With the rapid development of information technology, various approaches are applied to higher education. Massive open online course (MOOC), as a recent development of distance education, emerged in 2012. Nowadays, th...
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ISBN:
(纸本)9783038352679
With the rapid development of information technology, various approaches are applied to higher education. Massive open online course (MOOC), as a recent development of distance education, emerged in 2012. Nowadays, the utilization of MOOC has become the tide of globalization among universities. The aim of this paper is to take a deep look at MOOC for weighing its pros and cons. The reasons of popularity of MOOC via introducing its brief history, key characteristic and major advantages are explained in this paper. In addition, challenges and limitations of existing MOOCs worldwide are presented though course structure, course grades and completion rate as well as several solutions to deal with them as far as possible.
The extraction of valuable metals from low-nickel matte via a calcified roasting-acid leaching process was investigated. The influences of process parameters on the extraction of metals were studied, including the roa...
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The extraction of valuable metals from low-nickel matte via a calcified roasting-acid leaching process was investigated. The influences of process parameters on the extraction of metals were studied, including the roasting temperature, roasting time and the addition of CaCO3. Under the optimum condition, 92.4% of Ni, 97.1% of Cu, 95.1% of Fe, and 91.2% of Co were recovered. In addition, the removal of iron via goethite precipitation process was studied. The results show that 99.8% of Fe could be removed by goethite process. The reaction mechanism of calcified roasting of low-nickel matte was also studied by Xrd and XRF analysis. It was shown that the formation of ferrite can be effectively inhibited by CaCO3 addition, leading to enhancement of the metal recovery.
An efficient approach for the synthesis of isonucleoside of tubercidin was described. The key step in the synthesis was the direct coupling of pyrrolo [2,3-d]pyrimidine with the cyclic sulfate of 1-deoxy-D-ribose. Thi...
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In this paper, we report an efficient total synthesis of 5-deoxytoyocamycin, which was isolated from microbial sources with excellent antitumor activity. Our synthetic strategy uses 1,2,3-triacetate-5-deoxyribose as t...
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The black tourmaline, magnesium tourmaline, and spinel were ground into powder, and the infrared radiation material was prepared by adding the ceramic powder, clay and the other material into the tourmaline powder acc...
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The black tourmaline, magnesium tourmaline, and spinel were ground into powder, and the infrared radiation material was prepared by adding the ceramic powder, clay and the other material into the tourmaline powder according to a certain proportion. The infrared radiation property was tested and analyzed, the diesel was infrared radiation activated by the composite material, and the physicochemical property of fuel oil was analyzed pre-test and post-test. The result shows that the infrared absorption spectrum of the black tourmaline of different particle size is stable. After the diesel oil was infrared radiation activated by tourmaline composite materials, the physicochemical property of diesel oil was changed, the activation energy decreased, the viscosity and surface tension of fuel oil were reduced.
Reverse leakage current (IR) is a problem that degrade electrical characteristics and power diode effective. This paper presents the parameter extraction and analysis reverse leakage current of N-type silicon power-di...
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The ion density distribution plays central roles in many interfacial phenomena and phase-transformation processes, which indirectly influences the formation, morphology and physical (or chemical) properties of the tar...
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The ion density distribution plays central roles in many interfacial phenomena and phase-transformation processes, which indirectly influences the formation, morphology and physical (or chemical) properties of the target matters. In this work, we report a simple method to visualize the ion density distribution of phosphate around a condensed phosphate phase during its formation at the air-solid interface.
The Yangtze River is a typical river basin in China. As the third largest river in the world and closely related to the life of 4 hundred million people, the Yangtze River has attracted much attention. The heavy metal...
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The Yangtze River is a typical river basin in China. As the third largest river in the world and closely related to the life of 4 hundred million people, the Yangtze River has attracted much attention. The heavy metal content of sediments is an important part to evaluate the heavy metal pollution in aquatic ecosystem. In this work, seven kinds of heavy metals including Cu, Hg, Pb, Zn, Cr, Cd and As were selected as the research objects, and the potential ecological risk index method was selected as the analysis method. Based on the results on the investigations of heavy metals in Yangtze River sediments in recent 20 years that we could find until 2016, we conducted a collection and analysis. The results showed that the potential ecological risk of these seven heavy metals in the Yangtze River Basin in the past 20 years had a low level. In addition, the ecological risk factors of Cd and Hg were significantly higher than other heavy metals, which should be paid attention in the future management and control work.
This paper presents a fault-tolerant congestion control algorithm for Internet via dynamic output feedback. The controller is designed based on adaptive technique and robust H-infinity approach. Simulation result is g...
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ISBN:
(纸本)9783038352679
This paper presents a fault-tolerant congestion control algorithm for Internet via dynamic output feedback. The controller is designed based on adaptive technique and robust H-infinity approach. Simulation result is given to verify the effectiveness of the proposed algorithm.
The results of the same modal analysis exhibit obvious diversity due to the different options of the finite element types and the modeling methods. Modal analysis was carried out on EMU aluminum alloy welded profile u...
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