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1 微胶囊技术简介
微胶囊技术是当今世界发展迅速、用途广泛的一种技术。制备微胶囊的过程简称为微胶囊化(micmencapsulation),它是将固体、液体或气体包裹在一个微小的胶囊中。包封用的壁壳称为壁材;被包的囊芯称为芯材,芯材可以是单一的,也可以是复合的。囊壁厚度一般在0.1μm~200μm之间,微胶囊的粒子大小,因制备工艺及用途不同而不同,理论上可以制成0.01μm~1000μm的微胶囊。虽然对于微胶囊尺寸范围的分类还没有很统一的标准,但目前有人认为直径小于1μm的为毫微胶囊,而直径大于1000μm的为大胶囊。工业的微胶囊一般直径在3μm~800μm,含10%~90%的重量百分比的核。微胶囊的形状可以为球形、肾形、谷粒状、块状等。形成微胶囊的物质由于与外界环境相隔离,可以免受环境的影响,从而保持稳定,而在适当条件下,被包封物质又可释放出来。微胶囊技术在医药、食品、农药、印染等行业得到广泛应用。 相似文献
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微胶囊技术及其在医疗保健纺织品中的应用进展 总被引:1,自引:0,他引:1
微胶囊技术是一种用成膜材料将功能性气体、固体颗粒或液滴包覆形成微小粒子的技术。通常所说的微胶囊是指直径在2μ-2000μm,胶囊壁为典型厚度在0.5μm-150μm之间的微小容器,因其包裹的囊芯的功能不同而使微胶囊具有不同的功能。采用微胶囊技术的目的主要有以下几点:改善物质的物理性质、控制释放、提高稳定性、降低对健康的危害、屏蔽味道和气味、气味控制释放及不相容物质的分离。 相似文献
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近期,江苏丹毛纺织股份有限公司和国外公司合作开发了基于微胶囊技术的香薰理疗面料,以纺织后整理加工的方式赋予面料各种独特理疗功能。据介绍,该香薰理疗面料系列共包含维生素释放型面料、玫瑰香面料、异味中和面料三个品种,维生素释放型面料是将维生素A、维生素C和维生素E三种成分,通过微胶囊技术包裹成微小的颗粒,通过交联剂附着 相似文献
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微胶囊化技术开始于20世纪30年代,在20世纪50年代取得重大成果,并且广泛应用于无碳复写纸、医药、香料香精、防腐、纺织品、颜料、液晶显示、农药以及各种军事领域,但是相变材料微胶囊化技术(Microencapsulated Phase change Materials,简称MicroPeMs)的研究则大约从20世纪70年代才开始。 相似文献
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The overall goal of our paper is to understand the impact that irrigation in China has had on grain production and incomes, in general, and income and poverty alleviation in poor areas, in particular. The paper seeks to meet three objectives. First, we describe the relationship among irrigation status, yields and household crop revenue. Second, we seek to understand the magnitude and nature of the effect that irrigation has on yields and crop revenue. Finally, we seek to understand the impact that irrigation has on incomes in poor areas. Our analysis shows that irrigation contributes to increases in yields for almost all crops and in income for farmers in all areas. The importance of crop income in poor areas and the strong relationship between crop revenue and irrigation provides evidence of the importance of irrigation in past and future poverty alleviation in China. We also show that in the majority of the villages that invested in new irrigation, returns are positive even after accounting for increases in capital and production costs. 相似文献
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A growing gap between the production and consumption of food has led to a decline in consumer trust in food, and a desire for increased regulation of food. The aim of this study was to investigate the nature of consumer trust in food production and regulation in the wake of shifts in food technology, globalisation and production. Semi-structured interviews (n = 47) were conducted in 2009 with participants living in rural and metropolitan South Australia. Rural participants were more trusting of food production because of their direct experience with producing food than their metropolitan counterparts. Consumers’ embeddedness in food production impacts their trust in food. Increasing local food production and consumption may increase consumer trust in food, and decrease consumer dependence on government regulation. 相似文献
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国内外丁基橡胶生产现状和市场前景 总被引:1,自引:0,他引:1
目前,全球丁基橡胶的总生产能力约为892kt/a,2003年总消费量约为747kt/a。预计到2006年总消费量将超过800kt/a。目前我国丁基橡胶的总生产能力为30kt/a,2003年产量为27kt/a,消费量约为100kt/a,产不足需,每年都得大量进口。预计到2005年丁基橡胶的消费量将达到140kt/a,2010年消费量将达到210kt/a。针对目前我国丁基橡胶生产状况及存在的问题,提出了生产发展的建议。 相似文献
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Kwami Ossadzifo Wonyra Yacobou Sanoussi Ibrahima Sy Tomgouani Lanie 《Telecommunications Policy》2021,45(5):102123
The liberalization of the telecommunications sector in Togo aimed at ensuring access to a better quality of telecommunication services at affordable prices to everyone. While the liberalization policy has increased competition in the sector and reduced significantly telecommunication services prices charged to costumers, statistics on the access and use of telecommunication services in Togo reveal disparities with respect to individuals' socio-economic characteristics which could be an indication of the existence of inequalities of opportunities in the access and use of these services.This paper investigates the inequalities of opportunity in the access and use of telecommunication services in Togo using a parametric approach. The results of estimations indicate that, inequalities of opportunities are larger for men and the elderly than respectively women and youths and are more pronounced in urban areas and regions such as the Plateaux and Savanna regions. Moreover, the circumstance variables such as the ‘place of residence’ and the ‘region’ are the key variables in explaining the inequalities of opportunities in the access and use of telecommunication services in Togo. So, policies toward reducing inequalities of opportunity in the access and use of telecommunication services in Togo should be designed with regards to men, the elderly, and people living in urban areas and regions such as the Plateaux and Savanna regions. 相似文献
