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- It is mainly synthesized by two chemical ways: ring-opening polymerization and direct polycondensation. 合成聚苹果酸的化学方法主要有开环聚合法与直接聚合法。
- PPTA (polyphenylene terephthalamide) pulp was prepared by semi-continuous direct polycondensation using a co-current rotating and meshing twin screw extruder as main reactor. 摘要以同向啮合旋转的双螺杆挤出机作为主反应器，采用半连续化直接缩聚法制备了PPTA浆粕。
- PPTA(polyphenylene terephthalamide) pulp was prepared by semi-continuous direct polycondensation using a co-current rotating and meshing twin screw extruder as main reactor. 以同向啮合旋转的双螺杆挤出机作为主反应器,采用半连续化直接缩聚法制备了PPTA浆粕。
- The preparation methods, reaction mechanism and properties of poly( malic acid) synthesized by direct polycondensation are reviewed, and the prospects in this field are also introduced. 作者综述了直接聚合法合成聚苹果酸的方法、应机理及性质，并展望了直接聚合法合成聚苹果酸的前景。
- The preparation methods, reaction mechanism and properties of poly(malic acid) synthesized by direct polycondensation are reviewed, and the prospects in this field are also introduced. 作者综述了直接聚合法合成聚苹果酸的方法、反应机理及性质，并展望了直接聚合法合成聚苹果酸的前景。
- This review focused on the reasearch progress of polylactide synthesised either by direct polycondensation of lactic acid or ring-opening polymerization of lactide at home and aborad in recent years. 综述了近年来国内外聚乳酸直接合成法和丙交酯开环聚合法的研究进展,对聚乳酸改性方法进行了深入的总结和评述,并揭示了聚乳酸材料的研究开发前景。
- She cast her eyes down to avoid direct eye contact. 她垂下双目以避免对视。
- I'll book you on a direct flight to London. 我将为你预订直飞伦敦的航班。
- Keywords direct polycondensation;polyester;3-hydroxypropionic acid;hafnium （IV） tetrachloride; 直接缩聚;聚酯;3-羟基丙酸;四氯化铪;
- He has chosen the most direct route. 他选取了最直的路线。
- Keywords biodegradable material;poly（lactic acid-glycolic acid;PLGA）;copolymer;synthesis;ring-opening polymerization;direct polycondensation; 生物降解材料;聚（乳酸-乙醇酸）（PLGA）;共聚物;合成;开环聚合;直接缩聚;
- Keywords lactic acid;direct polycondensation;polylactic acids biodegradable material;solution polycondensation;melt polycondensation; 乳酸;直接缩合;聚乳酸类生物降解材料;溶液聚合;熔融聚合;
- She's very direct, believes in speaking her mind. 她为人直率，喜欢有什么说什么。
- Can you direct me to the shoe department? 请告诉我卖鞋部在哪里。
- Be there a direct train for Beijing to Nanning? 从北京到南宁有直达车吗？
- See that direct heat does not play on it. 当心别让它直接受热。
- It's a long way by road the train is more direct. 走公路很远--乘火车近。
- Would you please direct me to the zoo? 请问去动物园怎么走?
- My eyes were blinded by the direct rays of light. 在光线的直射下，我看不清楚东西。
- Her opinions are the direct opposite of mine. 她的意见与我的截然相反。
