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1.
对不同方法纯化魔芋葡甘露聚糖进行了研究,酶法结合乙醇沉淀法是最佳提纯魔芋葡甘露聚糖的方法。对提纯的魔芋葡甘露聚糖进行了改性,对比了改进魔芋葡甘露聚糖、魔芋葡甘露聚糖和魔芋精粉的溶胶特性和稳定性,其中以改性魔芋葡甘露聚糖的溶胶特性和稳定性最佳。  相似文献   

2.
十二烷基硫酸钠催化合成氯乙酸异丙酯   总被引:1,自引:0,他引:1  
研究了十二烷基硫酸钠催化氯乙酸与异丙醇酯化反应中各种因素对酯化率的影响.在醇酸摩尔比1.2/l、催化剂用量1.0%(以酸的摩尔数计量)、反应时间2.5h、反应温度为回流温度以及5mL苯作为带水剂的反应条件下,酯化率可达97.2%.与其他酯化催化剂相比较,十二烷基硫酸钠的催化活性与硫酸氢钠、对甲苯磺酸等Bronsted酸相当,比大多数Lewis酸的催化活性高.由FTIR方法推测出十二烷基硫酸钠水解生成的硫酸氢钠在催化过程中起到了关键性作用.  相似文献   

3.
为使膨润土能够在塑料中应用,需对膨润土有机化处理.以山东潍坊膨润土为原料,采用湿法提纯得到高纯度的膨润土,经无水碳酸钠钠化后选择不同的改性剂对其有机化处理,最终制备出有机膨润土,经测试分析表明:采用湿法提纯后,在65℃下加入质量分数为10%的Na2CO3恒温反应2h可得到钠基膨润土;在70℃条件下加入质量分数为20%的十八烷基苄基二甲基氯化铵和己内酰胺复合改性剂,调节pH为6后反应1.5h抽滤、干燥、粉碎后可得到改性效果优良的有机膨润土,其层间距可达到2.44nm.  相似文献   

4.
聚乙二醇催化合成取代苯氧乙酸   总被引:1,自引:0,他引:1  
水做溶剂,聚乙二醇-800做催化剂,苯酚的衍生物与氯乙酸在碱性条件下,加热回流制备取代苯氧乙酸.当反应物的浓度是3.5mol/L,苯酚衍生物与氯乙酸的摩尔比是1:1.1,反应时间是1h,合成了4种取代的苯氧乙酸,都获得了高产率.其中,4.氯苯氧乙酸产率95.2%,2,4-二氯苯氧乙酸产率91.4%.  相似文献   

5.
研究以魔芋精粉和鲜牛奶为原料制备功能性酸奶的工艺优化,采用磷酸法提纯魔芋精粉并以直投式发酵剂进行发酵。在单因素实验的基础上,通过Box-Benhnken响应面法得出功能性魔芋酸乳制备的最佳工艺条件为:糖添加量6.14%,发酵剂添加量6.71%,魔芋精粉添加量0.43%,发酵时间4h。直投式发酵剂具有类型多、活力强的优点,采用此发酵剂制备魔芋酸乳的过程简单,容易推广。  相似文献   

6.
高锰酸钾改性煤基活性炭催化合成环己酮乙二醇缩酮   总被引:3,自引:0,他引:3  
以高锰酸钾改性煤基活性炭为催化剂合成了环己酮乙二醇缩酮,并获得了较好的合成条件,即n(环己酮);n(乙二醇)=1:1.5,催化剂用量为总反应物料质量的3.3%(环己酮质量的6.5%),以8.0mL环己烷为带水剂,反应时间为2.5h,产率为89.6%.实验结果表明,该催化剂容易获得,可回收使用。具有较高的催化活性.  相似文献   

7.
TiSiW12O40/TiO2催化合成氯乙酸正丁酯   总被引:3,自引:0,他引:3  
首次以固载杂多酸盐TiSiW12O40/TiO2为多相催化剂,通过氯乙酸和正丁酸反应合成了氯乙酸正丁酯,并探讨了诸因素对产率的影响。实验表明:TiSiW12O40/TiO2具有良好的催化活性,醇酸物质的量比为1.4:1,催化剂用量为反应物料总量的2.0%,反应时间0.5h,反应温度130-139℃,产率可达66.51%。  相似文献   

