对土家族城镇中小学生体表面积调查研究

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.     

法律实施的效果与法治期待

法律实施是实行法治、建立社会主义法治国家的关键所在 ,在法治实践中 ,我们既不能用成熟法治国家的标准来衡量我国法律实施的现状 ,也不能假借具体国情的特殊性放任法律实施的低效运作。在现有法律明确规定的情况下 ,务求有法必依、执法必严 ,真正确立起法律的权威性 ,并切实维护法制的统一性。惟有如此 ,才有利于我们法治国家的健康成长。     

基于点云数据的复杂型面实体建模研究

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。     

国际学科教学知识的文献计量研究

学科教学知识(PCK)自舒尔曼1986年提出以来,受到了广泛关注。通过在Web of Science核心合集中对"PCK"进行文献计量研究,辅以CiteSpace进行关键词共现等分析,可以从整体上了解国际PCK的研究现状、研究热点与研究前沿问题。通过分析发现,在研究方法上,文献计量方法的综合使用有利于形成科学而准确的结论;在研究内容上,国际PCK的研究热点与研究前沿特征词较相似,体现了创新研究的不足。     

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

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.     

教师职业研究的新视角——情绪工作研究探析

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。     

英汉多个疑问词的句法分布

一个句子的焦点是句子语义的重心所在。疑问词是疑问句的语义重心，因而疑问句的焦点就是疑问词。本文以焦点和突显观为理论依据，考察了英汉多个疑问词在特指问句中的句法位置，揭示出在特指问句中英语多个wh-词移位和汉语多个疑问词原位的原因。英语特指问句中多个wh-词必须有一个移至句首，这是其自身显性的焦点性和突显性的结果。     

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

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.     

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

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.     

表面活性剂增敏光度法测定水样中的微量铁

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。