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961.
A new method for seed oil body purification and examination of oil body integrity following germination 总被引:1,自引:0,他引:1
Plant seeds store triacylglycerols as energy sources for germination and postgerminative growth of seedlings. The triacylglycerols are preserved in small, discrete, intracellular organelles called oil bodies. A new method was developed to purify seed oil bodies. The method included extraction, flotation by centrifugation, detergent washing, ionic elution, treatment with a chaotropic agent, and integrity testing by use of hexane. These processes subsequently removed non-specifically associated or trapped proteins within the oil bodies. Oil bodies purified by this method maintained their integrity and displayed electrostatic repulsion and steric hindrance on their surface. Compared with the previous procedure, this method allowed higher purification of oil bodies, as demonstrated by SDS-PAGE using five species of oilseeds. Oil bodies purified from sesame were further analyzed by two-dimensional gel electrophoresis and revealed two potential oleosin isoforms. The integrity of oil bodies in germinating sesame seedlings was examined by hexane extraction. Our results indicated that consumption of triacylglycerols reduced gradually the total amount of oil bodies in seedlings, whereas no alteration was observed in the integrity of remaining oil bodies. This observation implies that oil bodies in germinating seeds are not degraded simultaneously. It is suggested that glyoxisomes, with the assistance of mitochondria, fuse and digest oil bodies one at a time, while the remaining oil bodies are preserved intact during the whole period of germination. 相似文献
962.
最优特征子集选择问题 总被引:73,自引:0,他引:73
机器学习和模式识别面临的一个重要问题,就是特征子集的选择问题,即从一个大的已生征特集合,选择一个子集合来一致地描述已知例。特别,最优特征子集选择问题,即最小的特征子集问题的 计算杂性至今学不清楚。 相似文献
963.
964.
An investigation has been carried out into the possibility of in situ formation of MoS2 within porous anodic films on aluminium, to improve subsequent tribological behaviour, by re-anodizing in thiomolybdate electrolyte. Acidification of thiomolybdate was employed to simulate the conditions for formation of the sulphide at the anodic film/electrolyte interface, followed by appropriate vacuum heat treatments to study possible temperature effects on the sulphide due to either friction or Joule heating during anodizing. The products of both acidification and heat treatment, characterized by X-ray powder diffraction and scanning electron microscopy, were compared with those formed by direct thermal decomposition of ammonium tetrathiomolybdate crystals. The precipitate formed by acidification was mainly amorphous molybdenum trisulphide (MoS3), which on heat treatment at 450 and 850°C yielded 3R-MoS2. 3R-MoS2 also formed by the thermal decomposition of thiomolybdate crystals. Thermogravimetric and differential thermal analyses showed that the decomposition of MoS3 to MoS2 occurred in the range 220–370°C and revealed the sequence of reaction steps. The findings suggest that mainly amorphous MoS3 is formed as a consequence of changes in the pH of the film/electrolyte interface during re-anodizing but the product is relatively easily transformed to crystalline MoS2 on moderate heating which may occur during wear processes. 相似文献
965.
966.
967.
在基于单片机的智能化重力加速度测试仪中采用C语言编程简化了程序设计任务,对于汇编语言难于处理的浮点数运算及汉字打印输出可通过C语言编译器的内部库函数调用实现,介绍了一种专为8051系列单片机设计的C语言编译器Frankilin C51,它具有代码优化功能,能产生极高效率的机器码,并且提供了丰富的内部函数库。描述了C51函数库所支持的IEEE标准浮点数的内存格式以及采用sprintf()函数处理包括 相似文献
968.
单分散六边形扁平溴碘化银微晶的结构与性能的研究 总被引:1,自引:1,他引:0
应用可控双注仪制备了一系列碘含量相同而碘在微晶中分布不同的单分散六边形扁平溴碘化银乳剂。用扫描电镜(STEM)与X-射线能谱仪(EDS)对单个微晶进行了微区分析,并用介电损耗,微波光导等方法研究了此类乳剂微晶的结构与性能的关系。结果表明:严格控制微晶成核、成熟、生长三个阶段的条件,可制得含六边形颗粒92%以上的扁平溴碘化银乳剂,颗粒大小变化系数小于12%。此外碘在微晶中的分布明显影响微晶的电性质和 相似文献
969.
本文报道 Nb,Ti 微合金钢的热变形动态模拟变形抗力模型。在试验中用热加工模拟试验机进行高温压缩试验,其变形温度为1123—1423K,变形速率为0.1—60s~(-1)。结果表明,在峰值以前该钢种的流变应力数学模型为:σ=5.99.ε~(0.167)·(?)~(6.47×10~(-5)·T)·exp(4064/T)。形变激活能(Q)为444 kJ/mol,β系数为0.080。峰值应力(σ_p),临界应变(ε_c)和温度补偿应变速率参数(Z)之间的关系分别为:σ_p=12.56·lnZ-391.8;lnε_c=0.157·lnZ-7.39。 相似文献
970.