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A program for the potentiometric determination of the protonation constants of mononuclear polyproticsubstances is described.A maximum of twelve parameters can be determined simultaneously,includingup to six protonation constants,four electrode calibration parameters,the protolysis constant of thesolvent and the titrant concentration.Optimization is carried out by using the non-simplifiedNewton-Raphson method,which is potentiated by the Marquardt algorithm and a distance speeding-upcoefficient.A direct search method is also used to improve the initial set of values.Variances arecalculated very accurately,since the real Hessian function is used.Statistical weights and ionic strengthcorrections are also considered,The program has been tested by using simulated titration curves ofpolyprotic acids with close constants. 相似文献
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The model selection from EMF data of pH titration curves has been studied for binary and ternarysystems(Ni~(2+)-glycine and Ni~(2+)-methionine-taurine respectively)by using the MINIGLASSprogram.Comparison between experimental and calculated titration curves with this interactive programindicates the presence(and the pH range)of the different species in equilibrium. 相似文献
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Y. D. Zykov F. M. Lyakhovitskiy O. P. Chervinskaya 《Geophysical Journal International》1984,76(1):269-272
Summary. The paper presents experimental data on elastic anisotropy of ultrasonic waves in thin-layered periodic models composed of ice and clay, and how such models were constructed. Experiments were carried out in the temperature range from -1° to -12°C. The dependence of the anisotropy coefficient on moisture and temperature is analysed. A comparison is given of theoretical and experimental data on elastic-wave velocities. 相似文献
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1 IntroductionA certain pattern of channel is the product of its self-adjustment under given boundary, discharge and sediment conditions[1]. A lot of experiments have been performed in flumes, usually with an initially-regulated straight channel being constructed in the flume, to determine the impact of these conditions on channel morphologies and patterns[2-6]. Schumm's experiments[3] demonstrated that when the bed-load channels transport only sand at constant discharge, channels develop from… 相似文献
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A certain pattern of channel is the product of its self-adjustment under given boundary, discharge and sediment conditions. Based upon the principle of process-response model, an experimental study with 18 runs is carried out in LESRC. This paper is focused on the variation of the energy dissipation versus the channel morphology during and after the bedmaking process of braided channel. The results show that there exists a good empirical relationship between the energy dissipation rate and channel morphology. According to this relationship and the theory of minimum rate of energy dissipation, the authors explain the metamorphosis of the model channel with the development of the braided river. 相似文献
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长江河口最大浑浊带水沙输运机制分析 总被引:33,自引:0,他引:33
本文根据大量的实测资料,运用机理的分析方法,讨论了长江口最大浑浊带中各输沙项的作用。结果表明,平均流输沙、斯托克斯漂流效应、潮汐捕集以及垂向不流是净输沙的主要部分。 相似文献
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为了对比渭河城区段天然河滩与由河滩改造的湿地公园中野生动物的分布情况,进而对河流天然河滩的园林化改造进行评估。2016年5月至2018年4月,采用样带法、典型样方法和坑穴诱捕法,调查了渭河咸阳城区段天然河滩和被改造为湿地公园的河滩中鸟类的巢和蛇类、蛙类、刺猬类、兔形类、鼠类的分布及其数量。研究结果表明,在天然河滩采样地中,诱捕到的5类野生动物和鸟巢的数量都显著大于其在湿地公园中的数量(p<0.05),且天然河滩被改造为湿地公园后,蛇类、刺猬类和兔形类野生动物几乎消失。可见,将天然河滩改造为湿地公园,实现了城市人居空间的延伸,增加了游憩功能,但是,因其改变了原天然河滩的地形、土壤和植物群落,使得湿地公园失去了原天然河滩的大部分生态功能,野生动物失去了它们赖以生存的独特环境,其分布种类和数量皆显著减少。 相似文献
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青海湖位于青藏高原的东北部,是一个典型的大陆微咸水湖.该湖湖水的水化学类型属硫酸钠亚型.其盐度为14.23‰,在化学组成上与海水有着明显的差别.该湖水为CaCO3所饱和,正在析出文石.为了查明该湖湖水的化学演化趋势、折盐序列和各种盐类析出的条件,1990年我们在该湖南岸采集了大量湖水样品,进行了蒸发和蒸发-冷冻-蒸发实验.其蒸发实验结果表明:随着湖水浓缩首先析出水菱镁矿,随后逐步析出石盐、无水芒硝、白钠镁矾、软钾镁矾、泻利盐、钾石盐和光卤石.其蒸发-冷冻-蒸发实验也首先拆出水菱镁矿,其后逐步析出芒硝、三水菱镁矿、石盐、泻利盐、光卤石和水氯镁石.这些实验的最终母液在室内保存了1-2个月,均有硼酸盐析出.上述实验所获得的折盐顺序和结晶途径不仅阐明了青海湖湖水的化学演化趋势,同时也阐明了青藏高原盐湖和我国东部第三纪古湖盆形成与演化过程,以及其各种盐类析出的条件. 相似文献
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首次从化学工程的角度 ,将盐田系统作为一类特殊的化学反应器和无机盐分离设备进行了详细的论述。在大量试验基础上 ,系统地分析和研究了 Na+,K+,Mg2 +∥Cl-,- H2 O四元水盐体系卤水在天然蒸发状态下的宏观蒸发动力学参数。从理论上对与卤水蒸发相关的多种参数进行了分析和合理简化 ,概述了卤水蒸发过程中的质量传递规律。并在此基础上通过计算机模拟方法建立了四元水盐体系高浓度卤水在特定地域中进行天然蒸发的卤水宏观蒸发动力学模型 ,证明了多种简化和理论假设的合理性。对该数学模型在盐湖卤水开发中的盐田设计、盐田生产的现代化自动管理和控制等进行了探讨。在卤水蒸发动力学模型建立的过程中 ,针对实际生产过程的需要 ,通过多种参数的分析 ,建立了多种参数关系 相似文献
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锂共存时对EDTA络合滴定Sr2+离子产生较强的干扰,使分析结果偏高。根据被测液中氯化锂的大约含量,通过加入适量混合醇,可消除Li+离子的干扰,质量滴定法相对误差<0.3%。在锂锶质量比为0.10014.5范围内,被测样中LiCl质量与加入混合醇体积呈线性关系。混合醇掩蔽体积范围为314.5范围内,被测样中LiCl质量与加入混合醇体积呈线性关系。混合醇掩蔽体积范围为35 mL。根据锂离子与水分子、短链醇形成蔟合物的键能,对消除Li+离子干扰络合滴定的机理进行探讨。 相似文献
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采用等温溶解平衡法研究了三元体系CaCl2?SrCl2?H2O温度从323.15 K到353.15 K范围内的相平衡。基于该三元体系多温下的相平衡数据,设计开展了实验室模拟南翼山油田卤水中氯化钙和氯化锶在温度323.15 K下的分离实验。实验室模拟钙锶分离实验结果表明,在323.15 K下时分离一次固相产品中的钙锶摩尔比可以从25.46:1降至1.73:1,SrCl2的回收率为52.47 %,所得一次固相产品在323.15 K下溶解并再次蒸发。钙和锶的摩尔比从1.73:1降至1.1:1,SrCl2的回收率为78.67 %。 相似文献