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941.
Objective: To investigate the evolution of pulmonary hypertension, the pathological changes of pulmonary arteries, and the expression of VEGFmRNA and eNOSmRNA of pulmonary arterial endothelial cells in immature rabbits treated with intratracheal bleomycin (BLM). Methods: Immature rabbits were divided into control and BLM group. Two and four weeks after intratracheal normal saline or BLM injection, the systolic, diastolic and mean pulmonary artery pressure (PASP, PADP, MPAP) were measured by micro-catheter; the pathological changes and the expression of VEGFmRNA and eNOSmRNA of endothelial cells in pulmonary arteries were evaluated by HE and in situ hybridization.Results: Two and four weeks after intratracheal injection of BLM, the PASP, PADP and MPAP increased 53%, 49%, 52%in 2 weeks, and 43%, 89%, 56% in 4 weeks; the wall thickness increased and the cavity in middle and small pulmonary arteries became narrow; the Thickness Index (TI) and Area Index (AI) increased 25%, 14% in 2 weeks, and 22%, 24% in 4 weeks; the level of VEGFmRNA and eNOSmRNA expression decreased 46%, 43% in 2 weeks, and 43%, 51% in 4 weeks.There was no significant difference between 2 weeks and 4 weeks BLM groups. Conclusion: The pulmonary artery pressure was elevated, the thickness of wall increased and the cavity became narrow in middle and small pulmonary arteries, and the level of VEGFmRNA and eNOSmRNA expression in pulmonary arterial endothelial cells decreased in immature rabbits after 2 weeks and 4 weeks of intratracheal 4 U/kg BLM injection. 相似文献
942.
本文以画面的运用及其引起的道德张力为切入点,探讨了华盛顿·欧文名作《瑞普·凡·温克尔》与荷兰风俗画的亲缘性,说明了前者无论在艺术形式上还是在潜在的道德价值上都是后者的"隐性的阐释". 相似文献
943.
金属拉丝用低温快速磷化处理工艺研究 总被引:2,自引:1,他引:2
针对PC钢绞线用热轧盘条在线生产中对其焊接区表面拉丝性能的要求,开发了一种低温快速磷化处理工艺与配方,探讨了磷化液中组分及磷化工艺对磷化膜质量的影响,并对磷化膜有关性能进行了测试.结果表明,低温快速磷化处理液的组成:Zn(H2PO4)2·2H2O为55~65g/L、Zn(NO3)2·6H2O为70~85g/L、浓H3PO4为5mL/L、氧化剂NaNO2加入量为0.2~0.4g/L;经40℃、10min的快速磷化处理后, 获得的磷化膜膜重大于10g/m2,结晶细小致密,与基体结合力强. 相似文献
944.
PENG Changsheng SONG Shaoxian & GU Qingbao .Instituto de Metalurgia Universidad Autónoma de San Luis Potosí Av.Sierra Leona San Luis Potosí C.P. Mexico .Chinese Research Academy of Environmental Sciences Beijing China 《科学通报(英文版)》2005,50(4):299-304
Surface forces between particles control phenomenasuch as dispersion, agglomeration, coatings, adhesion,wetting, friction, and polishing, which play a crucial rolein materials processing. The importance of surface forcesis more appreciated especially in colloidal processing,while materials in a colloidal state are frequently preferredin industrial processing operations (e.g., printing inks,toners, paints, skin creams, blood substitutes, gels used asdrug-delivery systems, etc.) because their lar… 相似文献
945.
The zircon SHRIMP chronology and trace element geochemistry of the Carboniferous volcanic rocks in western Tianshan Mountains 总被引:84,自引:0,他引:84
ZHU Yongfeng ZHANG Lifei GU Libing GUO Xuan ZHOU Jing 《科学通报(英文版)》2005,50(19):2201-2212
The genesis of the Carboniferous volcanic rocks in the Dahalajunshan group, mainly consisting of trachytes and trachy-andesites and distributing widely in western Tianshan Mountains, remains to be controversial. It has been proposed to be relevant to “rift” or “plume”. Detailed petrology and geochemical data presented in this paper show that these volcanic rocks represent typical continental arc magmatism. The volcanic rocks are mainly trachy-andesitic, and the magma source is enriched in LILE, Th and Pb, and depleted in HFSE and Ce. Trace element geochemical study suggests that the basalts could be modeled by 7% -11% partial melt of garnet Iherzolite. The volcanic rocks in the Dahalajunshan group are neither the products of “rift” nor so-called “plume”but represent the continental island arc of the Paleo-Southern Tianshan Ocean. The mantle wedge had been modified by the melt generating in subduction zone during a long evolution history of this island arc. The continental crust materials (i.e. mainly sediment on ocean floor) had been added into island arc through melt in subduction zone. Volcanic rocks occurring in different regions might represent magma eruption in different time. The zircon SHRIMP dating indicates that the ages of the basalt varies between 334.0 Ma and 394.9 Ma. The 13 analyses give an average age of 353.7±4.5 Ma (MSWD = 1.7). The apparent ages of zircons in trachy-andesite vary between 293.0 Ma and 465.4 Ma. All analyses fall on the U-Pb concordant line and are divided into two groups. 8 analyses produce an average age of 312.8±4.2 Ma (MSWD = 1.7), which represents the crystallizing age of zircon rims in trachy-andesite. The acquired two ages (i.e. 354 and 313 Ma) belong to the Early Carboniferous and Late Carboniferous epochs, respectively. Thus, the Dahalajunshan group would be separated into several groups with the accumulation of high-quality age dating and data of trace element and isotopic geochemistry, in our opinion. 相似文献
946.
提出了面向激光雕刻管状冠状动脉支架的通用化制作工艺流程,包括支架的结构设计、材料选择、切割、真空退火和电化学抛光等关键工序.研究了金属覆盖率、网孔、轴向短缩率和支撑效率等的相互影响,以选择合理的支撑环和连杆形式;确定了激光切割加工中最优化切割路径和机器参数;阐述了抛光前处理时酸洗液的选择、酸洗温度和时间的控制,以及真空退火时升温速度、冷却速度和保温时间的控制;分析了抛光液的选择和电极设计,以及抛光温度、电压和时间对电化学抛光效果的影响;并设计制作出了符合体外测试要求的支架样件. 相似文献
947.
甘肃省城镇社会体育的发展相对落后,体育人口比例低,且存在着阶层差异性和地域不平衡性.针对存在的问题,从发展的观点提出了甘肃省城镇社会体育的运行机制,旨在推动全民健身运动在落后地区城镇的快速开展. 相似文献
948.
报道不同路易斯酸性催化剂作用下二苯甲酮肟的Beckmann重排反应的结果,即分别以PCl5、H2S04、HCl-Ac2O、H2SO4-Ac2O、H3PO4-Ac2O、PPA、HCl-Ac2O-AcOH为催化剂进行比较实验.发现H3PO4-Ac2O是二苯甲酮肟进行Beckmann重排反应的理想催化剂之一. 相似文献
949.
950.
Laplacian分布表面超声背向散射的研究 总被引:1,自引:1,他引:0
李继凯 《河南师范大学学报(自然科学版)》1998,26(3):36-37
本文假设随机粗糙表面符合Laplacian分布,建立了来自粗糙表面的背向散射声强与物体表面粗糙度、超声频率和掠射角之间的闭形解析表达式.其结果的近似程度在大掠射角时,比文献预言的更好. 相似文献