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1.
在1BXB结构基础上, 通过分子对接方法构建木糖异构酶与抑制剂木糖醇的复合物模型, 为合理设计解除木糖醇对木糖异构酶的抑制及进一步揭示木糖醇对该酶抑制机理提供参考.  相似文献   

2.
毛细管区带电泳法分离发酵液中的木糖和木糖醇   总被引:1,自引:0,他引:1  
陈冠华  张利平  田益玲  王秀敏 《色谱》2001,19(6):549-551
 建立了利用毛细管区带电泳分离发酵液中木糖和木糖醇的新方法。研究表明 :采用硼砂缓冲溶液时 ,木糖和木糖醇的分离度随硼砂浓度的增高而加大 ,在室温下硼砂最高浓度为 130mmol/L ;分离度还与溶液的 pH有关 ,在pH 9 5 5处分离度有最大值 ;缓冲液中十六烷基三甲基溴化铵的浓度为 4× 10 -6mmol/L~ 8× 10 -4 mmol/L时对分离度无显著影响 ;在优化的分离条件下 ,木糖和木糖醇可在 6min内基线分离。测定了发酵过程中样品各组分的含量和加标回收率 ,5次测定木糖的相对标准偏差 (RSD)为 1 42 %~ 3 11% ,回收率为 96 0 %~ 10 8 0 % 。  相似文献   

3.
HPLC法测定半纤维素水解液中糖的研究   总被引:3,自引:1,他引:2  
研究了用HPLC分离测定毛竹水解液中的木糖、阿拉伯糖及葡萄糖等。探讨了试样的净化方法和分离条件,试样经活性炭和SepPakG8小柱净化,色谱柱为YWG-NH2,10μm,4.6×250,流动相为乙腈+水=85+15,流量为0.8mL/min,获最佳分离。木糖、阿拉伯糖、葡萄糖的平均回收率(%)分别为99.1、101和95.0,相对标准偏差为1.25%、1.39%和1.53%。  相似文献   

4.
电膜法生产木糖醇工艺   总被引:3,自引:0,他引:3  
黄玉秀 《应用化学》1997,14(3):105-106
电膜法生产木糖醇工艺黄玉秀(华南理工大学应用化学系广州510641)关键词木糖,木糖醇,制备,电还原法1996-09-10收稿,1997-01-23修回目前生产木糖醇都用高压加氢法[1,2].此法工艺流程长,对设备要求高,生产不安全.应用电膜法生产木...  相似文献   

5.
木糖和木糖醇的色谱模型   总被引:1,自引:1,他引:0  
利用集总模型,以柱床的物料衡算方程式、吸附等温线模型、传质推动力及初始和边界条件组成木糖、木糖醇的色谱模型,用计算机模拟得到柱中液相浓度分布仿真结果。  相似文献   

6.
H点标准加入光度法同时测定葡萄糖和木糖   总被引:1,自引:0,他引:1  
余燕影  曹树稳 《分析化学》1998,26(9):1160-1160
1引言葡萄糖和木糖是自然界中最常见的两种单糖,其结构和化学性质极为相似,用普通方法很难将其分离和分别测定。本文利用硫酸-苯酚与糖的显色反应,采用H点标准加入法对葡萄糖和木糖不经分离进行同时测定。本法简便、快速、结果准确,已应用于食用纤维的分析。2方法原理在二元混合物(组分为x和y,浓度为CxCy)体系中,将不同量已知浓度的x分别准确加入到一系列混合体系中,然后分别在λ1和λ2处测量其分析信号A1和A2。其表达式为:A1=kx1Cx+Ky1Cy+Kx1Cix(1)A2=kx2Cx+Ky2Cy+kx…  相似文献   

7.
高效液相色谱法分析蜂蜜中的糖   总被引:13,自引:4,他引:9  
本文研究了用四乙撑五胺(简称TEPA)作为胺基改善剂,在硅胶柱上定量分析蜂蜜含糖量的方法,并成功地分离了木糖、果糖、葡萄糖、蔗糖、麦芽糖和乳糖。对操作条件进行了探讨。采用示差折光检测器检测,含0.01%TEPA的乙腈-水(77+23)作流动相。六种糖的相对标准偏差均小于3.5%。  相似文献   

8.
用反相高效液相色谱法测定了吴茱萸及制剂中吴茱萸碱和吴茱萸次碱,建立了中药及制剂中吴茱萸碱、吴茱萸次碱分离、测定的色谱方法。色谱条件:ODS柱,乙腈+水+四氢呋喃+乙酸(52+48+1+0.1)为流动相,紫外检测波长280nm。方法简便、灵敏、准确、快速。  相似文献   

