大米蛋白对幼鼠血脂及脂质代谢调控因子基因表达水平的影响

为了探讨大米蛋白对生长期幼鼠血脂水平及脂质代谢相关因子的调控作用,分别给雄性Wistar 7周龄幼鼠饲喂添加1%胆固醇及0.25%胆酸钠的大米蛋白及酪蛋白(粗蛋白含量为20%),自由摄食3周后,测定实验鼠血浆总胆固醇、血浆高密度脂蛋白胆固醇、血浆三酰甘油水平及肝脏3-羟基-3甲基-戊二酰CoA还原酶(HMG-CoA R)、乙酰辅酶A乙酰基转移酶2(ACAT2)、固醇调节元件结合蛋白-1(SREBP-1)的基因表达水平。对照酪蛋白,大米蛋白显著降低幼鼠血浆总胆固醇、血浆非高密度脂蛋白胆固醇、血浆三酰甘油水平,并且显著降低了肝脏HMG-CoA R、ACAT2、SREBP-1的基因表达水平。实验结果表明,大米蛋白具有降低幼鼠血脂水平的功效,其主要作用机制之一是抑制其脂质合成与吸收。     

大米蛋白提取方式对幼鼠生长性能的影响

目的：探讨不同方式提取的大米蛋白对生长性能的调控效果。方法：分别给7周龄雄性Wistar幼鼠投喂粗蛋白质为20％的酪蛋白及经碱法、酶法提取的大米蛋白3w后,检测各组实验鼠生长状况、体重增加量、蛋白质功效、内脏器官（肝脏、脾脏、肾脏）重量及脏器指数。结果：大米蛋白各组实验鼠末体重、总体重增加量、蛋白质功效及肝脏、脾脏、肾脏重量均显著低于酪蛋白组（P〈O．05）,但大米蛋白组幼鼠的日采食量及肝脏指数、脾脏指数、肾脏指数则与酪蛋白组差异无统计学意义（P〉0．05）。结论：提取方式是大米蛋白调控幼鼠体重及生长性能的影响因素之一。酶法提取的大米蛋白调控体重增加量效果优于碱法提取大米蛋白组。     

碱处理对大米蛋白氨基酸组成与含量的影响

选用质量分数0.1%、0.2%、0.3%碱液进行大米蛋白的提取,探讨碱处理对各种氨基酸含量的影响.结果显示,不同质量分数碱液对大米蛋白纯度及提取率无显著影响(P>0.05).随着碱液质量分数的增加,大米蛋白的Arg、Pro、Lys等氨基酸含量呈现下降的趋势,但各组间无显著差异(P>0.05).碱处理降低了大米蛋白Lys/Arg及Lys/Ala比例.说明不同质量分数的碱处理能够影响大米蛋白氨基酸组成与含量,碱处理是影响大米蛋白含硫氨基酸水平的制约因子之一.     

巴拉圭茶对高脂血症小鼠血脂的影响

目的:探讨不同剂量巴拉圭茶对高脂血症小鼠血脂的影响。方法:通过高脂日粮建立高脂血症小鼠模型,随机分为模型组、巴拉圭茶低剂量组、巴拉圭茶高剂量组,对照组饲喂基础日粮,模型组饲喂高脂日粮,巴拉圭茶低剂量组、巴拉圭茶高剂量组饲喂高脂日粮并分别灌胃1 g·kg^-1、2 g·kg^-1巴拉圭茶,连续灌胃4周,处死小鼠,测定小鼠血清中总胆固醇、甘油三酯、高密度脂蛋白胆固醇和低密度脂蛋白胆固醇的含量。结果:与模型组相比,低剂量和高剂量巴拉圭茶均可显著降低高脂血症小鼠血清中的总胆固醇、甘油三酯、低密度脂蛋白胆固醇含量(p<0.05),高剂量巴拉圭茶可显著提高小鼠血清中高密度脂蛋白胆固醇含量(p<0.05)。结论:巴拉圭茶对调节高脂血症小鼠血脂代谢具有一定的作用。     

