期刊文献+
共找到2篇文章
< 1 >
每页显示 20 50 100
PCBN复合片单向喷液电火花线切割研究 被引量:1
1
作者 马秀丽 滕凯 《机械设计与制造》 北大核心 2019年第6期65-67,共3页
对聚晶立方氮化硼(PCBN)复合片进行了电火花线切割加工试验研究。试验结果表明:在大峰值电流、小脉冲间隔、常压供液加工条件下,电火花线切割的正向运丝切割效率明显低于反向运丝。为提高正向运丝切割效率,供液系统加装了高压喷液供液装... 对聚晶立方氮化硼(PCBN)复合片进行了电火花线切割加工试验研究。试验结果表明:在大峰值电流、小脉冲间隔、常压供液加工条件下,电火花线切割的正向运丝切割效率明显低于反向运丝。为提高正向运丝切割效率,供液系统加装了高压喷液供液装置,有效增加聚晶层极间的工作液进入量和流速,提高电蚀粒子和气泡等电蚀产物的排出,改善了极间放电条件,较常压浇注方式切割效率明显提高,富钴层台阶减小,表面质量得到进一步提高。 展开更多
关键词 聚晶立方氮化硼 电火花线切割 运丝方向 冲液条件 高压喷 高效切割
下载PDF
Induction of Recombinant Uridine Phosphorylase and Its Application in Biosynthesis of Pyrimidine Nucleosides 被引量:1
2
作者 丁庆豹 欧伶 +3 位作者 魏东芝 魏晓琨 许彦梅 张春艳 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2011年第1期122-127,共6页
Recombinant Escherichia coli pUDP,which overexpressed uridine phosphorylase(UPase),was constructed.0.5 mmol·L 1lactose had a similar induction effect as the commonly used inducer IPTG during 2.5-5.5 h of cell g... Recombinant Escherichia coli pUDP,which overexpressed uridine phosphorylase(UPase),was constructed.0.5 mmol·L 1lactose had a similar induction effect as the commonly used inducer IPTG during 2.5-5.5 h of cell growth.The lactose-induced UPase was stable at 50°C.Wet cells of pUDP was used as catalyst to biosynthesize 5-fluorouridine from 30 mmol·L 1uridine and 5-fluorouracil in phosphate buffer(pH 7.0)catalyzed at 50°C for 1.5 h and the yield of 5-fluorouridine was higher than 68%.Under the optimum reaction conditions for production of 5-fluorouridine,5-methyluridine and azauridine were synthesized from uridine by pUDP,the yield was 61.7%and 47.2%respectively.Deoxynucleosides were also synthesized by pUDP,but the yield was only about 20%. 展开更多
关键词 5-fluorouridine LACTOSE uridine phosphorylase pyrimidine nucleoside URIDINE 5-FLUOROURACIL
下载PDF
上一页 1 下一页 到第
使用帮助 返回顶部