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由点电荷在空间激发电场的电位公式,用两种不同的方法求出了均匀带电圆盘电位的空间分布。 相似文献
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I. H. Haines 《国际虫害防治杂志》2013,59(4):362-371
Abstract Informal training in plant protection and public health, particularly that aimed at non‐graduates, is often poorly planned and sometimes irrelevant due to the inaccurate identification or total disregard of real training needs. Such training usually leads to poor job performance and, where pesticides or machinery are involved, to dangerous working practice. A method is described for identifying training needs through job and trainee analysis, and it is shown how to develop training programmes based on these needs. The importance of behavioural objectives in training is explained. Emphasis is given to the planning of training in plant protection and public health with special reference to pesticide management, but, because a systematic approach is adopted, the methods used are appropriate to training situations in other disciplines. Guidelines on the selection of visual aids and on methods of presentation are also given. 相似文献
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荷电黏性液体射流线性不稳定性分析 总被引:1,自引:0,他引:1
根据线性不稳定性理论分析了扰动压强场和扰动电场,对荷电液体射流受力特性进行分析,建立了荷电黏性液体射流色散方程,通过数值计算分析了射流速度、荷电电压及黏度对荷电液体射流不稳定性的影响.研究结果表明:增加射流速度或荷电电压均能使射流不稳定性增加,表面波最大增长率及其对应的最优波数、最大波数均增大,射流破碎形成的液滴特征尺寸减小.黏度的提高使射流趋于稳定不易破碎,表面波最大增长率及其对应的最优波数减小,射流破碎形成的液滴特征尺寸增大,而最大波数保持不变.射流速度在0—1m/s范围内,非荷电与荷电情况下0阶表面波始终存在;非荷电时,只有当射流速度达到一定数值时1阶表面波才出现,荷电后,1阶表面波在更小的射流速度时即可出现;0阶表面波最大增长率大于1阶表面波最大增长率,在液体射流破碎过程中占据主导地位. 相似文献
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荷电液滴蒸发破碎过程的数学模型 总被引:2,自引:0,他引:2
针对荷电液滴蒸发破碎过程伴随的电荷衰减、质量和热量的传递问题进行了理论分析,得出荷电液滴电荷衰减规律,建立荷电液滴蒸发破碎过程的数学模型.建立重力作用下作平抛运动液滴的轨道模型,得出了水平方向与竖直方向上的最大输运距离.研究表明,液滴所带电荷是随时间作指数规律衰减,液滴电导率越高,介电常数越小,电荷衰减越快;液滴完全蒸发所需时间基本上与液滴初始半径的平方成正比.荷电液滴在蒸发过程中,临界电量随液滴温度的增加而减小,当液滴带电量q大于等于临界电量qc时,蒸发过程中发生库仑分裂,并实现了对库仑分裂时刻的预测. 相似文献
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Emmy Van Balen 《European journal of plant pathology / European Foundation for Plant Pathology》1982,88(1):33-37
The application of electrical charges on carbon-coated formvar films had a marked effect on the trapping of virus particles by immunosorbent electron microscopical techniques. On grids, positively charged with ethidium bromide, numbers of virus particles were high, and almost equal to those trapped with the aid of protein A in combination with a negative charge.Samenvatting Het aanbrengen van elektrische lading op koolstof-formvar vliezen beïnloedde de adsorptie van virusdeeltjes aan het vlies, bedekt met homoloog antiserum (-globulinen). Op vliezen met een positieve lading werd een veel groter aantal virusdeeltjes waargenomen dan op de neutrale of negatief geladen vliezen. Positief geladen vliezen werden verkregen door behandeling met ethidium-bromide. Negatief geladen vliezen werden verkregen door behandeling met geïoniseerd argongas. Op de negatief geladen vliezen bleken grote hoeveelheden verontreinigingen van allerlei aard te precipiteren. Bovendien was het beeld van de virusdeeltjes vaag. Negatief geladen vliezen gaven wel goede resultaten ten aanzien van het vangen van virusdeeltjes in combinatie met proteine A en -globulinen. 相似文献
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本文研究琼枝多糖凝胶的结构和性质。大多数碱金属盐、碱土金属盐和含二个氨基以上的化合物能够改良这种带负电荷的多糖凝胶的性能。从扫描电子显微镜研究各种凝胶的结果看出,琼枝多糖象绞合的纤维束同方向地聚集;琼枝多糖-KCl凝胶象疏松绞合着的纤维束同方向聚集;琼枝多糖-乙二胺凝胶象多锁链同方向聚集;琼枝多糖-明胶凝胶却象海绵一样网状聚集。根据试验结果,作者对琼枝多糖形成凝胶的机理进行了推断。 相似文献