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101.
Junzhen Ren Pengqing Bi Jianqi Zhang Jiao Liu Jingwen Wang Ye Xu Zhixiang Wei Shaoqing Zhang Jianhui Hou 《国家科学评论(英文版)》2021,8(8)
Developing photovoltaic materials with simple chemical structures and easy synthesis still remains a major challenge in the industrialization process of organic solar cells (OSCs). Herein, an ester substituted poly(thiophene vinylene) derivative, PTVT-T, was designed and synthesized in very few steps by adopting commercially available raw materials. The ester groups on the thiophene units enable PTVT-T to have a planar and stable conformation. Moreover, PTVT-T presents a wide absorption band and strong aggregation effect in solution, which are the key characteristics needed to realize high performance in non-fullerene-acceptor (NFA)-based OSCs. We then prepared OSCs by blending PTVT-T with three representative fullerene- and NF-based acceptors, PC71BM, IT-4F and BTP-eC9. It was found that PTVT-T can work well with all the acceptors, showing great potential to match new emerging NFAs. Particularly, a remarkable power conversion efficiency of 16.20% is achieved in a PTVT-T:BTP-eC9-based device, which is the highest value among the counterparts based on PTV derivatives. This work demonstrates that PTVT-T shows great potential for the future commercialization of OSCs. 相似文献
102.
疫情的反复,让在线教育成为中学授课的强有力支撑,但教学模式及质量控制难度也成了亟待解决的难题.PDCA循环是产品质量管控经典设计理念,更是航天工程质量管控成败的决定因素.本文结合物理教学特色,借鉴航天工程质量管理经验,对整个在线教学环节精准拆分并采用模块化设计实现,结合任务驱动的教学观念,用PDCA管理策略量化分析,为... 相似文献
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104.
Taís Rieping Guilherme Eustáquio Furtado Matheus Uba Chupel Juan C. Colado Eef Hogervorst 《Research quarterly for exercise and sport》2019,90(1):36-45
Purpose: The aim of this study was to test the effects of chair-based exercise programs on salivary stress hormones, physical fitness, and functional autonomy of institutionalized older women. Method: In total, 47 participants (80 ± 8.04 years old) were recruited and allocated into three groups: chair-based aerobic exercises (CAE, n = 19), chair-based elastic-band strength exercises (CSE, n = 15), and a control group (CG, n = 13). A 14-week exercise intervention was done for the CAE and CSE groups, two times per week, in no consecutive days. Members of the CG did not participate in any type of exercise but kept their regular lifestyle. Fear of falling, autonomy, physical fitness, salivary cortisol, and alpha-amylase levels were assessed before and after the intervention. Results: The CAE group improved upper and lower body strength, agility–dynamic balance, and autonomy, with fear of falling decreasing significantly (p < .05, moderate effect size). Both exercise groups showed a trend toward an increase in salivary alpha-amylase levels (CAE = 43%, d = .31, and CSE = 44%, d = .41). Conclusion: Both exercise programs were able to improve functional autonomy, even in elders older than 80 years of age. It might be interesting to investigate the effectiveness of combining both aerobic and strength exercises in a unique protocol. The modulation effect of exercise in the hormonal responses needs to be further explored. 相似文献
105.
Luis García-González Javier Sevil-Serrano Angel Abós Nathalie Aelterman Leen Haerens 《Physical Education & Sport Pedagogy》2019,24(4):344-358
Background: A distinction is made in Achievement Goal Theory (AGT) between task-oriented (i.e. effort, intra-individual progress, and self-comparison) and ego-oriented (i.e. inter-individual progress and normative comparison) climates. Combining insights from AGT and Self-Determination Theory (SDT), studies in the PE context have shown that a task-oriented climate positively relates to need satisfaction, although the findings regarding the motivating role of an ego-oriented climate are inconsistent. Moreover, little is known about the role of task- or ego-oriented climates in explaining experiences of basic psychological need frustration.Purpose: Grounded in AGT and SDT, the aim of the present study was to examine if experiences of basic psychological need satisfaction and need frustration can explain why task- and ego-oriented climates elicit positive and negative motivational outcomes in PE, respectively.Research design: Cross-sectional study.Method: A sample of 524 secondary school students (51.1% boys, Mage?=?14.51; SD?=?1.81) from five different secondary schools participated in this study. Students reported on their perceptions of task- and ego-oriented climates, motivational regulations, basic psychological need satisfaction, and need frustration, as well as positive and negative outcomes in PE. Structural equation modeling was used to investigate our objective.Results: We found that a task-oriented climate had a strong and positive relationship with basic psychological need satisfaction, eliciting a bright pathway to autonomous motivation and affective attitude. An ego-oriented climate was positively related to basic psychological need frustration, eliciting a dark pathway to amotivation and boredom. A negative cross-path from task-oriented climate to basic psychological need frustration was also found, while no significant cross-paths were found from ego-oriented climate to basic psychological need satisfaction.Conclusions: This study provides a better understanding of the mechanisms that explain why task- and ego-oriented climates shape students’ motivational experiences in PE lessons. It is suggested that a task-oriented climate elicits a bright pathway towards more optimal functioning, because it fosters experiences of need satisfaction and buffers against experiences of need frustration. In contrast, an ego-oriented climate is primarily positively related to feelings of need frustration and negative motivational outcomes. Practical implications for PE teacher training are discussed. 相似文献
106.
