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砼断裂韧度尺寸效应的试验研究 被引量:6
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作者 胡若邻 黄培彦 周绪平 《华南理工大学学报(自然科学版)》 EI CAS CSCD 北大核心 2008年第6期47-51,共5页
为研究混凝土断裂韧度的尺寸效应,将基于Weibull统计理论的尺度律与基于Bazant能量释放原理的尺度律进行对比,进行了3种混凝土断裂韧度,即起裂韧度Ki1nci、失稳韧度Ku1nc及临界裂缝尖端张开位移δc的试验研究.采用在建桥梁所用高强混凝... 为研究混凝土断裂韧度的尺寸效应,将基于Weibull统计理论的尺度律与基于Bazant能量释放原理的尺度律进行对比,进行了3种混凝土断裂韧度,即起裂韧度Ki1nci、失稳韧度Ku1nc及临界裂缝尖端张开位移δc的试验研究.采用在建桥梁所用高强混凝土材料制作了6组共18根几何相似、最大尺寸为1280mm×320mm×160mm(长×高×宽)的带预制缺口的素混凝土平面应变三点弯曲试件,应用MTS材料试验机、动态应变仪等测试手段获得了试件的荷载-加载点位移、荷载-裂缝嘴张开位移的全过程曲线以及裂缝前沿应变等.计算结果表明,考虑了裂缝前沿过程区影响的混凝土断裂韧度仍然表现出一定程度的尺寸效应,而Bazant能量释放尺度律较Weibull统计理论尺度律更适用于预测大尺寸混凝土材料的断裂韧度. 展开更多
关键词 尺寸效应 起裂韧度 失稳韧度 临界裂缝尖端张开位移
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Early activated hepatic stellate cell-derived molecules reverse acute hepatic injury 被引量:2
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作者 Wen-Ju Chang Lu-Jun Song +7 位作者 Tuo Yi Kun-Tang Shen Hong-Shan Wang Xiao-Dong Gao Min Li Jian-Min Xu Wei-Xin Niu Xin-Yu Qin 《World Journal of Gastroenterology》 SCIE CAS 2015年第14期4184-4194,共11页
AIM: To test whether hepatic stellate cells(HSCs) at different activation stages play different roles in acetaminophen(APAP)-induced acute liver injury(ALI).METHODS: HSCs were isolated from mouse liver and cultured in... AIM: To test whether hepatic stellate cells(HSCs) at different activation stages play different roles in acetaminophen(APAP)-induced acute liver injury(ALI).METHODS: HSCs were isolated from mouse liver and cultured in vitro.Morphological changes of initiation HSCs [HSCs(5d)] and perpetuation HSCs [HSCs(p3)] were observed by immunofluorescence and transmission electron microscopy.The protective effects of HSCderived molecules, cell lysates and HSC-conditioned medium(HSC-CM) were tested in vivo by survival and histopathological analyses.Liver injury was determined by measuring aminotransferase levels in the serum and by histologic examination of tissue sections under a light microscope.Additionally, to determine the molecular mediators of the observed protective effects of initiation HSCs, we examined HSC-CM using a highdensity protein array.RESULTS: HSCs(5d) and HSCs(p3) had different morphological and phenotypic traits.HSCs(5d) presented a star-shaped appearance with expressing α-SMA at non-uniform levels between cells.However, HSCs(p3) evolved into myofibroblast-like cells without lipid droplets and expressed a uniform and higher level of α-SMA.HSC-CM(5d), but not HSC-CM(p3), provided a significant survival benefit and showed a dramatic reduction of hepatocellular necrosis and panlobular leukocyte infiltrates in mice exposed to APAP.However, this protective effect was abrogated at higher cell masses, indicating a therapeutic window of effectiveness.Furthermore, the protein array screenrevealed that HSC-CM(5d) was composed of many chemokines and growth factors that correlated with inflammatory inhibition and therapeutic activity.When compared with HSC-CM(p3), higher levels of monocyte chemoattractant protein-1, macrophage inflammatory protein-1γ, hepatocyte growth factor, interleukin-10, and matrix metalloproteinase-2, but lower levels of stem cell factor and Fas-Ligand were observed in HSCCM(5d).CONCLUSION: These data indicated that initiation HSCs and perpetuation HSCs were different in morphology and protein expression, and provided the first experimental evidence of the potential medical value of initiation HSC-derived molecules in the treatment of ALI. 展开更多
关键词 HEPATIC stellate cells Acute liver INJURY initiati
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震源初始破裂位置对地表地震动影响分析
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作者 胡进军 谢礼立 《振动与冲击》 EI CSCD 北大核心 2015年第24期66-70,共5页
近断层地震动受地震震源参数的影响显著,基于典型的地震有限断层模型,通过离散波数有限元数值模拟方法,计算了断层上可能的三种不同初始破裂位置条件下的一系列地表场点的地震动时程,比较不同初始破裂位置对地震动参数的影响,结果表明:... 近断层地震动受地震震源参数的影响显著,基于典型的地震有限断层模型,通过离散波数有限元数值模拟方法,计算了断层上可能的三种不同初始破裂位置条件下的一系列地表场点的地震动时程,比较不同初始破裂位置对地震动参数的影响,结果表明:1初始破裂位置越靠近地表,地震动的峰值越大,而且初始破裂位置对地震动的加速度影响最大,对速度和位移的影响较小;2对地震动不同分量的分析表明,初始破裂位置对地震动的垂直断层分量影响较大,对平行断层和竖向分量影响很小;3初始破裂位置深度的增大会降低地表地震动的幅值,但是断层破裂不同方向上的地震动幅值相对差异仍然存在。因此,断层面上的初始破裂位置也是地震动模拟和预测中需要考虑的一个重要因素。 展开更多
关键词 地震断层 初始破裂位置 地震动参数 数值模拟
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