对土家族城镇中小学生体表面积调查研究   总被引：4，自引：0，他引：4  

李继国  邹炜  段辉涛  倪东业  张有平 《北京体育大学学报》2004,27(8):1055-1056

为了解和建立土家族中小学生这方面的形态学指标,采用适合中国人的Stevenson标准公式,对土家族中小学生的体表面积进行了调查研究.结果显示:1)土家族中小学生体表面积值随着年龄增长而增长,且其增长速度男女生均可分为匀速增长期、快速增长期、速度减缓期3个不同时期;2)男女生体表面积曲线出现双交叉现象,即11岁时女生体表面积值超过男生,14岁时男生的体表面积又超过女生,15岁以后二者体表面积值的差异逐渐增大,表现出显著性差异.  相似文献   

腰部竖脊肌疲劳运动过程中表面肌电信号线性和非线性指标的变化   总被引：1，自引：0，他引：1  

王翔 《浙江体育科学》2008,30(6):104-106

通过等长背伸运动负荷诱发腰部竖脊肌疲劳并记录全程表面肌电（sEMG）信号,分别以快速傅立叶变换（FFT）计算平均功率频率MPF和非线性RQA方法计算确定性线段百分数（?T）。结果显示,MPF随着肌肉疲劳的发展而逐渐下降,而?T呈现反向变化趋势,提示肌肉疲劳时的sEMG信号规律性在增强。?T的变异系数CV比MPF的小,说明?T作为腰部肌肉功能状态的评价指标具有独特的优势。  相似文献   

基于点云数据的复杂型面实体建模研究   总被引：1，自引：1，他引：0  

陈雪芳 《苏州市职业大学学报》2006,17(2):64-66

文章针对复杂型面产品的特点,从工业产品设计的实际应用出发,提出将正向设计的尺寸和定位关系设计方法和逆向设计的复杂曲面设计方法有效结合起来,基于点云数据实现产品的实体模型重建。以摩托车覆盖件为例,利用逆向工程软件从点云数据中提取和重构特征曲线与曲面,然后将这些几何元素信息在正向设计系统中结合特征建模方法创建整体三维CAD模型。  相似文献   

Development of a chemically defined medium for Planctopirus limnophila to increase biomass production     

《Electronic Journal of Biotechnology》2021

BackgroundPlanctomycetes is a phylum of biofilm-forming bacteria with numerous biosynthetic gene clusters, offering a promising source of new bioactive secondary metabolites. However, the current generation of chemically defined media achieves only low biomass yields, hindering research on these species. We therefore developed a chemically defined medium for the model organism Planctopirus limnophila to increase biomass production.ResultsWe found that P. limnophila grows best with a 10 mM sodium phosphate buffer. The replacement of complex nitrogen sources with defined amino acid solutions did not inhibit growth. Screening for vitamin requirements revealed that only cyanocobalamin (B12) is needed for growth. We used response surface methodology to optimize the medium, resulting in concentrations of 10 g/L glucose, 34 mL/L Hutner’s basal salts, 23.18 mM KNO₃, 2.318 mM NH₄Cl and 0.02 mg/L cyanocobalamin. The analysis of amino acid consumption allowed us to develop a customized amino acid solution lacking six of the amino acids present in Aminoplasmal 10%. Fed-batch cultivation in a bioreactor using the optimized medium achieved a final ΔOD₆₀₀ of 46.8 ± 0.5 after 108 h, corresponding to a cell dry weight of 13.6 ± 0.7 g/L.ConclusionsThe optimized chemically defined medium allowed us to produce larger amounts of biomass more quickly than reported in earlier studies. Further research should focus on triggering P. limnophila biofilm formation to activate the gene clusters responsible for secondary metabolism.How to cite: Kruppa OC, Gerlach D, Fan R, et al. Development of a chemically defined medium for Planctopirus limnophila to increase biomass production. Electron J Biotechnol 2021;54. https://doi.org/10.1016/j.ejbt.2021.09.002.  相似文献   

空气质量响应曲面模型在杭州市的应用     

戴志翔  胡诗玮  罗坤  高翔  樊建人  岑可法 《中国科学院大学学报》2017,34(2):179-185

基于CMAQ模拟结果，统计、归纳出各种污染物排放控制因子与污染物浓度之间的函数关系，建立空气质量响应曲面模型RSM，通过留一法交叉验证和外部验证对模型进行可靠性验证。使用RSM，研究不同污染物的PM_2.5响应值，评估现有政策不变（Ⅰ）和政策收紧（Ⅱ）两种减排情景，发现NO_X、SO₂、NH₃和VOC对PM_2.5浓度体现明显的非线性响应特征，情景Ⅱ的减排效果明显好于情景Ⅰ，夏季的减排效果好于冬季。  相似文献   

