It is generally believed in academia that there are two theoretical explanations of tunneling and financing advantage for the creation of pyramidal structure. However, there is no definitive conclusion on which explan...It is generally believed in academia that there are two theoretical explanations of tunneling and financing advantage for the creation of pyramidal structure. However, there is no definitive conclusion on which explanation holds sway. Based on non-equilibrium panel data of seven years between 2004 and 2010, this empirical study uses the product market competition variables of ＂inter-sector competition＂ and ＂intra-sector competition＂ and the hierarchy and complexity of pyramidal structure, examines the correlation between pyramidal structure of Chinese private manufacturing listed firms and product market competition and patterns of change, and reveals the major causes of pyramidal structure. Empirical result indicates that, for Chinese private manufacturing listed companies, there is a significant negative correlation between product market competition and the hierarchy and complexity of pyramidal structure, which indicates that the creation of pyramidal structure has a preference on tunneling by controlling shareholders. On the basis of further considerations on corporate tunneling and financing restraint categorization, high-tunneling firms and firms with low financing restraint demonstrate significant tunneling motivations; low-tunneling firms and firms with high financing restraint demonstrate significant effect of financing advantage, which further testifies both theoretical explanations for the creation of pyramidal structure. Conclusions of these studies have not only enriched and supplemented relevant studies on the root causes for the creation of pyramidal structure by Chinese private business groups, but provide practical support for firms to make correct and effective use of pyramidal structure as well.展开更多
Purpose： The aims of this study were to assess differences of limb symmetry index （LSI） in strength- and coordination-related tasks between high-level, competitive, noninjured ski racers of different age-related pe...Purpose： The aims of this study were to assess differences of limb symmetry index （LSI） in strength- and coordination-related tasks between high-level, competitive, noninjured ski racers of different age-related performance levels and to prospectively assess limb differences as a possible risk factor for traumatic and overuse injury in youth ski racers. Methods： The study （Study 1） included 285 high-level competitive ski racers （125 females, 160 males） of 3 age-related performance levels and based on the school system： 95 youth （10-14 years, secondary modem school）, 107 adolescent （15-19 years, grammar school）, and 83 elite athletes （20-34 years）. To investigate the second aim （Study 2）, 67 of the 95 youth athletes were included and any traumatic or overuse injuries were prospectively recorded over 2 seasons. All athletes performed 4 unilateral tests （strength related： one-leg counter movement jump （OL-CMJ） and one-leg isometric/isokinetic press strength test （OL-ILS）; coordination related： one-leg stability test （OL-ST） and one-leg speedy jump test （OL-SJ））. The LSI was calculated by dividing the dominant leg by the nondominant leg and multiplying by 100. Kruskal-Wallis H tests and binary logistic regression analyses were conducted. Results： There were significant differences between the LSI of the 3 age-related performance-level groups only in the strength-related tests： the OL-CMJ （X^2（2, 285） = 9.09; p = 0.01） and the OL-ILS （X^2（2,285） = 14.79; p 〈 0.01）. The LSI for OL-ILS was found to be a significant risk factor for traumatic injury in youth ski racers （Wald = 7.08; p 〈 0.01）. No significant risk factors were found for overuse injuries. Conclusion： Younger athletes display slightly greater LSI values only in the strength-related tests. The cut-off value of limb differences of 〈 10% for return to sport decisions seems to be appropriate for elite athletes, but for youth and adolescent athletes it has to be critically discussed. It seems to be necessary to define thresholds based on specific performance tasks （strength vs. coordination related） rather than on generalizations, and age-related performance levels must be considered. Limb differences in unilateral leg extension strength represent a significant injury risk factor in youth ski racers.2018 Published by Elsevier B.V. on behalf of Shanghai University of Sport. This is an open access article under the CC BY-NC-ND license. （http：//creativecommons.org/licenses/by-nc-nd/4.0/）.展开更多
