Sums of Fourier coefficients associated with Hecke cusp forms

Lithuanian Mathematical Journal - Let Hk denote the space of holomorphic Hecke cusp forms of even integral weight k for the full modular group Γ = SL(2, ℤ). Let λf (n), λg(n),...     

磺化聚苯硫醚铑配合物催化剂初探

苯硫醚具有与三苯基磷相似的配位化学性能,膦类配体具有比苯硫醚强的络合能力,但毒性较大,热稳定性和抗氧稳定性不如苯硫醚类配体。能否以含有机硫的配体替代膦类配体,这是开发新型催化剂的一个值得探索的方向。聚苯硫醚经发烟硫酸磺化后,可制得水溶性的磺化聚苯硫醚。经XPS测定,磺化度为     

钆铁磁－顺磁相变的正电子寿命研究

通过测量金属钆在居里点附近的正电子湮没寿命谱随温度变化的关系，发现钆的正电子湮没寿命在居里点近邻Ｔ＜ＴＣ一侧随温度有显著变化，而在此温区以外几乎不随温度变化     

SYNTHESIS OF SEGMENTED COPOLYMERS WITH POLYSULFONES CONTAINING BISPHENOL A OR PHENOLPHTHALEIN UNITS AS HARD SEGMENT

Two series of segmented copolymers with polysulfones, containing bisphenol A and phenol-phthalein units as hard segments respectively, were synthesized. Isocyanate-terminated polyoxy-propylene was used as soft segments for both series.     

Development of a miniature simultaneous MPT spectrometer

An unique miniature simultaneous microwave plasma torch (MPT) atomic emission spectrometer employing linear UV intensified charge-coupled device (ICCD) array detector has been developed and studied preliminarily. The detection limits and precisions of the spectrometer for Ag, Al, Ba, Ca, Cr, Cu, Fe, Mg, Mn, Sr and V by using different CCD exposure times have been determined. An analysis of a practical sample has been carried out. The preliminary results demonstrate that such simultaneous spectrometer has advantages of saving sample and time, especially suitable for use as detector for chromatography and in combination with flow injection systems. Taking analytical figures of merit and portability into accounts, the miniature simultaneous MPT system will have extended application areas and greater competition potential as compared with commercialized scanning MPT spectrometers.     

端基含葡氨糖衍生物的聚乳酸的合成与表征

端基含葡氨糖衍生物的聚乳酸的合成与表征张国栋冯新德（北京大学高分子科学与工程系北京１００８７１）顾忠伟（国家计生委科研所药化室北京１０００８１）关键词壳多糖，聚乳酸，生物医用材料，化学修饰自从发现高分子量聚乳酸在人体内能够降解，并把这类材料引入...     

Instrumental NAA of carbonate rocks and its application for the analysis of secondary sedimentary environments in shallow sea

Aiming at distinguishing between the sedimentary environments in shallow sea using elemental geochemical markers, the determinations of trace elements in carbonate rocks by thermal neutron, epithermal neutron and short-irradiation activation analysis have been studied, and more than 30 major and trace elements determined. Al, Cl, Sc, Ti, V, Cr, Fe, Co, As, Br, Rb, Sb, Cs, Lu, Hf, Ta, Th and U were found to be the effective distinguishing markers for the secondary environments in shallow sea.     

XPS STUDIES ON SURFACE MODIFIED POLY [1-(TRIMETHYLSILYL)-1-PROPYNE] MEMBRANES Ⅱ SURFACE MODIFICATION BY BROMINE VAPOR*

Surface modification of poly [1-(trimethylsilyl)-1-propyne] (PTMSP) membranes bybromine vapor has been studied. It is shown that Br/C atomic ratio at the surfaces increased withthe time of bromination until about 60 min, then it reached a plateau. The results of XPS and IRstudies indicated that the addition of bromine to double bonds and the replacement of H on CH_3 bybromine had taken place so that a new peak at 286.0 eV (C--Br)in C_(1s) spectra and some newbands, e. g. at 1220 and 580cm~(-1) in IR spectra were formed. The fact,t Po_2, permeability ofoxygen, decreased and α_(O_2/N_2), separation factor of oxygen relative to nitrogen, increased withbromination time, shows that surface modification of PTMSP by bromine may be an efficient approach to prepare PTMSP membranes used for practical gas separations.     

新型含有机硅二元多嵌段共聚物的研究

报道了聚羟基醚（ＰＨＥ）、聚羟基醚砜（ＰＨＥＳ）、酚酞聚羟基醚（ＰＰＨＥ）和聚对羟基苯乙烯（ＰＨＳ）与端胺基聚二甲基硅氧烷（ＰＤＭＳ）通过羟胺缩合生成ＡＢｍｎ新型结构的可溶性含有机硅二元多嵌段共聚物，ｍ值在１～６之间，详细讨论了反应物浓度对共缩聚反应的影响，并通过分子量测定、红外光谱分析和动态力学分析（ＤＭＡ）技术初步确定了其反应机理、结构和动态力学性能．     

三甲基硅烷基丙炔与五甲基二硅烷基丙炔共聚物膜及其气体透过性

研究了三甲基硅烷基丙块与五甲基二硅烷基丙块共聚物〔poly(TMSP-co-PMDSP)〕的成膜特点。poly(TMSP-co-PMDSP)膜的气体透过系数分别为:P_(O2):4×10~3～12×10~3,P_(N2):3×10~3～8×10~3和P_(CO2):2×10~4～4×10~4barrer,气体透过稳定性低,透过行为偏离第二Fick定律,过系数下降,其中溶解系数降低的比例远大于扩散系数的增加比例,在含有凝聚性气体的环境里,膜的气体透过出现表面吸附控制的特征。