“鱼安康”对日本鳗鲡非特异性免疫功能和抗病力的影响

本文报告在饲料中添加“鱼安康”投喂日本鳗鲡(Anguilla japanica)后,对供试日本鳗鲡非特异性免疫功能指标变化状况的测定结果。根据“鱼安康”在饲料中添加量不同而将试验分为5组,在各组饵料中“鱼安康”的添加量依次为0mg/kg(对照组)、20.0mg/kg.B.W.(试验I组)、40.0mg/kg.B.W.(试验Ⅱ组)、60.0mg/kg.B.W.(试验Ⅲ组)和80.0mg/kg.B.W.(试验Ⅳ组)。连续投喂28d后,取血液测定其中白细胞的吞噬活性、血清溶菌活性和补体活性,探讨了“鱼安康”对日本鳗鲡非特异性免疫功能的影响。研究结果表明,试验Ⅱ组、Ⅲ组和Ⅳ组日本鳗鲡白细胞吞噬活性和溶菌酶的活性均显著高于对照组(t测验,P<0.05),而各试验组之间未出现显著差异(t测验,P>0.05),补体C3和C4活性最高的是投喂量为80.0mg/kg.B.W.的第Ⅳ组,但是第Ⅰ组与对照组之间无显著性差异(t测验,P>0.05)。研究结果证明“鱼安康”能有效地增强日本鳗鲡的非特异性免疫功能,在饵料中的添加量以40.0mg/kg.B.W.以上为宜。     

巴拉圭茶对高脂血症小鼠氧化还原状态的影响

探讨不同剂量巴拉圭茶对高脂血症小鼠氧化还原状态的影响。通过高脂日粮建立高脂血脂小鼠模型,随机分为模型组、巴拉圭茶低剂量组、巴拉圭茶高剂量组,对照组饲喂基础日粮,模型组饲喂高脂日粮,巴拉圭茶低剂量组、巴拉圭茶高剂量组饲喂高脂日粮并分别灌胃1 g·kg^-1、2 g·kg^-1巴拉圭茶,连续灌胃4周,处死小鼠,测定小鼠肝脏中活性氧自由基(ROS)水平、超氧化物歧化酶(SOD)活性、过氧化氢酶(CAT)活性、丙二醛(MDA)的含量。与模型组相比,低剂量、高剂量巴拉圭茶可显著降低小鼠肝脏中ROS水平、MDA含量(p<0.05),可显著提高小鼠肝脏中SOD、CAT活性(p<0.05)。巴拉圭茶对高脂血症小鼠氧化应激具有一定的调节作用。     

氮素对五味子幼苗光合作用的影响

以2年生五味子苗木为试验材料,在田间试验条件下,通过施以不同水平和不同形态比例的氮素,分析氮素对五味子苗木最大光合速率(Amax)、表观量子效率(Q)、暗呼吸速率(Rd)、光补偿点(Lcp)和光饱和点(Lsp)的变化影响,并拟合光响应曲线。结果表明:在前期生长阶段(6月份),不同氮素水平条件下,五味子最大光合速率、暗呼吸速率、光饱和点差异显著,但表观初始量子效率和光补偿点差异不显著;不同氮素形态比例对五味子苗木的最大光合速率(Amax)、初始表观量子效率(Q)、暗呼吸速率(Rd)无显著(p0.05)影响,但在光补偿点(Lcp)和光饱和点(Lsp)存在显著差异,表明单一形态的氮素使得五味子对弱光的利用能力降低,但会相应的增加五味子对强光的利用范围。     

林农对林业合作组织感知度分析——以江西铜鼓县3个林业合作社为例

本研究利用2011年江西省铜鼓县调查的217份3个林业合作社的林农调查问卷,目的是为了检验当地林农参与林业合作社生产生活的变化以及他们的感知度,包括生产收益、成本以及经济补偿费用的感知。研究结果表明:就3个林业合作社整体而言,参与合作社前后,林农实际生活水平提高了和林农生活水平感知是一致的。林农生产成本的感知受经济发展水平影响不显著(P>0.05),林农普遍认为农业生产的各种成本增加了;然而,收益的感知和经济补偿的大部分感知受经济水平的影响很明显(P<0.05)。本研究结果认为,如果林农的基本生计没有得到保障,林农更多关心的是自己的生存问题,对林农而言,在一定时期内直接关注的必然是参与合作社带来的现实经济收益和政府实际补助水平。本研究为中国林权改革以及江西省林业合作组织的可持续发展做有益帮助。     

