共查询到20条相似文献,搜索用时 62 毫秒
1.
2.
3.
4.
5.
6.
7.
8.
9.
O—甲基异脲硫酸盐的合成新工艺研究 总被引:3,自引:0,他引:3
以尿素和硫酸二甲酯为原料二步反应合成O-甲基异脲硫酸盐。(1)尿素和硫酸二甲酯经缩合(甲基化反应)、酸解、水解反应得O-甲基异脲硫酸氢盐,收率43%;(2)O-甲基异脲硫酸氢盐和氢氧化钠在甲醇溶液中反应制得游离O-甲基异脲,游离O-甲基异脲和氢盐中和制得O-甲基异脲硫酸盐,收率78%。 相似文献
10.
11.
12.
13.
提出用高效液相色谱法测定1,3-二氨基胍盐酸盐的含量,选用甲醇与乙酸铵缓冲盐体积比75:25为流动相,c8色谱柱,检测波长314nm。试验结果表明:测试结果的相对标准偏差小于2.03%;回收率在97.8%~100.2%;1,3-二氨基胍盐酸盐和三氨基胍盐酸盐得到较好的分离。该法操作简单、实用且定量分析结果准确稳定。 相似文献
14.
对三氟乙酰赖氨酸的合成工艺进行了研究。三氟乙酸与乙醇在浓硫酸作用下酯化形成三氟乙酸乙酯,然后与L-赖氨酸经酰化反应得到三氟乙酰赖氨酸。酰化反应的优化条件为:pH值为11~13,反应温度-5~5℃,反应时间2h,酰化收率91.8%,HPLC分析含量达95.8%。 相似文献
15.
17.
考察了蜂房哈夫尼菌(H.alveiAS1.1009)的L-赖氨酸脱羧酶对L-赖氨酸的脱羧作用,分析了培养基、温度、pH、激活剂等因素对酶活力的影响。实验结果表明,最适培养基成分为:ρ(蔗糖)=20 g/L、ρ(玉米浆)=20g/L、ρ(酵母膏)=5 g/L、ρ(牛肉膏)=3 g/L、ρ(蛋白胨)=10 g/L、ρ(氯化钠)=5 g/L、ρ(硫酸铵)=2 g/L、ρ(维生素B6)=5 g/L和ρ(L-赖氨酸)=5 g/L,100 mL发酵液中接种量为5 mL液体菌种。最佳转化工艺条件为:转化体系温度35℃、pH=5.0,ρ(菌体)=10 g/L,ρ(吐温-80)=0.15 g/L。L-赖氨酸脱羧酶在最适发酵和转化条件下比酶活可达7 984.43 U,底物转化率可达70%。 相似文献
18.
Xiaosheng Tao Fujian Jiang Kang Cheng Zhenzhen Qi Vamsi K. Yadavalli Shenzhou Lu 《International journal of molecular sciences》2021,22(13)
Silk fibroin (SF) has attracted much attention due to its high, tunable mechanical strength and excellent biocompatibility. Imparting the ability to respond to external stimuli can further enhance its scope of application. In order to imbue stimuli-responsive behavior in silk fibroin, we propose a new conjugated material, namely cationic SF (CSF) obtained by chemical modification of silk fibroin with ε-Poly-(L-lysine) (ε-PLL). This pH-responsive CSF hydrogel was prepared by enzymatic crosslinking using horseradish peroxidase and H2O2. Zeta potential measurements and SDS-PAGE gel electrophoresis show successful synthesis, with an increase in isoelectric point from 4.1 to 8.6. Fourier transform infrared (FTIR) and X-ray diffraction (XRD) results show that the modification does not affect the crystalline structure of SF. Most importantly, the synthesized CSF hydrogel has an excellent pH response. At 10 wt.% ε-PLL, a significant change in swelling with pH is observed. We further demonstrate that the hydrogel can be glucose-responsive by the addition of glucose oxidase (GOx). At high glucose concentration (400 mg/dL), the swelling of CSF/GOx hydrogel is as high as 345 ± 16%, while swelling in 200 mg/dL, 100 mg/dL and 0 mg/dL glucose solutions is 237 ± 12%, 163 ± 12% and 98 ± 15%, respectively. This shows the responsive swelling of CSF/GOx hydrogels to glucose, thus providing sufficient conditions for rapid drug release. Together with the versatility and biological properties of fibroin, such stimuli-responsive silk hydrogels have great potential in intelligent drug delivery, as soft matter substrates for enzymatic reactions and in other biomedical applications. 相似文献
19.
20.
麦加保 《精细与专用化学品》2001,9(18):3-5
我国饲料级赖氨酸的生产还不能满足饲料生产的需要,大部分产品需从国外进口。2000年国内L-赖氨酸需求量约为7万t,而产量不足2万t。大量的低价进口产品导致国内饲用赖氨酸市场几近饱和。作者指出,国内企业应把重点放在开发赖氨酸的其他用途上,例如,挖掘赖氨酸的医用价值。目前已有3种L-赖氨酸及其复配药获得国家药监局批准使用。 相似文献