渭河流域上游干湿状况时空分布及其与地表水资源的关系

根据渭河上游渭源等11县（区）国家基本（一般）气象站1971年-2008年逐月气温、降水量、相对湿度、日照时数、风速等资料及渭河上游北道水文站1971年-2008年径流量资料,利用Penman-monteith（98版）公式计算了该区域的潜在蒸散量。建立了评价该地区干湿状况的干燥指数模型,对该区域气候、潜在蒸散量、干湿指数的变化特征及其干湿状况对地表水资源的影响进行了分析。结果表明,自1971年以来,渭河上游区域气温以0.3℃/10a的线性趋势上升;降水量呈较明显的周期变化;潜在蒸散以23mm/10a的线性趋势增加。干燥指数总体呈上升趋势,变化阶段性较强。1971年-1984年以0.826/10a的线性趋势降低,1984年-1997年以0.852/10a的线性趋势升高。渭河干流区域干燥指数较高,干燥指数较高的区域,正好与甘肃河东区域气候上的＂干舌＂相对应。1971年-2008年径流量以2567×104m3/10a的线性趋势减少。1984年-1997年径流量以9023×104m3/10a的线性趋势减少。干燥指数持续增大比较明显地影响了上游地表水资源,在一定程度上对下游水资源安全造成威胁。     

Electromyographic analysis of hip adductor muscles in soccer instep and side-foot kicking

ABSTRACT

A possible link between soccer-specific injuries, such as groin pain and the action of hip adductor muscles has been suggested. This study aimed to investigate neuromuscular activation of the adductor magnus (AM) and longus (AL) muscles during instep and side-foot soccer kicks. Eight university soccer players performed the two types of kick at 50%, 75% and 100% of the maximal ball speed. Surface electromyography (EMG) was recorded from the AM, AL, vastus lateralis (VL) and biceps femoris (BF) muscles of both kicking and supporting legs and the kicking motions were three-dimensionally captured. In the kicking leg, an increase in surface EMG with an increase in ball speed during instep kicking was noted in the AM muscle (p < 0.016), but not in AL, VL or BF muscles (p > 0.016). In the supporting leg, surface EMG of both AM and AL muscles was significantly increased with an increase in the ball speed before ball impact during both instep and side-foot kicks (p < 0.016). These results suggest that hip adductor muscles markedly contribute to either the kicking or supporting leg to emphasise the action of soccer kicks.     

一种化简二次曲面方程的新方法

利用平面上的坐标轴旋转变换消去两坐标变量的混乘项,再用空间中的移轴变换化简二次曲面方程,得到了化简二次曲面方程的一种新方法,依此方法易见曲面在给定坐标系中的位置。     

吹扫捕集-气相色谱-质谱法测定地表水中苯和甲苯

建立了吹扫捕集-气相色谱-质谱检测地表水中苯和甲苯残留量的方法,选择离子扫描模式检测,在10μg/L～100μg/L范围内呈现良好的线性关系,相关系数大于0.9997,在10、20μg/L添加水平下,苯和甲苯的加标回收率在98.3%～101.2%之间,方法的检出限为5.0μg/L,该方法灵敏度高,分离效果良好,能有效地消除复杂基质带来的干扰,可以作为地表水中苯和甲苯残留量的检测和确证方法。     

基于正交实验法的低速走丝线切割气中精加工工艺参数的研究

为了进一步提高低速走丝线切割的表面质量,本文采用了气液混合多次切割的工艺。并采用正交设计法研究了脉冲宽度、脉冲间隔、峰值电流、伺服电压、伺服进给速度5个因素对表面粗糙度的影响,并通极差分析和利用二元表找出了在考虑上述5个因素交互作用下各因素的最佳水平,为进一步研究低速电火花线切割加工工艺提供了基础。     

Reliability and prevalence of an atypical development of phonological skills in French-speaking dyslexics

In the present study, conducted with French-speaking children, we examined the reliability (group study) and the prevalence (multiple-case study) of dyslexics’ phonological deficits in reading and reading-related skills in comparison with Reading Level (RL) controls. All dyslexics with no comorbidity problem schooled in a special institution for children with severe reading deficits were included in the study (N = 15; Chronological Age [CA]: 111 ± 8 months; RL: 80 ± 3 months). For the group study, the 15 dyslexics were matched pairwise on reading level, non-verbal IQ, and gender to 15 younger RL controls (CA: 85 ± 4 months). For the multiple-case study, the RL control group included 86 average readers (CA: 83 ± 4 months; RL: 85 ± 5 months). To assess the relative efficiency of the sublexical (or phonological) and lexical reading procedures, we relied on two comparisons: pseudowords vs. high-frequency regular words (the comparison mainly used in languages with a shallow orthography); and pseudowords vs. high-frequency irregular words (the comparison mainly used with English-speaking dyslexics), pseudowords and irregular words being either short or long. The dyslexics’ skills in the domains supposed to explain their reading deficit were also examined: phonemic awareness, phonological short-term memory and rapid naming. In the group study, the dyslexics lagged behind the RL controls only when they were required to read long pseudowords. The results of the multiple-case study indicated that the prevalence of this deficit was high (the accuracy scores of all but two of the 15 dyslexics being more than 1 SD below the RL control mean), and that deficits in phonemic awareness were more prevalent (seven cases) than deficits in phonological memory (one case) and in rapid naming (two cases). Three unexpected results were observed in the group study: the difference between regular words and pseudowords (to the detriment of pseudowords) was not greater for the dyslexics; the difference between irregular words and pseudowords (to the benefit of pseudowords) was more significant for the RL controls; and there were no significant differences between the groups in reading-related skills. To explain these results, the severity of the dyslexics’ reading deficit and the remediation they have benefited from must be taken into account. In addition, the fact that the outcomes of the comparison between pseudoword vs. regular or irregular word reading were not the same will make it possible to understand some discrepancies between studies carried out either in English or in a language with a shallower orthography (French, for instance).

溶胶-凝胶法在石英基片上制备氧化锌薄膜

氧化锌是一种宽禁带的半导体材料,它在太阳能电池、气体传感器等各种光电子器件中有广泛的应用前景.本文用溶胶-凝胶法制备ZnO溶胶,再甩膜在石英基片上,最后经微波加热而获得ZnO薄膜.分别用原子力显微镜、分光光度计和荧光谱仪研究不同厚度薄膜的表面形貌和光学性质.实验结果表明:制备薄膜随着薄膜厚度的增加,薄膜的生长模式由层状生长向岛状生长转变;所有薄膜在可见光范国内的透射率都超过65%;样品发光特性良好.     

拉脱法测量液体表面张力的局限性

本论文揭示了拉脱法无法准确测量溶液或浑浊液的表面张力,仅适用于测量纯液体表面张力.     

基于空间啮合原理对弧面分度凸轮廓面的研究

弧面分度凸轮的工作廓面复杂，设计繁琐，很难用常规的制图方法绘制。为了将复杂的凸轮机构可视化，实现机构的运动仿真状态，在对弧面分度凸轮轮廓曲面分析的基础上，利用空间啮合原理建立了弧面分度凸轮的轮廓曲面方程。     

反求工程技术在快速成型中的应用

随着RP行业的迅速发展,反求工程技术在快速成型制造领域中的作用日趋重要。它作为一种新的产品设计思想和方法越来越广泛地应用于快速成型制造领域,并取得了很多成果。本文阐述了反求工程(RE)的基本概念和作用,分析了目前反求工程技术中的坐标点采集、数据处理以及曲面拟合等关键技术,介绍了快速反求工程技术在快速成型制造技术中的应用。