嘟声频率以及嘟声空白音的时长比对电话接通前时距知觉的影响

目的:本项研究探讨电话接通前嘟声频率和其与空白音的时长比对时距知觉的影响。方法 :本实验通过设置模拟电话接通前的等待情境,采用3(手机铃声嘟声频率:6、9、12次/45秒)×5(嘟声空白声的时长比:1:4、2:3、1:1、3:2、4:1)的两因素被试内设计,被试听完每段音频后口头报告对音频的时长估计。结果:嘟声频率以及嘟声空白音时长比这两个因素的主效应都显著,其交互作用也显著。并且,频率为6次/45秒时,嘟声空白音时长比为1:4时,被试的时距估计值最短。结论:等待电话接通前,手机铃声的嘟声频率以及嘟声与空白音时长比会影响人们的时距知觉。     

不同滴灌频率对大田覆膜小西瓜生长特性及品质的影响

在灌溉定额一定的情况下,研究了不同滴灌频率对大田膜下小西瓜在果实膨大期以及成熟期内有关特性的影响,以期为豫北平原地区大田膜下滴灌小西瓜生长中后期阶段确定最佳的滴灌频率。结果表明:不同灌溉频率对小西瓜生长过程中根粗、茎粗和蔓长的影响不是特别明显。从试验数据来看,以果实膨大期中频(T3),果实成熟期低频(T5)处理效果较好。此灌溉频率组合下不仅小西瓜长势好,而且甜度较大,省工省时又节水。     

为何我国用电频率是50H

<正>供电系统有史以来究竟出现过多少种频率恐怕难以说清。据有限的文献记载,除航空器外,历史上出现过的交流电网频率高的有13313Hz(双极8 000 r/min),低的有1623Hz(双极1 000 r/min),千差万别。1诸多技术元素左右着频率选择1.1负荷特性以供照明负荷为主的电网趋于选择较高的频率,白炽灯在     

基于平面模型的雷达多路径效应分析

本文在平面模型下,结合一般海况及平面粗糙度,使用频率分集技术,对雷达多路径效应进行了分析、仿真。通过仿真结果可知,该技术可减小多路径效应影响,提高雷达跟踪精度。     

汽轮发电机组的弹性负载运行和频率支持系统

本篇文章介绍了西门子电站的现行发电能力满足了这些要求。本篇文章重点介绍了汽轮发电机组的一些特点。     

犬心血管疾病诊断的多项体格检查

1呼吸 呼吸困难通常可引起犬只焦虑。患病动物常可出现呼吸用力、鼻孔张缩,以及呼吸频率加快。低氧血症、高碳酸血症或酸中毒常可引起呼吸深度增加。肺水肿可增加肺的硬度,引起快而浅的呼吸,以尽可能减小呼吸做功。在无原发性肺部疾病时,休息状态下呼吸频率增加是发生肺水肿的早期症状。存在大量的胸腔积液或其他胸腔疾病时,患病动物通常表现强烈的呼吸动作,用力使萎陷的肺扩张。     

Response of grain yield and related agronomic traits of oilseed flax to diversified cropping rotations北大核心CSCD

