共查询到20条相似文献,搜索用时 109 毫秒
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为了提高严酷环境下建筑的耐久性,研究了防腐阻锈剂和防腐阻锈混凝土。以三乙醇胺、硝酸铝和Ca(OH)2为原料,经化学反应,制备新型固体醇胺,再按一定质量分数将固体醇胺、固废磷化渣、石膏和苯甲酸钠混合、球磨,制得复合型防腐阻锈剂,将其掺入基准混凝土中,制得防腐阻锈混凝土,并研究其力学性能和防腐阻锈性能。结果表明:掺复合型防腐阻锈剂的防腐阻锈混凝土,抗压强度和抗折强度显著提高,抗渗等级达P12,碳化深度大幅降低,抗冷热干湿循环和抗冻融性能优异,用含防腐阻锈剂的海水混合液浸泡钢筋2年,钢筋无腐蚀行为。用复合型防腐阻锈剂制备的防腐阻锈混凝土能有效延缓建筑混凝土的腐蚀进程。利用固废磷化渣制备防腐阻锈剂,变废为宝,可为新型防腐阻锈剂的开发提供借鉴。 相似文献
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In the United States, the Environmental Protection Agency (EPA) registers pesticides and sets crop-specific tolerances while the Food and Drug Administration (FDA) enforces EPA regulations by testing plant-based foods for pesticide residues. Pesticide treatment histories are almost always unknown, especially on imported produce, posing an empirical question: to what extent do FDA’s residue testing methods used on imported produce correspond to the pesticides used on the crops? In this article I show that FDA residue testing would have missed residues of the majority of pesticides used on two crops exported to the US from Costa Rica in 2003, suggesting that FDA residue testing on imported produce is inadequate in its coverage. Policy recommendations discussed include better communication of US tolerances to exporters around the world; increased testing for pesticides, especially fungicides, that are currently not part of FDA’s regular testing procedures; and the creation of price floors and fair trade relationships in the transnational vegetable market to support farmers’ attempts to comply. 相似文献
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《Food Policy》2013
Subjective risks of having contaminated apples elicited via the Exchangeability Method (EM) are examined in this study. In particular, as the experimental design allows us to investigate the validity of elicited risk measures, we examine the magnitude of differences between valid and invalid observations. In addition, using an econometric model, we also explore the effect of consumers’ socioeconomic status and attitudes toward food safety on subjects’ perceptions of pesticide residues in apples. Results suggest first, that consumers do not expect an increase in the number of apples containing only one pesticide residue, but, rather, in the number of those apples with traces of multiple residues. Second, we find that valid subjective risk measures do not significantly diverge from invalid ones, indicative of little effect of internal validity on the actual magnitude of subjective risks. Finally, we show that subjective risks depend on age, education, a subject’s ties to the apple industry, and consumer association membership. 相似文献
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建立了异菌脲在梨和土壤中气相色谱分析方法。梨、土壤样品用乙腈提取,Florisil固相萃取小柱净化,淋出液浓缩后用正己烷定容,气相色谱仪电子捕获器检测。试验结果表明,异菌脲的含量与峰面积之间呈线性关系,异菌脲的最小检出量为0.005ng。对于梨样本,异菌脲最低检测量为0.01mg/kg,添加平均回收率为94%~107%,变异系数为3.2%~6.5%;对于土壤样本,异菌脲最低检测量为0.01mg/kg,添加平均回收率为98%~110%,变异系数为4.0%~10.5%。结果表明该残留分析方法的灵敏度、准确度、精密度等均符合农药残留检测的要求。 相似文献
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建立一种简便、快速的检测水产品中孔雀石绿及其代谢物残留量的方法。采用乙腈提取、固相萃取柱净化浓缩,氧化剂将隐性孔雀石绿氧化为孔雀石绿,用化学比色法观察结果,从而建立一种简便、快速的初筛方法。加标回收率为70%~95%,相对标准偏差为5.46%~9.90%,孔雀石绿及代谢物的检出限分别为2μg/kg和4μg/kg。本方法相对于国标法操作更简便快速,适用于大批量样品检测。 相似文献
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H. Youn Kim 《Review of Industrial Organization》1999,15(4):321-339
This paper develops and estimates a model of economic capacity utilization and its determinants by allowing for the firm's full optimization behavior that considers endogenous output choice. The model consists of deriving the short-run output supply function and the capital demand function which generate optimal and capacity output. Optimal capacity utilization is determined as the ratio of optimal to capacity output and its determinants are identified. Evidence from U.S. manufacturing shows that capital expansion not accompanied by market growth and higher materials and capital prices has contributed to lower capacity utilization. Energy price increases have exerted a stimulating impact on capacity utilization. Conventional capacity utilization measures are found to be biased and fail to capture the influences of changes in economic conditions facing firms. 相似文献
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生物质能利用的现状、前景及应用指标 总被引:4,自引:3,他引:1
简要地介绍了世界各国在其特殊的国情下生物质能的应用情况,对可再生能源的合理利用进行了分析,指出对其合理利用的原则是“将合适的能源放在合适的地方”;提出了生物质液体燃料应用的几个重要指标,其中之一是基于全生命周期分析的“绿度”。最后强调:对可再生能源的利用一定要因地制宜;与自然和谐相处是可再生能源发展的最高准则。 相似文献
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由中东原油生产的劣质减压渣油,可作为延迟焦化原料,也是生产沥青的好原料。文章重点探讨了沥青生产的工艺路线,脱沥青油的处理,以及在沥青产品处于淡季时,将沥青与减渣掺混后作延迟焦化原料的可行性。文章以某企业的减压渣油为例,考虑了3种加工方案。方案1:减压渣油全部作延迟焦化原料;方案2:减渣抽出一部分去丙烷脱沥青,脱沥青油去加氢裂化,脱油沥青与减渣掺混后作延迟焦化原料;方案3:减渣抽出一部分去丙烷脱沥青,脱沥青油去加氢裂化,部分脱油沥青与少量减渣调合后生产重交通道路沥青产品,其余减渣与脱油沥青去延迟焦化。通过对以上3种加工方案的技术经济分析,认为方案3经济效益较好。 相似文献
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针对型煤干燥过程能源利用效率低、粉尘污染严重等问题,设计开发了一套通过在煤层下方铺设导热油管提供热量,并利用余热回收装置提高能源利用效率的型煤干燥装置。介绍了型煤干燥设备的总体结构,并对该装置的导热油炉、干燥室、余热利用装置3部分进行了结构分析,其中干燥室内铺设多层导热油管以逐步加热煤层和空气,从而能够在较小的风速条件下实现型煤的高效率干燥。通过结构分析和企业应用情况反馈表明,在保持相同干燥效率条件下,与不采用换热排管的装置相比,本装置在干燥过程中型煤几乎没有破损,干燥风速降低30%以上,单产能量消耗降低超过10%。因此,所设计的装置可以显著提高型煤成品率,降低粉尘污染,提高能量利用效率,降低企业生产成本,有助于型煤的推广利用。 相似文献