This paper summarized the three things included in concept of core-competitiveness： integrative ability, core technology and core product. It reviewed main factors for increasing core-competitiveness, which include c...This paper summarized the three things included in concept of core-competitiveness： integrative ability, core technology and core product. It reviewed main factors for increasing core-competitiveness, which include core technology, resource integration, information exchange and strategic alliance establishment. It studied the wildly used indicators in core-competitiveness assessment model, such as financial status, business management, technology innovation and enterprise culture. Through case study in China Railway Jiujiang Bridge Engineering Co.Ld, the writer got the conclusion that Chinese Railway and Bridge enterprises should focus on industrial integration and innovation to enhance core-competitiveness.展开更多
This paper summarizes the encrgy consumption of rail transit and the current situation of energy saving. Then it puts forward a number of policy support measures on the technology management from several aspects, such...This paper summarizes the encrgy consumption of rail transit and the current situation of energy saving. Then it puts forward a number of policy support measures on the technology management from several aspects, such as the raft line, traction power supply, energy-saving mode and so on The related research helps urban rail transit enterprises save energy consumption, reduce costs to improve their market competitiveness, as well as to promote the enterprises to fulfill social responsibility and carry out the sustainable development idea.展开更多
Photocatalytic reduction of carbon monoxide(CO)is a promising route to the production of high-value chemicals and fuels,as a supplement to high energy-input Fischer-Tropsch synthesis(FTS)and a key step in direct photo...Photocatalytic reduction of carbon monoxide(CO)is a promising route to the production of high-value chemicals and fuels,as a supplement to high energy-input Fischer-Tropsch synthesis(FTS)and a key step in direct photo/electro-reduction CO_(2) to multi-carbon products.However,many current research efforts for high-efficiency FTS/CO_(2) reduction mainly focus on the metal-based catalysts,while metal-free and solar-driven photocatalysts are rarely explored.Here,by means of Lewis acid sites,a metal-free composite photocatalyst for CO reduction,namely boron(B)doped-graphene/g-C_(3)N_(4) heterostructure,is proposed.First-principles calculations show that the dopants(B)as catalytic sites can effectively capture and activate CO molecules and reduce CO to CH_(3)OH and CH_(4) in different doping content.It is worth noting that C_(2) products,i.e.,C_(2)H_(5)OH,can be produced with low free energy barriers on paradoped graphene/g-C_(3)N_(4).Meanwhile,the competitive hydrogen evolution reaction(HER)can be greatly suppressed,leading to the high selectivity of CO reduction.Moreover,the formation of a built-in electric field in heterostructure enhances the separation of photogenerated electrons and holes,which further accelerates the transmission of photogenerated electrons to the catalytic sites and improves the reaction efficiency.Overall,this work not only proposes a new strategy from a new perspective to solve problems of high energy consumption and low selectivity of FTS,but also provides a tandem strategy to solve problems of CO_(2) to multi-carbon products.展开更多
文摘It is generally believed in academia that there are two theoretical explanations of tunneling and financing advantage for the creation of pyramidal structure. However, there is no definitive conclusion on which explanation holds sway. Based on non-equilibrium panel data of seven years between 2004 and 2010, this empirical study uses the product market competition variables of ＂inter-sector competition＂ and ＂intra-sector competition＂ and the hierarchy and complexity of pyramidal structure, examines the correlation between pyramidal structure of Chinese private manufacturing listed firms and product market competition and patterns of change, and reveals the major causes of pyramidal structure. Empirical result indicates that, for Chinese private manufacturing listed companies, there is a significant negative correlation between product market competition and the hierarchy and complexity of pyramidal structure, which indicates that the creation of pyramidal structure has a preference on tunneling by controlling shareholders. On the basis of further considerations on corporate tunneling and financing restraint categorization, high-tunneling firms and firms with low financing restraint demonstrate significant tunneling motivations; low-tunneling firms and firms with high financing restraint demonstrate significant effect of financing advantage, which further testifies both theoretical explanations for the creation of pyramidal structure. Conclusions of these studies have not only enriched and supplemented relevant studies on the root causes for the creation of pyramidal structure by Chinese private business groups, but provide practical support for firms to make correct and effective use of pyramidal structure as well.
