正交试验优选蒙椴树总黄酮的提取工艺

研究了蒙椴树中总黄酮的最佳提取条件.采用L9 (34)正交表设计方案进行试验,以芦丁为标准品,用紫外-可见分光光度法测定蒙椴树乙醇提取物中的总黄酮含量.结果表明:乙醇浓度对蒙椴树总黄酮的提取影响较大,其他3个因素影响程度排序为:提取时间>提取次数>乙醇用量.10倍量95%乙醇,提取次数2次,每次提取时间3小时为本次实验筛选出的最佳条件.     

小叶椴复合体的叶、花形态连续变异观察

紫椴(Tilia amurensis)和蒙椴(T.mongolica)是分布于北方的主要椴树属植物,形态上有差别但不易区分,二者均可称为小叶椴,本研究将其处理为"小叶椴复合体".利用形态扫描及便携式数码显微镜(Digital Portable Microscope)观察,对小叶椴复合体的叶、花形态指标进行测量,有助于深入了解其形态上的变异规律.研究结果显示,小叶椴复合体的叶、花形态存在连续性,特别是存在着雄蕊退化不完全的现象.     

蒙椴树叶化学成分的研究

研究了蒙椴(Tilia mongolica Maxim.)树叶的化学成分.运用溶剂萃取、硅胶柱色谱、HPLC和重结晶技术对蒙椴树叶提取成分进行分离和纯化.从树叶提取物分离得到5个化合物,根据化合物的红外光谱和核磁共振谱数据鉴定其结构.其结构鉴定分别为:β-香树脂醇乙酸酯(Ⅰ)、28α-同-β-香树脂醇乙酸酯(Ⅱ)、β-香树脂醇(Ⅲ)、β-谷甾醇(Ⅳ)和棕榈酸(Ⅴ).化合物Ⅱ和Ⅴ为首次从本属植物中分离的化合物,其中化合物Ⅱ是一个新化合物.     

用核糖体DNA的ITS序列探讨滇桐属的系统学位置

采用PCR直接测序方法 ,对来自椴树科、梧桐科、木棉科 17属的 33个种和作为外类群的锦葵科 2属4个种的核糖体DNAITS区 (含 5 8S区 )序列进行了分析。结果表明 ,滇桐属 (Craigia)与椴树属为姐妹群关系 ,二者构成单系类群 ,因而将滇桐属置于椴树科中较为合理 ;刺果藤属和翅子树属有较近的亲缘关系 ,并与蚬木属和柄翅果属构成一个单系类群 ,二者可能与椴树科有更近的亲缘关系 ;榴莲属与椴树科的破布叶属构成单系类群 ;山芝麻属与椴树科、梧桐科和木棉科构成并系关系 ;因此 ,这些属的系统位置尚需进一步确定。综合分析的结果支持将椴树科、梧桐科和木棉科归并到锦葵科中的观点。     

蒙椴树皮提取物化学成分的气相色谱-质谱分析

用不同极性的有机溶剂对蒙椴树皮进行提取,对得到的油状成分利用气相色谱-质谱法分析了其化学组成,鉴定了其中的57种化学成分,并通过峰面积归一化法确定了它们的相对含量,鉴定成分占总组分的73.26%;主要成分为酯类化合物,同时鉴定出烷烃类、酸、醇、醛、酮类化合物.     

蒙药材多叶棘豆挥发油化学成分的GC/MS分析

鉴定了蒙药材多叶棘豆挥发油的化学成分.用水蒸汽蒸馏法提取蒙药材多叶棘豆中的挥发油,采用GC-MS法测定其化学成分.共分离出60种组分,鉴定出其中的9种组分.已鉴定出的多叶棘豆挥发油中主要化学成分为1-甲氧基-4-[1-丙烯基]-苯,1-甲基-4-6,10,14-三甲基-2-十五烷酮,己醛等.     

季鳞盐柱撑蒙脱土的制备及表征

采用离子交换法将不同组份的十烷基三丁基溴化鳞交换到蒙脱土的层间得到柱撑蒙脱土.用热重分析(TGA)、X-射线衍射(XRD)和傅里叶变换红外光谱法(FTIR)等对其结构进行了表征,并测定其抗菌活性.研究发现柱撑蒙脱土中季鳞盐的热分解起始温度大于210℃,具有较好的热稳定性;季鳞盐含量越高,柱撑蒙脱土的层间距越大,抗菌活性越高.     

蒙药材白花龙胆和尖叶假龙胆的薄层色谱鉴别

目的:建立蒙药材白花龙胆和尖叶假龙胆的鉴别方法.方法:采用薄层色谱法鉴别白花龙胆和尖叶假龙胆.结果:建立了两种色谱鉴别方法.结论:该方法简便,具有专属性、重现性好、结果稳定可靠,可用于白花龙胆和尖叶假龙胆的质量控制.     

用于煤矿防灭火的高吸水树脂的合成与吸水性能研究

以蒙脱土、丙烯酸为主要原料,采用溶液聚合法合成了超强吸水性复合树脂.讨论了蒙脱土加入量、引发剂加入量、交联剂的用量、丙烯酸的中和度对高吸水性复合树脂吸水倍率的影响,优化了该复合材料吸自来水性能的配方,即蒙脱土添加量为40％,单体的中和度为80％,交联剂用量为0.08％,引发剂用量为0.15％.在此配方下制备的复合材料吸自来水倍率达到156倍.傅里叶红外光谱图研究证实蒙脱土能够有效地与高聚物结合,不但提高了树脂的保水能力和耐热性,而且大大降低了树脂成本.     

Photoshop中图层蒙版的使用

蒙版是Photoshop中的一项重要工具，图层蒙版是蒙版的常用方式之一，通常用于图像的融合，在处理图形图像的过程中广泛使用。本文以实例来解析图层蒙版的使用方法，通俗易懂、简洁明了。     

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