9.
Eu(3+)在HAc-NaAc(pH4.6)溶液中与五碳醛糖有弱的络合作用,用循环伏安法和微分脉冲极谱可以观察到D-核糖,D-阿拉伯糖,D-木糖对Eu(3+)还原波形的络合影响,使还原和氧化过程变得较为可逆,其中D-核糖最为明显,而来苏糖无影响.Eu(3+)与氨基酸在相同实验条件下有络合作用,且在汞电极上有吸附现象,因此分别加入L-苯丙氨酸、L-组氨酸和L-蛋氨酸等,进一步改善了Eu(3+)的波形而接近于可逆氧化-还原过程,其中以Eu(3+)-D-核糖-L-苯丙氨酸最明确。绘出了在电极表面形成三元络合物的示意图。  相似文献   

10.
木糖醇的由来及用途   总被引:2,自引:0,他引:2  
张宝成 《化学教育》2006,27(6):7-8,29
介绍了木糖醇的由来及合成,以及在改善糖尿病症状、治疗肺感染和其他领域中的用途,并展望了木糖醇的发展前景。  相似文献   

11.
高效液相色谱法测定大蒜及其制品中的大蒜素   总被引:8,自引:0,他引:8  
采用人工合成的大蒜素做为标准品,建立了高效液相色谱法直接测定大蒜及其制品中的大蒜素含量的方法。使用Sphcrisob ODS2色谱柱,流动相为甲醇+水=60+40,检测波长254nm,进样体积25μL。大蒜素最小检测量为 2.0 mg/L,相对标准偏差为2.8%,回收率为90.4%~103.0%,线性范围为 0~120mg/L  相似文献   

12.
Three double-headed molecules were synthesized by linking a photoreactive linear (1, 2) or angular (3) furocou-marin via a linear 10- or 5-carbon chain to an electro-philic α-methylene-γ-butyrolactone. The photochemical behavior of these molecules was investigated in ethanol at 365 nm and the photocycloadducts obtained from each compound were isolated and characterized. In all cases, the photoreactivity results showed the 3,4-pyrone double bond of the psoralen (linear or angular) to be the most reactive and [2 + 2] intramolecular photocycloadducts between the 3,4-pyrone and the exomethylenic double bonds were obtained. With compounds 1 and 2, two kinds of intramolecular photocycloadducts were obtained, namely cissyn-exo derivatives in 46% and 36% yield, respectively, and trans-syn-exo derivatives in 14% and 18% yield, respectively. With compound 3, only the trans-syn-exo derivative was obtained in 33% yield.  相似文献   

13.
建立了测定豆芽中4-氯苯氧乙酸钠和6-苄基腺嘌呤的固相萃取–高效液相色谱法。样品以0.1 mol/L的盐酸溶液为提取剂,经C18固相萃取柱净化处理,以乙腈–10 mmol/L乙酸铵水溶液(体积比25∶75)为流动相,Tech Mate C_(18)–ST色谱柱分离,4-氯苯氧乙酸钠和6-苄基腺嘌呤的紫外检测波长分别为228 nm和267 nm,色谱峰面积外标法定量。在0.50~100.00 mg/L浓度范围内,4-氯苯氧乙酸钠的相关系数为0.999 8,精密度在1.3%~8.2%之间(n=6),回收率在103.1%~109.0%之间;在0.05~10 mg/L浓度范围内,6-苄基腺嘌呤相关系数为0.999 9,精密度在0.9%~3.8%之间(n=6),回收率在88.0%~95.4%之间。4-氯苯氧乙酸钠和6-苄基腺嘌呤的检出限(S/N=3)分别为0.24,0.02 mg/kg。该法可以同时完成豆芽中4-氯苯氧乙酸钠和6-苄基腺嘌呤的分析检测。  相似文献   