文摘Purpose： The aims of this study were to assess differences of limb symmetry index （LSI） in strength- and coordination-related tasks between high-level, competitive, noninjured ski racers of different age-related performance levels and to prospectively assess limb differences as a possible risk factor for traumatic and overuse injury in youth ski racers. Methods： The study （Study 1） included 285 high-level competitive ski racers （125 females, 160 males） of 3 age-related performance levels and based on the school system： 95 youth （10-14 years, secondary modem school）, 107 adolescent （15-19 years, grammar school）, and 83 elite athletes （20-34 years）. To investigate the second aim （Study 2）, 67 of the 95 youth athletes were included and any traumatic or overuse injuries were prospectively recorded over 2 seasons. All athletes performed 4 unilateral tests （strength related： one-leg counter movement jump （OL-CMJ） and one-leg isometric/isokinetic press strength test （OL-ILS）; coordination related： one-leg stability test （OL-ST） and one-leg speedy jump test （OL-SJ））. The LSI was calculated by dividing the dominant leg by the nondominant leg and multiplying by 100. Kruskal-Wallis H tests and binary logistic regression analyses were conducted. Results： There were significant differences between the LSI of the 3 age-related performance-level groups only in the strength-related tests： the OL-CMJ （X^2（2, 285） = 9.09; p = 0.01） and the OL-ILS （X^2（2,285） = 14.79; p 〈 0.01）. The LSI for OL-ILS was found to be a significant risk factor for traumatic injury in youth ski racers （Wald = 7.08; p 〈 0.01）. No significant risk factors were found for overuse injuries. Conclusion： Younger athletes display slightly greater LSI values only in the strength-related tests. The cut-off value of limb differences of 〈 10% for return to sport decisions seems to be appropriate for elite athletes, but for youth and adolescent athletes it has to be critically discussed. It seems to be necessary to define thresholds based on specific performance tasks （strength vs. coordination related） rather than on generalizations, and age-related performance levels must be considered. Limb differences in unilateral leg extension strength represent a significant injury risk factor in youth ski racers.2018 Published by Elsevier B.V. on behalf of Shanghai University of Sport. This is an open access article under the CC BY-NC-ND license. （http：//creativecommons.org/licenses/by-nc-nd/4.0/）.
文摘This paper summarized the three things included in concept of core-competitiveness： integrative ability, core technology and core product. It reviewed main factors for increasing core-competitiveness, which include core technology, resource integration, information exchange and strategic alliance establishment. It studied the wildly used indicators in core-competitiveness assessment model, such as financial status, business management, technology innovation and enterprise culture. Through case study in China Railway Jiujiang Bridge Engineering Co.Ld, the writer got the conclusion that Chinese Railway and Bridge enterprises should focus on industrial integration and innovation to enhance core-competitiveness.
文摘This paper summarizes the encrgy consumption of rail transit and the current situation of energy saving. Then it puts forward a number of policy support measures on the technology management from several aspects, such as the raft line, traction power supply, energy-saving mode and so on The related research helps urban rail transit enterprises save energy consumption, reduce costs to improve their market competitiveness, as well as to promote the enterprises to fulfill social responsibility and carry out the sustainable development idea.
基金supported by the National Natural Science Foundation of China(22033002,21525311,21773027,21703032,and 21973011)the China Postdoctoral Science Foundation(2020M681450)。
文摘Photocatalytic reduction of carbon monoxide(CO)is a promising route to the production of high-value chemicals and fuels,as a supplement to high energy-input Fischer-Tropsch synthesis(FTS)and a key step in direct photo/electro-reduction CO_(2) to multi-carbon products.However,many current research efforts for high-efficiency FTS/CO_(2) reduction mainly focus on the metal-based catalysts,while metal-free and solar-driven photocatalysts are rarely explored.Here,by means of Lewis acid sites,a metal-free composite photocatalyst for CO reduction,namely boron(B)doped-graphene/g-C_(3)N_(4) heterostructure,is proposed.First-principles calculations show that the dopants(B)as catalytic sites can effectively capture and activate CO molecules and reduce CO to CH_(3)OH and CH_(4) in different doping content.It is worth noting that C_(2) products,i.e.,C_(2)H_(5)OH,can be produced with low free energy barriers on paradoped graphene/g-C_(3)N_(4).Meanwhile,the competitive hydrogen evolution reaction(HER)can be greatly suppressed,leading to the high selectivity of CO reduction.Moreover,the formation of a built-in electric field in heterostructure enhances the separation of photogenerated electrons and holes,which further accelerates the transmission of photogenerated electrons to the catalytic sites and improves the reaction efficiency.Overall,this work not only proposes a new strategy from a new perspective to solve problems of high energy consumption and low selectivity of FTS,but also provides a tandem strategy to solve problems of CO_(2) to multi-carbon products.
