排序方式: 共有4条查询结果,搜索用时 15 毫秒
1
1.
§1.引言 整系数多项式的因式分解问题,历来都引起数学家们的注意。在这方面做过一些研究,他不仅详细地论述了整系数多项式的可约性,而且还专门探讨了系数具有相同符号或交错符号的整系数多项式的因式分解问题,他给出的因式分解法与常见的因式分解法相比有其独到之处,他在[1]中所 相似文献
2.
作者用分光光度计测定25℃下甲苯在十五种盐水溶液中的盐析常数k。所用的盐为:LiCl,NaCl,KCl,CsCl,NH4Cl,NaF,NaBr,NaClO3,NH4Br,(CH3)4NBr,(C2H5)4NBr,MgCl2,CaCl2,SrCl2,BaCl20在十五种盐中,只有两个溴化季铵盐对甲苯起盐溶作用,其余均起盐析作用。对于1-1价盐,k值的次序是NaF>NaCl>KCI>NaBr>NaClO3>LiCl>NH4Cl>CsCl>NH4Br>(CH3)4NBr>(C2H5)4NBr。这次序和一般非极性非电解质的盐析效应次序相同。定性地符合vanderWaals力理论,Dcbye-McAulay的静电理论以及McDevit和Long的内压力理论。对于2-1价盐,k值的次序是BaCl2>SrCl2>CaCl2>MgCl20即盐析效应随离子晶体半径的增加而上升。这次序和色散力理论的次序恰相反。但是,如果假设二价离子对水的静电作用能伸展到原水化层以外的水分子,并考虑水化离子和水的静电作用,以及它和甲苯的色散作用,以上四种盐的反常次序就得到解释。 相似文献
3.
Two compounds C_8H_(18)N_2Br_3Mn_(0.5)(1) and C_(12)H_(26)N_2Cl_4Mn(2) based on triethylenediamine derivatives were synthesized by solution method and were characterized by elemental analysis, infrared spectroscopy, single-crystal X-ray structure analysis, fluorescence test, circular dichroism(CD) analysis and dielectric measurement, respectively. According to single-crystal X-ray determination, compound 1 crystallizes in the cubic system, space group Pa3 with a = b = c = 13.7246(5) ?, Z = 24, V = 2585.2(3) ?~3; and compound 2 crystallizes in the orthorhombic system, space group P212121 with a = 7.9716(13), b = 15.309(3), c = 15.804(3) ?, Z = 4 and V = 1928.7(6) ?3. Fluorescent analysis of compound 1 showed an intense emission band at 670 nm when the exciting radiation was set at 378 nm and fluorescent analysis of compound 2 showed an intense emission band at 515 nm when the exciting radiation was set at 363 nm. Dielectric constants of compounds 1 and 2 were measured at different frequencies with temperature variation. 相似文献
4.
1