反相高效液相色谱法测定苦丁茶中的熊果酸

建立反相高效液相色谱法测定苦丁茶中熊果酸的新方法。乙醇回流提取 ,酸碱沉淀分离制备样品溶液 ,在以甲醇 -水 -磷酸二氢钠 -二乙胺 (90∶ 10∶ 0 .10∶ 0 .0 2 )为流动相、hypersil- C18柱、检测波长 2 2 0 nm、流速为 0 .6 m L/min的条件下 ,熊果酸与其他三萜成分在 2 0 min内达到基线分离。熊果酸在 0 .16 0 8—0 .80 4 0 mg/m L范围内 ,浓度与峰面积呈良好的线性关系 ,加标回收率为 98.0 6 %— 10 1.8% ,RSD=1.73%— 2 .16 %。该法适用于苦丁茶药材及其他制剂中熊果酸的质量分析检验 ,为天然植物中熊果酸的开发提供了简便、准确的测定方法。     

胶束增敏荧光法测定山楂中总黄酮含量

以金丝桃苷为对照品用荧光法测定山楂中总黄酮量.实验表明:乙醇胺与金丝桃苷作用可产生强的荧光,加入CTMAB后,荧光强度进一步增强.金丝桃苷在4×10-7-1.5×10-5mol/L浓度范围内与其荧光强度呈良好的线性关系,其线性回归方程为:y=3.085×107x 122.56;检出限为2.4×10-7mol/L.本方法用于山楂中总黄酮量的测定,其回收率为95.8%-100.0%,RSD为1.64%.     

反相高效液相色谱法同时测定车前草中熊果酸和齐墩果酸

利用超声-微波协同萃取技术从车前草中提取熊果酸与齐墩果酸,研究建立了反相高效液相色谱法快速测定车前草中熊果酸与齐墩果酸含量的方法。采用安捷仑C18柱（4.6mm×250mm,5μm）色谱柱,流动相为乙腈-0.5%乙酸铵（体积比80∶20）,流速为0.8mL/m in,UV检测波长210nm。在该色谱条件下熊果酸与齐墩果酸能在12m in内达到基线分离。熊果酸在1.01—10.1μg范围内线性关系良好,r=0.9995,平均加标回收率为98.8%,相对标准偏差RSD为1.7%（n=5）;齐墩果酸的峰面积与其质量浓度在0.39—3.9μg范围内呈良好的线性关系,r=0.9992,平均加标回收率为97.9%,RSD为1.3%（n=5）。该方法简便、快速、准确,可用于车前草中熊果酸与齐墩果酸的含量测定。     

高效液相色谱法同时测定心可舒胶囊中齐墩果酸和熊果酸

建立高效液相色谱法同时测定心可舒胶囊中齐墩果酸和熊果酸的含量。采用HypersiL ODSC₁₈（4.6mm×250mm,5μm）色谱柱;流动相:甲醇-乙腈-水=79:5:16（V/V/V）;柱温:30℃;流速:1mL/min;检测波长:210nm。齐墩果酸在2.04—81.60μg/mL浓度范围内线性关系良好（r=0.9998）,熊果酸在5.00—80.00μg/mL浓度范围内线性关系良好（r=0.9998）,齐墩果酸的平均回收率为100.54%,RSD为1.56%,熊果酸的平均回收率为101.10%,RSD为1.13%。该法简单、准确、快捷,可用于心可舒胶囊中齐墩果酸和熊果酸的含量测定。     

高压消解-双道氢化物发生-原子荧光光谱法同时测定苦丁茶原植物中的砷和汞

采用HNO3/H2SO4预消解、HNO3/H2O2高压消解,硫脲-抗坏血酸预还原等手段,建立了高压消解-双道氢化物发生-原子荧光光谱同时测定苦丁茶原植物中砷和汞含量的分析方法。讨论并优化了分析测定条件,结果表明,砷和汞的线性范围分别为1.0×10-3—11.0×10-3mg.L-1和1.0×10-4—10.0×10-4mg.L-1,相关系数r分别为0.9986、0.9970,检出限分别是4.73×10-5mg.L-1和8.70×10-6mg.L-1;相对标准偏差(n=6)砷不大于4.25%,汞不大于4.92%。应用于5种苦丁茶原植物砷和汞含量的测定,该方法操作性强、用时短、灵敏度高。     

食品容器、包装材料用聚氯乙烯树脂及成型品中残留1,1-二氯乙烷的测定方法研究

探讨了食品容器、包装材料用聚氯乙烯树脂及成型品中残留1,1-二氯乙烷的气相色谱顶空进样的分析方法.该方法具有良好的线性相关性,相关系数为0.9988,回收率达到98.3%-100.8%,RSD小于5%(n=5).该方法操作简便,可靠,灵敏度高,重复性好.     

