虹桥图书馆自动化管理系统与信息管理

本文就国家科技图书文献中心联机编目项目成果虹桥图书馆管理系统的信息关联功能给予了较为详细的介绍。     

试析园林桥在法国古典主义园林中鲜见之因——以凡尔赛宫苑为例

法国古典主义园林在欧洲造园史上具有很高的地位,凡尔赛宫苑是其杰出代表作品之一,然而其中很难见到园林桥的应用。本文试图从政治、文化、历史、景观、功能和科技诸方面解析原因,寻找属于那个时代的特质。     

Polygon of crossability between eleven species of Ipomoea: section Batatas (Convolvulaceae)

Summary Crossability within Ipomoea section Batatas is complex because of genetic, cytogenetic and physiological interactions. This complexity is responsible for the fact that knowledge about phylogenetic relationships within this section remains preliminary. Between 1988 and 1991, studies of planting, pollination and evaluation of progenies were carried out at the facilities of CIP in La Molina and San Ramon, Peru. Self-compatibility was found in nine diploid species. Self-incompatibility was found in diploid I. trifida, tetraploid I. tiliacea and both tetraploid and hexaploid I. batatas. Sexual compatibility is though to be related to a multiallelic sporophytic incompatibility system which is expressed in the stigmatic papillae. Altogether, 4,162 cross pollinations were made between 11 species and 76 interspecific combinations of 110 possible combinations in a diallel 11×11 design. From these 76 interspecific combinations only 38 survived, and in these crossability (= proportion between number of fruits harvested/pollinations made) ranged from 0.01 to 1.00 at La Molina. At San Ramon, 11 out of 17 cross combinations were successful, and in these crossability ranged from 0.01 to 0.71. Crossability appeared to be influenced by latitude which is related to flowering synchrony. The early death of seedlings is hypothesized to be related to a genomic imbalance between embryo and endosperm. Maternal effects were found in crosses between diploids and tetraploids which produced triploid and diploid offspring, and in crosses between hexaploids and diploids which gave rise to hexaploid offspring. This study shows that I. trifida and I. x leucantha may act as bridge species for gene flow from wild Ipomoea species to the genepool of the sweetpotato.     

杂交水稻混播制种技术研究进展

将含水稻除草剂敏感(致死)基因的水稻变异系农林8号M系,采用有性杂交的手段,将其转移到含强恢复基因的架桥系中,进而培育含敏感基因的三系恢复系1m056-1,同步选育与该恢复系播始历期相近的三系不育系绿三A配制杂种,选育成功能混播混栽,可以进行机械化收割的强优势组合2E06.采用混播混栽方法制种,在授粉后喷施9 000mL/hm2苯达松,杀死父本,保留母本.制种产量可达6 690kg/hm2,比常规制种产量提高40%左右;商品代杂交种单产可达10 500kg/hm2左右,比对照增产10%左右.     

胶合木桥的设计、制备及其结构性能试验研究

在做出设计方案,包括技术条件、设计规范、材料参数及桥梁选型等的基础上,利用通用有限元软件MIDAS／Gen对木桥进行了结构分析,主要的计算工况包括全跨活荷载、半跨活荷载及人致振动等。分析结果表明,该桥的应力水平及结构刚度等均满足承载能力及正常使用要求。同时简要介绍了胶合木加工工艺及木桥的装配过程,并且通过静力堆我试验对整桥进行了结构性能测试,试验结果与有限元分析结果吻合较好。     

哈尔滨松花江公路大桥动载试验

本文通过介绍哈尔滨松花江公路大桥动载试验，一方面验证了该桥的承载能力，另一方面研究了车辆荷载作用下的动荷载效应问题，尤其是其中的动态增量或冲击系数。     

林用装卸桥起升机构的改进设计

为了缩小装卸桥起升机构体积及减轻其重量,以NGW型行星齿轮减速器取代JZQ型圆柱齿轮减速器作传动装置,是一种行之有效的方法。     

Research on Bridge Structure Noise of Railroads and Underground

This paper analyses the generating mechanism of radiation noise which produced by bridge structures and vibro-acoustic characteristics, and reviews the current situation of the researches on the relevant standards of structure noise at house and abroad. The author summarizes the method of measurement and calculation about structural noise at house and abroad, further notes their limits. This paper explores the impact of such factors as rain speed and other different fluids on structure noise. The noise characteristics of structures like cavity structure and thin-slab structure are also discussed. Strategies for reduce the bridge structure noise are summed up by reducing the vibration of track structure, altering the structure of boundary conditions, increasing the stiffness and changing the bridge cross section. Finally it comes to a conclusion that a combination of these strategies is the root way to settle the question of the bridge structure noise.     

大陆桥上干旱区工矿资源型城市发展研究——镍都金昌的发展分析

本文以镍都金昌为例探讨了新亚欧大路桥上干旱区工矿资源型城市的发展问题。通过对该类城市目前具有的优势和影响其持续发展的障碍的分析,提出今后发展对策。     

抗生素在土壤中的吸附行为研究进展

抗生素是畜禽养殖和水产养殖中常用的一类化学品,其使用量大,体内代谢率低,可通过畜禽粪便的农业施用直接进入土壤环境,在土壤中易残留,富集到一定水平就可能影响生态健康和安全.目前,抗生素污染最令人类担忧的风险是抗性基因和抗性病菌的滋生和传播.抗生素在土壤中的吸附作用是影响其持留、分布、迁移、转化及最终归趋的关键过程.本文选择四环素类、磺胺类、大环内酯类和喹诺酮类4类常用抗生素,论述了pH值、离子强度和金属离子、有机质以及其他土壤理化性质等因素对其吸附的影响,并对抗生素在土壤中的吸附机理进行了初步的探讨.