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91.
92.
马勇 《重庆大学学报(英文版)》2003,2(1)
1. Introduction SnO2 is an n-type semiconductor with rutile crystal structure and with a wide band gap of about 3.6 eV. SnO2 has a wide range of applications as photo-detectors, heat mirrors, transparent electrodes for solar cells, conductive filler, thick resistors, catalysts and gas sensors. One of the most important applications of SnO2 lies in gas sensors [1]. SnO2 gas sensors have been attracting much attention [2-5] because of their many advantages over current technologies for detect… 相似文献
93.
杨世国 《重庆大学学报(英文版)》2005,4(1):55-58
1 Stewart formula and inequalities for a simplex Given a triangle ABC, suppose that , ,a bw w and cw are respectively the lengths of the angle bisectors of ?ABC, a, b and c are the lengths of the sides of ?ABC. The well-known Stewart’s formula for a triangle is proved as follows 222222222,( ),( ).( )abca bcw bc b cab cw ac a cabcw ab a b? = ?? +??? = ?? +??? = ? +?? (1) Let 1 2 1n nA A A? += be an n-dimensional simplex in the n-dimensional Euclidean space nE , V be the volume of ;n? kF… 相似文献
94.
李中恢 《宁波教育学院学报》2006,8(4):71-72,79
对于正多边形、圆、旋转变换、等腰直角三角形等有关平面几何问题,用复数法来求解或求证显得较为简捷方便。 相似文献
95.
Although the use of dynamic software in high school mathematics in the United States has emerged as a research topic, little research has been conducted on how teachers integrate new software in relation to at-home technology networks. Interviews with eight mathematics teachers from four North Carolina counties participating in 1:1 laptop initiatives are analyzed to trace similar decision-making themes, including Internet access, laptop availability, software use, and teacher training. This article outlines how current technologies in classrooms were critically examined by the teachers and how network connectivity impressions affected hardware and software use. 相似文献
96.
游士琴 《淮南职业技术学院学报》2003,3(1):63-65
以机械工程中的近似取代为基点,运用微分几何中的等距变换理论为工具,建立起以渐开线为齿廓曲线的螺旋锥齿轮近似齿廓方程。 相似文献
97.
向冬媛 《昭通师范高等专科学校学报》2002,24(2):61-63
在初中几何教学中 ,要注重数学思想和方法的引导 ,充分激励和发挥学生学习的积极性 ,加强图形教学 ,通过“一题多解、一题多变”帮助学生开拓思维、提高能力 . 相似文献
98.
The purpose of this study was to analyse associations between lean soft tissue (LST), a surrogate of skeletal muscle mass and key fracture-related geometric characteristics of the proximal femur. Moreover, we examined the role that muscle played on the proximal femur geometry in response to physical activity (PA). Participants were 83 young adults. Leg LST (exposure) was assessed by dual energy X-ray absorptiometry (DXA). Proximal femur geometry was derived from a left hip DXA scan. Geometric variables (outcomes) included the femoral neck axis length (FNAL), the femoral neck width (FNW), the neck–shaft angle and FNW|FNAL (an index of robustness). PA was evaluated by accelerometry. Linear regression was used to analyse relationships. Additional exposure variables included body height and mass. In males, leg LST explained 17.4% of variation in FNAL (P < 0.001) and 15% in FNW (P = 0.015). In females, it explained 8.8% of the variance in FNAL (P = 0.020). Associations remained significant in males, but not in females, when vigorous PA was added to the models. These results suggest that public health approaches to promote PA may be particularly important in females since vigorous PA seems to convey advantages in femur geometry and consequently in bone strength. 相似文献
99.
Aiming at the problem of air-cooled condenser output limit,a spray humidification system was presented to reduce the inlet air temperature.The pressure atomizing nozzle TF8 was chosen for inlet air spr... 相似文献
100.
John Cockcroft 《Journal of sports sciences》2016,34(4):321-329
This study describes foot positioning during the final two steps of the approach to the ball amongst professional rugby goal-kickers. A 3D optical motion capture system was used to test 15 goal-kickers performing 10 goal-kicks. The distance and direction of each step, as well as individual foot contact positions relative to the tee, were measured. The intra- and inter-subject variability was calculated as well as the correlation (Pearson) between the measurements and participant anthropometrics. Inter-subject variability for the final foot position was lowest (placed 0.03 ± 0.07 m behind and 0.33 ± 0.03 m lateral to the tee) and highest for the penultimate step distance (0.666 ± 0.149 m), performed at an angle of 36.1 ± 8.5° external to the final step. The final step length was 1.523 ± 0.124 m, executed at an external angle of 35.5 ± 7.4° to the target line. The intra-subject variability was very low; distances and angles for the 10 kicks varied per participant by 1.6–3.1 cm and 0.7–1.6°, respectively. The results show that even though the participants had variability in their run-up to the tee, final foot position next to the tee was very similar and consistent. Furthermore, the inter- and intra-subject variability could not be attributed to differences in anthropometry. These findings may be useful as normative reference data for coaching, although further work is required to understand the role of other factors such as approach speed and body alignment. 相似文献