微波辅助萃取-高效液相色谱法测定苦丁茶中熊果酸的含量

采用微波辅助萃取—高效液相色谱法测定了苦丁茶中熊果酸的含量.苦丁茶粉碎后以乙醇为溶剂,微波高火提取4 min,采用高效液相色谱法（HPLC）测定熊果酸的含量.色谱柱为InertsilC18柱（5μm,4.6×150 mm）;流动相为甲醇/水（体积比90∶10）,流速为0.8mL/min,柱温40℃,检测波长为210nm.结果表明熊果酸在0.0996~0.4980mg/mL范围内线性关系良好,平均回收率为100.8%,RSD=1.12%,苦丁茶中熊果酸的含量为14.55 mg/g.     

高效液相色谱法测定木瓜中熊果酸的含量研究

采用HPLC法,以YPW-Kromasil TMC18为色谱柱,甲醇-水-冰醋酸(90∶10∶0.1)为流动相,流速0.6mL/min,柱温25℃,检测波长210 nm,建立了木瓜中熊果酸的高效液相色谱含量测定方法.结果表明:熊果酸在0.03～0.15 mg/mL范围内呈良好的线性关系,该方法的平均回收率为101.8%(n=5),RSD为1.16%.     

无土栽培中NH4+-N和NO3--N的测定

2mol.l-1KCl溶液可作为无土栽培中基质的NH4 —N和NO3-—N的提取剂,其固∶液=1∶5,振荡时间为30min,NH4 —N测定采用靛酚蓝比色法,测定波长为645nm,标准曲线的回归方程为:A=0.7358C 0.0044,r=0.9994(n=7),回收率为:103.6%。NO3-—N测定采用紫外分光光度法,测定波长为205nm,标准曲线的回归方程为:A=0.5654C 0.0127,r=0.9994(n=9),回收率为:102.4%。     

RP-HPLC-PDAD法测定青叶胆中齐墩果酸和熊果酸的含量

目的建立了青叶胆中齐墩果酸和熊果酸的反相高效液相色谱-光电二极管阵列检测器(RP-HPLC-PDAD)定量分析方法。方法采用95%乙醇为溶剂超声提取,色谱柱为Kromasil C18柱(4.6mm×250 mm,5μm),柱温30℃。以甲醇∶水∶磷酸(88∶12∶0.15,v/v/v)为流动相等度洗脱,流速0.9 m L·min-1,采用光电二极管阵列检测器进行检测,检测波长210 nm。结果齐墩果酸进样量在0.1048~2.6200μg时,与峰面积呈良好的线性关系(r=0.9999),平均回收率为96.9%,RSD为1.7%(n=9);熊果酸进样量在0.2304~5.7600μg时,与峰面积呈良好的线性关系(r=0.9999),平均回收率为97.5%,RSD为1.5%(n=9)。结论方法准确,操作简便,数据可靠,可用于青叶胆中齐墩果酸和熊果酸的含量测定。     

金匮肾气丸中三萜类成分的质量比测定研究

建立金匮肾气丸中三萜类成分的质量比测定方法.以HPLC法选用SymmetryC18柱（4.6 mm×250 mm,5μm）测定该复方中茯苓酸、熊果酸及齐墩果酸的质量比.茯苓酸质量比测定色谱条件为：检测波长为242 nm;流动相为甲醇-水-磷酸（75∶25∶0.2）;流速为1 mL/min;柱温为30℃.熊果酸及齐墩果酸的色谱条件：检测波长为215 nm;流动相为乙腈-甲醇-水-乙酸胺（62.5∶15.5∶22∶0.55）;流速为0.8 mL/min;柱温为30℃.茯苓酸、熊果酸及齐墩果酸的质量比分别为0.116 mg/g、0.287 mg/g、0.134 mg/g.结果表明,该方法简便、准确、重现性好,适用于金匮肾气丸中三萜酸类成分的定量分析.     

