情报学界的发展与进步

50年来,我国科技情报学界经历了从初创、形成,到发展、成熟和成功的过程。现在,出现了引人注目的几个新亮点:形成了完整的情报学学科体系;情报研究机构发展模式多元化;第三次发展机遇期来临;正在展开的重大研究领域。     

清绥远城修筑时间和过程考

笔者据档案奏折,考定绥远新城是经雍正、乾隆两朝皇帝厦永泰、通智、瞻岱、王山、王常五位官员不懈努力,于乾隆二年二月初七日正式动工,历872天修筑,乾隆四年六月二十二日竣工。这些奏折基本勾勒出绥远城修筑的大致经过。     

系泊力设计原则

回顾系泊船舶的行为和在泊位设计时系缆配备的一般原则.系泊力是码头及泊位靠泊能力的一个重要因素.影响系泊力的因素有风、流及波浪等,这些外力的影响通过缆绳传递给泊位及码头自身.结合油船系泊的行业要求,分析系泊设计的基本要求.探讨频率域和时域模型在船舶系泊上的应用.     

海峡西岸经济区出口加工贸易产业现状分析

出口加工贸易产业的发展对海峡西岸经济区经济的发展至关重要。通过回顾海峡西岸经济区出口加工贸易产业发展的历史,结合出口加工贸易产业发展的现状,运用SWOT分析法对海峡西岸经济区的出口加工贸易产业进行分析,希望能够为制定发展海峡西岸经济区出口加工贸易产业的政策提供参考。     

成人教育脱产学生现状及其工作针对性的探索

本针对成人教育脱产学习形式的快速发展，及其学生教育、教学管理上探索与实践的不成熟；通过对成人教育脱产学生的调查分析，探索出适合成人教育脱产学生教育、教学管理的方法。     

沈从文的时间意识

沈从文的时间意识与死亡意识相生相成,构成沈从文“生命哲学”的重要而又特殊的组成部分。他认为时间的魔力巨大,能消融生命,能治疗痛苦,还能造就创作;他的时间意识停留在“过去”,具有“过去式”、“静态化”与“突变性”的特点。     

Accelerometer data requirements for reliable estimation of habitual physical activity and sedentary time of children during the early years - a worked example following a stepped approach

This study presents a worked example of a stepped process to reliably estimate the habitual physical activity and sedentary time of a sample of young children. A total of 299 children (2.9 ± 0.6 years) were recruited. Outcome variables were daily minutes of total physical activity, sedentary time, moderate to vigorous physical activity and proportional values of each variable. In total, 282 (94%) provided 3 h of accelerometer data on ≥1 day and were included in a 6-step process: Step-1: determine minimum wear-time; Step-2: process 7-day-data; Step-3: determine the inclusion of a weekend day; Step-4: examine day-to-day variability; Step-5: calculate single day intraclass correlation (ICC) (2,1); Step-6: calculate number of days required to reach reliability. Following the process the results were, Step-1: 6 h was estimated as minimum wear-time of a standard day. Step-2: 98 (32%) children had ≥6 h wear on 7 days. Step-3: no differences were found between weekdays and weekend days (P ≥ 0.05). Step-4: no differences were found between day-to-day variability (P ≥ 0.05). Step-5: single day ICC’s (2,1) ranged from 0.48 (total physical activity and sedentary time) to 0.53 (proportion of moderate to vigorous physical activity). Step-6: to reach reliability (ICC = 0.7), 3 days were required for all outcomes. In conclusion following a 7 day wear protocol, ≥6 h on any 3 days was found to have acceptable reliability. The stepped-process offers researchers a method to derive sample-specific wear-time criterion.     

基于学习共同体的中小学生学习心理机制及有效教学策略

学习共同体的学习方式有别于传统的教师主讲式的课堂授课形式。学习共同体特别强调"师-生"之间,"生-生"之间缔结一个相互联系、相互制约、彼此促进的共同体来完成学生的学习活动。基于学习共同体的中小学生学习心理机制是一种主动建构、信息加工的过程,即:"1.输入信息、注意保持、认知观念;2.加工信息、内化知识、建构系统;3.改组经验、解决问题、生成能力"。学习共同体旨在教师引导下,让学生通过自主探究、小组讨论、合作分享、获得知识、生成能力。教师实施有效的教学策略,充分发挥学习共同体的功能,会促进培养中小学生的核心素养,提升学生分析问题解决问题能力。     

One hundred and fifty years of sprint and distance running – Past trends and future prospects

Sprint and distance running have experienced remarkable performance improvements over the past century. Attempts to forecast running performances share an almost similarly long history but have relied so far on relatively short data series. Here, we compile a comprehensive set of season-best performances for eight Olympically contested running events. With this data set, we conduct (1) an exponential time series analysis and (2) a power-law experience curve analysis to quantify the rate of past performance improvements and to forecast future performances until the year 2100. We find that the sprint and distance running performances of women and men improve exponentially with time and converge at yearly rates of 4% ± 3% and 2% ± 2%, respectively, towards their asymptotic limits. Running performances can also be modelled with the experience curve approach, yielding learning rates of 3% ± 1% and 6% ± 2% for the women's and men's events, respectively. Long-term trends suggest that: (1) women will continue to run 10–20% slower than men, (2) 9.50 s over 100 m dash may only be broken at the end of this century and (3) several middle- and long-distance records may be broken within the next two to three decades. The prospects of witnessing a sub-2 hour marathon before 2100 remain inconclusive. Our results should be interpreted cautiously as forecasting human behaviour is intrinsically uncertain. The future season-best sprint and distance running performances will continue to scatter around the trends identified here and may yield unexpected improvements of standing world records.     

单片机延时方法的分析及应用

单片机开发应用中经常用到延时控制，延时控制的基本方法有纯软件、纯硬件及软硬件结合方法，它们都有各自的特点及应用范围，以1秒延时为例给出用三种方法实现的过程，并介绍了软硬件结合延时的应用实例。