民国时期农业发展滞后的原因--以20世纪二三十年代农业发展的内部因素为例     

王军 《安徽广播电视大学学报》2015,(4):117-122

民国时期作为中国农业近代化的重要转型时期,由于受到帝国主义和封建势力的双重压迫,我国农业出现持续而急剧的衰落。农民普遍贫穷、农村资本外流和大量农民为求生计“离村”另谋出路造成近代农业衰落,加之我国农业改良受阻和农业商品经济出现病态发展,导致农业发展严重滞后。  相似文献   

湘粤两省货币政策区域效应的差异性研究--基于动态分布滞后模型     

易昱烨 《科教文汇》2015,(17)

本文选取中部地区和沿海地区中的代表省份湖南省和广东省作为研究对象,基于货币政策的内部与外部传导机制,实证检验并分析了统一货币政策在湘粤两省产生的不同效应。实证结果表明,在货币政策操作中,应考虑区域非均衡因素,提高政策工具的灵活性和可操作性,以提高货币政策的有效性,达到缩小地区经济发展差距的目的。  相似文献   

基于文化角度浅析近代中国科技落后的原因     

郝福为  张法瑞 《中国科技纵横》2014,(20):286-286

中国是四大文明古国之一,在科技方面曾经取得过举世瞩目的成就,在众多领域都位居于世界前列,为人类文明进步和发展做出了突出的贡献。可是,到了近代以后,中国的科技发展缓慢、停滞甚至倒退,最终被西方超过而落后于世界。探讨近代中国科技落后的原因,总结经验,吸取教训,对于中国发展科技事业,实施科教兴国战略以及建设创新型国家都有重要意义。近代中国科技落后的原因是多方面的,对此学界已有很多论述,并且成果颇多。此文从文化角度探讨近代中国科技落后的原因。  相似文献   

三次样条分布滞后模型初探     

司颖华 《商丘师范学院学报》2012,(3):23-25

多项式分布滞后模型常被用来处理有限分布滞后问题,但在有些应用中,对系数的多项式逼近效果不尽如人意.考虑到三次样条函数在局部拟合中的优越性,本文提出三次样条对分布滞后模型中系数的拟合,并通过示例显示了三次样条在拟合系数中的优越性.  相似文献   

人民币汇率波动对广西外贸的影响     

张丹  张蓓 《柳州职业技术学院学报》2013,13(1):7-9,13

在研究国内外学者的研究成果的基础上,提出他们的不足,充分考虑了滞后解释变量,并使用了最新的月度数据进行研究,使用了非线性的方程对出口额和进口额进行估计,并对滞后阶数进行了判定。使用阿尔蒙特多项式进行的估计,模型参数基本上通过了检验,得到了估计模型,并确认了人民币汇率波动对广西外贸的影响是符合经济理论的。  相似文献   

基于模糊控制的新型回流焊机温度控制系统的设计     

刘莉宏 《北京工业职业技术学院学报》2013,12(1):31-33

介绍一种基于模糊控制的新型回流焊机温度控制系统,其设计思想是在现有的PID控制的基础上,引入模糊控制技术、温度滞后补偿和多温区解耦设计,以解决回流焊机温度控制存在的问题,使多温区热风回流焊机温度控制更加优化、合理。  相似文献   

The stress of travel     

J Waterhouse  T Reilly  B Edwards 《Journal of sports sciences》2013,31(10):946-966

International travel is an essential part of the life of elite athletes, both for competition and training. It is also becoming increasingly common among recreational sportspersons. Long-distance travel is associated with a group of transient negative effects, collectively referred to as 'travel fatigue', which result from anxiety about the journey, the change to an individual's daily routine, and dehydration due to time spent in the dry air of the aircraft cabin. Travel fatigue lasts for only a day or so, but for those who fly across several time zones, there are also the longer-lasting difficulties associated with 'jet lag'. The problems of jet lag can last for over a week if the flight crosses 10 time zones or more, and they can reduce performance and the motivation to train effectively. Knowledge of the properties of the body clock enables the cause of the difficulties to be understood (an unadjusted body clock), and forms the basis of using light in the new time zone to promote adjustment of the body clock. Sleep loss and its effects are important components of jet lag, and attempts to promote sleep by the use of melatonin and other hypnotics are also relevant. Sleep loss is also found in those who undertake challenges that involve long periods where the normal consolidated sleep of 8 h length is not possible. Advice on sleep regimens in such circumstances is given.  相似文献   

The longest journeys in Super Rugby: 11 years of travel and performance indicators     

Michele Lo  Robert J. Aughey  William G. Hopkins  Nicholas Gill 《Journal of sports sciences》2013,31(18):2045-2050

ABSTRACT

Regular air travel is common in sport. The aim of this study was to understand the extent to which travel has affected Super Rugby teams’ performance from 2006, the first season with available Key Performance Indicators (KPIs), to 2016. Data were analysed with mixed linear models for the effects of number of time-zones crossed (east or west), travel duration, the away-match disadvantage, difference in ranking, a set of amendments to the laws of Rugby Union in 2008, a change in competition format (introduction of a conference system) in 2011, and a secular trend. In 2006, the predicted combined effects of travelling 24 h across 12 time-zones and playing away were trivial or small and negative but generally unclear for most of the KPIs in both directions of travel. In 2016 more effects were clear, small and negative for westward travel, while most effects for eastward travel were clear, small to moderate and negative. Most KPIs showed small to moderate increases over the 11 years, while difference in ranking, the introduction of new rules and game format led to mostly small changes. Changes in the physical demands of the game, and inadequate recovery time for long-haul travel can explain these effects.  相似文献   

Out of your zone? 21 years of travel and performance in Super Rugby     

Michele Lo  Robert J. Aughey  William G. Hopkins  Nicholas Gill 《Journal of sports sciences》2013,31(18):2051-2056

ABSTRACT

The extent to which travel has affected Super Rugby teams’ performances was analysed using outcomes of all matches played from the beginning of the competition in 1996 to the end of the 2016 season. Points difference and matches won or lost were predicted with general and generalized mixed linear models. The predictors were the linear effects of number of time zones crossed and travel duration based on the teams’ locations for each match and their locations in the previous week. The away-match disadvantage was also estimated, along with trends in all these effects. In 1996 the predicted combined effect of eastward travel across 12 time zones was a reduction of 5.8 points scored per match, resulting in 4.1 more matches lost every 10 matches. Corresponding effects for westward travel were 6.4 points and 3.1 matches. In 2016 effects travelling eastward were 3.7 points and 2.3 matches, whereas travelling westward the effects were 3.7 points and 1.5 matches. These travel effects were due mainly to the away-match disadvantage: 5.7 points and 3.2 matches in 1996; 5.2 points and 2.3 matches in 2016. Teams in Super Rugby are dealing successfully with long-haul travel and should now focus on reducing the away-match disadvantage.  相似文献   

具有时滞的直接控制系统的振动性     

张孟秋 《湖南师范大学教育科学学报》1994,(2)

本文讨论了具有时滞的直接控制系统(dx_i(t))/dt=sum from j=1(ai_j(t)x_j(t-τ(t)))+b_if(σ),σ=sum from i=1 to n(c_ix_i(t))(i=1,2,…,n)解的振动性,获得了其解振动的充分条件。对比以前的文献,可以看出,这些条件简洁且使用方便。  相似文献