菌制剂在应用中存在的问题及解决途径探讨

菌制剂是近几年推广的一种广泛用于种养业的生物技术产品。本文针对菌制剂在作物上应用时的增产效果进行了试验研究。结果表明:菌制剂在提高作物产量方面具有正效应,但不稳定。本文就这一特性及其解决途径进行了探讨。     

基于Mathematica求解时滞方程

结合具体的例子,主要介绍了运用Mathematica7求解时滞微分方程的方法,以及如何通过软件探讨时滞方程数值解对初始函数的敏感性与由于时滞的增加引起解的变化.     

On resolvable PBIB designs

Resolvable solutions for some two associate PBIB designs obtained by duplicating some non-resolvable designs are given. For the same designs 2-, 3- and 5-resolvable solutions are reported by Clatworthy (1973). A method of construction and some new resolvable PBIB designs obtained through this are given.     

Families of regular designs based on geometries

Recently Bush and Ostrom (1979) settled most of the open questions with respect to inequivalent solutions of a class of semiregular (SR) designs which can be constructed from nets. This paper is a study of the same nature for two families of regular (R) designs derived from finite projective planes. One family presents no problems, but the other which is a ‘double’ family with two parameters is much more difficult. In fact it is here solved only for designs based on planes of orders 3, 4, 5 and 8. Certain general methods exist which are indicated, but we were unable to resolve even the case 7 using this technique.Basically we show the existence of either inequivalent solutions or show there is but one solution settling a number of open cases. In particular for the case λ₁ = 2, λ₂ = 1 we give new solutions to a number of D(2) designs or group divisible designs with two associate classes which have no repeated blocks in contrast with the published solutions which have this undesirable property for a number of applications.     

浅析凉山民族地区农村劳动力转移的现状及对策

凉山州有较多的剩余农村劳动力,近年来已有20万人向非农产业转移,并取得了较为可观的劳动收入,但是这部分劳动力占全州农村剩余劳动力的比例还较少,并存在受教育程度较低,职业技能水平低,竞争力低等诸多问题,限制了剩余农村劳动力的转移。本文结合民族地区农村劳动力的转移的调查,论述了民族地区农村劳动力转移的特点及面临的问题和对策,提出了加强农村劳动力教育和职业技能培训,加强政府的服务、管理、引导的职能等措施,降低劳动力转移的风险,从而鼓励和推动凉山民族地区农村剩余劳动力的转移。     

独生子女家庭空巢风险分析

在中国的人口转变过程中,由于独生子女的大量增加,已经出现了一种全新的空巢现象,即越来越多的独生子女家庭提前进入空巢期,并使空巢期延长,增加了独生子女父母养老和心理健康风险。本文对独生子女空巢家庭产生的原因、发展趋势、特征及其风险进行了深入分析,最后提出了化解独生子女家庭空巢风险及其危害的对策。     

Persistent age distributions for an age‐structured two‐sex population model*

In this paper we formulate an age‐structured two‐sex population model which takes into account a monogamous marriage rule and the duration of marriage. We are mainly concerned with the existence of exponential solutions with a persistent age distribution. First we provide a semigroup method to deal with the time‐evolution problem of our two‐sex population model. Next, by constructing a fixed point mapping, we prove the existence of exponential solutions under homogeneity conditions.     

高校特困生现象分析与对策思考

特因生问题是目前高校学生管理工作中比较突出的问题,重视这个问题并切实解决好,对高校的稳定和学生的成才起着十分重要的作用.本文从高校特困生产生的原因、存在的特点和解决的对策几个方面对这一问题作了分析,以期得到人们对这一问题的重视和对特困学生的关心.     

我国农村人力资本存量地区差异的成因及对策

文章从人力资本投资的角度,分析了我国农村人力资本存量地区差异产生的政策原因,即城市倾向的国家财政教育投资政策和地区经济非均衡发展战略而引致城乡教育投资差异和地区之间的教育投资差异。由于这些差异形成了我国人力资本存量的城乡差距,东中西差距,农村内部不同地区之间的差距;而农村人口非农化又进一步加剧了这些差距,使得农业人力资本存量在所有的职业中最低。文章根据这些差距产生的原因,提出了相应的对策建议。     

新媒体管理中存在的问题及对策

新媒体管理中存在着管理观念落后、不良信息传播、缺乏有效监管等问题。必须采取有效对策,一是以自律公约的形式强化自我约束和管理力度,规范行为,发展经营;二是整顿市场秩序,构建完善的市场监督机制;三是建立良性循环的商业模式;四是积极引导新媒体为构建和谐社会服务。