共查询到20条相似文献,搜索用时 109 毫秒
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建立了微波辅助衍生结合液相色谱-串联质谱(MAD-LC-MS/MS)同时测定水产养殖用水中硝基呋喃类代谢物3-氨基-2-唑烷基酮(AOZ)、5-甲基吗啉-3-氨基-2-唑烷基酮(AMOZ)、氨基脲(SEM)、1-氨基-2-丙酰脲(AHD)和3,5-二硝基水杨酸肼(DNSAH)的分析方法。样品经2-硝基苯甲醛微波辅助衍生1 min,乙酸乙酯提取,Acquity UPLC BEH C18色谱柱分离,以乙腈-乙酸铵(5 mmol/L,0.1%甲酸)溶液为流动相,梯度洗脱,电喷雾正负离子切换模式电离,多反应监测模式(MRM)测定。结果表明:5种代谢物在0.2~50 μg/L范围内线性关系良好,相关系数均大于0.997,方法的定量限为0.02~0.05 μg/L;在0.1~5 μg/L的3个添加水平下,回收率在79%~102%之间,相对标准偏差(RSD)在3.6%~10.1%之间。该方法快速、简便,且易于推广,可以同时监测养殖水体中5种硝基呋喃代谢物的残留。 相似文献
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本文报道了1-(4-硝基苯基)-3-(4-硝基-噻唑)-三氮烯(NPNTT)的合成及其与镉的显色反应研究。在O(P聚乙二醇辛基苯基醚)的存在下,pH11.0的Na2B4O7-NaOH缓冲溶液中,该试剂能与镉发生显色反应,镉与NPNTT形成摩尔比为1:3型的配合物,在450nm处有一最大正吸收,在540nm处有一最大负吸收。以450nm为参比波长,540nm为测量波长进行双波长测定,表观摩尔吸光系数为5.23×105L/(mo·lcm),镉的浓度在0~400μg/L范围内符合比尔定律。用拟定方法测定废水中的微量镉,结果满意。 相似文献
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研究了一种新型偶氮苯甲酸类试剂2-(6-硝基-2-苯并噻唑偶氮)-5-二甲氨基苯甲酸(简称6-NO2-BTAMB)在乙醇介质中与锌(Ⅱ)反应的最佳条件.结果表明,以六次甲基四胺-硝酸[(CH2)6N4-HNO3]为缓冲液(pH6.4~6.8)、乙醇为反应介质,6-NO2-BTAMB与锌可形成摩尔比21的蓝绿色络合物,λm=632nm,ε632=7.O×104L·mol-1·cm-1,锌在O~8.Oμg/10mL范围内符合比尔定律.据此,建立了6-NO2-BTAMB与锌显色反应新体系.该方法用于镁合金和模拟合金样品中微量锌的测定,结果令人满意. 相似文献
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《生命科学仪器》2017,(2)
3,4-二羟基丁酸(3,4-dihydroxybutyric acid,3,4-DHBA)及其内酯3-羟基-γ-丁内酯(3-hydroxy-γ-butyrolactone,3HBL)均是重要的手性C4平台化合物,它们是许多天然产物合成的重要原料,也是重要的医药中间体。3,4-二羟基丁酸及其内酯目前的合成方法主要为化学合成,但因其较低的产率﹑严苛的反应条件﹑无法避免的副产物生成和环境污染等缺点使其难以实现大规模生产。本综述对近年来3,4-二羟基丁酸及其内酯的相关合成研究进行总结,详细论述了相关化学合成法,同时总结了现有的生物合成3,4-二羟基丁酸及其内酯的研究进展。 相似文献
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In a recent paper, the Ritz method with simple algebraic polynomials as trial functions was used to obtain an eigenvalue equation for the free vibration of a class of homogeneous solids with cavities. The method presented is here extended to the study of a class of non-homogeneous solids, in which each solid is composed of a number of isotropic layers with different material properties. The Cartesian coordinate system is used to describe the geometry of the solid which is modelled by means of a segment bounded by the yz, zx and xy orthogonal coordinate planes and by two curved surfaces which are defined by fairly general polynomial expressions in the coordinates x, y and z. The surface representing the interface between two material layers in the solid is also described by a polynomial expression in the coordinates x, y and z. In order to demonstrate the accuracy of the approach, natural frequencies are given for both a two- and three-layered spherical shell and for a homogeneous hollow cylinder, as computed using the present approach, and are compared with those obtained using an exact solution. Results are then given for a number of two- and three-layered cylinders and, to demonstrate the versatility of the approach, natural frequencies are given for a five-layered cantilevered beam with a central circular hole as well as for a number of composite solids of more general shape. 相似文献
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通过分析膨胀套在实际使用产生滑移受阻现象、卡死现象原因的实质,并在分析产生问题原因的基础上提出了改进措施即:增加导向机构。 相似文献
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设计了磨粉机快辊轴承座的加工工艺和具体的工装夹具.利用卧式加工中心加工磨粉机快辊轴承座,辅以能够高效快速夹紧的夹具,既可以保证加工精度,又能够提高加工效率. 相似文献
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一种涡旋压缩机径向随变机构的设计 总被引:1,自引:0,他引:1
详细介绍了运用随变原理设计的一种新型径向密封机构的结构特点,工作原理及主要参数的确定方法,该机构可补偿由于涡旋体加工精度不高而造成的功率损失,适用于涡旋压缩机的批量生产。 相似文献
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本文以某些积算和双笔记录仪产品为例说明由于仪表功能设计的不合理或选型不当,影响了仪表的正常使用,制造厂和用户应关注这类问题。 相似文献
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V. P. Dragunov E. G. Kostsov 《Optoelectronics, Instrumentation and Data Processing》2009,45(3):234-242
Specific features of operation of one- and two-capacitor microelectromechanical converters (MEMC) of energy of mechanical microscopic vibrations into electric energy with a modulated electrode-gap magnitude and with allowance for the mutual influence of electrical and elastic forces are analyzed, and the characteristics of these two devices are compared. The main factors restricting the increase in MEMC power are demonstrated to be the effects of “collapsing” and the condition of conservation of positive rigidity of the system. Expressions for estimating the limiting MEMC parameters are derived. The possibility of electrical energy generation in the presence of “real“ sources of wide-spectrum microscopic vibrations is considered. 相似文献
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针对目前市场对工业设计人才的需求,本文论述了我校在工业设计教育方面的改革措施,着重介绍了我校工业设计教育在软件和硬件方面所进行的一系列的改革。 相似文献