条斑紫菜藻红蛋白纯化方法的研究   总被引：2，自引：0，他引：2  

马海乐  肖海芳  骆琳 《农业工程学报》2007,23(2):249-253

为了解决目前藻红蛋白纯化方法过于复杂,处理量小等问题,采用“盐析→超滤→HA柱层析或DEAE-52柱层析”的工艺路线,建立了一种简化而高效的条斑紫菜藻红蛋白纯化方法。结果显示：1)对藻红蛋白纯度(以OD₅₆₁/OD₂₈₀表示)为0.365的条斑紫菜粗提物采用盐析法沉淀藻红蛋白时,得到藻红蛋白的纯度为0.45,回收率为90.53%;2)采用截留分子量为5万Da的超滤膜对藻红蛋白盐析物进行脱盐和出去小分子杂蛋白处理,得到的藻红蛋白的纯度为0.74,回收率为93.11%;3)进一步分别采用HA柱层析和DEAE-52柱层析纯化超滤液,藻红蛋白最高纯度分别为2.76和1.74,回收率分别为59.3%和56.81%。研究结果表明,采用盐析和超滤相结合的方法,可以较为方便而高效地得到食用级藻红蛋白,进一步通过HA柱层析,即可达到药用级的要求。  相似文献   

草莓胡萝卜复合澄清汁后浑浊机理研究     

王振斌  马海乐  钟惠惠  骆琳  何荣海  马晓珂 《农业工程学报》2007,23(6):246-251

为探讨草莓胡萝卜复合澄清汁的后浑浊机理,研究了化学试剂、贮藏温度和顶隙大小对草莓胡萝卜复合澄清汁的澄清度、褐变指数、黄烷醇类多酚含量、可溶性蛋白含量的影响。结果表明：贮藏温度越高,包装顶隙越大,氧气存留越多,随贮藏时间延长,果蔬汁浑浊形成越多,褐变程度越大,黄烷醇类多酚降解程度越大,可溶性蛋白损失越多;果蔬汁中添加尿素和十二烷基磺酸钠(SDS),都能减少果蔬汁中浑浊的产生,抑制产品褐变,减缓黄烷醇类多酚的降解,减少可溶性蛋白的损失,说明氢键和疏水键都是和浑浊有关的化学键。蔗糖的添加对果蔬汁浑浊的形成没有太  相似文献   

广东小耳花猪仔猪初生重对其产房死亡率的影响     

唐民  唐景霖  余海乐  李镇养  韦明飞  王永江  阳林芳  刘小红  曾检华 《养猪》2020,(1):55-56

为研究广东小耳花猪仔猪初生重对哺乳期死亡率的影响,研究对两栋分娩舍内272头广东小耳花猪仔猪的初生重和死亡率进行了统计分析。结果表明:初生重低于等于0.4千克的仔猪死亡率高达81.25%,初生重在0.41耀0.6千克的仔猪死亡率为12%,当仔猪初生重大于0.8千克的时候死亡率仅为3.61%。初生重越大的仔猪,其死亡率呈现降低趋势并走向稳定。仔猪的死亡高峰期为出生后的8天内,64%的仔猪在该时期内死亡。死亡仔猪的主要原因为病弱和压死,两者总共占比为68%。此外,对两栋分娩舍进行对比发现,初生重越大的仔猪,其断奶重也越高。  相似文献   

脉冲超声辅助提取莲房多酚的工艺   总被引：4，自引：1，他引：3  

段玉清  张海晖  李金凤  闫永胜  刘伟民  马海乐 《农业工程学报》2009,(Z1)

为了充分利用莲房资源,利用脉冲超声技术辅助提取其中的多酚类化合物,研究了温度、超声时间、超声功率、料液比对多酚和原花青素得率的影响。试验结果表明,莲房多酚最佳提取工艺条件为:温度55℃,超声功率1000W,超声时间35min,料液比1∶35。在此条件下,莲房多酚和原花青素的得率分别为11.82%和6.60%,比70%丙酮回流提取法分别高2.0倍和2.9倍。并建立了多酚和原花青素得率与温度、超声功率、超声时间、料液比关系的数学模型。脉冲超声辅助提取莲房多酚与常规法相比,具有提取时间短、得率高等优点,有着较为广阔的应用前景。  相似文献   

Contour furrows for in situ soil and water conservation, Tigray, Northern Ethiopia     

Tewodros Gebreegziabher  Jan Nyssen  Bram Govaerts  Fekadu Getnet  Mintesinot Behailu  Mitiku Haile  Jozef Deckers 《Soil & Tillage Research》2009,103(2):257

