Numerical analysis on intermittent flow in a longitudinal section of Bingham fluid along a slope

The transition process of intermittent flow in a longitudinal section of Bingham fluid from initial distribution to fully developed state was numerically investigated in this paper. The influences of slope θ. dimensionless runoff Q* and viscosity μ0* on the dimensionless surge speed U* were also presented in a wide range of parameters. By one typical example, the intermittent flow possessed wave characteristics and showed a supercritical flow conformation for a fully developed flow. The distributions of gravity and bed drag along the flow path and the velocity distribution of flow field were also analyzed.     

Modulating multidrug resistance through inhibiting of protein kinase C activity by phenothiazines

In the present study, actions of phenothiazines(PTZ) in reversing multidrug resistance(MDR) and inhibiting PKC activity were investigated. It was found that the three PTZs caused 2.49, 36.58 and 75.78 fold reversal of K562/AO2 MDR cells resistant to adriamycin, respectively, while the chemosensitizer verapamil caused 40 fold reversal in the same condition, indicating that PTZ11 is a novel reversal agent of MDR and a potential chemotherapeutic reagent for tumor therapy. PKC activity analysis in the presence of PTZs showd that PTZ6 and PTZ11 inhibited rat brain protein kinase C activity in a manner of dose_dependent. The IC 50 values were (489.77±31.4) and (113±9.64) μmol/L, respectively. PTZ7 had no inhibition on PKC activity. Further study showed that PTZ11 could reduce PMA_mediated activation of PKC in a manner of dose_dependent, suggesting that PTZ11 might compete for the high_affinity phorbol ester binding site within PKC molecule. Recently, an X_ray structure of PMA in complex with PKC Cys2 activator_binding domain was solved. We therefore decided to explore the possible binding model of PTZ11 with PKC molecule using SYBYL 6.02 program. It was shown that the binding site of PTZ11 with PKC molecule partially overlapped with that of PMA, providing for the first time new data for designing PKC inhibitors and MDR reversal drugs.     

头部重点低温对缺血后再灌注时兔脑神经元转归的影响

探讨头部重点低温（ＳＨＣ）能否改善受损兔脑神经元的转归,以及相应的生化机制,方法：采用“四血管”模式造成脑缺血３０ｍｉｎ,然后将１６８只新西兰兔随机分为三组,Ｉ组为未缺血对照组,其余两组动物的３个来组均在缺血３０ｍｉｎ后分别再灌注３０,１８０和３６０ｍｉｎⅡ组为常温财灌注组,Ⅲ组为ＳＨＣ治疗组,开始再灌注时实施ＳＨＣ（２８℃）,检测了脑组织中２１项生化指标的变化和采用计算机图像分析技术,将１２个脑     

平头立铣刀无过切干涉刀位轨迹的自动生成

提出了一种空间自由曲面平头立铣刀无过切干涉的刀位轨迹自动生成的新方法,对三轴和五轴联动数控加工的情形都加以了详细论述,并在计算机上成功地实现了无过切干涉刀位轨迹的自动生成．     

样条曲线在三维激光切割控制系统中的应用

研究了一种新型的基于工业ＰＣ的三维激光切割控制系统．由于实现了示教点的样条拟合和三维曲线的直接插补,而不必采用传统的以直线段或圆弧段拟合的方式,从而在加工轨迹数学模型的获取与后续加工的集成方面较好地满足了大功率三维激光切割机的使用要求．     

钙对杂交水稻离体叶片衰老的影响

以叶绿素和蛋白质的质量分数下降作为衰老的生理指标,研究了Ｃａ２＋和Ｃａ２＋的螯合剂ＥＤＴＡ对杂交水稻离体叶片衰老的作用．结果表明,Ｃａ２＋能延缓杂交水稻离体叶片中叶绿素和蛋白质的质量分数的下降,提高超氧化物歧化酶（ＳＯＤ）、过氧化氢酶（ＣＡＴ）、抗坏血酸过氧化物酶（ＡｓＡ－ＰＯＤ）和谷胱甘肽还原酶（ＧＲ）的酶活性;增加抗坏血酸（ＡｓＡ）和谷胱甘肽（ＧＳＨ）的的质量分数;降低膜脂过氧化产物丙二醛（ＭＤＡ）的质量摩尔浓度．１～２０ｍｍｏｌ／ＬＥＤＴＡ降低叶片中叶绿素和可溶性蛋白质的质量分数;降低ＡｓＡ－ＰＯＤ和ＣＡＴ的酶活性;降低ＡｓＡ、ＧＳＨ的质量分数;提高ＳＯＤ酶活性,但对ＧＲ酶活性的影响不大．外加Ｃａ２＋可使ＥＤＴＡ的抑制作用减轻．     

鲇鱼苗烂尾病病原体的初步研究

鲇鱼烂尾病（暂定名）是近期发现、危害严重的一种细菌性鱼病．作者从病鱼病灶中分离出Ｚ４－２菌株，经过人工感染后分离再感染成功．通过形态学观在和生理生化测定，初步确定Ｚ４－２为病原菌，是一种气单胞菌（Ａｅｒｏｍｏｎａｓｓｐ．）．对青霉素、保而鲜等不太敏感，对氯霉素，呋喃唑酮、鳗康素、强力霉素等敏感。     

甲异羟肟酸与甲羟肟酸互变异构的MNDO研究

应用半经验ＭＮＤＯ方法研究了甲异羟肟酸与甲羟肟酸的互变异构平衡。确定了互变异构体及过渡态的几何构型、相对能量和活化能。得出甲羟肟酸的能量比甲异羟肟酸低１０．０ｋＪ／ｍｏｌ．同时得出甲异羟肟酸经１，３－分子内氢迁移互变异构为甲羟肟酸的活化能为２７１．０ｋＪ／ｍｏｌ．     

（Y，Gd）_2O_3·2B_2O_3：Bi~（3＋），Eu~（3＋）的发光性质

研究了荧光材料（Ｙ，Ｇｄ）_２Ｏ_３·２Ｂ_２Ｏ_３：Ｂｉ~３＋，ＥＵ~３＋的合成和晶体结构．经ＸＲＤ确定为六方晶系，晶胞参数：ａ＝３．７８６，ｃ＝８．８２４．在２５４ｎｍ紫外光激发下，荧光材料有较强的红色发光．观察到Ｂｉ~３＋→Ｇｄ~３＋→Ｅｕ~３＋的能量传递现象，Ｂｉ~３＋→Ｇｄ~３＋能量传递机理为交换作用；Ｇｄ~３＋→Ｅｕ~３＋能量传递机理为电偶极──电四极相互作用．