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排序方式: 共有6443条查询结果,搜索用时 734 毫秒
71.
72.
一种用于空气中二氧化碳现场测定的新方法于爱民,杨广德,王锐,金钦汉(吉林大学化学系,长春130023)关键词微波诱导等离子体,离子化检测器,气相色谱仪,二氧化碳二氧化碳在植物生长代谢及其生态平衡过程中起着重要作用,现场测定二氧化碳是目前农业、环境科学... 相似文献
73.
The effect of ohmic and conventional heat processing of different food products on their chemical and physical parameters
was studied. Depending on the food being analysed, parameters such as pH, total solids, ash, titratable acidity, ascorbic
acid, total sugars, total fatty acids, total phenolic compounds, and anthocyanins content were determined before and after
ohmic and conventional pasteurization techniques and the results were compared using one-way analysis of variance. In goat
milk samples treated by ohmic technology the pH value (6.58) and total fatty acids content in milk fat (86.5 mass %) were
comparable to those found in milk treated by conventional process, however, ohmically treated samples presented a lower content
of lactic acid, 0.13 %. In cloudberry jam samples treated by ohmic technology the results of some of the main parameters tested,
such as total sugar content 46.1 mass %, ascorbic acid content 2.83 mass %, and titratable acidity 6.01 mass % (as citric
acid) did not show significant differences when compared with samples treated by conventional technology.
Presented at the 33rd International Conference of the Slovak Society of Chemical Engineering, Tatranské Matliare, 22–26 May
2006. 相似文献
74.
Nicolas Le Calvez 《中国化学会会志》2002,49(4):585-592
The aim of this study was to develop an analytical method to determine the organochlorine concentrations in sediments. Combination of Microwave assisted Solvent Extraction (MASE) and capillary gas chromatography with specific detection (electron capture detector) was a viable approach for the determination of pesticides in solid matrixes. In this study, MASE development was focused on the selection of a suitable extraction solvent for all the target analytes. MASE procedure was validated by comparison with conventional methods such as Soxhlet and sonication extraction. The proposed method was then applied to determine the organochlorine insecticides concentrations in samples from Authie Bay (France). Environmental water samples were analysed and five target analytes were detected in concentrations from 0.03 to 0.56 ng/g of dry sediment. These investigations showed the accumulation and the persistency of these products in sediments in spite of the fact they were banned a few decades ago. 相似文献
75.
76.
The present paper has made a dynamic and diagnostic study of the process of explosive deepening of an extratropical cyclone over North China on April 25-26, 1983, in order to gain an insight into the physical mechanism of explosive development of cyclone over land. It turns out that this cyclone occurred in the strong baroclinic zone, and the vorticity and thermal advection triggered the initial development of the cyclone. Subsequently, as the rainfall increased, the effect of condensational heating became more and more important. During the time period of rapid intensification (from 1200GMT 25 to 0000GMT 26 April, 1983, the central surface pressure fell down from 998. 2 to 988. 3 hPa), the peak of diabatic heating profile continuously descended, leading to a rapid increase in heating amount in the lower troposphere. This condition is favorable to the explosive development of rotational circulation or vortex. The numerical simulations have further demonstrated the importance of the lowering of heating p 相似文献
77.
本文论述了WO_3薄膜氢离子敏器件的结构、原理、制备技术和测试分析。利用WO_3薄膜在H+溶液中由绝缘转化为导电特性,成功地研制成氢离子敏器件。这是一种简易而经济的微型pH敏器件技术。 相似文献
78.
O. F. Shlensky 《Journal of Thermal Analysis and Calorimetry》1993,40(3):941-947
New modifications of a contact heater are suggested for investigating thermal decomposition processes, as well as for determining
kinetic characteristics of substances under conditions of intense heating to a fixed constant temperature.
Zusammenfassung Zur Untersuchung von thermischen Zersetzungsprozessen und der Bestimmung der Reaktionskinetik von Substanzen bei intensivem Erhitzen auf vorgegebene konstante Temperaturen wird eine neue Abart von Kontakterhitzern beschrieben.相似文献
79.
80.
以巯基丙酸(MPA)为稳定剂, 利用微波辐射加热方法制备了水溶性的Cu掺杂的ZnS纳米晶. 通过改变微波条件, 可以在460~572 nm之间实现对ZnS∶Cu纳米晶发射峰位的连续调控. 通过XRD、 UV-Vis、荧光及荧光衰减对ZnS∶Cu纳米晶的结构和发光性质进行了详细探索, 并利用时间分辨荧光光谱对其发光机理进行了初步研究. 相似文献