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1.
功能性低聚糖作为双歧杆菌增殖因子的研究开发与应用越来越受到学者的关注,目前已证实具有特殊保健功能的低聚糖有低聚果糖、低聚异麦芽糖、低聚木糖、大豆低聚糖和低聚乳糖等。介绍了几种重要低聚糖的化学组成、特性、制法和应用等。  相似文献   

2.
有机溶剂中微量水的荷移光谱法测定   总被引:11,自引:0,他引:11  
研究了氯冉酸与有机溶剂中水的反应,确定了反应条件,氯冉酸与水的络合物的最大吸收波长为530nm。在乙醇、甲醇,正丙醇,异丙醇、正丁醇,正庚醇,正己醇溶剂中,水的含量分别在0-5%(V/V)或0-8%(V/V)范围内呈线性关系,相关系数为0.998或0.999;该方法重现性好,灵敏度高,操作简单,用于测定乙醇中微量水的含量,与标准值相符;加入回收法测得甲醇中水的回收率分别为98%-103%,结果令人满意。  相似文献   

3.
 以N2-H2混合气为反应气,与三氧化钼进行多段程序升温反应制得了氮化钼.考察了反应气组成和氮化温度等条件对氮化钼结构组成的影响.结果表明,在n(N2)/n(H2)=0.25~1,θ=650~750℃的条件下,生成的氮化钼结构组成为β-Mo2N0.78.其生成机理与γ-Mo2N有类似之处.β-Mo2N0.78催化噻吩加氢脱硫反应的结果表明,β-Mo2N0.78催化剂对该反应有较高的催化活性,在360℃下,其活性比硫化钼催化剂高一倍左右.  相似文献   

4.
刘祥  杨锐 《广州化学》2004,29(2):19-24
用转糖苷法合成了新型表面活性剂——烷基糖苷。对影响得率的因素如反应物配比、催化剂量、反应时间和温度分别进行了讨论。实验结果用非线性回归的方法得到数学模型,求解非线性规划得到反应的最佳条件:葡萄糖、正丁醇、十二醇、催化剂的摩尔比为1720.008,反应温度为120,反应时间为1 h。测定了不同浓度下溶液的表面张力,得到其临界胶束质量浓度为0.006%。实验证明,烷基糖苷具有较好的泡沫力和泡沫稳定性。  相似文献   

5.
测定浓缩菠萝汁中乳酸的毛细管气相色谱法   总被引:3,自引:0,他引:3  
建立了毛细管气相色谱快速测定浓缩菠萝汁中乳酸的方法,样品经甲醇-浓硫酸衍生化处理,四氯化碳萃取,采用氢火焰检测器,SUPELCOWAX-10石英毛细管柱,外标法定量,GC-MS确认;在0.01-1g/L的范围内乳酸含量与峰面积具有良好的线性关系,标准曲线的相关系数为0.999,检出限为0.008g/L,回收率为90%-96%,相对标准偏差为4.0%;方法具有快速、简便、准确的特点。  相似文献   

6.
CsCuHPVAsMoO杂多化合物对异丁烯选择性氧化反应的催化性能   总被引:2,自引:0,他引:2  
 用组合法合成了CsCuHPVAsMoO系列杂多化合物催化剂,并采用FT-IR,H2-TPR,NH3-TPD和TG-DTA等方法对催化剂进行了表征.在自制固定床反应器中对异丁烯进行选择性氧化,考察了Cs,Cu和As含量、催化剂焙烧温度及反应条件对催化剂催化性能的影响.结果表明,Cs的引入有利于提高催化剂的选择性;Cu和As的引入在提高催化剂活性的同时,也提高了催化剂的选择性;当焙烧温度为340℃时,催化剂的活性和选择性最高.组成为Cs0.1Cu0.2HxPVAs0.2Mo10Oy的催化剂对异丁烯具有很强的选择性氧化能力,在最佳反应条件下,甲基丙烯酸、甲基丙烯醛和乙酸的收率分别可达52.84%,12.05%和18.21%.  相似文献   

7.
测定戒毒病人尿中吗啡含量的HPCE法   总被引:3,自引:0,他引:3  
采用高效毛细管电泳法测定戒毒病人尿中吗啡含量,5mL尿样加碱调节pH值,用GDX-301作为固相萃取剂,氯仿-异丁醇洗脱,收集液在40℃下氮气吹干,定容进样;缓冲液由20mmol/L磷酸盐、20mmol/L硼酸盐、50mmol/L十二烷基硫酸钠、5%(φ)乙腈组成,pH=8.2;吗啡在紫外波长210nm检测,出峰时间为6.17min,线性范围为2.5-30mg/L,测得线性回归方程Y=0.521+8.836ρ,相关系数r=0.999,检出限为50μg/L,日内和日间误差分别低于4%和6%;与HPLC比较,测定结果与HPLC无显著性差异(P>0.05);结果表明该法分析速度快,分离效果好,适用于临床疗效观察。  相似文献   

