利用垃圾堆肥改良水稻土I:对水稻土物理化学性状的影响

根据上海市农业产业结构调整过程中对土质的要求，本文从资源化利用上海市城市生活垃圾的角度出发，将自然堆置多年的垃圾堆肥应用于土壤改良．由于垃圾堆肥质地粗松，含有较高的营养成分，同时考虑到水稻土对垃圾堆肥的承纳量，本实验设计了0、7．5、15、22．5kgm^-2 4个垃圾堆肥施用剂量，经过一个完整的生长季节后采集土壤样品进行理化分析．结果表明，相较对照小区(0kg m^-2)，施用垃圾堆肥可以有效地改良水稻土的物理化学性状：有机质、全N、全P、碱解N和速效P的含量分别提高5％—240％，土壤中细砂含量升高，粘粒含量下降．而且这种改良的效果随着垃圾堆肥施用量的增加而增加．在不同耕作深度上，以0-10cm土层的效果最佳，10—20cm次之，20—40cm最低．本实验结果表明，垃圾堆肥不仅是上海市水田旱作土壤的有效改良添加剂，而且是解决城市生活垃圾出路的一条有效途径．表2参7     

不同类型土壤镉含量对香芋镉吸收的影响

为探明香芋(Colocasia esculenta)镉(Cd)超标的关键原因,在湖南临武香芋主产区分别选择紫色页岩和第四纪红壤发育的Cd污染水稻土,研究土壤Cd含量、Cd活性及土壤基本理化性质对香芋Cd吸收的影响,以期为香芋的安全种植提供技术支撑。结果表明,两个试验点所有香芋Cd质量分数皆超过食品安全国家标准(0.1 mg·kg^-1),且各试验点内田块间土壤Cd含量、pH差异显著,而土壤有机质和阳离子交换量变异较小;紫色页岩发育的中碱性水稻土壤Cd活性、Cd在土壤-香芋系统中的转移系数(TFstem/taro、TFtaro/soil)皆低于第四纪红壤发育的酸性水稻土;紫色页岩发育的中碱性水稻土中,香芋Cd含量主要受土壤全Cd、TFtaro/soil的正调控;而第四纪红壤发育的酸性水稻土壤中,香芋Cd含量既受土壤全Cd、DTPA-Cd、TFtaro/soil的正调控,还受土壤pH的负调控。为实现香芋的安全生产,紫色页岩发育的中碱性水稻土中,应优先选择Cd吸收能力较低的香芋品种,或选择土壤全Cd低于0.65 mg·kg^-1的土壤进行种植;而在第四纪红壤发育的酸性水稻土壤中,则可优先选择Cd吸收能力较低的香芋品种,或选择土壤全Cd含量低于0.41 mg·kg^-1的土壤,或调理土壤pH至6.26以上,以及钝化土壤DTPA-Cd至0.19 mg·kg^-1以下的技术措施,抑制土壤Cd向香芋的迁移转运。     

Social foraging and dominance relationships: the effects of socially mediated interference

In socially foraging animals, it is widely acknowledged that the position of an individual within the dominance hierarchy of the group has a large effect upon its foraging behaviour and energetic intake, where the intake of subordinates can be reduced through socially mediated interference. In this paper, we explore the effects of interference upon group dynamics and individual behaviour, using a spatially explicit individual-based model. Each individual follows a simple behavioural rule based upon its energetic reserves and the actions of its neighbours (where the rule is derived from game theory models). We show that dominant individuals should have larger energetic reserves than their subordinates, and the size of this difference increases when either food is scarce, the intensity of interference suffered by the subordinates increases, or the distance over which dominant individuals affect subordinates increases. Unlike previous models, the results presented in this paper about differences in reserves are not based upon prior assumptions of the effects of social hierarchy and energetic reserves upon predation risk, and emerge through nothing more than a reduction in energetic intake by the subordinates when dominants are present. Furthermore, we show that increasing interference intensity, food availability or the distance over which dominants have an effect also causes the difference in movement between ranks to increase (where subordinates move more than dominants), and the distance over which dominants have an effect changes the size of the groups that the different ranks are found in. These results are discussed in relation to previous studies of intra- and interspecific dominance hierarchies.     

1420铝锂合金模锻件锻造工艺的研究

利用高温变形实验 ,研究了 14 2 0铝锂合金在不同变形条件下的变形行为 ,获得合金的塑性图、变形抗力图、晶粒尺寸 变形程度关系图 ,确定出合金的锻造工艺参数 :锻造温度为 35 0～4 2 0℃ ,临界变形程度为 8%～ 10 % ,变形速率以低速为宜。结合实际情况 ,制定出合理的、经济的14 2 0铝锂合金模锻件成形工艺 ,即 6 0 0 0t水压机上多方锻开坯→车成锥体→ 80 0 0t卧式挤压机上终压模成形。生产出的 14 2 0合金模锻件尺寸精度高 ,综合性能优良。     

