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91.
R. Quintanilla 《Continuum Mechanics and Thermodynamics》2001,13(6):415-420
Received August 29, 2001 / Published online November 15, 2001 相似文献
92.
Despite mathematics educators’ research into more effective modes of teaching, lecture is still the dominant mode of instruction in undergraduate mathematics courses. Surveys suggest this is because most mathematicians believe this is the best way to teach. This paper answers a call by mathematics education researchers to explore mathematicians’ needs and goals concerning teaching. We interviewed eight mathematicians about findings in the mathematics education research literature concerning common pedagogical practices of instructors of advanced mathematics classes: “chalk talk,” the presentation of formal and informal content, and teacher questioning. We then analyzed the responses for resources, orientations, and goals that might influence the participants to engage in these practices. We describe how participants believed common lecturing practices allowed them to achieve their goals and aligned with their orientations. We discuss these findings in depth and consider what implications they may have for researchers that aim to change mathematicians’ teaching practices. 相似文献
93.
94.
The growing social awareness and consequent concern for the environment has driven environmental analytical chemistry to a position of great prominence. In recent times, this position has translated into taking advantage of the great benefits provided by cloud computing and the Internet of Things (IoT), which are especially appropriate when devices such as chemical sensors are used. The use of such sensors is very common when in situ monitoring of environmental parameters is performed, but until recently, it was limited to the deployment of a small number of sensors. Currently, this approach has given way to genuine smart sensing systems (for instance, fully consolidated wireless sensor networks) that are able to provide a substantial amount of information. This type of sensor (the so-called smart sensor) is fundamentally characterized by (a) low consumption, versatility, and autonomy, (b) ease of integration with cloud solutions, (c) durability and reliability of IoT platforms and sensors, and (d) easy installation and deployment of sensor nodes. For all these reasons, and given the increasing importance and use of this type of device, a revision of the recent literature relating the development of smart sensors with environmental issues has been conducted, with major contributions being discussed, most notably those addressing the continuous in-line monitoring of water quality. 相似文献
95.
Ultrasound-assisted solvent extraction (UAE) was applied to extract underutilized Madhuca longifolia seed oil. The effect of extraction time, temperature, solvent type, solvent/sample ratio, and amplitude on the oil yield and recovery were investigated. Approximately 56.97% of oil yield and 99.54% of oil recovery were attained using mild conditions of 35 min, 35 °C, 40% amplitude, isopropanol to acetone (1:1), and solvent to sample (20 mL/g). UAE oil yield and recovery were comparable with Soxhlet extraction (SXE) whilst mechanical pressing (ME) yielded < 50% of UAE recovery. UAE does not affect the fatty acids composition (46% C18:1; 22% C16:0; 21% C18:0, 10% C18:2), and triacylglycerol profile (23% POO, 17% POS, 16% SOO, and 14% POP). Interestingly, UAE extracted oil conferred remarkably (P < 0.05) higher antioxidant capacity (IC50 of DPPH 106.60 mg/mL and ABTS 39.80 mg/mL) than SXE (IC50 of DPPH 810.40 mg/mL and ABTS 757.43 mg/mL) or ME (IC50 of DPPH 622.38 mg/mL and ABTS 392.87 mg/mL). 相似文献
96.
以平衡程序Jsolver 为基础开展了紧凑型聚变裂变混合堆先进等离子体平衡位形设计,重点研究了反剪切运行模式,并在此位形下研究了自举电流的计算、分布及份额。 相似文献
97.
A. Houmia 《Applicable analysis》2013,92(12):2559-2573
This paper deals with some problems of calculus of variation for functionals with deviating arguments. We use the direct method to establish some existence results and extend the corresponding results obtained in literature. 相似文献
98.
In this paper,we study the asymptotic behavior of solutions to a class of higher order nonlinear integro-differential equations with deviating arguments. And some properties of the oscillatory solutions are given. Our results generalize and improve the previous results. 相似文献
99.
The advanced oxidation process (AOP) for the pretreatment of model palladium catalysts has been studied. Most standard metal analysis techniques are for metal ions free of organic ligands. Spent palladium catalysts contain organic ligands that need to be removed prior to analysis. AOP uses a combination of hydrogen peroxide and UV light to generate radicals that decompose such ligands, freeing up metals for further analysis. Palladium acetate Pd(OAc)2, palladium acetylacetonate Pd(acac)2, and tris(dibenzylideneacetone)dipalladium (Pd2(dba)3) were chosen as model precious metal catalysts for investigation. AOP was found to decompose ligands in Pd(OAc)2, Pd(acac)2 and give accurate Pd(II) quantification, while ligand decomposition and oxidation of Pd(0) to Pd(II) were demonstrated in treatments involving Pd2(dba)3. The effects of solubility of the palladium complexes, continuous addition of H2O2 during AOP treatments, sample pH, concentration of H2O2, and length of UV irradiation are reported. 相似文献
100.
In this paper we prove a result on the existence and global attractivity of solutions of a nonlinear functional integral equations with deviating arguments. The investigations are placed in the Banach space of real functions defined, continuous and bounded on the real half-axis. The main tool used in consideration is a fixed point theorem of Krasnosel’skii type. A few examples illustrating the obtained results are also included. 相似文献