This research aimed to identify a suitable planting pattern for oilseed flax production in a dry-farming region. A long-term field experiment was started in 2012 with a 4-year crop rotation cycle,designed to measure the effects on flax crop performance of previous crop,and various patterns of flax planting interval within the four-year rotation,compared with continuous flax cropping. Crop parameters measured included plant height,stem diameter,dry matter accumulation and distribution,and the experiment included six different crop rotation patterns：Flax→flax →flax→flax［（F）FFF］;Flax→wheat→potato→flax［（F）WPF］;Flax→potato→flax→wheat［（F）PFW］;Flax→ flax→wheat→potato［（F）FWP］;Flax→wheat→flax→potato［（F）WFP］and flax→wheat→potato→wheat［（F）WPW］. Results for the ninth year showed significantly increased grain yield（29. 89%-109. 57%）in crop rotation treatments compared with continuous cropping of oilseed flax. The ranking of the six tested rotations for yield was：（F）WPW>（F）FWP>（F）WFP>（F）PFW>（F）WPF>（F）FFF. The grain yield of oilseed flax was significantly affected by previous crop,frequency and years interval of flax cropping and number of years of continuous flax cropping. Yield was increased by 54. 45%-59. 29% under wheat stubble and potato stubble compared with oilseed flax stubble,and increased by 30. 66% and 109. 57%,respectively,under 50% and 25% frequencies,compared with 100% frequency. The grain yield of oilseed flax under two-year continuous cropping was higher by 29. 89% than four-year continuous cropping,and increased with increase in years interval between flax crops. Correlation analysis identified a significantly positive correlation between oilseed flax grain yield and effective capsule number,branch number and 1000-seed weight. The effective capsule number,branch number and 1000-seed weight of oilseed flax under rotation treatment were increased by 35. 88%-108. 91%,15. 47%-46. 19% and 14. 61%-16. 34%,respectively（P<0. 05）,compared with continuous cropping. In addition,the high grain yield of oilseed flax was accompanied by an increase in plant height,stem diameter and dry matter accumulation and these increases were,respectively,5. 11%-42. 24%,2. 77%-39. 92% and 31. 25%-117. 89% under the rotation regimes,compared with continuous cropping. Reduction in the number of years of continuous cropping years,change of crop stubble,decreased flax planting frequency and increased of interval between flax crops also improved flax crop performance. In summary,crop rotation improved the vigor of oilseed flax,resulting in greater plant height and stem diameter,improved dry matter accumulation and distribution,leading to increased branch number,effective capsule number and 1000-seed weight,and increase in the crop yield of oilseed flax. The results indicated that a multiple-crop rotation pattern was an effective way to avoid the yield reduction caused by continuous cropping in oilseed flax. The rotation： Flax→wheat→potato→wheat performed best among those tested and can be recommended as an appropriate cropping rotation for oilseed flax production in the dry region of northwest China. © 2022 Editorial Office of Acta Prataculturae Sinica. All rights reserved.     

饲喂频率对妊娠母猪背膘厚和繁殖性能的影响

[目的] 研究饲喂频率对妊娠母猪背膘厚和繁殖性能的影响。[方法] 挑选加系杜洛克经产母猪480头,配种时按照胎次（2~7胎）、背膘厚（11~22 mm）相近的原则随机将母猪分为T1组（每天饲喂1次）和T2组（每天饲喂2次）,两组每天等量饲喂。T1组母猪220头,饲喂时间为8：00;T2组母猪260头,饲喂时间为8：00和15：00,每次饲喂量为总量的一半,定位栏饲养。[结果] ①饲喂频率不影响妊娠56 d、开配-妊娠56 d的背膘厚（妊娠56 d背膘厚-开配背膘厚）（P>0.05）;T2组妊娠110 d（P=0.06）、妊娠56-110 d（P=0.09）背膘厚（妊娠110 d背膘厚-妊娠56 d背膘厚）有高于T1组的趋势。②饲喂频率对窝产总仔数、活仔数、死胎数、木乃伊胎数、初生窝重以及初生个体重均无显著（P>0.05）影响。③在三胎母猪中,T2组妊娠110 d（P=0.01）、妊娠56-110 d（P=0.04）背膘厚均显著高于T1组;五胎及以上母猪,T2组妊娠56-110 d（P=0.08）背膘厚有高于T1组的趋势。④饲喂频率不影响二胎母猪窝产总仔数、死胎数、木乃伊胎数、初生窝重以及初生个体重（P>0.05）,但二胎母猪中T2组活仔数有高于T1组的趋势（P=0.07）。[结论] 饲喂频率由每天两餐减少到每天一餐不会对母猪的繁殖性能产生不利影响。     

三个复粒水稻材料的复粒频率及其复芽率

对3个复粒水稻材料的复粒频率和复芽率进行了研究。粳型CDR-2的复茅率和芽基数增加率显著高于籼型CDR-1和CDR-3;CDR-1在剥去颖壳下催芽,复芽率和芽基数增加率明显提高。     

基于频域特征参数曲线拟合法的柴油机故障诊断

柴油机的频域分析是指将所测得时域信号经过某种变换(如傅立叶变换),将其转换到频域进行分析的一种方法.频域特征参数主要包括重心频率FC、均方频率MSF、方根频率RMSF、频率方差VF和频率标准差RVF.本文利用柴油机工作时频域特征参数拟合曲线与所设标准故障频域特征参数拟合曲线之间的距离来判断柴油机故障类型.