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In this paper we study the impact of the regulations on Maximum Residue Levels (MRLs) of pesticides on the trade of apples and pears and related processed products with the aim of understanding how their similarity (or dissimilarity) affect trade. Most studies investigate the impact of sanitary regulations introducing directly in the analysis the MRL put in force in the importing country. They introduce in the analysis the level of the regulation in the importing country without taking into account the rule in force in the exporting country. Rather than focusing on a particular pesticide we take into account the entire list of substances set out by the various regulations. We then build a similarity index and introduce it into a gravity equation to assess the impact of the differences in MRL of pesticides on trade. Results suggest that the differences between regulations matter and may, in some case, hinder trade. 相似文献
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目前,全球苯酚的总生产能力约为9260kt/a,2004年总消费量约为7745kt/a。预计到2009年总生产能力将达到11350kt/a,总消费量将达到9452kt/a。2005年我国苯酚的总生产能力约为580kt/a,2004年产量为410kt/a,消费量约为689.6kt/a,产不足需,每年都得大量进口。预计到2010年我国苯酚的总生产能力将达到约1000kt/a,消费量将达到约855kt/a。针对目前我国苯酚生产存在的问题,提出了今后的发展建议。 相似文献
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This paper examines the development of the role of government support in the financial situation of organic farms in selected Western and Eastern European countries, contrasting dependency on direct payments with that of conventional farms and assessing the impact of foreseeable changes in the political and economic environment. The results show that direct payments play an important role in the financial viability of organic farms in both Western and Eastern European countries. The level of specific support for organic farming is put into perspective, as other support payments and market returns contribute larger shares to total farm revenue in all the countries analysed. Modelling analyses show that support payments will continue to play an important role in the profitability of organic farms in Western Europe after implementation of the 2003 reform of Common Agricultural Policy in the EU. For organic farmers in Eastern European countries, the importance of support payments increases strongly with EU accession, as first pillar payments are introduced and environmental payments are expanded significantly. 相似文献
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At a time when choices for voice service and funding for universal service were growing, the United States experienced an unprecedented drop in household telephone penetration. Universal service in voice telephony is generally taken for granted in the United States. However, recent data from the FCC shows a significant decline in the number of U.S. households that have a telephone of any kind (including mobile), from a peak in telephone penetration of 95.5% in March 2003 down to 92.9% in November 2005. This decline is both statistically significant and meaningful, as approximately 2.6% of U.S. households could not easily reach 911 for emergencies. This study uses regression analysis of state-level data to determine what drove this decline in universal service. The results demonstrate that the recent decline in universal service in the U.S. is driven by an increase in black population, inadequate consumer protection laws, and increases in wireless telephones per capita. Lifeline effectiveness does not appear to mitigate the decline in penetration, while Link-Up effectiveness may have a limited effect. 相似文献
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《Food Policy》2019
Seasonal variation in nutritional status is a concern in sub-Saharan Africa. Seasonality in the food consumption of young Tanzanian children has a substantial and negative impact on later life outcomes. Seasonal variation in adult nutritional status has implications for labor productivity and prenatal health. Just as mean poverty status or mean health status varies within households, seasonal patterns in health status are likely to vary within households, as well as the mechanisms underlying seasonal variation. We parameterize and compare seasonality in nutritional status across multiple types of household members in rural, farming households in Tanzania, using a novel anthropometric measure of body mass index z-score that is comparable across adults and children. Young children not yet in school and working adults are most vulnerable to seasonal fluctuations in nutritional status. Children in school and older adults are relatively shielded. Seasonal variation in the nutritional status of working adults can be partly explained by variation in dietary quality and agricultural labor hours. Seasonal variation in the nutritional status of young children is not explained by either factor, nor is it mitigated by market access. Our results suggest we do not understand the data generating process behind seasonality in the nutritional status of young children, despite the critical implications of this seasonality for development and later life productivity. 相似文献
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The paper examines the role and function of public–private interplay in the development of municipal initiatives in the broadband sector. The analysis of initiatives in the Netherlands and Italy shows how the interaction between public and private stakeholders can facilitate local broadband initiatives. This interaction has been vital in aligning the interests of different private and (semi-)public parties, in designing the network and in aggregating sufficient demand for broadband services. The comparative analysis examines the steps involved in these initiatives and the strengths and weaknesses of joint public–private activities. The paper shows that the challenge for cooperating stakeholders has been to foster further investment in the upgrading of the network and in the provision of advanced broadband services. 相似文献