8.
化学冷烫剂是一种无毒无害的冷烫剂,并且冷烫时间短、不用电、对毛发无断无叉的一种较安全、使用方便的理想烫发剂。1制法(1)氯乙酸2kg氯乙酸中加入5kg水,并不断搅拌下使氯乙酸溶解,待完全溶解后滴加纯碱溶液(用适量的水把纯碱溶解),调节氯乙酸溶液的pH值至6-7为止。(2)硫脉硫腺1.6kg中加水skg,并倒入搪瓷桶中,加热,再加入已中和好的氯乙酸溶液,继续升温至85-90℃,不断搅拌半小时,然后用倾斜法留下沉淀物。归)氰化钡氰化钡s.zxg中加入固体烧碱1.65kg(30%烧碱溶液5.skg左右),放在搪瓷桶中,再加入硫腺溶液15kg,…  相似文献   

9.
洋县位于陕西省南部汉中市东端,年平均气温14.5℃,降水量799.2mm,相对湿度77%,日照时数1840.3h。魔芋是丘陵山区发展经济的优势产业,全县常年种植魔芋1333.33hm^2,总产2万t。  相似文献   

10.
目的:介绍魔芋葡甘露聚糖的实验研究,探讨其应用开发前景.方法:以魔芋粉为原料,对葡甘露聚糖的粗提、精制、纯化、物化性质、含量测定、毒性试验以及应用等方面的研究结果进行总结.结果:魔芋葡甘露聚糖理化性质稳定,安全性较高.结论:葡甘露聚糖可作为药用辅料开发,尤其在速释制剂辅料和辅助用药方面,值得进一步研究.  相似文献   

11.
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   

12.
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   

13.
AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…  相似文献   

14.
本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。  相似文献   

15.
Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with  相似文献   

16.
The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to  相似文献   

17.
18.
The explosive growth of the Internet and database applications has driven database to be more scalable and available, and able to support on-line scaling without interrupting service. To support more client's queries without downtime and degrading the response time, more nodes have to be scaled up while the database is running. This paper presents the overview of scalable and available database that satisfies the above characteristics. And we propose a novel on-line scaling method. Our method improves the existing on-line scaling method for fast response time and higher throughputs. Our proposed method reduces unnecessary network use, i.e. , we decrease the number of data copy by reusing the backup data. Also, our on-line scaling operation can be processed parallel by selecting adequate nodes as new node. Our performance study shows that our method results in significant reduction in data copy time.  相似文献   

19.
R-Tree is a good structure for spatial searching. But in this indexing structure,either the sequence of nodes in the same level or sequence of traveling these nodes when queries are made is random. Since the possibility that the object appears in different MBR which have the same parents node is different, if we make the subnode who has the most possibility be traveled first, the time cost will be decreased in most of the cases. In some case, the possibility of a point belong to a rectangle will shows direct proportion with the size of the rectangle. But this conclusion is based on an assumption that the objects are symmetrically distributing in the area and this assumption is not always coming into existence. Now we found a more direct parameter to scale the possibility and made a little change on the structure of R-tree, to increase the possibility of founding the satisfying answer in the front sub trees. We names this structure probability based arranged R-tree (PBAR-tree).  相似文献   

20.
The geographic information service is enabled by the advancements in general Web service technology and the focused efforts of the OGC in defining XML-based Web GIS service. Based on these models, this paper addresses the issue of services chaining,the process of combining or pipelining results from several interoperable GIS Web Services to create a customized solution. This paper presents a mediated chaining architecture in which a specific service takes responsibility for performing the process that describes a service chain. We designed the Spatial Information Process Language (SIPL) for dynamic modeling and describing the service chain, also a prototype of the Spatial Information Process Execution Engine (SIPEE) is implemented for executing processes written in SIPL. Discussion of measures to improve the functionality and performance of such system will be included.  相似文献   

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