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Preparation of fluorescence starch-nanoparticle and its application as plant transgenic vehicle 总被引:2,自引:1,他引:1
Starch-nanoparticles were synthesized in water-in-oil microemusion at room temperature, and the starch-nanoparticles were coated with poly-L-lysine. The surface of the starch-nanoparticles was combined with fluorescence material Ru(bpy)3^2+-6H2O, and then the particles were characterized via transmission electron microscope. The fluorescence nanoparticles were conjugated with plasmid DNA to form complexes, and then treated with ultrasound and DNase I. pEGAD plasmid DNA-nanoparticle complexes were co-cultured with plant suspension cells ofDioscrea Zigiberensis G H Wright, and treated with ultrasound. The results show that the diameter of the fluorescence starch-nanoparticles is 50-100 nm. DNA-nanoparticle complexes can protect DNA from ultrasound damage as well as from DNase I cleavage. Mediated by ultrasound, pEGAD plasmid DNA-nanoparticle complexes can pierce into the cell wall, cell membrane and nucleus membrane of plant suspension cells. The green fluorescence protein(GFP) gene at a high frequency exceeds 5%. This nano-biomaterial can efficiently solve the problem that exterior genes cannot traverse the plant cell wall easily. 相似文献
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致密多孔介质气体运移机理 总被引:1,自引:0,他引:1
气体在致密多孔介质中的运移受多种因素的影响,如孔隙结构、气体的赋存方式、温度和压力等。地层压力大,气体密度高,应属于稠密气体|另外,在页岩、煤岩、致密砂岩等多孔介质中发育了丰富的纳米级孔隙,使气体的运移机制极为复杂。详细研究了气体在致密多孔介质中的运移机理,并引入稠密气体理论,通过计算分子平均自由程,发现直径大于2nm的孔隙中,压力大于1.135MPa时(76.85℃),气体不会发生Knudsen型扩散,Fick型扩散和表面扩散可能是主要的扩散方式|并得到Knudsen渗透率修正因子随压力增加而减小,随温度的升高而增加,随孔隙半径的减小而增加,在较小孔隙中温度的影响更显著;气体从小孔扩散至大孔和裂缝系统是多种扩散机制的结果,孔隙的大小、气体的赋存方式和压力直接关系到气体的运移机理。对比分析Klinkenberg渗透率和Knudsen渗透率修正因子,发现Knudsen渗透率模型是更精确的渗透率模型,Klinkenberg渗透率修正因子可以看作是Knudsen渗透率修正因子的一级修正。
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基于兄弟铣床系统用户宏程序功能编程,以间递减进给的方式钻削深小孔,每次钻孔的深度随钻孔深度的增加而减小。该方法可以有效地解决钻削深小孔时钻头容易折断的难题,减少了刀具损耗,提高生产效率。 相似文献
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刘选 《机械工程与自动化》2006,(5):160-161
通过对变速器锁销式同步器的工作原理和工作过程以及保证实现同步的充分必要条件的分析,确立了锁销式同步器零件主要参数的计算式,以及各零件之间在设计计算中的关系式,从而确定了锁销式同步器的设计计算原则。 相似文献