可凝气体组分对涡流管能量分离效率的影响分析     

马庆芬  张燕  邱中华  胡施俊 《热带作物学报》2010,34(6):52-55

应用1952～2008年我国宏观农村居民消费和GDP数据,通过协整模型分析方法针对农民消费对GDP增长的促进作用进行实证分析。结果表明,农民消费与GDP增长在长期内稳定地存在着协同互动的均衡关系,并且二者互为格兰杰因果关系。通过协整模型发现,长期内,农村居民消费增长1%,我国GDP就会增长1.7483%,其对经济增长的促进作用较大。  相似文献   

Establishment of an acute renal failure animal model by renal transitory ischemia     

CHEN Ning  HUANG Di  LI Zhuo-ran  SHENG Dan  ZHAO Juan  YE Jing  LIU Xin  PEI Ai-ping 《园艺学报》2010,26(12):2493-2496

AIM: To establish an animal model of acute renal failure (ARF) according to the clinical manifestations by reducing renal blood flow.METHODS: Renal ischemia in rabbits was induced by the ligation of bilateral renal arteries incompletely for 20 min and then the ligation was released. Before and after incomplete ligation of bilateral renal arteries, and after resuming renal blood flow, the urine volume, serum creatinine, electrolytes and blood gas analysis in the experimental animals were determined. One kidney of each rabbit was harvested at different stages for pathological examination.RESULTS: After reducing renal blood flow, the urine volume of the rabbit decreased (P<0.05) and the serum levels of creatinine increased significantly (P<0.01). At the same time, the level of serum K⁺ appeared an elevated trend. pH and HCO^-₃ in the arterial blood decreased, and the negative value of BE increased markedly, indicating that metabolic acidosis developed. After resuming the kidney perfusion, the urine volume of the rabbits increased to normal, the level of serum creatinine also decreased to normal as the renal reflow recovery for 1 h, but metabolic acidosis remained continuously. The level of serum K⁺ decreased for a while and elevated again. No obvious pathological changes of the kidney were observed under microscope at the stage of ischemia for 20 min, reflow for 1 h and 5 h.CONCLUSION: Incomplete ligation of bilateral renal arteries develops multiple clinical manifestations and characteristics of functional ARF. This animal model of ARF is helpful for relevant purposes of teaching and research.  相似文献   

Establishment of insulinoma animal models and observation of tumor characteristics     

CHENG Lan-yun  XU Shi-qing  ZHANG Wen-jian  LOU Jin-ning  MEN Xiu-li 《园艺学报》2013,29(4):761-768

AIM：To establish the animal model of insulinoma and to analyze the properties of insulinoma for further study. METHODS：The hormone-releasing ability of rat insulinoma cell line INS-1 was detected in vitro. INS-1 cells were transplanted into the left kidney capsule of nude mice. The islets of the animals were destroyed by intraperitoneal injection of streptozocin (STZ) 3 d before transplantation or 2 weeks after transplantation. The venous blood was sampled, and the level of blood glucose less than 2.8 mmol/L was defined as successful establishment of insulinoma model. Different irritants were given to the model animals, and the changes of blood glucose and insulin content in serum were observed. The pancreatic tissues and the renal tissues in the injecting sites were taken from all mice for detecting insulin and glucagon by immunohistochemical staining. RESULTS：Insulinoma cells expressed insulin and glucagon at the same time. The blood glucose was less than 2.8 mmol/L 3 to 4 weeks after inoculation of INS-1 cells. Apparent tumor formed in the left kidneys where INS-1 cells were transplanted and the tumor diameters were more than 1 cm. The level of blood glucose transiently increased to higher than the normal level in the mice with tumor cell transplantation after intraperitoneal injection of STZ, and then decreased gradually and returned to less than 2.8 mmol/L after 2 weeks. The level of blood glucose in the normal nude mice after administration of STZ increased significantly. After transplantation of INS-1 cells, the level of blood glucose decreased gradually, and returned to less than 2.8 mmol/L after 4 weeks. After stimulated with high glucose, the blood glucose levels in the mice with 3 methods to establish the insulinoma models showed lower glucose peaks than that in the normal control mice. After stimulated with high glucose plus arginine or acetylcholine in the normal animals, the blood glucose peak was lower than that in the normal animals only stimulated with high glucose, and rapidly recovered to the normal level. However, the levels of blood glucose in the mice with 3 methods to establish the insulinoma models under the same stimulations were significantly higher than that in the mice only stimulated with high glucose. After stimulated with high glucose plus norepinephrine, the blood glucose peak time in the normal animals delayed, and the blood glucose level declined slowly. After stimulated with high glucose plus norepinephrine, the levels of blood glucose in the mice with 3 methods to establish the insulinoma models increased as compared with that in the mice only stimulated with high glucose. Compared with normal control group, serum insulin in insulinoma mice increased significantly. CONCLUSION：The insulinoma animal model is successfully established by transplantation of INS-1 cells into the renal capsule of nude mice. The insulinoma cells express both insulin and glucagon, and are not easily damaged by STZ.  相似文献   