Relationships between Danish organic farming and landscape composition

This article presents an investigation of relationships between organic farming and landscape composition in Denmark. Landscape composition was analysed in terms of density of uncultivated landscape elements (I), number of land uses per hectare (II), diversity of land use (III) and mean field size (IV). Two analytical approaches were used. The first was based on an examination of the national agricultural registers for 1998, 2001 and 2004. The second approach used aerial photo interpretation for an analysis of 72 conventional and 40 organic farms within three sample areas for 1982, 1995 and 2002. The national analysis indicated that organic farming has a direct effect on landscape composition. In 2001, organic farms were characterised by a higher number of land uses per ha, a higher land use diversity and smaller mean field sizes. From 1998 to 2004, conversion to organic farming was related to an increasing number of land uses per ha, increasing land-use diversity and decreasing mean field sizes. Relationships between organic farming and landscape composition were independent of variations in regional location, farm size or farm size change. At the level of sample areas, a significant relationship between organic farming and landscape composition was only found for densities of small biotopes. However, when differences in farm size and physical geographical conditions between conventional and organic farms were taken into account, several significant differences in landscape composition were clarified in two of the three sample areas. Furthermore, changes in landscape composition following conversion to organic farming were largely biased by the characteristics of the sample areas. Thus, in contrast to the national level, the sample area study indicated that differences in landscape composition between organic and conventional farms were not a direct implication of organic farming practices, but were related to variations within other parameters and to the location of organically farmed land.     

放射示踪法研究O2存在时14CS2与OH的光化学反应

用放射示踪法研究~(14)CS_2和OH的光化学反应,指出氧对反应有促进作用,在反应体系中(~(14)CS_2-H_2O_2-C_3H_8-N_2-O_2)主要产物为O~(14)CS,~(14)CO及少量~(14)CO_2。O~(14)CS和~(14)CO有相似的动力学曲线,~(14)CO_2则是另一种情况。总反应速率常数随氧压增加而增大,在氧压为33330Pa时,~(14)CS_2消失的总速率常数可高达3.4×10~(-12)cm~3mol~(-1)S~(-1)。在实验中观察到~(14)CS_2能在室温下转变为~(14)CO_2的现象。讨论了光化学反应的历程。     

SiC颗粒尺寸对喷射共沉积7075 Al/SiCp挤压及轧制的组织和性能的影响

研究了喷射共沉积方法制备的7075 Al / SiCp复合材料挤压及轧制过程中SiC颗粒的分布.通过拉伸实验、微观组织的金相及拉伸断口SEM观察分析了SiCp颗粒尺寸对材料组织和性能的影响.实验表明,SiCp在挤压过程中沿厚度方向形成分层分布,SiCp的尺寸及粒度分布对于聚集有较大的影响;轧制过程对挤压时形成的SiCp分层分布有一定的减弱作用,但改善程度和SiCp的尺寸有关;SiCp颗粒尺寸对复合材料的力学性能及断裂机制有很大的影响.     

AZ31B镁合金挤压工艺研究

在油炉中熔炼AZ31B镁合金 ,用熔剂保护 ,石墨模铸造圆锭。铸锭经 40 0℃× 1 2h的均匀化处理后 ,进行热挤压 ,其挤压温度为 40 0℃ ,挤压速度为 1～ 2 .5m/min ,挤压比为 1 0～ 45。共挤出了 1 1种规格的棒材、管材、型材 (工字型、槽型、角形、方形、T形等 ) ,挤压过程中均发生了动态再结晶 ,其抗拉强度σb 在 2 75～ 2 85MPa之间 ,屈服强度σ0 .2　在 2 2 0～ 2 2 5MPa之间 ,延伸率δ在 1 5 %～ 1 7%之间。所制订的工艺合理 ,挤压出的棒材、管材、型材有较好的力学性能     

A method for calculating the total ozone amount in the clear skies

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Effect of different design aspects of pipe for earth air tunnel heat exchanger system: A state of art

Earth air tunnel heat exchanger (EATHE) is a promising passive technique to provide thermal comfort condition in buildings. EATHE system uses undisturbed temperature of the ground for heating/cooling of air. Despite the several advantages, this technique has not become much popular owing to its high capital cost (mainly pipe cost and trench excavation cost) and large land area requirements. The primary objective of this study is to present a comprehensive review of different EATHE pipe layouts, pipe properties and positioning of the pipe with their advantages and limitations. It is observed that the ring pipe layout is the most cost-effective pipe-layout for small size EATHE system because it saves excavation cost by using a trench of the existing foundation of the building. However, Grid pipe-layout is an ideal layout for a large size EATHE system. Multi-layer pipe layouts should be used to reduce the land area requirement significantly. Moreover, EATHE system can be installed beneath the building (under building foot-print) to eliminate extra land area requirement for the installation of EATHE system. This review article shows that the Initial capital cost and land area requirement for the EATHE system can be substantially reduced by using appropriate pipe layout. It can be concluded that if EATHE system is installed with proper design strategies, it will be a clean and cost-effective method for building heating/cooling with significant power savings.