干旱区精河流域绿洲化过程中土壤养分时空变异研究

[目的]对干旱荒漠区不同土地利用方式下土壤养分时空特征进行研究,为绿洲土壤的科学施肥及更合理的土地资源开发利用提供理论依据,以促使土壤养分在精河流域平原绿洲系统中合理迁移和分布。[方法]以精河流域平原绿洲为靶区,基于GIS与地统计学方法,利用2003年和2018年不同土地利用方式下获取的土壤采样数据,对绿洲化过程中土壤养分(有机质、碱解氮、速效磷)的时空动态变化及重心迁移特征进行分析。[结果](1)2018年的土壤有机质、速效磷低于2003年,而碱解氮高于2003年。在空间上,各养分含量的高值区均出现在绿洲北部和西北部,低值区则主要位于绿洲边缘及南部区域;(2)对土壤养分综合分级评价结果显示,2003—2018年绿洲化过程中研究区土壤养分整体下降,中等及偏上水平的土壤养分重心沿精河向绿洲东北方向(艾比湖西南缘)及西北部的博乐绿洲方向迁移;(3)不同土地利用方式下,土壤养分含量均与土壤pH呈显著或极显著负相关关系,其中在草地、耕地和未利用地中呈极显著的差异(P<0.01),在林地中两者呈显著差异(P<0.05)。[结论]该研究对精河流域绿洲化过程中土壤养分变化和迁移特征进行的时空对比分析,有助于推进研究区平原绿洲耕地的利用和发展布局,为实现生态可持续发展提供重要参考。     

Production Efficiency of Jasmine Rice Producers in Northern and North‐eastern Thailand

The paper jointly evaluates the determinants of switching to Jasmine rice and its productivity while allowing for production inefficiency at the level of individual producers. Model diagnostics reveal that serious selection bias exists, justifying use of a sample selection framework in stochastic frontier models. Results from the probit variety selection equation reveal that gross return (mainly powered by significantly higher Jasmine rice price), access to irrigation and education are the important determinants of choosing Jasmine rice. Results from the stochastic production frontier reveal that land, irrigation and fertilisers are the significant determinants of Jasmine rice productivity. Significantly lower productivity in Phitsanulok and Tung Gula Rong Hai provinces demonstrate the influence of biophysical and environmental factors on productivity performance. The mean level of technical efficiency is estimated at 0.63 suggesting that 59% [(100 ? 63)/63] of the productivity is lost due to technical inefficiency. Policy implications include measures to keep Jasmine rice price high, increase access to irrigation and fertiliser availability, as well as investment in education targeted to farm households which will synergistically increase adoption of Jasmine rice as well as farm productivity.     

Impact of land fragmentation and resource ownership on productivity and efficiency: The case of rice producers in Bangladesh

The paper analyzes the impact of land fragmentation and ownership of resources on productivity and technical efficiency in rice production in Bangladesh using farm level survey data. Results reveal that land fragmentation has a significant detrimental effect on productivity and efficiency as expected. The elasticity estimates of land fragmentation reveal that a 1% increase in land fragmentation reduces rice output by 0.05% and efficiency by 0.03%. On the other hand, ownership of key resources (land, family labour, and draft animals) significantly increases efficiency. The mean elasticity estimates reveal that a 1% increase in family labour and owned draft animal improve technical efficiency by 0.04% and 0.03%, respectively. Also, a 1% increase in the adoption of modern technology improves efficiency by 0.04%. The mean technical efficiency in rice production is estimated at 0.91 indicating little scope to improve rice production per se using existing varieties. Policy implications include addressing structural causes of land fragmentation (e.g., law of inheritance and political economy of agrarian structure), building of physical capital (e.g., land and livestock resources), improvements in extension services and adoption of modern rice technology.     

