床反应,分析常见不良反应的相关特点。方法收集苏州大学附属第二医院骨科151例老年女性骨质疏松性骨折术后初次静脉应用双膦酸盐治疗病例,记录患者年龄、体质量、体质量指数(body mass index,BMI)、腰椎和股骨骨密度(bone mineral density,BMD)、肌酐清除率、Ⅰ型胶原C端肽交联(β-C-terminal peptide of typeⅠcollagen,β-CTX)、Ⅰ型原胶原N端前肽(procollagen typeⅠN-terminal prepeptide,P1NP)、术后用药时间、常见不良反应等数据;按患者不同年龄、体质量指数、骨密度分别分组,分析术后用药时间与不良反应发生的相关性;比较术后<2周内与术后≥2周用药时间与常见不良反应(发热、肌肉酸痛、腹泻、排尿困难、结膜充血、恶心、头晕和头痛)发生的相关性。结果在年龄分组中,80~89岁年龄段组术后用药时间(18.4±21.7)d与不良反应发生率(25%)的相关系数为-0.314,差异有统计学意义(P<0.05),其他各年龄组都提示术后用药时间与不良反应发生无相关性(P>0.05);在BMI、骨密度分组中,术后用药时间与不良反应发生无相关性(P>0.05);“术后<2周内应用组”与“术后≥2周应用组”之间,发热、肌肉酸痛、腹泻、排尿困难、结膜充血、恶心、头晕和头痛等不良反应发生率均差异无统计学意义(P>0.05)。结论80岁以上骨质疏松性骨折术后静脉应用双膦酸盐的时间间隔应适当延长;在骨科手术后静脉应用双膦酸盐时,早期应用(<2周)或晚期应用(≥2周)与常见不良反应发生无相关性。展开更多
基金Found by the National Natural Science Foundation of China(Nos.52072356 and 52032011)the Shandong Province Science and Technology Small and Medium-sized Enterprises Innovation Ability Improvement Project(No.2022TSGC1194)。
文摘Based on the structural characteristics of the high-speed loading tester,a four-point bending test device was designed to carry out the four-point bending strength test of glass under the action of static load and different impact velocities,and the formulae for calculating the maximum dynamic stress and strain rate of glass specimens under the action of impact loads were derived.The experimental results show that the bending strength values of the glass under dynamic impact loading are all higher than those under static loading.With the increase of impact speed,the bending strength value of glass specimens generally tends to increase,and the bending strength value increases more obviously when the impact speed exceeds 0.5 m/s or higher.By increasing the impact velocity,higher tensile strain rate of glass specimens can be obtained because the load action time becomes shorter.The bending strength of the glass material increases with its tensile strain rate,and when the tensile strain rate is between 0 and 2 s^(-1),the bending strength of the glass specimen grows more obviously with the strain rate,indicating that the glass bending strength is particularly sensitive to the tensile strain rate in this interval.As the strain rate increases,the number of cracks formed after glass breakage increases significantly,thus requiring more energy to drive the crack formation and expansion,and showing the strain rate effect of bending strength at the macroscopic level.The results of the study can provide a reference for the load bearing and structural design of glass materials under dynamic loading.
文摘通过燕麦草单播以及与光叶紫花苕、箭筈豌豆和毛苕子等3种苕子的混播试验,研究和比较燕麦草在单播和混播下饲草的生产性能和营养品质,为燕麦草的合理化利用提供依据。当燕麦草单播的播种量为225 kg/hm 2、与豆科牧草混播的播种量为75 kg/hm 2情况下,进行饲草田建植,然后在生长第二年分别测定饲料田的株高、生物量以及营养成分等指标,探讨了燕麦草在单播以及混播下牧草生长特点和营养水平。结果表明:(1)无论单播还是混播,牧草在抽穗-扬花(现蕾-开花)期生长速度最快,盛花期时牧草的株高为102.38~114.58 cm,其生长高度与生长天数的关系可以用logistic方程来表示来拟合;(2)成熟期混播牧草的生物量分别为781.33 g DM/m 2、712.71 g DM/m 2和697.40 g DM/m 2,分别比单播提高21.97%(P<0.05)、11.26%(P<0.05)和8.87%(P<0.05)。(3)花期混播牧草粗蛋白含量为9.67%~10.58%、比单播提高39.94%~53.11%(P<0.05),另外,粗纤维含量也得到显著降低。总之,燕麦草与苕子混播,可提高株高和生长速度,显著提高饲草的产量和品质。在混播的3种苕子中,光叶紫花苕更有利于提高混播草群的稳定性,更有利于提高饲草的产量和营养水平。
文摘目的了解老年女性骨质疏松性骨折患者手术后应用双膦酸盐的临床反应,分析常见不良反应的相关特点。方法收集苏州大学附属第二医院骨科151例老年女性骨质疏松性骨折术后初次静脉应用双膦酸盐治疗病例,记录患者年龄、体质量、体质量指数(body mass index,BMI)、腰椎和股骨骨密度(bone mineral density,BMD)、肌酐清除率、Ⅰ型胶原C端肽交联(β-C-terminal peptide of typeⅠcollagen,β-CTX)、Ⅰ型原胶原N端前肽(procollagen typeⅠN-terminal prepeptide,P1NP)、术后用药时间、常见不良反应等数据;按患者不同年龄、体质量指数、骨密度分别分组,分析术后用药时间与不良反应发生的相关性;比较术后<2周内与术后≥2周用药时间与常见不良反应(发热、肌肉酸痛、腹泻、排尿困难、结膜充血、恶心、头晕和头痛)发生的相关性。结果在年龄分组中,80~89岁年龄段组术后用药时间(18.4±21.7)d与不良反应发生率(25%)的相关系数为-0.314,差异有统计学意义(P<0.05),其他各年龄组都提示术后用药时间与不良反应发生无相关性(P>0.05);在BMI、骨密度分组中,术后用药时间与不良反应发生无相关性(P>0.05);“术后<2周内应用组”与“术后≥2周应用组”之间,发热、肌肉酸痛、腹泻、排尿困难、结膜充血、恶心、头晕和头痛等不良反应发生率均差异无统计学意义(P>0.05)。结论80岁以上骨质疏松性骨折术后静脉应用双膦酸盐的时间间隔应适当延长;在骨科手术后静脉应用双膦酸盐时,早期应用(<2周)或晚期应用(≥2周)与常见不良反应发生无相关性。
文摘在河南省黄河滩区土壤和气候条件下,燕麦播种量为225 kg/hm2时,通过对比试验,分别测定五寨、林纳、坝莜3号和加燕4个燕麦品种在不同生长期茎叶比、鲜干比、株高、干草产量等指标,研究不同燕麦品种生产性能和农艺性状的动态变化。结果表明:燕麦4个品种在扬花期茎叶比分别为65.34%、58.18%、70.05%、54.72%,鲜干比分别为3.12、3.17、3.07、3.31;燕麦的生长速度呈现出“低—高—低”的“S”形动态模式,在抽穗—扬花期生长速度最大,盛花期株高达分别到108.58、103.43、100.37、113.42 cm,干草产量分别为549.17、514.74、519.63、531.53 g DM/m2。4个燕麦品种均适合在黄河滩种植和生长,表现出生长快、产量高的特点,其中加燕品种各项性能表现更好。
