Two New Xanthone Glycosides from Polygala tenuifolia

Two new xanthone glycosides,polygalaxanthone IV and V were isolated from the roots of Polygala tenuifolia Willd. Their structures were established as 6-O-[α-L-rhamnopyranosyl-(1→2)-β-D-glucopyranosyl]-1-hydroxy-3,7-dimethoxyxanthone(polygalaxanthone IV), and 6-O-[α-L-rhamnopyranosyl-(1→2)-β-D-glucopyranosyl]-1,3-dihydroxyl-7-methoxyxanthone (polyga-laxanthone V),respectively, on the basis of chemical and spectral evidence.     

联萘冠醚的合成新方法

一种用于合成含联萘基冠醚的新方法。以消旋，手性联萘酚为起始原料，先与氯乙醇反应制得2,2'-二（2－羟基乙氧基）－1,1'－联二苯，再与二甘醇或三甘醇对二对甲苯磺酸酯反应，成功制得了4种联萘冠醚。     

An improved method for constructing a full-length enriched cDNA library using small amounts of total RNA as a starting material

We have developed an improved method for constructing a full-length cDNA library using small quantity of material by modifying the original oligo-capping method. In our devised method, total RNAs are used in sequential oligo-capping steps directly without preliminary mRNA purification. Using this method, we constructed full- length cDNA libraries from 100 mg of total RNA. These libraries contained 8x10(5) to 8x10(6) independent clones with average insert sizes of 2.0 kb. Moreover, the number of full-length cDNAs containing the translation initiation codon ATG in the constructed libraries was estimated to 60-70%. In addition, 54% of the known cDNAs had a longer 5' end than the corresponding genes in the public database. Our results show that the method can be effectively used to construct full-length enriched cDNA libraries, especially, if starting material is limited.     

Efficient Debromination of Vicinal α，β—Dibromo Carboxylic Acid Derivatives with the Sm／HOAc System

The α，β vicinal dibrome carboxylic acid and its derivatives were debrominated with Sm/HOAc system to afford the corresponding cinnamic acid and its derivatives in good yields under mild conditions.     

Concise synthesis of acyl migration-blocked 1,1-difluorinated analogues of lysophosphatidic acid

Lysophosphatidic acid (LPA, 1- or 2-acyl-sn-glycerol 3-phosphate) is an important phospholipid mediator produced by activated platelets and by ovarian cancer cells. Efforts to understand LPA signaling through G-protein-coupled receptors are hampered by the facile acyl migration that results in equilibration to a mixture of the 1- or 2-acyl species under physiological conditions. We describe a new and efficient route to enantiomerically homogeneous lysophospholipid analogues from D-mannitol 1,2:5,6-bis-acetonide to give two 1,1-difluorodeoxy analogues of (2R)-acyl-sn-glycerol 3-phosphate. These compounds are migration-blocked analogues of the labile sn-2 LPA species. The (19)F NMR of diastereotopic fluorines of the difluoromethyl group shows an unexpected solvent dependence.     

The Surface Imprinted Polystyrene Beads Prepared via Emulsion Templates

In this paper, the surface imprinted cross-linked polystyrene beads were prepared via suspension polymerization with styrene (St), divinylbezene (DVB), polyvinyl alcohol (PVA1788),the mixture of Span 85 and xylene or the mixture of Span 85 and paraffin as monomer,cross-linking agent, dispersion stabilizer and templates, respectively. The results indicate that there are dense cavities on the surface of beads, and the diameter and density of cavity are related with the composition and amount of emulsion template. The forming mechanism of cavity from thermodynamics and dynamics was proposed.     

Effect of nucleating agent on the structure and properties of polypropylene/poly(ethylene-octene) blends

The effect of the sorbital nucleating agent on properties of the ethylene-octene copolymer (POE) toughened polypropylene (PP) was studied. The results show that the addition of POE increases notched Izod and Charpy impact strength significantly but impair the tensile strength and flexural modulus. As a nucleating agent (1,3,2,4-di(p-methylbenzylidene) sorbitol, DM) was added, the toughness and stiffness of toughed PP increased simultaneously at the same content of POE. This result shows that the toughness and stiffness of toughed PP are in balance. Polarized light microscopy analysis shows that with the addition of POE and nucleating agent, only a low level of PP spherulites were observed.     

加速剂对化学镀镍层组成与结构的影响

加速剂对化学镀镍层组成与结构的影响方景礼，武勇，韩克平，张敏（南京大学应用化学研究所配位化学国家重点实验室南京２１００９３）关键词化学镀镍，Ｎｉ０Ｐ合金，加速剂，硫脲化学镀镍磷合金具有耐蚀性、可焊性、厚度均匀和硬度高等优点，已得到广泛应用。为提高生产...     

三乙胺与2-氯-5-甲氧基对苯醌光电子转移反应的CIDNP研究

用化学诱导动态核极化（CIDNP）方法研究了三乙胺与2-氯-5-甲氧基对苯醌在 C6D6，CH3CN溶剂中的反应机理，实验结果表明反应过程中首先形成基态电荷转移 络合物（CTC），在CD3CN中，光照电荷分离形成离子自由基对，使三乙胺亚甲基产 生发射极化信号。同时用UV-vis实验证实CTC的存在。     

高效液相色谱法测定橡胶促进剂TBBS

采用反相高效液相色谱法（HPLC）测定了橡胶促进剂N－叔丁基－2－苯并噻唑次磺酰胺（TBBS）的纯度，标准偏差小于0．3。