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51.
T. LUNDGREN E. U. ENGSTR
M R. LEVI-SETTI A. LINDE J. G. NORN 《Journal of microscopy》1994,173(2):149-154
The incorporation into rat incisor dentin of two calcium isotopes, the stable 44Ca and the radioactive 45Ca, was studied using secondary ion mass spectrometry (SIMS) stepscanning and imaging, and autoradiography, respectively. The results demonstrated a time-dependent incorporation of the calcium isotopes into the mineral phase of dentin. With the SIMS step-scanning, detecting 44Ca, the ion yield was high in the odontoblasts 2 min after intravenous injection. After 10 min a marked increase in signal intensity was found at the dentin mineralization front. This result was consistent with those obtained by 45Ca autoradiography; a peak of incorporation occurred 10 min after injection of the isotope. Likewise, localization of 44Ca to the mineralization front could be demonstrated 10 min after injection by SIMS imaging. In images obtained at earlier intervals, no such increase in ion yield could be detected. The results show that the nonradioactive, stable isotope 44Ca can be used as a marker for biomineralization in a similar way to radioactive 45Ca. 相似文献
52.
Harvesting experiments revealed that immature whole mushrooms with closed veils had higher 1-octen-3-0l levels than more mature whole mushrooms with open veils. The l-octen-3-01 content of the gills was higher in immature mushrooms with closed veils, gradually decreased with maturity as the veil opened, and finally increased after the gills were well exposed. Postharvest experiments demonstrated that storage temperature influenced the activity of lipoxygenase-hydroperoxide lyase, but no differences in 1-octen-3-01 content were observed. Enzyme activity as well as 1-octen-3-01 content decreased during storage. Addition of calcium chloride to irrigation water, employed to improve quality and shelf life of fresh mushrooms, increased the amount of l-octen-3-01 immediately after harvest. 相似文献
53.
AVO属性交会图解释技术在碳酸盐岩储层预测中的应用 总被引:5,自引:1,他引:4
AVO属性交会图解释技术是通过正演模型提取AV0属性,再根据模型和实际地震数据在AVO属性交会图上的分布关系,建立储层岩性参数、含流体特征与AVO属性间的对应关系。该法以模型正演分析为基础,以地震数据AVO属性为外推控制条件,将地震、地质和测井信息紧密地结合起来,从而达到识别储层的目的。本文以川东LJZ地区飞仙关鲕滩储层为例,通过对已知钻、测井资料分析和模型正演,确定鲕滩储层的地震属性响应模式及其交会图上的分布特征,识别储层岩性和含流体性质,进而确定储层的气水界面。 相似文献
54.
碱-碳酸盐反应热力学讨论 总被引:1,自引:0,他引:1
应用热力学方法探讨了温度对碱 碳酸盐反应的影响 ,反应温度升高时 ,反应的推动力减弱。对碱与碳酸盐发生反应生成沉淀时所需碱的浓度以及温度的影响进行了讨论。 2 98K ,pH≥ 10 .6时 ,碱 碳酸盐反应能发生 ,反应温度升高 ,碱 碳酸盐反应所需碱的浓度相应增大。对氢氧化锂与碳酸盐反应可能生成碳酸锂沉淀时溶液的碱的浓度作了计算 ,2 98K ,pH≥ 13.1时 ,氢氧化锂与碳酸盐反应除生成水镁石和方解石外还能生成碳酸锂沉淀 ,反应温度升高时 ,反应生成碳酸锂沉淀所需碱的浓度变化不大 相似文献
55.
甲醇与碳酸二甲酯共沸液的分离研究进展 总被引:8,自引:0,他引:8
综述了DMC-CH_3OH二元共沸液的各种分离方法。讨论了共沸精馏和萃取精馏的工艺流程。 相似文献
56.
57.
David C. Whitehead Katherine M. Goulden Roy D. Hartley 《Journal of the science of food and agriculture》1985,36(5):311-318
The distribution of 10 nutrient elements was assessed in three fractions of herbage samples of perennial ryegrass, tall fescue, white clover and lucerne. The cell wall fraction, prepared by mechanical disintegration of undried material, contained the following proportions of the total herbage content of the major elements: N, 2.9–16.4%; P, 3.0–6.9%; S, 3.6–17.2%; Ca, 11.3–51.8%; Mg. 6.4–27.6% and K, 0.1–1.7%. Substantial though more variable proportions of the trace element cations, Fe, Mn, Zn and Cu were also present in the cell wall fraction. The extent to which the elements were soluble in water was assessed by analysis of the water-insoluble fraction prepared from freeze-dried samples of each herbage. The proportions of the total herbage content of the major elements soluble in water were: N, 30–57%; P, 80–92%; S, 35–71%; Ca, 48–69%; Mg. 65–83% and K, 90–96%. With the trace element cations the proportions soluble in water were more variable, though they were generally less than 70% of the total. The extent to which the various elements were soluble in 80% aqueous ethanol was assessed by analysis of the insoluble fraction prepared from freeze-dried materials. With each of the major elements, smaller proportions of the total herbage content were soluble in 80% ethanol than in water, which may reflect in part the lower solubility of proteins and pectin. With the trace element cations, the differences in solubility between 80% ethanol and water were generally small and inconsistent. 相似文献
58.
59.
掺镉纳米SnO2的热稳定性,电导及气敏性能 总被引:3,自引:0,他引:3
本文研究了CdO掺杂对纳米SnO2粉料的热稳定性,电导及气敏特性的影响。结果表明,以非晶状态均匀分散在SnO2颗粒表面的CdO能阻止SnO2之间的相互扩散,提高了纳米SnO2的热稳定性;固溶于SnO2昌粒中的CdO量(Cd/Sn〈0.05)很小,但对元件的电导影响显著;纳米级的晶粒尺寸(〈6nm)及CdO的掺杂大大改善了SnO2的气敏特性。 相似文献
60.
Pedro H. Scarpelli Mateus F. Pecenin Celia R. S. Garcia 《International journal of molecular sciences》2021,22(1)
Ca2+ signaling has been involved in controling critical cellular functions such as activation of proteases, cell death, and cell cycle control. The endoplasmatic reticulum plays a significant role in Ca2+ storage inside the cell, but mitochondria have long been recognized as a fundamental Ca2+ pool. Protozoan parasites such as Plasmodium falciparum, Toxoplasma gondii, and Trypanosoma cruzi display a Ca2+ signaling toolkit with similarities to higher eukaryotes, including the participation of mitochondria in Ca2+-dependent signaling events. This review summarizes the most recent knowledge in mitochondrial Ca2+ signaling in protozoan parasites, focusing on the mechanism involved in mitochondrial Ca2+ uptake by pathogenic protists. 相似文献