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1.
目的 研究超声萃取法萃取银杏外种皮中白果酸的工艺过程。方法 采用高效液相色谱测定萃取液中白果酸含量,在单因素试验的基础上,通过正交试验得到了提取过程优化的工艺条件。结果 最优工艺条件:乙醇的体积分数为75%,料液质量与体积比为1:30,提取时间为30min,其中乙醇浓度对提取过程的影响最为显。结论 该方法具有省时、节能和萃取率高的优点。  相似文献   

2.
采用正交法研究了乙醇溶剂提取仙人掌中黄酮类物质的工艺条件.利用单因素试验,确定影响黄酮提取效果的4个因素:乙醇浓度、提取温度、提取时间和料液比的较优水平,用正交设计试验优化提取工艺条件.结果表明,最佳提取条件为乙醇浓度(V/V)90%、料液比20/1、温度55℃、时间1 h.  相似文献   

3.
为了研究羊耳菊最佳工艺,试验采用超声的方法来提取羊耳菊中黄酮类化合物,确定最佳的提取工艺条件。试验采用单因素和正交试验,分析乙醇浓度、料液比、提取时间及提取温度等四个因素对黄酮类化合物含量的影响,优化提取工艺条件。结果表明:乙醇浓度60%,料液比为1:10、提取时间为10min、提取温度为60℃,黄酮含量可以达到69.82mg/g。优选提取工艺简单可行,速度快,可提高葛花人参中有效成分的收率。  相似文献   

4.
在单因素试验基础上,采用正交试验法,对超声波辅助提取莴笋叶中黄酮类物质的工艺进行了优化.确定其最佳提取工艺为:90%乙醇作为浸提剂,超声功率500 W,超声时间50 min,液料比4 mL/g.在此条件下,黄酮类物质的提取率为0.35%.  相似文献   

5.
探讨用醇提法提取竹叶中黄酮类成分的最佳工艺,为竹叶的开发利用提供理论依据。以竹叶为试材,以乙醇为溶剂,采用分光光度法对竹叶中的黄酮类化合物的含量进行测试。通过单因素实验研究乙醇浓度、料液比、提取温度、提取时间对总黄酮提取率的影响,再采用正交试验法优化提取总黄酮的最佳工艺条件。单因素实验和正交试验表明:影响黄酮提取率的因素主次顺序是:料液比〉乙醇浓度〉提取温度〉提取时间。最佳实验条件为料液比1:20,60%的乙醇,60℃提取4h,竹叶中黄酮的含量为7.88mg.g-1。  相似文献   

6.
超声波提取抱茎苦荬菜总黄酮工艺的研究   总被引:1,自引:0,他引:1  
以抱茎苦荬菜全草为原料,在单因素实验基础上,以乙醇浓度、超声时间、超声功率、料液比4因素进行正交实验,优化超声波提取抱茎苦荬菜内总黄酮物质的提取工艺.在实验影响因素中,影响程度从大到小依次为超声波功率>乙醇浓度>料液比>超声提取时间.实验结果表明,抱茎苦荬菜全草中黄酮类物质的最佳提取条件为:7.72 mol/L乙醇,料液比1:20,超声功率400 W,在50℃提取60 min,连续提取2次,总黄酮得率高达1.102%.  相似文献   

7.
目的研究马鞭草总黄酮的超声波辅助提取方法。方法通过单因素试验和正交试验,探讨影响超声波辅助提取马鞭草总黄酮的优化工艺条件,并对马鞭草中黄酮类化合物的抗氧化活进行测定。结果马鞭草中总黄酮的最佳超声提取工艺条件为乙醇溶液体积分数70%、固液比1:40(g/mL)、超声功率500W、超声辅助提取温度70℃条件下提取20min,在此条件下提取率可达2.87%。影响马鞭草中总黄酮提取效果的主次因素为:固液比〉超声波功率〉提取温度〉乙醇体积分数。马鞭草黄酮类化合物具有清除羟自由基、超氧阴离子自由基的作用,其清除效果在一定范围内随着黄酮类化合物质量浓度的增加而增强。结论运用超声波辅助提取法从马鞭草中提取黄酮类化合物可以加快提取速度,提高提取效率,方法简单,结果准确,重现性好,是提取马鞭草总黄酮的有效途径。  相似文献   

8.
以芦丁为对照品,用分光光度法比较醇提法、超声法、煎煮法从锁阳干燥肉质茎中提取有效成分黄酮类化合物的提取效率。采用正交试验优化了超声法的提取工艺。结果表明料液比和超声时间对黄酮类化合物的提取效率有显著影响,乙醇浓度对提取效率影响不显著。得到最佳提取工艺为60%乙醇、1:60料液比、超声1.5h。  相似文献   

9.
研究了不同方法提取荸荠皮中总黄酮类物质,在不同条件下对荸荠皮中的总黄酮物质进行提取,用正交优选法选出适宜的条件。结果表明:采用超声波辅助提取方法得到的总黄酮提取物最多,该方法的适宜提取工艺为:提取时间为50 min,乙醇浓度为50%,提取温度为60℃,料液比为1∶30,该条件下,荸荠皮中总黄酮的得率为2.483%;其次是微波辅助法提取,该方法的适宜提取工艺为:功率为420 W,料液比为1∶30,乙醇浓度为50%,提取时间为5 min,该条件下,荸荠皮中总黄酮的得率为2.455%;加热提取的最少,适宜提取工艺为:提取温度为60℃,乙醇浓度60%,料液比为1∶30,提取时间为4 h,该条件下,荸荠皮中总黄酮的得率为1.618%。比较3种提取方法各有优劣,在实际工作中可以根据情况选择不同的提取方法。  相似文献   

10.
采用微波辅助乙醇-硫酸铵双水相体系,从苦荞麦粉中提取黄酮类化合物.确定乙醇-硫酸铵双水相提取黄酮类化合物的较优乙醇体积分数以及硫酸铵添加量;通过单因素实验确定苦荞麦粉黄酮类化合物的较优萃取条件.结果表明:微波辅助双水相的方法适合用于苦荞麦粉中黄酮类化合物的提取;响应面法优化微波辅助双水相提取苦荞麦粉黄酮的提取条件,较优提取条件为萃取剂含乙醇的体积分数30%,微波功率550 W,提取时间70 s,苦荞麦粉在提取溶剂中的质量浓度0.02 g/m L,苦荞麦粉中提取得到的黄酮类化合物占苦荞麦粉的质量分数为1.38%.  相似文献   

11.
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.  相似文献   

12.
何延凌 《科技信息》2008,(4):258-258
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.  相似文献   

13.
There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.  相似文献   

14.
The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3~4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰~ -7.8‰, PDB) and matrix dolomites (-6.6‰~ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084~0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078~0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.  相似文献   

15.
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。  相似文献   

16.
In the 19th century the society was controlled by men, and women were just appendants of them, they had not any rights and freedom. But Jane was an exception, she showed some characteristics of early feminist. Jane showed her characteristics of feminism in three aspects: rebellion, equality, and independence. These characteristics were helpful to her success, and feminism is the only way out for women of that time.  相似文献   

17.
王慧 《科技信息》2008,(10):240-240
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.  相似文献   

18.
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.  相似文献   

19.
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.  相似文献   

20.
The non-orthogonal localized molecular orbital(NOLMO)is the most localized representation of electronic degrees of freedom.As such,NOLMOs are thus potentially the most efficient for linear scaling calculations of electronic structures for large systems.However,direct ab initio calculations with NOLMO have not been fully implemented and widely used,partly because of the slow convergence issue in the optimization of NOLMO.We devel-  相似文献   

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