40年来我国粮食产量历史演变特征的初步分析

来源 :中国农业科学 | 被引量 : 0次 | 上传用户:yryr0804
下载到本地 , 更方便阅读
声明 : 本文档内容版权归属内容提供方 , 如果您对本文有版权争议 , 可与客服联系进行内容授权或下架
论文部分内容阅读
分析探讨40年来我国粮食生产的波动特征,对粮食产量的预测预报以及逐年稳定增长具有重要的现实意义。全国和部分省(区)单产序列的分析表明: 1.近40年来,我国粮食单产的增产年多于减产年,增产持续时间和增产幅度亦均大于减产年; 2.各省(区)的增减产年频数呈准正态分布,其累积频率曲线可分为稳定、不稳定和中间型三类; 3.增向转移概率大于减向转移概率,尤以减转增的概率为最大,减转减最小; 4.40年来我国粮食生产的发展经历了低产缓慢发展—波动发展—高速增长不稳定发展的3个阶段; 5.增减产年的历史演变具有较明显的准4年及其倍数周期的波动特征,各地主要波动周期的变化说明了粮食生产稳定性在地区上的差异。 It is of great practical significance to analyze and discuss the fluctuation characteristics of grain production in our country over the past 40 years, forecast and forecast the grain output and steadily increase year by year. The analysis of the yield series of the whole country and some provinces shows that: 1. The output of grain in China has increased more in the past 40 years than in the year of decline, and the duration and rate of increase in production have also exceeded the rate of decrease in production. 2. The increase in the number of provinces The annual frequency of production decreases quasi-normal distribution, the cumulative frequency curve can be divided into three categories of stability, instability and intermediate type; 3. Increase the transfer probability is greater than the probability of transfer reduction, especially the probability of reduction increase is the largest, minus 4. The development of grain production in our country experienced three stages of low-yield slow development-fluctuating development-unstable growth of high-speed growth in the past 40 years; 5. The historical evolution of the year of increase and decrease has obvious quasi-4 years and multiples of its cycle The fluctuation of the main fluctuating periods in all parts of the country illustrates the regional difference in the stability of grain production.
其他文献
南黄海西部陆架的浅表层沉积物一直被认为是年代地层框架的构建是古环境与气候研究的基础,年代地层框架的好坏直接决定着研究结论的准确程度。本项研究通过分析沉积岩芯的粒
Objective: To investigate U. parvum (previously Ureaplasma urealyticum biovar 1) and U. urealyticum (previously Ureaplasma urealyticum biovar 2) and their subty
Objective: To study the cellular immunity status of patients with recurrent genital herpes.Methods: Serum levels of interlukin-2 and its soluble receptor and in
以豫麦18等八种不同基因型小麦成熟胚为外植体,研究了不同处理方式(胚乳支持和胚乳不支持)及不同2,4-D浓度(2mg/L和8mg/L)对小麦成熟胚愈伤组织脱分化和分化的影响;为了研究小麦成熟胚脱分化和分化的生理特性,我们测定了与愈伤组织脱分化和分化有关的(质膜H~+-ATPase及草酸盐氧化酶)两种酶活性,并对其机理进行了分析。为了进一步对小麦成熟胚再生机理进行研究,通过Northern Blot
将修正的TTHG(two term Henyey-Greenstein)散射相位函数运用到电子散射理论中,并利用小角度近似条件推导出沙尘天气下激光信号脉冲时延和展宽的表达式。研究了脉冲时延、展
哥伦比亚广播公司、美国广播公司和国家广播公司是美国三家最大的电视广播公司。它们的电视网笼罩全国各地,竞争激烈。这三家公司都很重视电视新闻节目,收看率都相当高。但
本文以新农菜豆1号为材料,在稀植条件下,通过大田试验分别研究了氮肥对菜用大豆氮、磷、钾吸收分配的影响,密度对菜用大豆的生长发育的影响及播期对菜用大豆产量和品质的影响
Objective: For the purpose of understanding the changing process of syphilis histomorphology and its injury mechanism,the ultrastructure of dermatic tissues of
水分胁迫是严重影响作物生产的环境胁迫之一。根据水分供应情况,稻类作物经过长期的人工选择和自然选择分化为水稻和旱稻,水稻是天然“敏旱类型”,旱稻则是“抗旱类型”,为了初步
声乐是音乐艺术里的重要组成部分.声乐是人与人的情感交流传递中,运用歌唱技术的各种技巧、产生与内容相符的声音、以声音的变化为媒介、手段、传达美和情感.