整理活动方式对消除运动员运动后血乳酸效果的分析

采用实验法，比较安静休息、轻松整理活动和专项整理活动方式对运动后血乳酸的清除、消除心理疲劳的效果。结果发现：积极性的整理活动效果明显优于安静休息；轻松整理活动和专项整理活动对血乳酸的清除效果无显著性差异，但轻松整理活动对消除心理疲劳的效果优于专项整理活动。     

How silicon fertilizer improves nitrogen and phosphorus nutrient availability in paddy soil?

In order to reveal the mechanism of silicon(Si) fertilizer in improving nitrogen(N) and phosphorus(P) nutrient availability in paddy soil, we designed a series of soil culture experiments by combining application of varying Si fertilizer concentrations with fixed N and P fertilizer concentrations. Following the recommendations of fertilizer manufacturers and local farmers, we applied Si in concentrations of 0, 5.2, 10.4, 15.6, and 20.8 μg/kg. At each concentration of added Si, the availability of soil N and P nutrients, soil microbial activity, numbers of ammonia-oxidizing bacteria and P-decomposing bacteria which means that the organic P is decomposed into inorganic nutrients which can be absorbed and utilized by plants, and urease and phosphatase activity first increased, and then decreased, as Si was added to the soil. These indicators reached their highest levels with a Si application rate of 15.6 μg/kg, showing values respectively 19.78%, 105.09%, 8.34%, 73.12%, 130.36%, 28.12%,and 20.15% higher than those of the controls. Appropriate Si application(10.4 to 15.6 μg/kg) could significantly increase the richness of the soil microbial community involved in cycling of N and P nutrients in the soil. When the Si application rate was15.6 μg/kg, parameters for characterizing microbial abundance such as sequence numbers, operational taxonomic unit(OTU)number, and correlation indices of microbial community richness such as Chao1 index, the adaptive coherence estimator(ACE)index, Shannon index, and Simpson index all reached maximum values, with amounts increased by 14.46%, 10.01%, 23.80%,30.54%, 0.18%, and 2.64%, respectively, compared with the control group. There is also a good correlation between N and P mineralization and addition of Si fertilizer. The correlation coefficients between the ratio of available P/total P(AP/TP) and the number of ammonia-oxidizing bacteria, AP/TP and acid phosphatase activity(AcPA), AP/TP and the Shannon index, the ratio of available N/total amount of N(AN/TN) and the number of ammoniated bacteria, and AN/TN and AcPA were 0.9290, 0.9508,0.9202, 0.9140, and 0.9366, respectively. In summary, these results revealed that enhancement of soil microbial community structure diversity and soil microbial activity by appropriate application of Si is the key ecological mechanism by which application of Si fertilizer improves N and P nutrient availability.     

A theory of instruction for introductory programming skills

ABSTRACT

Background and Context: Current introductory instruction fails to identify, structure, and sequence the many skills involved in programming.

Objective: We proposed a theory which identifies four distinct skills that novices learn incrementally. These skills are tracing, writing syntax, comprehending templates (reusable abstractions of programming knowledge), and writing code with templates. We theorized that explicit instruction of these skills decreases cognitive demand.

Method: We conducted an exploratory mixed-methods study and compared students’ exercise completion rates, error rates, ability to explain code, and engagement when learning to program. We compared material that reflects this theory to more traditional material that does not distinguish between skills.

Findings: Teaching skills incrementally resulted in improved completion rate on practice exercises, and decreased error rate and improved understanding of the post-test.

Implications: By structuring programming skills such that they can be taught explicitly and incrementally, we can inform instructional design and improve future research on understanding how novice programmers develop understanding.     

基于“任务驱动+项目导向”的嵌入式系统设计课程教学研究与实践

分析了自动化类等相关专业嵌入式系统设计课程教学中存在的问题,进而对该课程的教学方法、教学手段、考核方式进行了改革和实践。在该课程的教学中引入慕课等线上资源,充分利用微信教学立方等现代教学手段进行课堂互动,并通过"任务驱动+项目导向"的教学模式督促学生自主完成学习任务。     

关于N(2,2,0)代数的弱幂零元的若干结果(英文)

引入了N(2,2,0)代数的弱幂元的概念,讨论了其弱幂元的若干性质.     

旋转二次曲面透镜基点和基面的位置确定

在光学仪器中,非球面透镜具有一定的实用价值,故对旋转二次曲面透镜光学性质的研究将有重要意义．根据等效光学系统理论和旋转二次曲面折射的焦距公式,并考虑了透镜两曲面的不同形状及不同曲率,导出了旋转二次曲面透镜的主距公式和焦距公式,统称为旋转二次曲面的基点位置公式．这些公式具有一般性,该文进行了分类讨论,最后给出了应用实例     

粘弹性阻尼对非线性弹性杆内纵向应变孤波运动的影响

本文采用基于KdV方程的守恒量建立起来的孤波参数的演化方程组,重新研究了粘弹性阻尼对非线性弹性杆内纵向应变孤波运动的影响,得到了孤波参数的演化规律。结果表明,粘弹性阻尼使孤波逐渐变矮、增宽、速度减慢,最后导致孤波的消失。     

基于灰色神经网络组合模型的电力消费量预测——以河北省为例

在分析灰色预测模型GM(1,1)以及BP神经网络预测模型2种单一模型在电力消费量预测方面不足的基础上,提出灰色神经网络组合预测模型。以河北省电力消费量为基础,分别用3种模型进行预测,并加以比较分析。结果表明,灰色神经网络组合模型提高了关于河北省中长期电力消费量的预测精度,对河北省未来电力系统及能源需求规划具有一定参考价值。     

卤化锂晶体能态密度的研究

利用扩展休克尔方法．计算了卤化锂晶体的能态密度,确定了价级位置,得出了能隙和价带宽度     

试析元话语的语篇功能与人际功能——以学术论文摘要为个案的研究

本文采用Hyland和Tse对元话语的分类方法,对学术论文摘要中元话语的语篇功能和人际功能进行了探讨。通过列举该类摘要中出现的多种引导式元话语与互动式元话语的使用,本文着重分析了元话语在构建语篇,表达命题内容,以及建立作者与读者人际对话关系中发挥的重要作用。