发动机凸轮轴磨削变形补偿技术研究     

刘勇军  范晋伟  李云 《农业机械学报》2013,44(6):274-279

针对发动机凸轮轴数控磨削时产生连续变化的弹性变形问题,分析了凸轮轴受到磨削力变形对凸轮轮廓精度的影响,对轴向和径向变形进行了解耦,推导了不同位置、不同相位下凸轮受力变形量求解方程.分析了数控凸轮轴磨床的插补原理,建立了含有变形量误差的、工件旋转轴和砂轮进给轴联动的磨削运动学方程,提出了X轴变形量与理论插补值进行几何叠加的指令修正误差补偿方法.对某发动机进排气凸轮轴磨削变形进行了建模与仿真,对数控凸轮轴磨床进行了补偿与加工试验,仿真与加工试验结果均表明磨削变形补偿可以将凸轮轴的轮廓精度提高5 μm.  相似文献   

大口径钢管圆度测量喷标系统设计与误差补偿研究     

李钊  周晓军  徐云  何强 《农业机械学报》2013,44(9):272-278

为满足大口径钢管测量精度的需要,设计了一种龙门架式钢管在线测量及喷标系统。利用龙门架两侧立柱激光传感器的竖直运动,测量钢管截面外径上点的坐标,利用最小二乘法求其圆心坐标,采用近似直径法求取该截面的最大直径和最小直径,从而求得该截面的圆度。实例证明该系统及数据处理算法可实现钢管外径及圆度的测量,并具有相当高的精度。对测量结果进行误差分析,得知影响测量结果的主要来源是钢管的摆放姿态,通过投影及坐标变换对误差进行补偿,补偿后结果得到了一定的改善,从而验证了误差分析的合理性和补偿方法的可行性,该系统可用于大口径钢管的在线测量。  相似文献   

基于LabVIEW的涡旋盘型线测试系统     

尹秉奎  刘维孟 《现代农业装备》2011,(12):50-53

介绍了基于虚拟仪器的渐开线涡旋型线测试系统,分析了该系统的机构原理,系统误差及误差纠正方法。该系统是利用直线运动与旋转运动的合成运动形成标准的圆渐开线轨迹,与待测零件型线轨迹进行比较的方法,进行测量型线轮廓度的误差;通过运用角编码器及丝杠误差的软件修正,可以较好的消除系统误差。将虚拟仪器技术应用到涡旋型线测试系统中,能...  相似文献   

圆柱度仪测量基准的误差分离技术   总被引：4，自引：0，他引：4  

李东升  王伟杰  谭久彬  赵维谦 《东北林业大学学报》1997,(2)

针对大尺寸试件的圆柱度误差的超精测量时仪器的测量基准的误差分离问题，提出了一种可分离出基准间的平行度误差以及直行基准的直线度误差的方法，即反向法误差分离技术。利用该方法建立的两截面及多截面误差分离模型已用于重要试件圆柱度误差的超精测量中，误差分离结果的不确定度为０．２２μｍ。该技术对超精密车床的误差检定亦有很好的指导意义  相似文献   

生物柴油物理特性参数的估算与误差分析   总被引：1，自引：0，他引：1  

阮登芳  王文彬  吴长河 《大豆科学》2009,28(6)

以生物柴油脂肪酸酯含量为基础,应用Matlab编制了包含15种脂肪酸酯的生物柴油物性参数预测程序,并应用所编程序估算了大豆油甲酯生物柴油的密度、表面活力、黏度和导热系数;分析比较了各种估算方法的精度.结果表明:在生物柴油密度估算中,修改Raekett方程的估算精度较高;Sastfi-Rao方法估算生物柴油低温黏度所得结果与实测值最接近,其估算精度较高;Miller方法和Macleod-Sugden关联式估算生物柴油表面张力的精度较其它几种方法高;建议在生物柴油导热系数估算中应用Sastri方法.  相似文献   

长悬臂坐标测量机动态力引起的误差分析与控制     

杨洪涛  费业泰  陈宝钢 《农业机械学报》2008,39(1):165-168

根据长悬臂测量机具有长悬臂和弱刚度的特性,分析了测量机动态力的来源,研究了动态力对测量机测量误差的影响和测头附加动态误差的来源,得出测量机测头附加动态误差具有三维特性,各个方向附加动态误差与3个方向导轨系统振动特性有关.推导了悬臂测杆系统振动数学模型,根据该模型采取了相应的动态力控制措施,实验结果证明了所采取控制措施的有效性.  相似文献   

玉米种子培养皿法发芽试验误差分析   总被引：4，自引：1，他引：3  

常梅 《中国农学通报》2006,22(4):134-134

培养皿法是玉米种子发芽试验常采用快捷方便的方法,但此方法的发芽率比较低、变异系数较大,不能反映种子本来固有的发芽水平。对此,笔者进行了培养皿法发芽试验的研究,结果表明,在培养皿内种胚向下是造成发芽率低和变异系数大的原因,若将种胚全部向上置放,就能减少发芽率的误差,体现出玉米种子的正常发芽水平。  相似文献