稻鳅共生种养模式试验研究

[目的]稻鳅共生是典型的稻田综合利用模式,符合生态农业发展方向。通过对稻鳅共生生态系统的生理生态学机制开展试验研究,为进一步推广稻鳅共生种养模式提供科学依据。[方法]采用田间试验方法,以水稻单作为对照,研究了不同泥鳅养殖密度下的稻鳅共生对水稻农艺性状、土壤理化性质、水稻产量构成的影响,并对稻鳅共生种养模式进行了经济效益分析。[结果]与对照处理相比,水稻长势在株高、有效分蘖率、根长等方面有一定提高。养殖田水稻株高增高了3%,有效分蘖率提高了8%~11%,根长提高了8.8%~31.3%。在土壤理化性质方面,与对照相比,土壤容重降低了7.1%~21.2%,孔隙度增加了4.1%~14.7%。实验前后养殖田内土壤有机质增加了3.5%~26.5%,对照田降低了2.5%~5.8%。土壤肥力(氮、磷、钾)减少,但减少幅度小于对照处理。稻鳅共生种养模式下水稻产量提高了5%~25%,同时稻田增收泥鳅1 725~3 375kg/hm2,净收入为1.836 0万~2.307 0万元/hm2,经济效益提高了3.65~4.84倍。稻鳅共生种养模式中泥鳅的养殖密度为30万尾/hm2时稻田的生态效益和经济效益最佳。[结论]稻鳅共生有效改善了土壤理化性质,促进了水稻的生长,提高了稻田产量和产值。     

甜菊糖苷的功能特性及其在饮料工业中的应用

甜菊糖苷作为天然的高甜度、低热量甜味剂,已被广泛应用于食品、饮料中。本文阐述了甜菊糖苷的化学结构、理化功能特性,综述了甜菊糖苷的研究现状以及在饮料工业中的应用,指出其发展前景广阔,为甜菊糖苷的深入研究提供参考。     

《技术制图》新旧标准对照

以对照方法介绍了《技术制图》与《机械制图》中三个基础标准的适用范围、采标情况及基本内容。     

On Conditional Density Estimation

With the aim of mitigating the possible problem of negativity in the estimation of the conditional density function, we introduce a so-called re-weighted Nadaraya-Watson (RNW) estimator. The proposed RNW estimator is constructed by a slight modification of the well-known Nadaraya-Watson smoother. With a detailed asymptotic analysis, we demonstrate that the RNW smoother preserves the superior large-sample bias property of the local linear smoother of the conditional density recently proposed in the literature. As a matter of independent statistical interest, the limit distribution of the RNW estimator is also derived.     

预应力拱支双层网壳的静力性能研究

双层曲面网壳在结构的稳定性方面较单层网壳有优越性,在一些跨度较大或支撑较弱的建筑中更多地采用双层曲面网壳结构。预应力拱支双层网壳结构体系是在综合双层网壳和预应力拱结构等优点的基础上,构思出的一种新型大跨空间结构形式。该文主要采用一算例讨论预应力拱支双层网壳结构在三种工况下的内力及变形特点等受力性能,显示出该新型杂交结构体系整体性能得到改善,具有一定的应用前景。     

18-run nonisomorphic three level orthogonal arrays

In this paper we construct all possible orthogonal arrays OA(18,q, 3,2) with 18 runs and 3 ≤ q ≤ 7 columns and present those that are nonisomorphic. A discussion on the novelty and the superiority of many of the designs found in terms of isomorphism and generalized minimum aberration has been made.      

现有知识产权制度对环境保护实施的影响及对策

把我国现有知识产权制度与环境保护现状有机地结合起来,针对性地研究了两者的相关性,系统、全面地分析了我国现有知识产权制度对环境保护的影响,指出了现有知识产权制度与环境保护实施不协调的若干具体问题,并就此提出了建设性意见及对策.     

矿山机电设备管理中存在的问题及解决对策

机电设备是矿山生产当中的重要工具,其能够帮助工作人员开展生产作业,提高工作效率,有效解放劳动力,使矿山企业拥有高效、快速、简便的生产方式。在矿山生产当中,利用机电设备进行作业,能够减少因工作人员的疏忽而造成的失误,提高矿山生产的安全性。所以在矿山生产当中,机电设备十分重要。论文首先分析矿山机电设备管理的意义,然后分析矿山机电设备管理中存在的问题,最后从三个方面分析矿山机电设备管理的措施。     

An axiomatic characterization of a generalized index of concentration

The Hannah-Kay [1977] generalized concentration index contains the well-known Herfindahl [1950]-Hirschman [1945] and the entropy indices as particular cases. In this papaer we show that the Hannah-Kay class can be regarded as a particular member of a generalized family of indices, which we refer to as self-weighted quasilinear means. We then show that among all self-weighted quasilinear means the Hannah-Kay family is the only class of concentration indices which satisfies the replication principle, a requirement which states that an m-fold replication of the industry, firm by firm, will multiply the concentration index by the factor 1/m.The refereeing process of this paper was handled through N.R. Adam.We are grateful to two anonymous referees for their suggestions.     

立体停车库及其设计要点

解决大、中城市汽车停车难的出路在于建造机械化立体停车库．介绍了各类立体停车库的结构、控制系统及其特点，给出了立体停车库的主要性能指标，并对立体停车库的设计要点进行了探讨