广州雾日的时空变化     

黄伟峰 《中山大学学报论丛》1990,(4)

讨论了广州雾日的时空变化.研究指出,由于广州近地层气温较高,加上城市热岛和干岛效应的影响,年平均雾日较少.34年的资料表明,广州平均雾日为4.8天,春季最多,冬季次之,夏季最少.1～4月为雾季,雾一股出现在清晨5～7时.50年代至70年代雾日增加,80年代开始雾日有减少的趋势.广州的雾可以分成4种类型:即辐射雾(占24％),锋面雾(占14％),平流雾(占14％)和平流辐射雾(占48％).最后指出,雾是稳定的象征,它与大气温度层结有密切的关系。  相似文献   

启动效应研究中的几个基本问题     

曾保春 《襄樊职业技术学院学报》2005,4(4):73-75

重点阐述了启动效应研究中的几个基本问题：启动效应中的意识问题、内隐记忆与外显记忆的本质区别以及认知神经科学对启动效应的研究。  相似文献   

不同语料下基于LDA主题模型的科学文献主题抽取效果分析     

关鹏  王曰芬  傅柱 《图书情报工作》2016,60(2):112-121

[目的/意义]潜在狄利克雷分布(Latent Dirichlet Allocation,LDA)在科技情报分析中用来发现学科主题、挖掘研究热点以及预测研究趋势等。对常见的科学文献文本语料库(关键词、摘要、关键词+摘要)进行LDA主题抽取效果的评价,以揭示不同语料库的主题抽取效果,提高LDA在科技情报分析中的应用效果。[方法/过程]对上述3种语料库下的LDA主题模型进行对比研究,采用基于查全率、查准率、F值以及信息熵的定量分析和基于主题抽取的广度和主题粒度的定性分析相结合的方法对主题抽取效果进行评价。[结果/结论]通过国内风能领域的科学文献数据实证研究发现,无论是从定量分析还是从定性分析来看,摘要和关键词+摘要作为语料的LDA主题抽取的效果均优于关键词作为语料的LDA主题抽取效果,并且前者在主题抽取的广度方面表现更好,而后者抽取的主题粒度更细。  相似文献   

化学实验中心供应室的网络化管理   总被引：1，自引：1，他引：1  

杨文玉  王书欣  李玉玲  白浩  阎生忠 《实验室研究与探索》2005,24(9):56-57,74

详细介绍了该校化学基础教学实验中心物品供应室国网络化管理系统的功能、特点、操作步骤和应用效果  相似文献   

对恢复高考英语听力测试的思考   总被引：2，自引：0，他引：2  

陶百强 《考试研究》2007,(4)

自2000年以来,我国开始在高考英语试题中逐渐推广听力测试,2003年高考英语听力测试在全国普及,促进了基础教育阶段学生英语听力水平的提高。但2005年起出现了部分省区取消或淡化高考英语听力的现象。本文探讨了此举的原因、危害,建议尽早恢复高考英语听力测试,发挥高考对基础英语教育的正面反拨作用,为培养学生的英语交际能力打下基础。  相似文献   

跳舞毯锻炼对老年女性身体灵敏性的影响效果     

宋清华  胡建平  赵新平 《湖北体育科技》2016,(12)

目的观察跳舞毯锻炼对老年女性身体灵敏素质的影响效果。方法从无健身锻炼习惯且身体灵活性较差的老年女性中筛选50例受试者,随机分成实验组和对照组,每组25例,对照组采用太极拳、实验组则采用跳舞毯训练的方式进行有氧健身锻炼,于锻炼前及经3个月锻炼后,分别对两组受试者的反应速度、身体稳定性及身体灵活性指标进行检测和比较。结果经3个月锻炼后,两组入选者的各检测指标较锻炼前分别有不同程度改善,且以实验组改善效果更显著,尤其反应速度及身体灵活性指标改善效果均明显优于对照组,均P<0.05。结论与太极拳锻炼相比较,跳舞毯锻炼对老年人身体稳定性的改善效果无明显优势,但反应速度及身体灵活性的改善效果明显优于太极拳锻炼,对老年人总体灵敏素质的提高效果更显著。  相似文献   

Relative age and birthplace effect in Japanese professional sports: a quantitative evaluation using a Bayesian hierarchical Poisson model     

