Environinental and economic consequences of technology adoption: IPM in viticulture

The impact of integrated pest management (IPM) on pesticide use, toxicity and other environmental characteristics, yields, and farm profits is examined for grape growers. The method is generally applicable for technology adoption and accounts for self-selectivity, simultaneity, and theoretical consistency. IPM adopters apply significantly less insecticides and fungicides than nonadopters among grape producers in six states, accounting for most of the U.S. production. Both the average toxicity and the Environmental Impact Quotient decrease slightly with adoption of insect IPM, but remain about the same for adopters and nonadopters of IPM for diseases. The effect of IPM adoption on yields and variable profits is positive but only significant for the case of IPM for diseases, i.e., the adoption of IPM for diseases increases yields and profits significantly.     

海内外各界对新四军抗战的经济支援

新四军之所以能在艰苦的环境里不断发展起来,并且没有发生八路军1941~1942年间出现的严重困难局面,除了新四军所在的华中地区比较富庶外,还得力于海内外各界对新四军的巨大经济支援。海内外各界的经济支援,保障了新四军最迫切的医药、衣被、器械等方面的急需,为新四军坚持华中敌后抗战提供了强有力的物质支撑。     

电梯主接触器故障分析

通过电梯出现的故障现象及故障代码来判断电梯故障发生的直接原因,为解除电梯故障确立一个分析方向,再通过逐层分析法和实验法将疑点逐一排除,找出引起故障的最终原因：主接触器触点接触不良。     

建筑施工中混凝土抗裂性问题及其对策

混凝土在建筑业中被称作是人工制造的"石头",因为不同类型的混凝土因其强度不同,形状相异,整体性能好,故而,在建筑施工中得到广泛应用。但是,混凝土也有许多缺点,关键的一点就是抗裂性能差。如何在应用过程中保证混凝土强度,提高混凝土抗裂性能在建筑施工过程中是最需要迫切解决的技术难题。所以,本文对混凝土在施工过程中造成裂缝的原因、如何提高混凝土抗裂性的问题进行研究和探讨。     

鸢尾属植物抗旱生理指标的测定

利用聚乙二醇(PEG-6000)以10%、20%、30%三个浓度,将四个品种鸢尾植株进行浸根处理,作为模拟土壤干旱胁迫。测定结果表明:马蔺具有较强的抗旱性。质膜透、MDA含量和SOD活性含量是鸢尾属植物重要的抗旱生理指标。     

高压配电网如何选择中性点接地方式

分析高压配电网中性点各种接地方式的特点,影响其选择的因素,及实际工程应用中应注意的问题。     

叠合箱受弯性能的试验研究与分析

混凝土叠合箱网梁楼盖是一种新型的楼盖形式,是由小型预制构件(混凝土叠合箱)与现浇混凝土肋梁结合成具有连续箱型截面的整体结构。本文通过对网梁楼盖的3块构件进行抗弯性能试验,得到了楼盖在受弯时的破坏机理,给出了截面抗弯承载力计算方法,为此种新的构件形式的工程应用提供了依据。     

抗战时期通货膨胀的计量研究

以抗战时期历年货币发行量为解释变量,以抗战时期物价指数为被解释变量,对货币的发行量和物价指数之间的关系进行回归分析,分析结果显示,作为解释变量的货币发行与被解释变量物价指数之间的相关系数为１４１２７,即货币发行量每增长１％,物价指数上涨１４１２７％,这表明通货膨胀的最主要因素是货币因素。但国民政府却主要通过物质供需平衡来治理通货膨胀,没有采取严格控制通货发行来管制物价,治理措施严重失当是造成物价快速上涨的主要原因。     

FARMERS’ WILLINGNESS TO COOPERATE IN ECOSYSTEM SERVICE PROVISION: DOES TRUST MATTER?

Ecosystem service provision in agriculture may require cooperation between farmers. Trust fosters cooperation in many economic and social interactions and is important to the success of traditional agricultural cooperatives. Little is known about how trust affects farmers’ willingness to cooperate to provide an ecosystem service, what types of trust are most important, and under what conditions trust may matter. In this study, we present results of a survey of Missouri crop farmers exploring the role trust plays in farmers’ stated willingness to cooperate to control pests. We find that most farmers say they are willing to cooperate, and most farmers are willing to trust others. However, we find little evidence that trust positively influences farmers’ willingness to cooperate to control pests. Instead, we find that trust may only matter under certain conditions, such as when participants’ farms are dissimilar, and that other determinants, such as the perceived benefit of cooperation and environmental concern, are more important than trust to farmers who are contemplating cooperation to control pests.     

非金属接地模块在变电站接地网中的应用

文章介绍了目前在变电站接地中常用的几种降低接地电阻的方法,详细阐述了非金属接地模块的组成及其降阻原理,并且通过对一个模拟地网进行仿真计算,分析了接地模块的安装位置、接地模块的个数、接地网面积,以及土壤电阻率等条件发生变化时接地电阻变化的规律。