教师职业研究的新视角——情绪工作研究探析     

王艳华 《桂林师范高等专科学校学报》2011,25(2):107-110

首先从情绪工作的定义、特征出发分析教师是属于高情绪工作者,之后阐述情绪工作的调节策略以及影响调节策略的相关因素,以期为研究教师职业提供一个新视角。  相似文献   

基于SWMM的地表径流量与城市下垫面和降雨特征关系的空间分析——以中国科学院大学雁栖湖校区为例     

罗英杰  张娜  李琪  王昕  景永才  乐荣武 《中国科学院大学学报》2020,37(1):27-38

以中国科学院大学雁栖湖校区为例，用城市雨洪管理模型（SWMM）模拟2016-2017年48场降雨事件中所有子汇水小区的径流过程；在验证可靠的基础上，探讨径流量空间分布与降雨和下垫面的关系，是开展防汛工作的重要基础。结果表明，径流量高值区多位于沥青小区，而低值区多位于绿地小区。沥青最易产流，绿地最不易产流。砌砖易产生中等量级的径流，混凝土较砌砖更易产流，但二者在不同降雨事件下的产流规律相似。沥青小区和砌砖小区的地表径流量均与坡度呈极显著或显著线性正相关关系。对沥青-砌砖和沥青-绿地小区，将非渗透面积比例（PIC）降至60%可明显控制其暴雨和大雨径流。要明显控制大暴雨径流，可将沥青-绿地小区的PIC降至30%以下；但降低PIC对沥青-砌砖小区大暴雨径流的控制作用不明显。研究结果可为海绵城市建设和城市内涝防洪提供理论依据和决策建议。  相似文献   

Exploring Developmental Appropriateness of Multitouch Tables in Prekindergarten: A Video Analysis     

Jennifer Ward  Stephanie Branson  Megan D. Cross  Ilene R. Berson 《Journal of Research on Technology in Education》2016,48(3):227-238

This study explored how developmentally appropriate practices influenced the affordances of a multitouch surface in an early childhood classroom. Children, ages 4 to 5 years old, were videotaped while engaged in a storymaking application on a multitouch table. As a result of the study, we found that some challenges with the functionality undermined children's autonomous control. The researchers observed numerous instances of issues with control of the medium, including height of the table, sensitivity to multiple types of touch, and limited instructions and prompts. Implications for future research and practice are discussed.  相似文献   

A kinematic analysis of the spine during rugby scrummaging on natural and synthetic turfs     

Ramesh Swaminathan  Jonathan M. Williams  Michael D. Jones 《Journal of sports sciences》2016,34(11):1058-1066

Artificial surfaces are now an established alternative to grass (natural) surfaces in rugby union. Little is known, however, about their potential to reduce injury. This study characterises the spinal kinematics of rugby union hookers during scrummaging on third-generation synthetic (3G) and natural pitches. The spine was sectioned into five segments, with inertial sensors providing three-dimensional kinematic data sampled at 40 Hz/sensor. Twenty-two adult, male community club and university-level hookers were recruited. An equal number were analysed whilst scrummaging on natural or synthetic turf. Players scrummaging on synthetic turf demonstrated less angular velocity in the lower thoracic spine for right and left lateral bending and right rotation. The general reduction in the range of motion and velocities, extrapolated over a prolonged playing career, may mean that the synthetic turf could result in fewer degenerative injuries. It should be noted, however, that this conclusion considers only the scrummaging scenario.  相似文献   

表面活性剂增敏光度法测定水样中的微量铁   总被引：4，自引：0，他引：4  

梁国柱 《南通职业大学学报》2005,19(2):29-31

在HAc-NaAc缓冲溶液(pH=5)存在下,以邻二氮菲(phen)作显色剂,表面活性剂曲拉通X-100对Fe(II)与邻二氮菲的显色反应具有增敏作用,形成的Fe(II)-phen-Triton三元络合物呈红色,络合物的最大吸收波长为510 nm,表观摩尔吸光系数为1.2×105L.mol-1.cm-1,铁含量在0.5~12μg/mL范围内符合比尔定律,用于水样中微量铁的测定,回收率在97.1%~98.0%之间。  相似文献