酶催化合成丁酸丁酯

以酶为催化剂，正丁醇与王丁酸一步反应可合成丁酸丁酯，本实验考察了不同类型的酶催化剂和普通催化剂、酶催化剂用量、醇酸摩尔比、反应温度、反应时间等因素对合成酯收率的影响．优化的反应条件：醇酸摩尔比为1．3：1．0，酶催化剂用量比为4．0％，反应时间为30min，反应温度为25—35℃，酯产率可达94．1％．     

S2O8^2-／TiO2-SiO2催化合成柠檬酸三丁酯

以固体超强酸S2O8^2-／TiO2-SiO2为催化剂合成柠檬酸三丁酯，考察了醇酸摩尔比、催化剂用量、反应时间、反应温度及催化剂重复使用对酯化反应的影响。结果表明酯化反应的最佳条件为：酸醇摩尔比为1：5．4，催化剂用量为反应物总质量的0．94％，反应时间为6小时，反应温度为130℃，此条件下酯化率可达93．4％。该催化剂具有制备简便，与产品分离容易，不易腐蚀设备，重复使用后仍保留良好的活性等优点。     

钛酸四丁酯催化合成柠檬酸三丁酯

以柠檬酸和正丁醇为原料，钛酸四丁酯为催化剂合成柠檬酸三丁酯，用单因素分析法研究醇酸摩尔比、催化剂用量、反应时间及反应温度对酯化反应的影响。结果表明，酯化反应的最佳条件为：n(醇)：n(酸)：3．6：1.0，催化剂用量为柠檬酸质量的0．40％，反应时间4h，反应温度130～140℃，酯化率达到94．51％，纯度大于99．1％。     

固体超强酸树脂催化合成戊二酸二丁酯

以固体超强酸树脂为酯化催化剂合成了戊二酸二丁酯，考察了醇酸摩尔比、带水剂用量、催化剂用量及反应时间对酯化率的影响，通过极差分析，确定了合成戊二酸二丁酯的优化反应条件：以0．25mol戊二酸二丁酯为基准，醇酸摩尔比为3．0，催化剂用量为0．6％，带水剂环己烷24ml，反应时间为90min，戊二酸二丁酯收率可达99．3％以上。     

硫酸钛催化合成丙酸丙酯

以硫酸钛为催化剂催化丙酸与正丙醇的酯化反应合成了丙酸丙酯,研究了催化剂用量，醇酸摩尔比，反应时间，带水剂用量对酯化反应的影响，在最佳工艺条件下丙酸丙酯的收率为96．5％。     

固体超强酸TiO2/SO2-4催化合成丙酸苄酯

以固体超强酸ＴｉＯ２／ＳＯ＾２－４为催化剂,环己烷为带水剂,合成了丙酸苄酯、考察了催化剂制备,催化剂用量,原料配比,反应时间等因素对酯化率的影响,其最佳反应条件为：醇酸摩尔比１：３,催化剂用量１ｇ,反应时间１．５ｈ,反应温度９５－１１０℃,酯化率达到８８％。     

超声辅助SiW12/SiO2催化合成乙酸苄酯及动力学

制备负载型硅钨酸( SiW12/SiO2)催化剂,并在超声条件下将催化剂应用于乙酸苄酯的合成中.采用红外光谱仪(IR)和X线衍射仪(XRD)对催化剂进行表征.考察反应温度、催化剂用量、醇酸摩尔比和反应时间对酯化率的影响,并建立了动力学方程.结果表明:所制备的催化剂具有Keggin的结构;在超声频率10 kHz、超声声强1.0 W/cm2的条件下,得到最适宜的反应条件为反应温度110℃、催化剂用量1.5g、醇酸摩尔比值1.5、反应时间75 min.在最优条件下,酯化率可达95.3%.     

钛酸四丁酯催化合成柠檬酸三丁酯

以柠檬酸和正丁醇为原料,钛酸四丁酯为催化剂合成柠檬酸三丁酯,用单因素分析法研究醇酸摩尔比、催化剂用量、反应时间及反应温度对酯化反应的影响。结果表明,酯化反应的最佳条件为:n(醇):n(酸)=3.6:1.0,催化剂用量为柠檬酸质量的0.40％,反应时间4 h,反应温度130-140℃,酯化率达到94.51％,纯度大于99.1％。     

磷钼杂多酸银盐催化合成醋酸异戊酯的研究

本文以磷钼杂多酸银盐为催化剂,对醋酸异戊酯的合成反应进行了研究,探讨了催化剂用量、醇酸摩尔比、反应时间对酯产率的影响。结果表明：在异戊醇用量为０．２５ｍｏｌ的情况下,以环已烷为带水剂,用磷钼杂多酸银盐为催化剂,催化剂用量为 １．５ｇ,醇酸摩尔比为１：１．４,在回流温度下反应２小时后,再用分水装置反应１小时,酯产率达９２．８％。     

硫酸氢钠催化合成乙酸异戊酯

以乙酸和异戊酸为原料，采用硫酸氢钠为催化剂合成了乙酸异戊酯，当反应时间为1h，醇酸物质的量比为1：3，催化剂用量为醇酸总量的3．0％，反应温度为130～135℃，酯的产率可达85％以上。     

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.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

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.     

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.     

A computer generator for randomly layered structures

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

An Index mechanism for multi-scale view in spatial databases

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.     

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