比色法测定Annexin Ⅴ变体冻干品中的氯化亚锡含量

测定自制的Annexin Ⅴ变体冻干品中的氯化亚锡含量.在酸性条件下,用钼酸钠-硫氰酸钾比色法测定,λ=460nm.亚锡在5-50μg内线性关系良好,低、中、高三浓度平均回收率分别为102.9％,99.9％,101.0％;RSD分别为6.4％,8.1％,5.1％（n=6）.用比色法测定Annexin Ⅴ变体冻干品中亚锡含量,方法简便、迅捷、试剂易得,可用于冻干品中氯化亚锡的质量控制.     

原子吸收光谱法测定女贞属苦丁茶中金属含量

用火焰原子吸收光谱法测定贵州不同产地的女贞属苦丁茶中Cu、Zn、Ca,Mg 4种金属的含量,并比较含量差异.测定结果表明,女贞属苦丁茶中4种金属元素的含量较高,Cu元素含量为11.28-18.15μg·g-1、Zn元素含量为25.92-43.21μg·g-1、Ca元素含量为2371-12091μg·g-1、Mg元素含量...     

高效液相色谱法测定三姐妹中的齐墩果酸和熊果酸

应用高效液相色谱法同时测定三姐妹中齐墩果酸和熊果酸两种三萜酸类成分的含量.采用Kromasil C18色谱柱(4.6mm×250mm,5μm),以甲醇∶水∶磷酸(90:10∶0.1,V/V/V)为流动相,流速1.0mL·min-1,紫外检测波长210nm,柱温30℃.齐墩果酸进样量在0.684-6.84μg时,与峰面积呈良好的线性关系(r=0.9999),平均回收率为98.3％,RSD为1.9％(n=5);熊果酸进样量在1.064-10.64μg时,与峰面积呈良好的线性关系(r=0.9998),平均回收率为97.2％,RSD为2.4％(n=5).方法准确,操作简便,数据可靠,可用于三姐妹中齐墩果酸和熊果酸的含量测定.     

新疆人工栽培阿魏菇多糖含量的测定

采用可见分光光度法测定阿魏菇多糖的含量.以葡萄糖为对照品,以蒽酮-浓硫酸为显色剂,在625nm处测定样品溶液的吸光度.在0.00-20.00μg/mL范围内,葡萄糖质量浓度与吸光度呈良好线性关系,相关系数r=0.9995.回收率在98.3%-104.5%之间.相对标准偏差RSD为2.17%(n=5),新疆阿魏菇多糖含量...     

Linear and Nonlinear Raman Spectroscopy onⅡ-Ⅵ Semiconductor Quantum Wires and Dots

1.ＩｎｔｒｏｄｕｃｔｉｏｎＮａｎｏｓｔｒｕｃｔｕｒｅｄｓｅｍｉｃｏｎｄｕｃｔｏｒｓｗｉｔｈｓｐａｔｉａｌｄｉｍｅｎｓｉｏｎｓｏｆｆｅｗｎａｎｏｍｅｔｅｒｓａｎｄｌｅｓｓｓｈｏｗｃｅｒｔａｉｎｏｐｔｉｃａｌｐｒｏｐｅｒｔｉｅｓ,ｔｈａｔａｒｅｑｕｉｔｅ?..     

.NULL.

Ｔｈｅｎｂｕｔａｎｅｍｏｌｅｃｕｌｅｉｓｔｈｅｓｍａｌｌｅｓｔｈｙｄｒｏｃａｒｂｏｎｗｈｅｒｅｍｏｒｅｔｈａｎｏｎｅｇｅｏｍｅｔｒｉｃｃｏｎｆｏｒｍｅｒｃａｎｅｘｉｓｔ.Ｉｔｈａｓｂｅｅｎｔｈｅｓｕｂｊｅｃｔｏｆｍａｎｙｓｐｅｃｔｒｏｓｃｏｐｉｃａｎ?..     

