共查询到10条相似文献,搜索用时 53 毫秒
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在湿法磷酸生产过程中产生的粗磷酸母液和磷石膏中均含有微量的镧系元素.以这种潜在的稀土资源为研究对象,介绍了国外及云南省磷矿中稀土的含量及分布情况,探讨了湿法磷酸过程中镧系元素的转移机理,论述了从粗磷酸母液和磷石膏中回收提取镧系元素的方法、工艺以及高纯单一镧系元素的分离纯化技术,提出了云南省磷石膏中微量镧系元素提取技术是磷石膏综合利用的一个重要研究方向,对开发磷石膏的高附加值具有重要意义. 相似文献
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Michael Gaitan Laurie E. Locascio 《Journal of research of the National Institute of Standards and Technology》2004,109(3):335-344
This paper describes the first demonstration of temperature control and flow sensing of fluids using integrated circuit (IC)-based microheating elements embedded in microchannels molded in polydimethylsiloxane (PDMS). Fluid channels and connections to capillary tubing are molded in PDMS using a silicon wafer template. The PDMS film is then bonded to an IC that contains the micromachined microheating elements. Capillary tubes are inserted and fluids are externally pumped through the channels. Heating of the fluid is observed by the formation of bubbles on the microheating element. Sensing of fluid flow is demonstrated by measuring a change in the large signal resistance of the microheater analogous to a hot wire anemometer with a detection limit of ± 320 pL/s. 相似文献
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水是膳食的一个重要组成部分,是一切生命必需的物质,在生命活动中发挥着重要功能。电感耦合等离子体光谱法(ICP-AES)以及电感耦合等离子体质谱法(ICP-MS)由于其适用于多元素分析及痕量元素分析等特点,在水中的重金属测定中有着广泛的应用。本文对两种方法的测定进行介绍并对其原理和特点进行比较。 相似文献
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为更好地了解坝基开挖爆破施工质量,采用声波测试技术检测岩体的完整性,评价建基面岩体开挖质量.基于现场的声波测试,先对声波测试信号中的波速、波形、波幅的变化规律进行了分析,然后对建基面岩体质量进行了综合评价.检测结果表明:单孔、跨孔声波最大和平均衰减率均满足不超过10%的施工技术要求,岩石完整性较好,基础开挖施工符合设计... 相似文献
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Zhao Huaipu 《Strain》1992,28(1):13-17
In this paper, a new method for the measurement of three dimensional residual stresses in a multi-pass butt welded joint is presented. The method involves the measurement of strain changes at a through hole surface as a coupon of material with the hole is separated from the body of interest and split. The finite element calculations are used to relate the strain changes at the measurenent points to the initial residual stresses at the hole location. The accuracy of the method is demonstrated by using it to measure a known stress field in a bent beam. The method has been used to measure the through thickness distribution of three dimensional residual stresses in a multi-pass butt welded joint. It could also be applied to the measurement of residual stresses in other welded joints. 相似文献
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测量结果不确定度的应用范围很广,从原则上说,在给出任何测量结果的同时均应该给出测量结果的不确定度。不确定度按其获得的方法分为A、B两类评定分量,若要得到某测量结果的不确定度,必须根据其仪器、设备、实验方法、人员素质、环境条件等因素提出完整的数学模型。本文依照具体情况给出本实验测量结果的不确定度。 相似文献
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为保证定量包装商品净含量计量检验结果的统一性、有效性和准确性,依据JJF 1070-2005《定量包装商品净含量计量检验规则》,对影响定量包装商品净含量检验结果的不确定度的主要来源和检验的关键点进行分析,找出每种检验方法中影响净含量检验结果的测量不确定度,为今后科学地计量检验定量包装商品净含量奠定基础。 相似文献