植物源农药表面活性剂研究

随着现代化技术的发展和人们生活水平的日益提高,传统化学农药在使用过程中的很多缺点都逐渐显现出来了,也慢慢被人们所重视。植物源农药来源于自然,具有环保、长效、易光解、无残留等优点。运用表面张力法筛选出的植物源农药表面活性剂,能够增强药液在植物叶片上的持留和铺展能力,从而提高药液的有效利用率,减轻对环境和人体的危害。     

纳米乳的研究进展与潜在局限性

纳米乳以其独特的优势展现出巨大潜力,具有广阔的应用前景。近年来,纳米乳在食品、药品、化妆品等领域的应用,引起了相关研究人员的关注。本文主要阐述纳米乳的概念和制备方法,以及在递送系统中的研究进展与应用,并且围绕纳米乳技术的潜在局限性进行了分析与讨论,以期为纳米乳日后的研究与应用提供依据。     

水产养殖用环境改良剂与消毒药物的特点与使用方法(4)

<正>第4节季铵盐类消毒剂季铵盐类消毒剂是一种阳离子表面活性剂。其结构通式为:其中,Rl-R4代表有机根,它们与氮原子结合成一阳离子基团,为杀菌的有效部分。X为一阴离子,如卤素、硫酸根或其他类似的阴离子。用作消毒剂的季铵盐,在Rl-R4中,     

水产养殖中消毒剂的选择与使用(下)

<正>三、季胺盐类用于做消毒剂的季胺盐主要是一类阳离子表面活性剂。目前品种极多,达数十种,单一的季胺盐消毒剂的杀菌效果往往不理想。需要进行科学组方,并经大量的复配试验和     

水产常用卤素类消毒剂的使用方法及注意事项

<正>在水产养殖过程中,使用消毒剂杀灭水生环境中的有害微生物,改善水生动物生活环境,不仅能够有效防治病害的发生,提高养殖产品品质,并且具有使用方便、价格相对低廉的优点。而卤素类消毒剂已成为最常用的水产消毒剂。以下就几种常用的水产卤素类消毒剂作一介绍。     

农业对文化的传承作用

恩格斯指出:"首先是劳动,然后是语言和劳动一起,成了两个最主要的推动力,在它们的影响下,猿脑就逐渐过渡到人脑。"在人类的产生和发展过程中,农业劳动和农业无疑起到了决定性的作用;进入工业文明后,农业对于保持本民族特色、传承本国文化传统,也发挥了十分重要的基础性作用。     

Exploring the effect of land use on ecosystem services: The distributive issues

The current debate of ecosystem services has focused more on monetary valuation methods and payments for environmental services (PES) then on the classic economic analysis (i.e. assumptions regarding: sustainability, justice and efficiency). This paper examines, taking into consideration ecosystem services, income distribution from different land uses to stakeholders. We study the Portuguese common land ecosystem, which is characterized as having a wide range of ecosystem services. Allowing that all the benefits can be translated into economic value, we estimated the total economic value (TEV) associated with these territories on 5 different land use situations: forest, shrubland, water bodies, mountain agriculture and other uses, and analyzed the current institutional arrangements around these territories. We found that the distribution of the benefits of different land uses is relatively inequality. The results showed that the contemporary institutional arrangements of wealth distribution ensure a relatively fair distribution insider of system; however this institutional arrangement is unable to ensure equitable distribution of wealth by external stakeholders. We can conclude that different types of land use provide a very asymmetric distribution of income by different groups of humans: land owners; citizens of a country, and residents of Earth.     

The effect of intellectual property rights on agricultural productivity

This article explores how the strengthening of intellectual property (IP) protection affects agricultural productivity in a panel of countries for the period 1961–2011. Using an index of IP protection for plant varieties, we study the effect of stronger intellectual property rights (IPRs) on cereal yields and two different types of cereals: Open‐pollinated (wheat) and hybrid (maize). We found that the strengthening of IPRs has a positive effect on productivity of cereals for high‐ and low‐income countries. However, we found no significant effect for middle‐income countries. In addition, we found that becoming a member of the Trade Related Aspects of Intellectual Property Rights negatively affects cereal yields. Finally, we found evidence of the existence of nonlinearities in the effect of IPRs on agricultural yields, which confirms a threshold effect of IPRs that also varies for countries of different income level. The findings support the hypothesis that country specificities are important in determining the effect of IPRs and imply that there is no unique system that fits all.     

温度对毛果苔草种子萌发的影响

温度是种子萌发的三大要素之一.研究了温度对毛果苔草种子萌发的影响,发现变温30/20℃有利于种子萌发.     

The effect of the Canada–China canola trade dispute on canola prices

In March 2019, China revoked the canola export licenses of two major Canadian exporters. We estimate the impact of these restrictions on Canadian canola prices. Using a vector error correction model to generate counterfactual prices, we estimate that between March 2019 and February 2020 canola prices were 3.6% lower than would have been expected in the absence of the import restrictions. We discuss the implications of our finding for both the ongoing negotiations between Canada and China and producer support in Canada.     

The effect of site quality on economically optimal stand management

This paper proposes a discrete-time type timber harvesting model for simultaneously determining (i) the optimal quantity of seedlings to be planted, (ii) the optimal quantities of timber harvested by thinnings, and (iii) the optimal rotation age. With the help of Microsoft Excel Solver, a generalized reduced gradient algorithm, numerical examples are developed to evaluate the impact of the variations in the quality level of a forest site on the optimal harvest strategy. It is shown that the level of optimal rotation age and optimal quantity of seedlings to be planted can individually exhibit non-monotonicity to the increase in site quality.     

中国加入WTO对渔船船东互保工作的影响

我国渔船船东互保协会成立于1994年9月,本着互助共济,为会员的生命财产损失提供物质保障的原则,向会员提供安全生产服务,通过几年的实际工作,初步达到了提高会员防灾、抗灾能力,促进渔业生产持续稳定发展的目的,充分发挥了“稳压器”的作用。     

紫茎泽兰对酵母和发酵酒精的影响

在研究利用紫茎泽兰(Eupatorium adenophorum Spreng)发酵生产燃料乙醇可行性时,发现紫茎泽兰不仅抑制酵母(Saccharomycessp.)发酵产生酒精的功能,而且严重毒害酵母菌,导致酵母细胞的形态变异,从细胞学水平研究了紫茎泽兰抑制酵母发酵产乙醇本质机理:紫茎泽兰毒素使细胞癌肿膨大过早衰退或畸变死亡,同时变应性疾病样,使酵母芽细胞过早脱落成白血病式幼嫩细胞不能正常生长和行使功能。提出了对现有利用紫茎泽兰应注意检验毒性的看法和建议深入研究紫茎泽兰毒素指示菌。     

The effect of violent crime on sector-specific FDI in Latin America

ABSTRACT

This article looks at the impact of violent crime on FDI into Latin America and the Caribbean during the 1996–2010 period. FDI is disaggregated into primary, secondary and tertiary sectors and three variables related to violent crime are used: homicides, crime victimization and organized crime. Controlling for institutions and the traditional determinants of FDI, we find that the impact of crime on FDI depends on the sector and types of crime considered. Higher homicide rates are associated with less FDI in the secondary sector while organized crime reduces tertiary sector FDI. Crime victimization has a robust significant negative impact on the tertiary sector and in some estimations of the secondary sector. Crime has no impact on primary sector FDI. Our study highlights the need to continue efforts to decrease crime as we show in our analysis that crime has a negative effect on FDI in the secondary and tertiary sector.