The unique properties of carbon quantum dots （CQDs） make them promising materials in many ？elds. Herein, we present a facile method for the preparation of photo-luminescent CQDs using humins as the carbon precursor...The unique properties of carbon quantum dots （CQDs） make them promising materials in many ？elds. Herein, we present a facile method for the preparation of photo-luminescent CQDs using humins as the carbon precursor for the purpose of providing a high value-added solution for this “biomass conversion process waste”. The structure of the CQDs was analyzed, and the effects of reaction temperature and time on the CQDs’ ？uorescence were investigated. The results showed that humins were effectively carbonized during the reaction. The ？uorescence intensity of humin-based CQDs initially increased with reaction temperature and time, and subsequently decreased beyond 200℃ and 4 h. Polyaromatic structures and hydrophilic groups such as O-H, C-O, -COOH and C==O groups exist in the CQDs. The humin-based CQDs have the dimension of 3~7 nm with an average size of about 5.5 nm. The highest emission intensity of blue/cyan ？uorescence light at 440 nm is achieved on the excitation with UV light at the wavelength of 330 nm.展开更多
＂Without an appropriate research setting, a study cannot be qualified as a reasonable piece＂, this notion is manifested in the methodological polices. In this research, we attempt to examine previous studies within ...＂Without an appropriate research setting, a study cannot be qualified as a reasonable piece＂, this notion is manifested in the methodological polices. In this research, we attempt to examine previous studies within the scope of technology evolution and market perception in telecommunication industry through extracting research structures, methodologies, corresponding variables, and processing methods. A general process of social scientific research is adopted to analyze eighty-four selected papers; and simultaneously, the framework for doing this analysis is established, as well. In this manner, we inspect the subjects and the issues in these papers according to product types, academic domains, and divisions of technological evolution （from 1G to 4G）. Then, their research designs are anatomized into the key dimensions of general research conventions. This research eventually provides an entire picture of a research scenario for mobile telecommunication industry; and apparently, this framewbrk can help scholars to establish specific tendencies for academic scenarios in future research plans. Also, we propose the main streams and emerging issues can be expected to engage in the future within both theacademic and the operational fields.展开更多
Teaching and research universities cultivate innovative talents that should have the following characteristics： a strong curiosity and thirst for knowledge, strong ability of self-learning and exploration. They shoul...Teaching and research universities cultivate innovative talents that should have the following characteristics： a strong curiosity and thirst for knowledge, strong ability of self-learning and exploration. They should primarily get engaged in applied basic research, focus on knowledge development and operational needs of the basic technology for logic systems, and acquire subject knowledge and expertise, technological innovation. They should have a good moral training, be able to work or live together with others; have good health and good human qualities, be able to take hard work. For the purposes of teaching and Research University, it is to foster innovative talents, we must adhere to the fundamental status of undergraduate teaching, and gradually promote the study of teaching; we must adhere to the path of industry-university cooperation; students in general education system must be established.展开更多
基金supported by the Research Project for Hot Tracking Items of Beijing Forestry University(2017BLRD03)the National Natural Science Foundation of China(51603012)Beijing Municipal Natural Science Foundation(6182031)
文摘The unique properties of carbon quantum dots （CQDs） make them promising materials in many ？elds. Herein, we present a facile method for the preparation of photo-luminescent CQDs using humins as the carbon precursor for the purpose of providing a high value-added solution for this “biomass conversion process waste”. The structure of the CQDs was analyzed, and the effects of reaction temperature and time on the CQDs’ ？uorescence were investigated. The results showed that humins were effectively carbonized during the reaction. The ？uorescence intensity of humin-based CQDs initially increased with reaction temperature and time, and subsequently decreased beyond 200℃ and 4 h. Polyaromatic structures and hydrophilic groups such as O-H, C-O, -COOH and C==O groups exist in the CQDs. The humin-based CQDs have the dimension of 3~7 nm with an average size of about 5.5 nm. The highest emission intensity of blue/cyan ？uorescence light at 440 nm is achieved on the excitation with UV light at the wavelength of 330 nm.
文摘＂Without an appropriate research setting, a study cannot be qualified as a reasonable piece＂, this notion is manifested in the methodological polices. In this research, we attempt to examine previous studies within the scope of technology evolution and market perception in telecommunication industry through extracting research structures, methodologies, corresponding variables, and processing methods. A general process of social scientific research is adopted to analyze eighty-four selected papers; and simultaneously, the framework for doing this analysis is established, as well. In this manner, we inspect the subjects and the issues in these papers according to product types, academic domains, and divisions of technological evolution （from 1G to 4G）. Then, their research designs are anatomized into the key dimensions of general research conventions. This research eventually provides an entire picture of a research scenario for mobile telecommunication industry; and apparently, this framewbrk can help scholars to establish specific tendencies for academic scenarios in future research plans. Also, we propose the main streams and emerging issues can be expected to engage in the future within both theacademic and the operational fields.
文摘Teaching and research universities cultivate innovative talents that should have the following characteristics： a strong curiosity and thirst for knowledge, strong ability of self-learning and exploration. They should primarily get engaged in applied basic research, focus on knowledge development and operational needs of the basic technology for logic systems, and acquire subject knowledge and expertise, technological innovation. They should have a good moral training, be able to work or live together with others; have good health and good human qualities, be able to take hard work. For the purposes of teaching and Research University, it is to foster innovative talents, we must adhere to the fundamental status of undergraduate teaching, and gradually promote the study of teaching; we must adhere to the path of industry-university cooperation; students in general education system must be established.