14.
Graft (from linear homopolymers) and random (from a linear random copolymer) copolymer microgels of diallyldimethylammonium chloride (DADMAC) and acrylamide were synthesized via a free-radical mechanism using a γ-radiation technique. These copolymer microgels were evaluated as flocculants on a model dilute TiO2 colloid suspension using a turbidimeter and a disc centrifuge photosedimentometer, and their performances were compared with the linear homopolymers and their blends. It was found that microgels produced after an appropriate irradiation time showed improved flocculation behavior over their nonirradiated linear counterparts. The graft microgels performed better than the corresponding random microgels. For a γ-radiation dosage of 100 krad/h, the graft microgels obtained by irradiating a 30% DADMAC (by weight) homopolymer blend for 3 h showed the maximum reduction in the relative turbidity of the TiO2 suspension as well as the largest fraction of larger particles flocculated. Received: 18 May 1999 Accepted in revised form: 1 June 1999  相似文献   

15.
芳香族化合物生物降解性的QSBR研究   总被引:5,自引:0,他引:5  
陆光华  王超  包国章 《化学通报》2003,66(6):413-417
分别采用线性基团贡献法和人工神经网络法对芳香族化合物的生物降解最大去除率QTOD进行QSBR研究。得到不同基团对生物降解性的贡献顺序为 :C6H5>COOH >OH >CO >CH3 >C1 >NH2>NO2 。线性基团贡献法对于训练组和测试组的预测正确率分别为 86%和 80 % ,总的预测正确率达85 % ;而人工神经网络法的预测正确率分别为 94%、80 %和 92 %。结果表明 ,线性基团贡献法和神经网络法的预测效果均很好 ,而神经网络法的预测更精确。  相似文献   

16.
毛细管电泳有效分离测定甜菊糖苷新方法的研究   总被引:4,自引:0,他引:4  
本文采用100%二甲基甲酰胺(DMF)作为样品的溶剂,以Tris-硼砂作为分离甜菊糖苷的缓冲体系,探讨了进样量、柱温、电压、Tris-硼砂缓冲液浓度以及pH值等条件对甜菊糖苷分离结果的影响。通过优化各种分离条件,实现了毛细管电泳高效分离测定甜菊糖苷。  相似文献   

17.
18.
The linear relationship between Ca and Na interferences and energy potentials for a wide range of atomic and ionic lines is used to compensate for variable intensity suppression in robust axially and radially viewed inductively coupled plasmas (ICPs). In the axial configuration, intensity attenuation varied from 0 to 40% in the presence of 0.5% Ca and Na. In the radially viewed ICP, interferences were smaller, varying from 5 to 15% for 0.5% Na and from 10 to 30% for 0.5% Ca. Signal attenuation was broadly a linear function of the energies of the spectral lines. These linear functions were estimated by using spectral lines covering the energy range from Sb I 206.833 (5.98 eV), Y II 371.209 and Sc II 361.384 (9.9 eV), Sc II 255.237 (11.42 eV), and Be II 313.042 (13.28 eV) nm. These functions were then used as variable internal standards to compensate for Ca, Na, and mixed Ca–Na matrix effects. Whereas analyte recoveries without compensation varied from about 40 to 90%, they varied mostly from 100 ± 5% when these functions were used. In the presence of Ca and Na, the Mg II 280.270/Mg I 285.213 nm intensity ratio decreased from about 12 for an aqueous solution to 9 at 1.5 kW. Such values confirm that the radially and axially viewed ICPs were robust.  相似文献   

19.
微囊藻毒素分子印迹传感器的制备与应用   总被引:1,自引:0,他引:1  
申晴  崔莉凤  赵硕  李科 《分析化学》2012,(3):442-446
以邻氨基酚为单体,微囊藻毒素(MC-LR)为模板,采用循环伏安法在金电极的表面电聚合成膜分子印迹材料,制备了传感器。采用安培法对MC-LR进行检测。在制备影响条件最佳值(pH=4.5;单体/模板=1.4×108∶1;洗脱时间10 min)的基础上,对该传感器的线性范围、使用寿命、选择性等进行了研究,并与液相色谱方法进行对比,结果表明:该传感器对MC-LR具有良好的选择性和灵敏度,线性范围为0.05~0.35 mg/L;加标回收率为80%~105%;检出限为7.3μg/L。与液相色谱方法对比,当置信度为99%时,无系统误差。  相似文献   

20.
This article presents rotational splitting as a modification to the sampling process of the azimuthal angle used in the variance-reduction technique of azimuthal particle redistribution, with the goal to improve the efficiency of this variance-reduction technique for the Monte Carlo simulation of radiation transport in clinical linear accelerators. Using a constant azimuthal angle, instead of a random one, in the azimuthal particle redistribution technique, increases the efficiency of the simulation of a clinical linear accelerator by about 30% and reduces the latent variance of a 10×10 cm2 phase space by about 40%.  相似文献   

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