植物甾醇对油脂的抗氧化作用研究

目的:探讨植物甾醇对油脂的抗氧化作用。方法:以花生油为对象,采用高温诱导其发生脂质过氧化反应,以过氧化值和酸价为指标,并与二丁基羟基甲苯(BHT)和VC进行比较,研究了植物甾醇对油脂的抗氧化作用。结果:植物甾醇可有效地延缓油脂脂质过氧化反应,抑制油脂酸价和过氧化值的升高,其抗氧化作用明显优于BHT和VC。结论:植物甾醇是一种天然、安全、高效的油脂抗氧化剂。     

Changing food consumption patterns in rural and urban Vietnam: Implications for a future food supply system

Rapid income growth and urbanisation could significantly change the composition of the food basket in many emerging economies. This study estimates a demand system, including 15 major food items in Vietnam, with multiyear household survey data. We find a large variation in the estimated price elasticities (–0.05 to –0.88) and expenditure elasticities (–0.16 to 2.56). Food types, urban status and income groups can explain this variation. We also find that the staple food, rice, is already an inferior good for rich urban households in Vietnam. Moreover, food preferences are evolving away from rice but towards animal proteins (fish, pork, chicken, eggs and milk), fruits and vegetables, irrespective of urban status and income groups. As the Vietnam economy continues to grow with a doubling of gross domestic product (GDP) in the next decade, per capita rice consumption in both urban and rural areas and across different income groups will continue to decline, whereas demand for other high‐value products will rise. Thus, government policy should focus on encouraging demand‐oriented food production. In addition, crop diversification at the farm level needs to improve substantially to meet the rising demand for these food products due to income growth and urbanisation.     

Accounting for the Gender Technology Gap Amongst Smallholder Rice Farmers in Northern Ghana

Narrowing the gender technology gap in agricultural production has become a critical policy issue in sub‐Saharan Africa. A better understanding of the gender technology gap is essential for policy formulation and programme planning to ensure equity in resource allocation, and household‐level food security in low and middle income countries, such as Ghana. We employ a metafrontier approach to analyse the differences in the efficiency of male and female farmers, recognising the endogeneity of some of the variables in the inefficiency effects model, in particular the credit constraints of the rice farmers under study. Our findings show that while the rice farms themselves are very similar, average yields for male managed farms tend to be significantly higher than female managed farms reflecting higher seeding and fertiliser application rates on male managed farms. However, there is no significant difference between the genders in either land used for rice or total output per farm household. We find some evidence that relative to the metafrontier, male managed farms are less efficient than female managed farms. The results further show gender technology gap amongst the smallholder rice farmers with females’ technology gap ratio being significantly greater than that of males, with females operating on a production frontier closer to the metafrontier. Policies that provide females more access to productive resources and other agricultural services could assist in the generation of relatively higher output.     

蒲公英黄酮的提取工艺优化

蒲公英药用价值很高,含有多种活性物质,其中黄酮类活性物质广泛应用于现代药理学.本实验以蒲公英为原料,利用乙醇浸提法进行黄酮的提取,以黄酮的提取率作为指标,在单因素实验的基础上设计响应面实验优化提取参数.实验结果表明,最佳提取工艺组合参数为乙醇浓度53％、提取温度51℃、液料比21:1(mL:g)、浸提时间25 min,黄酮提取率可达4.86％.     

Technical change in Senegal's irrigated rice sector: impact assessment under uncertainty

This paper addresses the prospects for technical change in the irrigated rice sector of Senegal, and measures ex‐ante the economic returns to recent research efforts. In 1994, three new rice varieties were released to farmers in the Senegal River Valley (SRV), the major irrigated rice region in Senegal. The productivity advantage of the new varieties is based primarily on early maturity, which permits double‐cropping. (The seeds are also higher yielding than existing cultivars.) We use a conventional [Akino and Hayami (1975), Am. J. Agric. Econ. 57, 1–10] partial‐equilibrium model adapted to the Senegalese situation, to assess the social benefits of research and compare those to its costs in calculating the internal rate of return (IRR). To account for uncertainty regarding the future values of model variables we use simulation which allows us to generate a distribution of all possible outcomes of the IRR. We find that rice research is almost certain to have a very high payoff over the 1995–2004 period. The expected value of the IRR is calculated to be 121% per year, with a 97.5% probability that it lies above annual capital costs of 18%. ©2001 Elsevier Science B.V. All rights reserved.