João Pedro Araújo Naves Ana Cristina Silva Rebelo Lucas Raphael Bento E Silva Maria Sebastiana Silva Rodrigo Ramirez-Campillo Robinson Ramírez-Vélez 《European Journal of Sport Science》2019,19(5):653-660
High Intensity Interval Training (HIIT) can be performed with different effort to rest time-configurations, and this can largely influence training responses. The purpose of the study was to compare the acute physiological responses of two HIIT and one moderate intensity continuous training (MICT) protocol in young men. A randomised cross-over study with 10 men [age, 28.3?±?5.5years; weight, 77.3?±?9.3?kg; height, 1.8?±?0.1?m; peak oxygen consumption (VO2peak), 44?±?11?mL.kg?1.min?1]. Participants performed a cardiorespiratory test on a treadmill to assess VO2peak, velocity associated with VO2peak (vVO2peak), peak heart rate (HRpeak) and perceived exertion (RPE). Then participants performed three protocols equated by distance: Short HIIT (29 bouts of 30s at vVO2peak, interspersed by 30s of passive recovery, 29?min in total), Long HIIT (3 bouts of 4?min at 90% of vVO2peak, interspersed by 3?min of recovery at 60% of vVO2peak, 21?min in total) and MICT (21?min at 70% of vVO2peak). The protocols were performed in a randomised order with ≥48 h between them. VO2, HRpeak and RPE were compared. VO2peak in Long HIIT was significantly higher than Short HIIT and MICT (43?±?11 vs 32?±?8 and 37?±?8?mL.kg?1.min?1, respectively, P?0.05), as well as peak HR (181?±?10 vs 168?±?8 and 167?±?11, respectively, P?0.05), and RPE (17?±?4 vs 14?±?4 and 15?±?4, respectively, P?0.05), with no difference between Short HIIT and MICT. In conclusion, Long HIIT promoted higher acute increases in VO2, HR and RPE than Short HIIT and MICT, suggesting a higher demand on the cardiorespiratory system. Short HIIT and MICT presented similar physiologic and perceptual responses, despite Short HIIT being performed at higher velocities. 相似文献
107.
Alessandro Moura Zagatto Paulo Eduardo Redkva Rodrigo Araújo Bonetti de Poli Joel Abraham Martinez González Jeniffer Zanetti Brandani Thiago Penedo 《European Journal of Sport Science》2019,19(5):645-652
The purpose of this study was to investigate the use of a single 3-min all-out maximal effort to estimate anaerobic capacity (AC) through the lactate and excess post-exercise oxygen consumption (EPOC) response methods (AC[La?]+EPOCfast) on a cycle ergometer. Eleven physically active men (age?=?28.1?±?4.0?yrs, height?=?175.1?±?4.2?cm, body mass?=?74.8?±?11.9?kg and ?O2max?=?40.7?±?7.3?mL?kg?1?min?1), participated in the study and performed: i) five submaximal efforts, ii) a supramaximal effort at 115% of intensity of ?O2max, and iii) a 3-min all-out maximal effort. Anaerobic capacity was estimated using the supramaximal effort through conventional maximal accumulated oxygen deficit (MAOD) and also through the sum of oxygen equivalents from the glycolytic (fast component of excess post-exercise oxygen consumption) and phosphagen pathways (blood lactate accumulation) (AC[La?]+EPOCfast), while during the 3-min all-out maximal effort the anaerobic capacity was estimated using the AC[La?]+EPOCfast procedure. There were no significant differences between the three methods (p?>?0.05). Additionally, the anaerobic capacity estimated during the 3-min all-out effort was significantly correlated with the MAOD (r?=?0.74; p?=?0.009) and AC[La?]+EPOCfast methods (r?=?0.65; p?=?0.029). Therefore, it is possible to conclude that the 3-min all-out effort is valid to estimate anaerobic capacity in physically active men during a single cycle ergometer effort. 相似文献
108.
Germán Carretero-Navarro Doménico Cherubini Wolfgang Taube 《European Journal of Sport Science》2019,19(5):595-602
Weighted vests are widely used to improve running economy and performance. However, it is not well-studied how running mechanics are adapted to counteract the higher peak vertical ground reaction forces (Fpeak) while running with such a device. Therefore, the present study aimed to investigate the effects of different loading conditions on running mechanics at different velocities. Thirteen subjects participated in two separate sessions one week apart. In the first session, maximal aerobic speed (MAS) was determined through a maximal incremental running test while in the second session, they were instructed to run during one minute under different loading (0%, +10% and +20% of body mass [BM]) and velocity (60%, 80% and 100% of MAS) conditions in a random order. Spatiotemporal data were recorded and then running mechanics modelled using the spring-mass model. The main results indicated that vertical and leg stiffness (Kvert and Kleg, respectively) were increased (P?.001) as velocity increased but remained unaltered (P?>?.05) when load was changed. At the same time, alterations of the running kinematics were observed such as longer contact times, reduced flight times, stride frequencies and step lengths, as well as an increase of the centre of mass dynamics. Based on these results it is assumed that runners maintain a certain stiffness level for each velocity despite different loading conditions. As a consequence, Fpeak increases and this probably causes spatiotemporal adjustments in the movement kinematics. 相似文献
109.
110.
加入WTO对中国金融业产生的积极和消极方面的影响是现实而深远的。入世对中国银行业的影响总体效应是利大于弊。为此 ,我们应积极主动地思考和采取应对措施 ,推进入世后中国银行业的稳定发展 相似文献