双波长薄层扫描法测定解热止痛散中对乙酰氨基酚和咖啡因的含量

在Cs- 930薄层扫描仪上以紫外反射吸收方式 ,灵敏快速测定了解热止痛散中对乙酰氨基酚和咖啡因的含量 .扫描参数 :对乙酰氨基酚λs=2 4 8.5nm ,λR=34 0 .0nm ,咖啡因λs=2 73.0nm ,λR=34 0 .0nm ,散射参数Sx=3.采用双波长反射线齿型扫描 ,狭缝 1.2mm× 1.2mm ,所用薄层板为GF2 54,薄层厚度 0 .4mm ,展开剂为氯仿 :甲醇∶醋酸乙酯∶冰醋酸 =10∶2∶2∶0 .2 (体积比 ) ,平均回收率对乙酰氨基酚为 95.6% ,咖啡因为 10 8.4 %     

黔产蒲公英中熊果酸含量的高效液相色谱法测定

目的建立黔产蒲公英中熊果酸含量的高效液相色谱测定方法.方法采用 Dikma C18柱(250 mm ×4.6 mm,5μm),流动相为甲醇-乙腈-0.5%醋酸铵(16:65:20),柱温25℃,流速1.0 mL·min-1,检测波长为215 nm.结果熊果酸在10.2~102μg·mL-1范围内与峰面积呈良好的线性(r2=0.9999),平均加样回收率为99.52%,RSD为1.47%(n =6).结论所用方法简便、快速、准确,首次提出以熊果酸含量作为黔产蒲公英的质量控制指标     

薄层扫描法测定强骨颗粒中黄芪甲苷的含量

采用双波长薄层扫描法,以氯仿—甲醇—水(13∶7∶2)的下层溶液为展开剂,10%硫酸乙醇溶液显色,在105℃烘约5 min,λS=530 nm,λR=700 nm条件下扫描,以测定强骨颗粒中黄芪甲苷含量.结果表明:样品中黄芪甲苷分离完全,阴性供试品无干扰,黄芪甲苷在1.982~9.91μg范围内呈良好线性关系,r=0.9957,平均回收率为98.4%,RSD为2.1%,测得3批强骨颗粒中黄芪甲苷的平均含量为0.0639 mg/g.     

湘西桐叶药材熊果酸及齐墩果酸的HPLC法测定

建立一种高效、准确、稳定的桐叶熊果酸和齐墩果酸测定方法,测定湖南省湘西地区桐叶药材中熊果酸和齐墩果酸含量.采用高效液相色谱（HPLC）法,色谱条件依次为,色谱柱：TADE-PAKAF-C18柱（250 mm×4.6 mm,5 μm）;流动相：乙腈-甲醇-0.5%醋酸铵溶液（体积比61∶18∶21）;流速：1 mL/min;检测波长：210 nm;柱温：35 ℃;进样量：10 μL.结果表明：齐墩果酸与熊果酸分离度为1.73,均符合要求;熊果酸和齐墩果酸对照品分别在0.497 6～9.952 0 μg/mL和0.126 1～2.523 0 μg/mL范围内线性关系良好（r均为0.999 9）;熊果酸、齐墩果酸平均加样回收率分别为99.93%,98.97%;湘西产桐叶含熊果酸4.54～7.07 mg/g,含齐墩果酸2.50～3.20 mg/g.HPLC法分离效果好、灵敏度高、准确度高,是检测桐叶中熊果酸、齐墩果酸含量的科学有效手段.     

枸骨根中三萜类物质含量的测定

本文以采集于湘潭县的枸骨根为材料,选用熊果酸为对照品,5%香草醛—冰乙酸和高氯酸为显色剂,以分光光度法测定枸骨根中总三萜的含量.实验结果表明:在549 nm波长下,标准品在4.4～26.4 mg/L范围内,吸光度与含量呈良好的线性关系,其回归方程为:y=0.0357x-0.0809,R2=0.9984.样品吸光度在5～40 min内相对比较稳定,其三萜含量为3.20%,RSD值为0.31%.该方法操作简便,快速,灵敏度高,重复性好.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the