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近年来,稀土冠醚配合物的研究受到重视,但稀土高氯酸盐冠醚配合物的研究报道尚少,有关高氯酸钇与18-冠-6(18C6)的配合物还未见报道。我们用改进的半微量相平衡方法研究了Y(ClO_4)_3·3H_2O-18C6-CH_3CN三元体系在20℃时的溶解度,以便确定三水高氯酸钇与18-冠-6在乙腈中能否形成配合物,能生成几种配合物,以及它们的相区如何,为合成固态配合物提供依据。在此基础上,分离、制备了固态配合物,利用化学分析,DTG、TG、DSC以及电导考查了配合物的组成与性质。 相似文献
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将盐酸羟胺吡啶溶液与六甲基二硅胺烷混合,混合后过滤,滤液再加到标准的 D-甘露糖、D-半乳糖和 D-葡萄糖中,从而改进了糖肟三甲基硅醚衍生物常规的制备方法,解决了在常规制备方法中气相色谱法对标准己糖难分离的问题。用 OV—17固定液,气相色谱法分析了三种已糖混合物,结果三种己糖被分离,并对新的制备方法作了研究。 相似文献
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发展了毛细管电泳(CE)和高效液相色谱-质谱(HPLC-MS)相结合的用于天然产物中活性成分筛选和鉴定的方法。该方法中,用HPLC半制备柱对天然产物粗提物进行分离纯化,再用CE对HPLC纯化后的组分进行活性测试。根据HPLC-MS/MS提供的二级质谱数据,即可确定活性成分的化学结构。以乙酰胆碱酯酶为实验模型,对我们发展的筛选方法进行了验证。从黄连粗提物中确定了药根碱、巴马汀等7种活性成分,并通过CE测定了它们的半抑制率(IC50)值。与传统的天然产物分离纯化和活性筛选方法相比,该方法具有简单、微量、快速、准确的优点。本文建立的方法为天然产物粗提物中活性成分的筛选提供了新技术。 相似文献
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O8肽的HPLC分析与制备研究 总被引:1,自引:0,他引:1
系统建立了化学合成小分子肽(08肽)的反相HPLC分离分析方法.考察了色谱填料种类、流动相组成及梯度条件对样品分离的影响.通过从分析型到半制备型分离线性放大过程中分离条件与分离效果的关系的探讨.建立了等度洗脱条件下较大规模地分离制备该小肽的方法试验结果表明:硅胶基质的色谱柱比聚合物基质的色谱柱更适合于分离该小肽,而粒径(5μm.10μm)对分离的影响不大;较缓的梯度条件可以明显改善分离,但所需分离时间延长一在制备分离中应综合考虑分离效果与运行时间的关系。 相似文献
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《Journal of computational chemistry》2017,38(27):2298-2306
Complete free energy surface in the collective variable space provides important information of the reaction mechanisms of the molecules. But, sufficient sampling in the collective variable space is not easy. The space expands quickly with the number of the collective variables. To solve the problem, many methods utilize artificial biasing potentials to flatten out the original free energy surface of the molecule in the simulation. Their performances are sensitive to the definitions of the biasing potentials. Fast‐growing biasing potential accelerates the sampling speed but decreases the accuracy of the free energy result. Slow‐growing biasing potential gives an optimized result but needs more simulation time. In this article, we propose an alternative method. It adds the biasing potential to a representative point of the molecule in the collective variable space to improve the conformational sampling. And the free energy surface is calculated from the free energy gradient in the constrained simulation, not given by the negative of the biasing potential as previous methods. So the presented method does not require the biasing potential to remove all the barriers and basins on the free energy surface exactly. Practical applications show that the method in this work is able to produce the accurate free energy surfaces for different molecules in a short time period. The free energy errors are small in the cases of various biasing potentials. © 2017 Wiley Periodicals, Inc. 相似文献
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针对两嵌段高分子链的跨膜输运过程,分别给出与不同输运次序相对戍的高分子链的自由能,进而通过求解Fokker-Planck方程并在不同条件下对平均首次通过时间进行了数值计算.计算结果表明,当共聚高分子链由良溶剂区向不良溶剂区输运时,不能发生线团一链滴转变的链首先输运总是有利于整个高分子链的输运.而在给定输运次序的情况下,化学势、线团一链滴转变、共聚链的组成以及输运速率等因素对输运时间可产生显著影响.相关研究结果可为调控实际生物高分子链的输运时间提供可能的理论线索. 相似文献
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1. | The potential of the interaction of two similar atoms of a noble gas can be represented in the form of a Buckingham potential for which the principle of corresponding states is satisfied, one of the manifestations of this being the constancy of the complex C8/(R2C6) for different gases. |
2. | In accordance to the principle of corresponding states the coefficient C8 in the Buckingham potential for adsorption interactions is 6 times greater than the value adopted at the present time in the theory of physical adsorption. |
3. | In order to accelerate the calculation of the lattice sums in various calculations on the zeolites and other adsorbents it is possible to calculate the lattice sum by the usual method at reference points and write the result in the memory of a computer and in all the subsequent calculations to find the value of the lattice sum at a given point by interpolation. With an accuracy of 0.5% this method leads to an acceleration of the calculation by a factor of 2.103. |
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Hiroshi Nakazawa Tamayo Okahira Takeshi Ishiyama Katsuhiko Miyoshi 《Phosphorus, sulfur, and silicon and the related elements》2013,188(8-9)
The reaction of Cp anion, [C 5 H 4 CH 2 CH 2 P(TMS)Mes] m with (CH 3 CN) 3 Mo(CO) 3 leads to the formation of [( m 5 --C 5 H 4 CH 2 CH 2 --P(TMS)Mes)Mo(CO) 3 ] m , which then reacts with MeI to give a metallaphosphacyclopropane complex with silyl migration. 相似文献