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1.
用固体氯化物催化合成柠檬酸三丁酯,柠檬酸三丁酯和乙酸酐反应合成乙酰柠檬酸三丁酯。研究了催化剂用量、原料配比、反应温度、反应时间对合成反应的影响,确定了最佳工艺条件:(1)酯化反应:柠檬酸∶正丁醇为1∶3.5(mol);反应温度为130℃;反应时间5h,催化剂用量0.7%;(2)乙酰化反应:柠檬酸三丁酯∶乙酸酐为1∶1.6,反应温度为85℃,反应时间为1h,催化剂用量为0.06%。酯化收率为96.3%,乙酰化收率为98.5%。  相似文献   

2.
2-甲基-1,2,5,6-四氢-5,6-二氧-1,2,4-三嗪-3-硫醇的合成研究   总被引:1,自引:0,他引:1  
研究了在甲醇的碱性介质中,通过1-甲基-1-氨基硫脲与草酸二乙酯的缩合反应制备医药中间体三嗪环。适宜的反应条件为1-甲基-1-氨基硫脲、草酸二乙酯、甲醇钠的量(摩尔)比为1∶1.1∶2.0,其收率可达60%  相似文献   

3.
豹子沟一带金矿床位于北祁连山镜铁裂谷南侧与中祁连山北侧接壤部位,成矿构造地质环境复杂,构造-岩浆-热液活动强烈。通过对该区1∶10万区域化探异常特征的研究,揭示了该地区金矿床金异常与构造破碎带的关系,并对该区金矿床成因进行了初步分析,提出了进一步的找矿思路。  相似文献   

4.
用五种Schif碱型双(苯并_15_冠_5)为离子载体,在水_1,2_二氯乙烷体系中研究了其对碱金属苦味酸盐的萃取性能,测定了分配比D和萃取平衡常数Ke.结果表明,这些双冠醚与苦味酸钠以1∶1(冠醚单元∶金属离子)形式络合,而与苦味酸钾和苦味酸铷则以2∶1形式络合.  相似文献   

5.
研究了负载在活性炭上的镍催化剂在乙醇气相羰化合成丙酸及丙酸乙酯反应中的应用,考察了各种影响反应的因素。在250℃、0.1MPa、CO∶C2H5OH∶C2H5I=2∶1∶0.1条件下,丙酸和丙酸乙酯的收率达到80%。催化剂以Ni的质量百分数为10的活性最高  相似文献   

6.
在深入研究黔东南从江地虎金银多金属矿成矿地质背景及构造特征的基础上,从构造地球化学方面对黔东南从江地虎金银多金属矿构造特征进行研究,进行了变形、破裂实验,成矿物质活化、迁移实验和压力溶解、韧性流动模拟实验,并进行宏观及微观构造对比。实验结果初步验证了地虎金银多金属矿的构造特征,为该区构造控制金矿提供了重要的实验材料,同时为研究该区的找矿提供了有益信息。  相似文献   

7.
研究了新试剂4-(2-噻唑偶氮)-间甲基酚(MTAC)与钯的显色反应,在水杨酸(R)的存在下,于pH=5.0的醋酸盐缓冲溶液中,形成了配位比为Pd∶MTAC∶R=1∶1∶1的橙红色的三元混配配合物.λmax=520nm,表观摩尔吸光系数为ε=6.28104L/mol.cm,通过配合物的紫外和红外光谱性质,研究了三元混配配合物的结构.方法应用于钯催化剂中钯元素含量的测定,结果满意  相似文献   

8.
研究了镉与DBON- PF 显色反应的条件- 在pH 9 的硼砂- 硼酸缓冲溶液中,有CTMAB存在下,镉与DBON- PF形成蓝紫色络合物,最大吸收波长为610 nm ,表观摩尔吸光系数为2 .64 ×105 L·mol- 1·cm - 1 ,络合物的配合比为Cd( Ⅱ)∶DBON- PF∶CTMAB= 1∶1∶2 ,镉量在0 ~0 .16 μg/mL 符合比耳定律- 通过巯基棉柱富集、分离,除去大量的干扰离子,本法灵敏度高,稳定时间长,能应用于环境水样和废水中微量镉的测定- 图1 ,表1 ,参6-  相似文献   

9.
通过三峡电站钢衬钢筋混凝土压力管通大比尺(1∶2)平面结构模型试验,研究了内水压力作用下的裂缝性态及温度荷载作用下裂缝张合特征,试验研究成果更接近工程实际.  相似文献   

10.
贵州青岩油杉种群生物量研究   总被引:1,自引:0,他引:1  
本文对贵州省青岩镇20年生珍稀植物—青岩油杉种群生物量进行测定和研究。按平均标准木法实测了树干、树枝、针叶和根的生物量,根据实测结果用相对生长规律建立了测定单株木及器官的回归模型,进而亦得出了测定整个种群生物量的回归模型,模型的计测精度符合要求,具有实用价值。研究结果表明:20年生青岩测杉种群生物量为52.58t/ha,其中树干、树枝、针叶和根的生物量比为4∶1.3∶1∶2.1  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.
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   

14.
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   

15.
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-  相似文献   

16.
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-  相似文献   

17.
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  相似文献   

18.
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  相似文献   

19.
Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of  相似文献   

20.
<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with  相似文献   

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