8.
以ACQUITY UPLC BEH Amide柱为分析柱,乙腈-0.2%三乙胺一水作为流动相,建立了超高效液相色谱-蒸发光散射检测器测定卷烟烟丝中鼠李糖、木糖、果糖、甘露糖、葡萄糖、蔗糖、麦芽糖7种水溶性糖的分析方法。7种水溶性糖回归方程的线性相关系数均大于0.999,检出限为0.56~1.11μg/mL。7种水溶糖的回收率在90.43%106.41%之间,相对标准偏差为1.66%-4.35%仰:6)。该方法灵敏度、准确度高,稳定性好,可用于大批量卷烟烟丝中水溶性糖含量的测定。  相似文献   

9.
用固载强酸TiO2/SO42-催化甲基紫罗兰酮合成中的环化反应   总被引:7,自引:0,他引:7  
崔志敏  陈学恒  李楠 《化学通报》2002,65(2):130-134
研究了以固载强酸TiO2/SO4^2-作催化剂,用假性异甲基紫罗兰酮环化合成甲基紫罗兰酮的新方法,提高了α-异甲基紫罗兰酮的收率,获得了最佳反应条件;投料比n(假性异甲基紫罗兰酮):n(甲苯):n(硫酸)=1:3.5:0.04,控制反应温度15-25℃,反应时间1.5h,该优化条件下,合成收率为93%-94%,产物中α-异甲基紫罗兰酮占78(wt)%左右。  相似文献   

10.
二甲醚的电催化氧化反应   总被引:2,自引:0,他引:2  
王世忠 《催化学报》2003,24(9):695-700
 考察了负载于镓酸镧基电解质上的镍电极与镍-钐掺杂氧化铈复合电极电催化二甲醚氧化反应的特性.结果表明,反应的主要产物均为CO,H2和CH4,同时生成少量完全氧化的产物H2O和CO2.在开路电位下二甲醚发生裂解反应,生成的CO,H2和CH4三种主要产物的比例接近于1.在有电泵氧存在下,二甲醚的电催化氧化反应强烈地依赖于阳极及电解质材料的组成.Ni/La0.9Sr0.1Ga0.8Mg0.2O3界面上发生的主反应是二甲醚的部分氧化,且存在有严重的积碳现象.电极中掺入SDC(15%Sm3+-掺杂的CeO2)后,二甲醚完全氧化性能明显增强;随着电流的增大,氢的生成速率显著减小,并生成大量的H2O.采用掺钴镓酸镧基电解质后,Ni-SDC主要表现为催化二甲醚部分氧化反应,且显著抑制了积碳的发生.Ni-SDC/La0.8Sr0.2Ga0.8-Mg0.11Co0.09O3上二甲醚电催化氧化反应的主要产物为1∶1的CO和H2.掺钴电解质引起Ni-SDC具有特殊的催化性能,可能与电解质中p型电导的存在有关.  相似文献   

11.
The spectral-polarization characteristics of absorption and phosphorescence of molecules of the initial form of nitro-substituted indolinospirobenzothiopyran were studied in oriented polyethylene films and in solutions with different polarity. An oscillator model of the electron transitions responsible for the formation of absorption and luminescence spectra was suggested. It was established that the principal differences in the spectral and photophysical properties of the compound studied and its oxygen-containing analog are associated with the fact that the electronegativity of the S atom is lower than that of the O atom. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1143–1146, June, 1997.  相似文献   

12.
非那雄胺能抑制5α-还原酶的活性,明显降低二氢睾酮水平,是一种治疗良性前列腺增生的有效药品。该合成工艺以甾烯酮酸为原料,将其与氯化亚砜反应,无须分离即与叔丁胺反应得17β-酰胺化合物,再氧化开环,环合,氢化,脱氢合成了非那雄胺。经元素分析、IR、1HNMR、13CNMR、MS分析表征了其结构。该法无须使用昂贵的2,2-二吡啶二硫化物和剧毒药品苯亚硒酸酐,且以乙酸铵代替氨气,降低了对设备的要求和腐蚀,更适用于工业生产。  相似文献   

13.

