Synthesis and characterization of a poly(N‐isopropylacrylamide) with β‐cyclodextrin as pendant groups

A novel linear poly(N‐isopropylacrylamide) (PNIPA) with β‐cylodextrin (β‐CD) moiety (PNIPA‐β‐CD) was synthesized by the conjugation of β‐CD carrying amino groups (EDA‐β‐CD) onto PNIPA with epoxy groups (P(NIPA‐co‐GMA), M_n = 3.86 × 10⁴), and the related reaction conditions are investigated. PNIPA‐β‐CD was characterized by means of IR, NMR and UV spectroscopes, element analysis, and differential scanning calorimetry (DSC). The number‐average molecular weight (M_n) and the β‐CD content of the obtained PNIPA‐β‐CD are 4.87 × 10⁴ and 18.8 wt %, respectively. PNIPA‐β‐CD can not only respond to temperature stimuli but also include guest molecules. Lower critical solution temperature (LCST) of aqueous PNIPA‐β‐CD solution is similar to that of PNIPA. The association constant (K_a) for PNIPA‐β‐CD with methyl orange (MO) is 2.4 × 10³ L mol^?1 at pH 1.4, which is comparable to that of EDA‐β‐CD (K_a = 2.9 × 10³ L mol^?1). © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3516–3524, 2005     

基于有序介孔碳/纳米金/L-半胱氨酸修饰电极测定铜(Ⅱ)

将纳米金(NG)电沉积在有序介孔碳(OMC)修饰玻碳电极表面,并将L-半胱氨酸(L-Cys)自组装至OM C/NG修饰电极表面,制备了OM C/NG/L-Cys修饰电极。采用透射电子显微镜考察了OM C的结构,扫描电子显微镜研究了OMC/NG/L-Cys修饰电极的表面形貌。考察了Cu2+在该修饰电极上的电化学行为,优化了Cu2+的测定条件。在最优条件下,溶出峰峰电流与Cu2+浓度在0.05~6.0μmol/L范围内呈良好线性关系,检出限为0.03μmol/L(S/N=3)。方法用于河水样品分析,其加标回收率在92.7%~101.6%之间。     

雷公藤碱丁和碱辛的结构

从雷公藤中分离了二个生物碱: 碱丁(Wilfortrine)和碱辛(Neowilforine),用化学和光谱法测定了它们的结构, 碱辛是一种新生物碱.     

一个消费者测度空间的均衡存在定理

研究消费者测度空间经济均衡的存在性问题，给出了一个均衡存在定理。     

Neutron-induced defects in the lithium tetraborate single crystals

The X-band ( x ; 9.4 v GHz) electron spin resonance (ESR) spectra of the un-doped isotopically enriched lithium tetraborate (LTB) Li 2 B 4 O 7 single crystals, irradiated by thermal neutrons (fluences | n =2.74 ‐ 10 15 1 1.79 v ‐ 10 18 v cm m 2 ) were investigated at 300 and 77 v K. The LTB crystals of high chemical purity and optical quality with different isotope compositions ( 6 Li 2 10 B 4 O 7 , 6 Li 2 11 B 4 O 7 , 7 Li 2 10 B 4 O 7 and 7 Li 2 11 B 4 O 7 ) were grown by Czochralski technique. The thermal neutrons (the total quantity >90%) with fluence near 10 18 v cm m 2 induce at least 4 different types of stable paramagnetic centers in the Li and B isotopically enriched LTB crystals. The ESR spectra, electron structure and efficiency of generation for centers, induced by thermal neutrons, essentially depend on neutron fluence and isotope composition of the LTB crystals. The local symmetry and the spin Hamiltonian parameters of the observed paramagnetic centers were determined and their electron structure were established. The possible models and formation mechanism of the radiation defects, induced by thermal neutrons in the LTB lattice, are proposed.     

Fluctuation theory of hydrogen bonding applied to vibration spectra of HOD molecules in liquid water. I. Raman spectra

Statistical distributions of the frequencies of OH vibrations calculated from the experimental Raman spectra of HOD molecules over the temperature range of 10–200 C using the recently developed deconvolution technique have been analysed in the framework of fluctuation theory of hydrogen bonding. Two temperature independent functions that are the basis of the Zhukovsky theory for describing the temperature transformation of frequency distribution functions of OH vibrations in a statistical ensemble of O—H…O bonds were established and analytically approximated. This made it possible to reconstruct the entire set of initial spectra and to extrapolate their forms to a wider temperature range. These results support the continuum model of liquid water structure.     

高校图书馆员素质提高的设想

基于对高校图书馆发展趋势的概述,以及这种趋势对图书馆员的要求,本文着重探讨了提高馆员综合素质的各项措施,即:通过加强政治思想教育、树立良好的职业道德,加强图书情报专业知识、计算机知识、图书馆自动化知识、网络知识、外语知识、相关学科和新学科知识的培训,建立一支具有合理的学历结构、学科背景的合格的学科馆员队伍,以适应高校图书馆发展的目标要求。     

含立方项非线性振子系统运动研究

对含立方项振子运动微分方程进行数值积分,在不同的参数情况下,给出了振子运动的相图,直观地显示了系统的运动情况.     

桂西北红椎次生林生长及土壤的理化性质

对桂西北12～15年生红椎次生林分的生长量、林地枯枝落叶现存量及其养分含量以及土壤理化性质等进行测定，并与相似立地条件的杉木人工林(15年生，中坡)进行比较分析。结果表明：(1)不同立地红椎次生林分的平均胸径、平均树高及平均蓄积量显示出中坡和下坡林分最大，是上坡林分的1．6～4．0倍；(2)不同立地红椎次生林分枯枝落叶现存量及其最大持水量和主要养分(N、P、K)含量测定结果中，中坡林分比相应杉木人工林高；(3)不同立地红椎次生林分土壤理化条件也比相直杉木人工林略好；(4)不同立地红椎次生林分土壤(0～40cm)有机质含量为1．127％～2．228％。全氮、有效磷和速效钾总量依次为2．39～4．16g／kg，0．90～1．40mg／kg和29．04～41．44mg／kg，说明该地区红椎坎生林分具有较显著的生态经济效益。     

聚合物驱垂直井筒流动和视粘度模型

与常规油井相比，聚合物驱抽油机井因其产出液粘度明显增大导致抽油杆受力状况变差，杆管偏磨现象严重。通过实验对聚合物产出液的流变特性进行了研究。考虑油井举升过程，利用幂律模式绘制了幂律指数与稠度系数随聚合物浓度、温度变化的关系图版。以非牛顿流体流变学理论和人工举升理论为基础，按照不同的流动规律，给出了从地层到井口聚合物驱垂直井筒流动的运动方程及其边界条件，并对方程进行求解得到了视粘度模型。应用结果表明，该模型能够提高设计结果的误差精度，为聚合物驱抽油机井的优化设计提供理论指导。