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This study employed a case-study approach to reveal how an ability to think with mental models contributes to differences
in students’ understanding of molecular geometry and polarity. We were interested in characterizing features and levels of
sophistication regarding first-year university chemistry learners’ mental modeling behaviors while the learners were solving
problems associated with spatial information. To serve this purpose, we conducted case studies on nine students who were sampled
from high-scoring, moderate-scoring, and low-scoring students. Our findings point to five characteristics of mental modeling
ability that distinguish students in the high-, moderate-, and low-ability groups from one another. Although the levels of
mental modeling abilities have been described in categories (high, moderate, and low), they can be thought of as a continuum
with the low-ability group reflecting students who have very limited ability to generate and use mental models whereas students
in the high-ability group not only construct and use mental models as a thinking tool, but also analyze the problems to be
solved, evaluate their mental models, and oversee entire mental modeling processes. Cross-case comparisons for students with
different levels of mental modeling ability indicate that experiences of generating and manipulating a mental model based
on imposed propositions are crucial for a learner’s efforts to incorporate content knowledge with visual-spatial thinking
skills. This paper summarizes potential factors that undermine learners’ comprehension of molecular geometry and polarity
and that influence mastery of this mental modeling ability. 相似文献
63.
Marcus J.C. Lee David G. Lloyd Brendan S. Lay Jacqueline A. Alderson 《Journal of sports sciences》2019,37(10):1123-1128
Increasing knee stability via appropriate muscle activation could reduce anterior cruciate ligament (ACL) injury risk during unplanned sidestepping. High-level athletes may activate their knee muscles differently from low-level athletes when responding to quasi-game realistic versus non game-realistic stimuli. Eleven high-level and 10 low-level soccer players responded to a non game-realistic arrow-planned condition (AP), a quasi game-realistic one-defender scenario (1DS) and two-defender scenario (2DS), and an arrow-unplanned condition (AUNP), that imposed increasing time constraints to sidestep. Activation from eight knee muscles during sidestepping was measured during pre-contact and weight-acceptance. Knee flexor-extensor co-activation ratios were established. Muscle activation levels increased by approximately 27% solely in the 1DS in both sidestepping phases. In the 2DS, the shift from a flexor dominant co-activation strategy in pre-contact toward extensor dominance in weight-acceptance commenced earlier for the high-level players. Quasi game-realistic information allowed for anticipatory increases in knee muscle activation regardless of expertise levels but only when the time demands to respond were low (1DS). High-level players were better at interpreting complex game-realistic information (2DS) to activate their knee extensors earlier in preparation for single-leg landing during weight-acceptance. 相似文献
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We assessed the net forces created when towing swimmers while gliding and kicking underwater to establish an appropriate speed for initiating underwater kicking, and the most effective gliding position and kicking technique to be applied after a turn. Sixteen experienced male swimmers of similar body shape were towed by a motorized winch and pulley system. A load cell measured net force (propulsive force - drag force) at speeds of 1.6, 1.9, 2.2, 2.5 and 3.1 m x s(-1). At each speed, the swimmers performed a prone streamline glide, a lateral streamline glide, a prone freestyle kick, a prone dolphin kick and a lateral dolphin kick. A two-way repeated-measures analysis of variance revealed significant differences between the gliding and kicking conditions at different speeds. The results demonstrated an optimal range of speeds (1.9 to 2.2 m x s(-1)) at which to begin underwater kicking to prevent energy loss from excessive active drag. No significant differences were found between the prone and lateral streamline glide positions or between the three underwater kicking techniques. Therefore, there appears to be no significant advantage in using one streamlining technique over another or in using one kicking style over another. 相似文献
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Language disabilities in men of eminence 总被引:3,自引:3,他引:0
Lloyd J. Thompson M.D. 《Annals of dyslexia》1969,19(1):113-120
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