The heats of detonation of 20 simple high explosives and explosive mixtures were determined by means of an adiabatic detonation calorimeter designed by the authors. The results indicated that the performance of the instrument was reliable and the experimental data were very accurate. For explosive mixtures, there was a linear accumulative relationship between the heats of detonation of the explosive mixture and its components. Accordingly, the heats of detonation of explosive mixtures could be calculated directly from the heats of detonation of simple explosives and the characteristic heats of other components. The experiments showed that the gold or brass shell of the cylindrical charge could be substituted by a thick-walled porcelain shell, which had the advantage of cheapness.

  相似文献   

14.
Two vanilloids, (5E)-8-(4-hydroxy-3-methoxyphenyl)oct-5-en-4-one (1) and 4-[3-hydroxydecyl]-2-methoxyphenol (2), isolated from the dried seeds of Grains of Paradise (Aframomum melegueta), were synthesized; the latter compound was made as the S-enantiomer and the material derived from the seeds was found to be a 1:1.7 mixture of the R and S isomers. The synthetic route used should allow the preparation of analogs having extended alkyl chains and consequently different lipophilicity, and 3, a homolog of 2, was also prepared.  相似文献   

15.
In this review, the research of the author in the field of colloidal systems is summarized. The factors influencing colloidal stability are systematized and analyzed. Examples are presented to illustrate the practical utilization of the theory of stability of colloids and thin films.This review was prepared on the basis of the works of the author, which were awarded the State Premium for 1991 in the field of science and technology, chemistry section.Institute of Physical Chemistry, Russian Academy of Sciences, 117915 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 8, pp. 1708–1717, August, 1992.  相似文献   

16.
Main hydration products of two cement pastes, i.e. CSH-gel, portlandite (P) (and specific surface S) were studied by static heating, and by SEM, TEM and XRD, as a function of cement strength (C-33 and C-43) hydration time (th) and subsequent hydration in water vapour.Total change in mass on hydration and air drying, Mo, increased with strength of cement paste and with hydration time. Content of water escaping at 110 to 220°C, defined as water bound with low energy, mainly interlayer and hydrate water, was independent on cement strength but its content increased with (th). Content of chemically bound (zeolitic) water in CSH-gel, escaping at 220-400°C, was slightly dependent on strength and increased with (th). It was possibly derived from the dehydroxylation of CSH-gel and AFm phase. Portlandite water, escaping at 400-500°C, was independent on cement strength and was higher on longer hydration. Large P crystals were formed in the weaker cement paste C-33. Smaller crystals were formed in C-43 but they increased with (th). Carbonate formated on contact with air (calcite, vaterite and aragonite), decomposed in cement at 600-700oC. It was high in pastes C-33(1 month) and C-43(1 month), i.e. 5.7 and 3.3%, respectively; it was less than 1% after 6 hydration months (low sensitivity to carbonation) in agreement with the XRD study showing carbonates in the air dry paste (1month), and its absence on prolonged hydration (6 months) and on acetone treatment. Water vapour treatment of (6 months) pastes or wetting-drying increased this sensitivity.Nanosized P-crystals, detected by TEM, could contribute to the cement strength; carbonate was observed on the rims of gel clusters.This revised version was published online in November 2005 with corrections to the Cover Date.  相似文献   

17.
翟宗玺  刘树深  夏树屏 《化学学报》1990,48(10):946-950
用氧化镁氯化镁水溶液制备了8水合氯氧化镁[nMg(OH)2·MgCl2·8H2O], 并测定了其在盐酸中的溶解热, 实验结果表明, 氯氧化镁溶解热与n值呈线性关系, 根据溶解热求出5Mg(OH)2·MgCl2·8H2O和3Mg(OH)2·MgCl2·8H2O的生成热分别为-7727.1和5888.1kJ·mol^1^-。  相似文献   

18.
19.
The enthalpies of solution of several oxosulfides of rare-earth elements and the high-temperature enthalpies of oxosulfides and oxosulfates of lanthanum and yttrium were measured using solution calorimetry and high-temperature microcalorimetry techniques. Standard enthalpies of formation and some thermodynamic properties of oxosulfides and oxosulfates were calculated. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2 pp. 294–297, February, 1997.  相似文献   

20.
设计了铁的锈蚀实验,说明了铁钉的处理方法,增加了温度、酸、碱的影响条件,实现了铁跟蒸馏水及空气中氧气快速反应而生锈,使实验在5 min左右就能够得到准确的结果。  相似文献   

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