In Tigray (Northern Ethiopia), soil moisture has been identified as the most limiting factor in agricultural production; on the other hand, loss of rain water through runoff as well as the induced soil loss has been determined as a critical problem in the region in the last two to three decades. To alleviate the above paradox, the government has mobilized communities and resources for the construction of physical soil and water conservation structures (stone bunds, terraces) in almost all land uses. However, yield improvement was mainly concentrated within the vicinity of the structures and runoff continued to overtop the structures, as no measures for in situ soil conservation were taken. The terwah system, consisting of traditional ploughing followed by making every 1.5–2 m contour furrows, and permanent raised beds with contour furrows at 60–70 cm interval treatments, were considered and evaluated as practices that could increase the efficiency of in situ water utilization and soil conservation. An experiment was started in Gum Selasa, which is one of the drought prone areas in Tigray, whereby runoff volume and sediment load were measured after every rain event. Permanent raised beds with contour furrows at 60–70 cm interval significantly (P < 0.05) reduced runoff volume, runoff coefficient and soil loss as compared to traditional ploughing: 255, 381 and 653 m³ ha⁻¹ runoff was recorded from permanent bed, terwah and traditional ploughing, respectively during the whole cropping season. The above runoff induced 4.7 t ha⁻¹ soil loss from permanent bed, 7.6 t ha⁻¹ from terwah and 19.5 t ha⁻¹ from traditional ploughing. Overall, contour furrows and permanent raised beds can be part of the ongoing intensification process which includes physical soil and water conservation, slope reforestation, irrigation development and agro forestry in crop lands. Moreover, the use of permanent raised beds if combined with crop mulching and crop diversification is an important component for the development of sustainable conservation agriculture practices in the region.  相似文献   

Effects of conservation agriculture on runoff,soil loss and crop yield under rainfed conditions in Tigray,Northern Ethiopia     

Tesfay Araya  W. M. Cornelis  J. Nyssen  B. Govaerts  H. Bauer  Tewodros Gebreegziabher  Tigist Oicha  D. Raes  K. D. Sayre  Mitiku Haile  J. Deckers 《Soil Use and Management》2011,27(3):404-414

The aim of conservation agriculture (CA) is to improve soil quality and crop yield whilst reducing runoff and topsoil erosion. An experiment was carried out in a rainfed field using a permanent raised bed planting system for 3 yr (2005–2007) in Adigudem, northern Ethiopia in order to evaluate the effect of CA on runoff, soil loss and crop yield. CA practices were introduced in fields with Vertisols in a randomized complete block design on permanent 5 × 19 m plots. Three treatments were evaluated: (1) conventional tillage (CT) with a minimum of three tillage operations and removal of crop residues, (2) terwah (TER) that was similar to CT except that contour furrows were included at 1.5 m intervals, and (3) derdero+ (DER+), which consists of permanent raised beds with a furrow and bed system, retention of 30% of standing crop residues and zero tillage on the top of the bed. All ploughing as well as the maintenance of the furrows of the permanent raised beds was done using a local ard plough called maresha. Results from monitoring over 3 yr showed that soil loss and runoff were significantly higher (P < 0.05) in CT followed by TER and DER+. Average soil losses of 5.2, 20.1 and 24.2 t/ha were recorded from DER+, TER and CT, respectively. Runoff was 46.3, 76.3 and 98.1 mm from DER+, TER and CT, respectively. Grain yield was significantly lower (P < 0.05) in DER+ under teff in 2006, probably due to the high sensitivity of teff to weeds. The yield of wheat in 2007 was significantly higher in DER+ followed by TER. The terwah system is recommended as a first measure for wider adoption to reduce runoff and soil loss and to increase crop yield. The long‐term goal is to achieve a derdero+ system, i.e. a permanent raised bed planting system along with the application of crop residues.  相似文献   

果胶酶对草莓果汁澄清效果的研究   总被引：35，自引：1，他引：35       下载免费PDF全文

王鸿飞  李和生  马海乐  孙玉喜  黄静 《农业工程学报》2003,19(3):161-164

澄清是果汁加工中的关键技术环节之一，利用果胶酶澄清果汁，有快速、简便、效果好等特点，在生产中有重要的应用价值。草莓中因含有果胶物质，制得的果汁易产生浑浊、沉淀等现象，严重影响产品的质量。用果胶酶对草莓果汁进行了单因素澄清试验及最适澄清工艺条件的研究。结果表明，果胶酶用量为0.035～0.075 mL/kg、温度35～45℃、pH 3.0～4.0的条件下澄清草莓果汁，透光率达97%以上，果汁中的可溶性固形物含量基本不变；在单因素试验的基础上，通过正交试验，果胶酶对草莓果汁澄清的最佳工艺条件是：果胶酶用量为0.035 mL/kg，温度为35℃，pH值为3.5。  相似文献   

