Nutrient transfer functions: the site of integration between feeding behaviour and nutritional physiology

Summary. We describe and extend a graphical approach to quantitative nutrition that focuses on the interplay between behavioural and physiological components of nutritional regulation. The site of integration is the nutrient transfer function, which is the function describing the time course of nutrient transfer between serially connected nutritional compartments (e.g., from the gut to the blood). The relationship between the shape of the nutrient transfer function and the temporal patterns of feeding determines the values of two key quantitative parameters of nutrition: the rate ('power') and the efficiency of nutrient acquisition. The approach can be extended to consider, in addition to the short-term behavioural and physiological decisions made by animals, some ecological determinants and longer-term, life history consequences of such decisions. Most importantly, this category of models can provide insights into the interplay among the various nutrients in an animal's diet. We illustrate this using hypothetical examples, and also present preliminary data for the power-efficiency relationships of protein and digestible carbohydrates in locusts. Finally, we consider existing evidence for the various means available to these and other insects for regulating such relationships. Received 24 September 1997; accepted 9 December 1997.     

基于荷载试验的空心板桥加固效率分析

基于3座预应力混凝土空心板桥在试验荷载下加固前后荷载试验及理论计算得出的板底平均应力和挠度结果,对比粘贴碳纤维筋加固、简支转连续加固和粘贴钢板加固3种方法对简支预应力空心板桥结构的力学性能的提升效果.结果表明,粘贴碳纤维筋加固及粘贴钢板加固方法对结构刚度有轻微提高,对结构的延性及承载力有一定的提高;简支转连续加固方法在...     

用废腈纶制备高分子增稠剂

以废腈纶为原料，经碱法水解反应和扩链反应制取乳液用高分子增稠剂。水解工艺条件为水解温度95℃，水解时间4h；水解配方为m(PAN)：m(NaOH)：m(H2O)=1：0．6：5；扩链反应温度95℃，扩链反应时间约4h。对不同乳液体系进行的增稠性能评价及应用表明，利用该技术制备出的高分子增稠剂性能优良，应用范围广泛。现已建成一套生产能力为1000t/a的工业装置。     

以雨水为核心的城市水环境构建思路

在研究国内外利用雨水构建城市水环境的文献基础上,得出城市水环境构建要空中层、地表层和地下层综合构建三位一体的指导思想,以雨水为核心的城市水环境构建的思路是：从易到难,分步骤进行构建。     

废电子焊料综合利用研究

针对电子产品焊接过程中产生的波峰焊渣、SMT过程中产生的废电子焊膏及废电子信息产品回收拆解过程中产生的废电子焊料的回收利用,开发经济实用的废电子焊料综合利用工艺技术与设备。在H2SiF6-Pb(Sn)SiF6电解液中,控制游离H2SiF6在100～150 g/L,Pb2(+Sn2+)在60～120 g/L,电流密度100 A/m2,槽电压0.3～0.5 V,常温电解,实现Pb-Sn合金的提纯精制,生产出合格的Pb-Sn合金焊料。然后用常规方法从电解阳极泥中进一步回收银等贵金属。     

我国重金属污染土壤的利用研究

检测了重金属污染地区粮食、蔬菜、水果等不同作物的重金属含量。结果表明,这3类作物对高背景值耕地土壤中有害元素吸收能力的顺序为:蔬菜粮食水果。同一地区不同地块采样点土样中重的金属含量有所差异,同一有害元素在不同作物中的积累特性不同,不同作物种类对高背景值元素的吸收差异较大,为合理开发利用被重金属污染的土地资源提供了理论依据。     

Net value royalties : Practical tool or economist's illusion?

The petroleum industry has traditionally generated substantial revenues for governments. Where governmental power is divided, as in federations like Canada and Australia, a junior level of government normally collects royalties while the senior level levies a variety of imposts (income tax, export duties, excises on production). The combination of recent sharp reductions in prices, more price volatility and an era of freer markets has subjected existing tax and royalty systems to severe strain and has shifted attention to the design of fiscal systems that are more profit- sensitive. For the royalty element, interest focuses on net value royalties (NVRs). This paper deals with the nature and problems of NVRs. It proceeds by looking first at the application of resource rent royalties in Australia. It then focuses on recent megaproject royalty arrangements in Alberta and evaluates the degree to which Alberta's current royalty system is profit- sensitive. Problems associated with NVRs are discussed in the fourth section; concluding remarks are made in the last section.     

江苏省南通县农业资源的开发利用

本文根据江苏省南通县农业资源开发利用的现状,运用聚类分析法和模糊综合评判法,以乡为基本单元,将各乡划分为若干类。找出各类特征,明确开发整治的方向,制定开发利用的措施。     

和田河流域景观空间格局演变的初步分析

利用1990年、1999年TM和2002年中巴假彩色合成卫星遥感影像数据作主要信息源,经图像增强处理和解译,获得了和田河流域的区域土地利用景观类型图.采用景观生态学的方法,对研究区域进行土地利用景观空间格局演变进行了初步分析,并根据生态系统学基本理论,提出了综合利用水资源进行和田河流域生态环境整治的基本方案.     

水资源的可持续开发与利用

水是一切生物生存环境的最重要支撑,只有可持续地开发利用水资源,才能创造一个可持续发展的社会和生存环境。针对日趋严重的淡水资源危机,本文以水资源的可持续存在为基础,从整体的角度出发,而不是就水论水,探讨了可持续开发、利用水资源的五个途径:经济向生态效益型转向、可持续开发水资源、建立水资源核算体系、建立水资源政策分析机制、人人参与水资源管理,从而实现环境完整性、经济效率和平衡三个基本目标。