乙烯系单体自由基聚合的阻聚效应──XIX．取代哌啶羟胺和二叔丁基羟胺及其稳定自由基对苯乙烯－丙烯腈共聚合的影响

研究了二叔丁基羟胺（ＤＴＢＨＡ），二叔丁基氮氧自由基（ＤＴＢＮＯ·），２，２，６，６－四甲基－４－羟基哌啶羟胺（ＴＭＨＰＨＡ）和２，２，６，６－四甲基－４－羟基哌啶－１－氧自由基（ＴＭＨＰＯ·）对过氧化苯甲酰（ＢＰＯ）６０℃引发的苯乙烯（Ｍ１）－丙烯腈（Ｍ２）共聚合的阻聚行为．结果表明，这些阻聚剂对Ｓｔ－ＡＮ共聚均表现良好的阻聚行为，其中氮氧自由基优于相应羟胺．同时观察到Ｓｔ—ＡＮ竞聚率的改变，羟胺使ｒ１有所降低，ｒ２略有增大．但相应的氮氧自由基是相反结果．阻聚剂为２００ｐｐｍ时，共聚物中的恒比共聚点由对照实验的０．６１９变化为０．５３３，０．６４５，０．５８９和０．６９８相对于ＤＴＢＨＡ，ＤＴＢＮＯ·，ＴＭＨＰＨＡ和ＴＭＨＰＯ·．     

Bonding of the chain structure for novel boranes B3k+pH−5k+p+3

The molecular orbitals obtained from conventional quantum chemistry calculations, are expressed in terms of symmetrized valence bond functions of fragment, and a direct picture of chemical bonding can be drawn easily. This method is utilized, together with extended Huckel calculations, to interpret the bonding properties of a centipede-like chain structure for novel laser-producing boranes B_3k+pH^?_5k+p+3 which is constructed from the repeated unit B₃H₅ halted to each other by three B—H—B bonds.     

Exact quantum mechanical vibration-rotation kinetic energy operator of four-particle system in various coordinates

The vibration-rotational kinetic energy operators of four-particle system in various coordinates are derived using a new and simple angular momentum method. The operators are respectively suitable for studying the systems described by scattering coordinate, valence coordinate, Radau coordinate, Radau/Jacobi and Jacobi/valence hybrid coordinates and so on. Certain properties of these operators and their possible applications are discussed.     

激光光散射研究丙烯酰胺-二甲基二烯丙基氯化铵共聚物的溶液行为

用激光光散射技术表征了阳离子含量受控的丙烯酰胺 二甲基二烯丙基氯化铵共聚物 (简称P(AM DMDAAC) )在 0 1mol LNaCl溶液中的基本参数和溶液行为 .表观基本参数 : Mw ,app =5 0 4× 10 5g·mol- 1 、app =39 9nm和A2 ,APP =1 5× 10 - 4cm3·mol·g- 2 .动态光散射研究结果表明 ,扩散系数Dt 与角度、浓度皆呈非线性依赖关系 ,当C >C 或在较大的散射角域 ,Dt 偏离线性关系所预示的理论值而向减小的方向发展 ,表明存在缔合物 ;流体力学半径Rh 分布有大、小两个范围 ,并随温度升高向小尺寸方向发展 ,证明了体系中存在缔合行为以及升温的解缔合作用 .在一定条件下 ,“亚稳定性”的存在有力地旁证了体系的缔合行为     

CRYSTAL STRUCTURE AND MORPHOLOGY OF NASCENT SAMPLES OF SYMMETRIC AROMATIC POLYESTERS I.POLY(P-PHENYLENE TEREPHTHALATE)

The morphology and crystal structure of poly(p-phenylene terephthalate) (PPT), prepared by confined thin film melt (CTFMP) and solution (CTFSP) and bulk solution polymerization, were characterized by transmission electron microscopy, electron diffraction and molecular modeling. The unit cell is monoclinic (P21/a space group) with parameters a =7.89, b = 5.49, c =12.65 A α= γ= 90°,β= 100.33°, density = 1.48 g/cm3, the a, b andβ values differing slightly from those reported previously in the literature. A degree of variation in relative intensities of hk0 reflections in, apparently, untilted [001] ED patterns was observed from a given sample, suggesting some variation in molecular packing. ED evidence was found for a second phase, with [001] appearing the same as for phase Ⅱ of the related poly(p-oxybenzoate) (PpOBA)polymer. CTFMP crystals polymerized above 220°C (up to 370°C) and CTFSP crystals polymerized at 300°C consisted of lamellae 100-200 A thick.     

原位氧化还原沉淀水热合成法制备LixMn2O4尖晶石

Li xMn2O4尖晶石是新一代的锂离子二次电池正极材料 [1], 其合成方法对材料的电化学性质影响很大[2].常规合成大多采用高温固相反应法, 此法具有反应温度高, 反应时间长, 容易产生缺陷和产物不纯净等缺点, 导致所合成的锂离子二次电池正极材料的性能较差. 目前用水热合成法制备电池正极材料Li xMn2O4尖晶石尚未见文献报道. 本文在常规水热合成法的基础上采用原位氧化还原沉淀水热合成法 [3]制备前驱物, 该法合成条件更温和, 而且使材料的综合性能得到了改善和提高.      

Microwave-assisted Preparation of Temperature Sensitive Poly（N-isopropylacrylamide） Hydrogel with Improved Responsive Properties

Poly(N-isopropylacrylamide) (PNIPAM) hydrogel, which is insoluble but shrinkable or swellable in aqueous media when temperature rises or drops across 33oC1,2, has been extensively studied due to its potential applications in the fields of controlled drug …     

肿瘤患者化疗后骨髓抑制的护理探讨

通过对113例化疗后骨髓抑制患者采用保护性隔离，皮肤、口腔、上呼吸道、泌尿道护理及饮食、心理等综合性护理措施的观察，发现113例化疗后骨髓抑制患者，经过综合护理措施仅13例出现感染、发热，2例经抗生素治疗无效，死于感染性休克，其余患者的血象均恢复正常，康复出院。所以本护理措施，对促进化疗后骨髓抑制患者的康复有一定的应用价值。     

白卡奴鸽动脉粥样硬化模型微量元素谱的计算机多元分析

用ＩＣＰ－ＡＥＳ测定了白卡奴鸽动脉粥样硬化模型和对照组的器官和组织中１９种元素含量，通过因子分析，取得一系列因子得分图，结果表明，动脉粥样硬化和对照组样品点分布在不同区域，且可分辨。     

双柱气相色谱法测定有机物的正辛醇/水分配系数

通过对烷烃，醇类等有机物在五种不同极性固定相上的气相色谱保留值的测定，提出了从有机物气相色谱保留值测定其正辛醇/分配系数的公式，研究了从不同极性固定相上测得的保留值来测定其分配系数的准确性，得出烷烃类在所有柱上测得的保留值与其分配系数间均具有很好的关联，烷烃醇类在极性相异柱上的保留值之比值与其分配系数间也有很好的相关性，从而为烷烃及醇类等有机物分配系数的测定提供了一种简单、可靠，易行的新方法。