Ancient biomolecules from deep ice cores reveal a forested southern Greenland   总被引：2，自引：0，他引：2  

Willerslev E  Cappellini E  Boomsma W  Nielsen R  Hebsgaard MB  Brand TB  Hofreiter M  Bunce M  Poinar HN  Dahl-Jensen D  Johnsen S  Steffensen JP  Bennike O  Schwenninger JL  Nathan R  Armitage S  de Hoog CJ  Alfimov V  Christl M  Beer J  Muscheler R  Barker J  Sharp M  Penkman KE  Haile J  Taberlet P  Gilbert MT  Casoli A  Campani E  Collins MJ 《Science (New York, N.Y.)》2007,317(5834):111-114

It is difficult to obtain fossil data from the 10% of Earth's terrestrial surface that is covered by thick glaciers and ice sheets, and hence, knowledge of the paleoenvironments of these regions has remained limited. We show that DNA and amino acids from buried organisms can be recovered from the basal sections of deep ice cores, enabling reconstructions of past flora and fauna. We show that high-altitude southern Greenland, currently lying below more than 2 kilometers of ice, was inhabited by a diverse array of conifer trees and insects within the past million years. The results provide direct evidence in support of a forested southern Greenland and suggest that many deep ice cores may contain genetic records of paleoenvironments in their basal sections.  相似文献   

Stone bunds for soil conservation in the northern Ethiopian highlands: Impacts on soil fertility and crop yield     

Karen Vancampenhout  Jan Nyssen  Desta Gebremichael  Jozef Deckers  Jean Poesen  Mitiku Haile  Jan Moeyersons 《Soil & Tillage Research》2006,90(1-2):1-15

In the Ethiopian highlands, large-scale stone bund building programs are implemented to curb severe soil erosion. Development of soil fertility gradients is often mentioned as the major drawback of stone bund implementation, as it would result in a dramatic lowering of crop yield. Therefore, the objectives of this study are to assess soil fertility gradients on progressive terraces and their influence on crop yield, in order to evaluate the long-term sustainability of stone bunds in the Ethiopian Highlands.

The study was performed near Hagere Selam, Tigray and comprises (i) measurement of P_av, N_tot and C_org along the slope on 20 representative plots and (ii) crop response measurement on 143 plots. Results indicate that levels of P_av, N_tot and C_org in the plough layer are highly variable between plots and mainly determined by small-scale soil and environmental features, plot history and management. After correcting for this “plot effect” a significant relationship (p < 0.01) was found between the position in the plot relative to the stone bund and levels of P_av and N_tot, which are higher near the lower stone bund, especially on limestone parent material. For C_org and on basalt-derived soils in general no significant relationship was found. Although soil fertility gradients are present, they are not problematic and can be compensated by adapted soil management. Only in areas where a Calcaric or Calcic horizon is present at shallow depth, care should be taken. Crop Yields increased by 7% compared to the situation without stone bunds, if a land occupation of 8% by the structures is accounted for. Yield increased from 632 to 683 kg ha⁻¹ for cereals, from 501 to 556 kg ha⁻¹ (11%) for Eragrostis tef and from 335 to 351 kg ha⁻¹ for Cicer arietinum.

No negative effects reducing stone-bund sustainability were found in this study. Soil erosion on the other hand, poses a major threat to agricultural productivity. Stone bund implementation therefore is of vital importance in fighting desertification and establishing sustainable agriculture in the Ethiopian highlands.  相似文献   

杜仲雄花乙酸乙酯提取物的抗惊厥作用研究   总被引：1，自引：0，他引：1  

李欣  朱文学  樊金铃  肖海芳  杜琳  马海乐  刘少阳 《农产品加工．学刊》2009,(8):8-10

研究杜仲雄花乙酸乙酯提取物的抗惊厥作用。观察不同剂量乙酸乙酯提取物对小鼠自主活动的影响、直接中枢镇静作用和抗惊厥作用。杜仲雄花乙酸乙酯提取物具有显著的中枢镇静作用,显著减少小鼠的自主活动次数;显著减少惊厥小鼠数,延长惊厥潜伏期。杜仲雄花乙酸乙酯提取物具有良好的抗惊厥作用。  相似文献