Hideaki Ishigami 《Journal of sports sciences》2016,34(2):143-154

Relative age effect (RAE) in sports has been well documented. Recent studies investigate the effect of birthplace in addition to the RAE. The first objective of this study was to show the magnitude of the RAE in two major professional sports in Japan, baseball and soccer. Second, we examined the birthplace effect and compared its magnitude with that of the RAE. The effect sizes were estimated using a Bayesian hierarchical Poisson model with the number of players as dependent variable. The RAEs were 9.0% and 7.7% per month for soccer and baseball, respectively. These estimates imply that children born in the first month of a school year have about three times greater chance of becoming a professional player than those born in the last month of the year. Over half of the difference in likelihoods of becoming a professional player between birthplaces was accounted for by weather conditions, with the likelihood decreasing by 1% per snow day. An effect of population size was not detected in the data. By investigating different samples, we demonstrated that using quarterly data leads to underestimation and that the age range of sampled athletes should be set carefully.  相似文献   

Effects of 12 weeks of combined training without caloric restriction on inflammatory markers in overweight girls     

Wendell Arthur Lopes  Neiva Leite  Larissa Rosa da Silva  Diego Trevisan Brunelli  Arthur Fernandes Gáspari  Rosana Bento Radominski 《Journal of sports sciences》2016,34(20):1902-1912

The objective of the present study was to investigate the effects of combined training without caloric restriction on inflammatory markers in overweight girls. Thirty-three girls (13–17 years) were assigned into overweight training (n = 17) or overweight control (n = 16) groups. Additionally, a normal-weight group (n = 15) was used as control for the baseline values. The combined training programme consisted of six resistance exercises (three sets of 6–10 repetitions at 60–70% 1 RM) followed by 30 min of aerobic exercise (walking/running) at 50–80% VO_2peak, performed in the same 60 min session, 3 days/weeks, for 12 weeks. Body composition, dietary intake, aerobic fitness (VO_2peak), muscular strength (1 RM), glycaemia, insulinemia, lipid profile and inflammatory markers (C-reactive protein, interleukin-6, tumour necrosis factor-alpha, interleukin-10, leptin, resistin and adiponectin) were measured before and after intervention. There was a significant decrease in body fat (P < 0.01) and increase in fat-free mass (P < 0.01), VO_2peak (P < 0.01), 1 RM for leg press (P < 0.01) and bench press (P < 0.01) in the overweight training group. Concomitantly, this group presented significant decreases in serum concentrations of C-reactive protein (P < 0.05) and leptin (P < 0.05), as well as in insulin resistance (P < 0.05) after the experimental period. In conclusion, 12 weeks of combined training without caloric restriction reduced inflammatory markers associated with obesity in overweight girls.  相似文献   

The key to success in elite athletes? Explicit and implicit motor learning in youth elite and non-elite soccer players     

L. Verburgh  E. J. A. Scherder  P. A. M. van Lange  J. Oosterlaan 《Journal of sports sciences》2016,34(18):1782-1790

In sports, fast and accurate execution of movements is required. It has been shown that implicitly learned movements might be less vulnerable than explicitly learned movements to stressful and fast changing circumstances that exist at the elite sports level. The present study provides insight in explicit and implicit motor learning in youth soccer players with different expertise levels. Twenty-seven youth elite soccer players and 25 non-elite soccer players (aged 10–12) performed a serial reaction time task (SRTT). In the SRTT, one of the sequences must be learned explicitly, the other was implicitly learned. No main effect of group was found for implicit and explicit learning on mean reaction time (MRT) and accuracy. However, for MRT, an interaction was found between learning condition, learning phase and group. Analyses showed no group effects for the explicit learning condition, but youth elite soccer players showed better learning in the implicit learning condition. In particular, during implicit motor learning youth elite soccer showed faster MRTs in the early learning phase and earlier reached asymptote performance in terms of MRT. Present findings may be important for sports because children with superior implicit learning abilities in early learning phases may be able to learn more (durable) motor skills in a shorter time period as compared to other children.  相似文献   

粤东5种有害的外来入侵植物的研究   总被引：22，自引：0，他引：22  

曾宪锋 《韩山师范学院学报》2003,24(3):69-71,64

通过对粤东外来入侵植物的调查研究，确定南美蟛蜞菊(Wedelia trilobata)、微甘菊(Mikania micrantha)、五爪金龙(Ipomoea cairica)、飞机草(Eupatorium odoratum)和豚草(Ambrosia artemisiifolia)为最为有害的杂草，列为重点防除对象，并分析了这5种有害入侵植物的危害及入侵途径，并提出了防治措施．  相似文献