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洞庭湖水质变化趋势的研究 总被引：6，自引：0，他引：6
以洞庭湖1992-2010年系列监测资料为依据,对洞庭湖19年的整体水质情况、富营养化状况以及主要污染指标进行了评价分析。结果表明:洞庭湖水质污染以氮磷污染为主,水体状况呈逐渐恶化的趋势,富营养化程度逐年加剧。2007年对洞庭湖流域进行整治后,水体中化学需氧量降低,但水体总氮和总磷浓度仍呈上升趋势,致使洞庭湖水体中叶绿素a含量和浮游植物数量显著增加。 相似文献
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The purpose of this study was to examine the three-dimensional movement profile of the blade during a stationary slap shot,
as a function of player skill level. A total of 15 subjects participated; eight were classified as elite and the remaining
seven were recreational. Performances were evaluated by simultaneously recording the movements of the stick’s lower shaft
and blade with high-speed video (1000 Hz), the time of stick-ground contact with two uniaxial forceplates and time of blade-puck
contact with a uniaxial accelerometer mounted within the puck. Data were analysed with a two-way MANOVA for several dependent
variables including linear kinematics, temporal phase data and global angles. The results indicated that skill level affected
blade kinematics, with elite shooters tending to alter timing parameters (i.e. phase length), magnitude of linear variables
(i.e. displacement, etc.) and the overall blade orientation to achieve a higher velocity slap shot. These analyses identified
a unique ‘rocker’ phase within the execution of the slap shot in both groups. 相似文献
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Réginald Savard Marcelle Gingras Michel Turcotte 《International Journal for Educational and Vocational Guidance》2002,2(3):173-191
Clients walking into resources centers are experiencing difficulty locating relevant information and using it effectively in the decision-making process. Many affective, cognitive or technical constraints are influencing clients when interacting with the information and new technologies. What perspectives should the intervention be concerned with as regards the information and decision-making process? How can the human and physical resources be used in an optimal manner to meet information needs associated with the different stages of people's lives? The specificity of these different components and the circular nature of their dynamic form the backdrop for this study. 相似文献
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Jason Turcotte 《Mass Communication and Society》2013,16(3):239-258
Mediated debates provide audiences with invaluable campaign information, and the public does in fact learn from debate exposure. Debates have undergone format changes over the years, but their ability to attract a mass audience remains constant. The way news media cover U.S. presidential elections has also evolved; increasing commercial pressures drive heightened emphasis on infotainment, soft news, and electoral strategy—often at the expense of hard news and policy content. Yet little is known about the content of agendas that news professionals set in presidential debates. Through a quantitative content analysis, this study examines 20 years of general election debate questions to determine whether the commercial news values common in today's campaign coverage also influence debate agendas. The findings presented herein suggest not only the presence of these news values in debate agendas but that format and moderator also wield a degree of influence over the content of debate questions. 相似文献
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Yannick Michaud-Paquette Patrick Magee David Pearsall René Turcotte 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(1):12-21
The purpose of this study was to identify joint angular kinematics that corresponds to shooting accuracy in the stationary ice hockey wrist shot. Twenty-four subjects participated in this study, each performing 10 successful shots on four shooting targets. An eight-camera infra-red motion capture system (240 Hz), along with passive reflective markers, was used to record motion of the joints, hockey stick, and puck throughout the performance of the wrist shot. A multiple regression analysis was carried out to examine whole-body kinematic variables with accuracy scores as the dependent variable. Significant accuracy predictors were identified in the lower limbs, torso and upper limbs. Interpretation of the kinematics suggests that characteristics such as a better stability of the base of support, momentum cancellation, proper trunk orientation and a more dynamic control of the lead arm throughout the wrist shot movement are presented as predictors for the accuracy outcome. These findings are substantial as they not only provide a framework for further analysis of motor control strategies using tools for accurate projection of objects, but more tangibly they may provide a comprehensive evidence-based guide to coaches and athletes for planned training to improve performance. 相似文献
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目前在工程中，临时支撑卸载过程的分析和模拟主要有两种方法．利用这两种方法分别建立临时支撑卸载的有限元模型并在ANSYS中对这两个模型的卸载过程进行模拟和分析，从理论上和有限元分析结果上对这两种方法进行了探讨． 相似文献
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技术创新网络的扩张与核心企业的成长相互促进,相互决定,形成了复杂的共生演化关系。以知识为基础的企业,必须在各个层次上构建网络,维护多层交互作用,加强与其他企业的合作。从企业间关系耦合的视角,分析了技术创新网络中核心企业的形成过程,提出技术创新网络中各结点企业间的技术合作是一种相互间的知识协同。研究发现,企业间技术交流的过程就是企业间知识匹配——知识流动——知识控制的过程,而技术创新网络中的企业结点也是通过这三种状态,使自身能力得到提升,进而影响到与其他结点的知识协同,并最终成长为核心企业。 相似文献
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P. Morrison D. J. Pearsall R. A. Turcotte K. Lockwood D. L. Montgomery 《Sports Engineering》2005,8(2):91-97
The purpose of this study was to investigate the effect of skate blade hollow on oxygen consumption during forward skating
on a treadmill. Varsity level female hockey players (n = 10, age = 21.7 years) performed skating tests at three blade hollows [0.25 in (6.35 mm), 0.50 in (12.7 mm), and 0.75 in
(19.05 mm)]. The subjects skated for four minutes at three submaximal velocities (12, 14 and 16 km h−1), separated by five minutes of passive recovery. In addition, a VO2max test was performed on the day that the subjects skated at the 0.50 in hollow. The VO2max test commenced at 14 km h−1 and increased by 1 km h−1 each minute until volitional exhaustion was achieved. Four variables were measured for each skating bout, volume of gas expired
(V
E), volume of oxygen consumed (VO
2), heart rate (HR) and rating of perceived exertion (RPE). No significant differences (p < 0.05) were found in any of the four test variables (V
E, VO2, HR, RPE) across the three skate hollows. These results show that when skating on a treadmill at submaximal velocities, skate
blade hollow has no significant effect onV
E, VO2, HR or RPE. 相似文献
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根据TRS理论计算了^157Tm核的位能面，并预言了其三轴超形变的存在,计算的结果与文献上的结果符合得较好。 相似文献