Of heat capacity at homologous temperatures for metals showing h.c.p. ⇄ b.c.c. transformation

Some interesting aspects of the temperature dependence of the Planck’s functionφ and heat capacities of metals exhibiting the h.c.p. ⇄ b.c.c. transformation have been brought to light by the use of reduced temperature (T*) and Planck’s function (-φ T*). It has been shown that tangents drawn to the -φ T* vsT* plots of these metals at any chosen value ofT* intersect at a point whose coordinates are defined by the slope and intercept ofφ vs entropy plots at any homologous temperature and the selectedT* value. A generalized expression obtained for the temperature dependence ofφ has been used to demonstrate that the heat capacity of these metals may be visualized to have structural and material components.     

威耳逊对云室的实验研究

介绍了C.T.R.威耳逊的主要贡献和发明云室的过程.他由研究水滴的凝结规律入手,不断改进实验装置,拍摄了带电粒子的径迹照片,从而证明了康普顿效应;还分析了威耳逊取得成功的几个重要因素.     

Photolysis and E. S. R. Studies on Triphenylphosphinecarbethoxymethylene

Although several different groups have studied the photolysis of phosphorus ylides, none have utilized e. s. r. to support the postulated decomposition mechanisms. The fundamental question which awaits a definitive answer is which bond breaks first upon photolysis. Tschesche¹ and de Silva² utilizing the ylides (1) and (2) suggested that the carbon-phosphorus double bond was initially broken while Nagao³ using (3) proposed phenyl-phosphorus bond cleavage.     

E.S.R. Spectra of the Cyclobutanesemidiones Derived from Three Tricyclo[4. 4. 2. 01,6,]Dodecane-11-OL-12-Ones

The semidione radical anions derived from a variety of alicyclic ketones and α-hydroxyketones have been extensively investigated via esr by Russell and co-workers.¹Studies of the chemistry and spectra of the 1, 2-cyclobutanediones derived from the tricyclo[4. 4. 2. 0^1,6] dodecane-11-o1-12-one system²suggested that an examination of the esr spectra of the related semidiones would be of considerable interest. The recent reports on the esr spectra of cyclobutanes emidione^1cand several substituted cyclo-butanes emidiones^1bfurther prompt this communication.     

凹叶厚朴各部位挥发油成分比较研究

采用顶空固相微萃取(HS-SPME)提取凹叶厚朴不同部位的挥发油成分,气相色谱-质谱(GC-MS)分析其组成.结果显示:根鉴定出19个化合物,其中4(14),11-桉叶二烯(26.04％),(1S-顺)-1,4-二甲基-7-(1-甲基亚乙基)-奠(24.94％),石竹烯(9.41％),β-桉叶醇(7.28％)为主要成分...     

W.R. Grove and the fuel cell

Though known these days largely because he invented the fuel cell, Grove also had many other distinguished achievements to his credit. His monumental book On the Correlation of Physical Forces contained all the arguments that led to the enunciation of the first law of thermodynamics. He was also an extremely versatile natural philosopher who was, in addition, well versed in classical literature, particularly the works of the eminent scholars of ancient Greece and Rome. This article touches upon these qualities, but is predominantly concerned with the emergence and modern aspects of the H₂/O₂ fuel cell and its potential for the clean generation of energy.     

Bulk viscous L.R.S. Bianchi type V tilted stiff fluid cosmological model in general relativity

Locally rotationally symmetric (L.R.S.) Bianchi type V bulk viscous tilted stiff fluid cosmological model is investigated. To get the deterministic model of the universe, we have also assumed a condition A=Bⁿ between metric potentials A, B where n is the constant. The behaviour of the model in presence and absence of bulk viscosity and singularities in the model are also discussed. In general, the models represent accelerating, shearing, tilted and non-rotating universe. The models have point type singularity in presence and absence of bulk viscosity both.     

A. C. conductivity due to intimate pairs of charged defect centres

The influence of the association of charged defects into intimate pairs on a.c. conduction is discussed in the light of the fundamental mechanism being that of the simultaneous hopping of two electrons over the barrier separating two oppositely charged defect centres, the barrier height being correlated with the intersite separation via the Coulomb interaction. The behaviour of chalcogenide glasses is discussed in terms of the present theory, and it is concluded that the existence of two classes of a.c. conductivity behaviour into which these materials generally fall can be simply explained by the predominance of either intimate pairs or non-intimate pairs of charged defect states according to the conditions of preparation.