低浓度Na2CO3胁迫下星星草幼苗保护酶活性与活性氧之间的关系

对低浓度(0.2%)Na2CO3胁迫和无胁迫正常生长的星星草幼苗的相对电导率、可溶性蛋白质含量、SOD活性、POD活性、CAT活性、MDA含量、H2O2含量和产生O2-·速率的研究结果表明,星星草幼苗各保护酶、活性氧及相对电导率之间存在一定的变化关系,这种变化关系在0.2% Na2CO3胁迫和无胁迫正常生长的星星草幼苗间存在差异.在一定程度上揭示了抗盐碱植物在正常生长情况下与碱胁迫下的活性氧(H2O2和O2-·)代谢可能存在不同的调节机制.     

热处理降低哈密瓜果实活性氧代谢减轻冷害

为探讨热处理能否激发哈密瓜果实抗冷性,减轻冷害。该文以"西州密25号"哈密瓜为原料,在已有研究的基础上,将哈密瓜在55℃热水中浸泡3 min,以室温(22±2)℃清水浸泡3 min为对照,待其表面水分完全晾干以后,放置于3~5℃机械冷库中贮藏,测定贮藏期间哈密瓜品质及生理指标。结果表明,与对照相比,热处理诱导哈密瓜果肉过氧化氢H_2O_2和超氧阴离子O_2~-含量短暂增加,但明显减少贮藏中后期(14~35 d)H_2O_2,O_2~-的积累(P0.05),提高活性氧清除酶过氧化物酶和超氧化物歧化酶的活性(P0.05),抑制细胞膜相对渗透率和丙二醛含量上升,降低贮藏后期的冷害发生率(P0.05),缓解果实可溶性固形物和抗坏血酸含量下降(P0.05),保持果实较好的品质。热处理主要通过诱导活性氧信号分子,提高活性氧清除酶活性、减少膜脂过氧化作用,从而减轻果实的冷害。研究结果为哈密瓜采后贮藏技术提供理论参考。     

基于同步离散电流估计的磁轴承自传感方法与试验

针对自传感磁轴承的滤波法幅度解调模型结构复杂导致相移过大的问题,提出一种基于Cosine纹波的同步离散电流估计自传感方法。建立了磁轴承磁阻模型,得到了磁轴承开关工作电流与位移之间的关联变化规律。与以往的采样电流相比较,同步离散电流是同步于PWM周期并定点离散于其Cosine纹波函数为0处的采样电流,并建立了同步离散电流估计器(Synchronous-Sampling-based Discrete Current Estimator,SS-DCE)数学模型;该模型可消除主动磁轴承自传感路径中的滤波器,简化估计算法复杂度,从而使得历经估计器的相移减小。数值仿真结果表明:SS-DCE自传感算法在50～250μm量程范围内估计误差小于2.72%;在特征频率处幅值增益为2 dB,相位滞后为-22°,为系统稳定运行提供了158°相位裕度。搭建了自传感磁轴承实验平台,验证了SS-DCE的位移估计最大估计误差为5.06μm,对应的估计精度为2.53%,并获得较好的激励响应的跟随特性,研究结果为小相移的自传感磁轴承和高速运行的磁轴承设计提供参考。     

基于夏玉米冠层内辐射分布的不同层叶面积指数模拟

为了模拟夏玉米冠层内各层叶面积指数垂直分布,光合有效辐射（photosynthetically active radiation, PAR）是研究作物群体光合作用和长势的重要特征参数,阐明冠层内PAR的垂直分布规律与冠层结构等参数之间的相关关系,可为遥感定量反演冠层结构参数提供模型基础。该文基于PAR在冠层内的辐射传输规律结合冠层结构模拟不同太阳高度角的PAR透过率垂直分布模型,并用地面冠层分析仪测量值进行验证,结果表明模型对封垄前玉米抽雄期冠层内PAR透过率垂直分布模拟精度较高。通过不同太阳高度角PAR透过率的垂直分布模型结合消光系数运用不同算法分别反演层叶面积指数（leaf area index, LAI）,并与不同高度层LAI实测值进行比较。结果显示：Bonhomme& Chartier算法反演不同高度层LAI精度较高,上层均方根误差（root mean square error,RMSE）为0.18,中层RMSE为0.55,下层RMSE为0.09。不同太阳高度角反演结果存在差异,30°和45°高度角均能较好地反演下层LAI,RMSE分别为0.11与0.09;30°高度角反演中层LAI精度较高,RMSE为0.30;45°高度角反演上层LAI精度较高,RMSE为0.18。结果表明基于不同太阳高度角构建的层LAI反演模型更适于实现夏玉米不同高度层LAI的遥感估算。该研究可为模拟垄行结构冠层内LAI垂直分布提供参考。     

Antioxidant Activity of Pigment Extracted from Green-Wheat-Bran

The anthocyanin pigment extracted from green-wheat-bran was studied to identify its antioxidant activity.The antioxidant activities of the pigment were evaluated by anti-lipid peroxidation,total antioxidant activity （TAA）,superoxide anion radical scavenging activity （SARSA）,active oxygen scavenging activity （AOSA）,and DPPH （1,1-diphenyl-2 picrylhydrazyl free radical） radical scavenging activity.The results showed that the pigment had higher antioxidant activity and TAA,SARSA,AOSA and DPPH.scavenging activities at a certain concentration than Vc （antiscorbutic vitamin,vitamin C）,and the capacity increased with the increase of pigment concentration.Its TAA was 51.06 U mL-1,1.73 times of Vc,and SARSA 18 025.21 U mL-1,2.26% higher than Vc,and AOSA 3 776.31 U mL-1,1.24 times of Vc.As to the DPPH.scavenging activity of the pigment,there was a trend that higher concentration performed higher activity significantly improved with the company of Vc.The pigment showed significant antioxidant activities evaluated by different assays.Results will provide a better understanding on antioxidant activity of green wheat and allow the screening or breeding of green wheat varieties with higher antioxidant activity for food processing.     

应用Ovsynch技术促进奶牛产后卵巢周期活动恢复的研究

[目的]确定奶牛产后卵巢周期活动恢复的最佳方案。[方法]应用诱导促排卵（Ovsynch）技术GnRH＋PG、GnRH＋CIDR＋PG及2次PG方法对产后20·d体况评分为2．75～3．50、子宫复1日较好、卵巢无明显卵泡和黄体活动的奶牛进行处理，比较不同处理奶牛产后卵巢开始活动的时间、产后第1次发情时间、产后第1次配种时间、空胎天数等。[结果]GnRH＋CIDR＋PG及2次PG处理可显著缩短奶牛产后卵巢开始活动的时间、产后第1次配种时间和空胎天数；3个处理奶牛产后第1次发情时间无显著差异。[结论]GnRH＋CIDR＋PG及2次PG处理对奶牛产后卵巢周期活动恢复具有明显的促进作用。     

空气净化网上光催化剂和活性炭相互增强净化能力的作用机理

采用浸涂法在活性炭空气净化网上负载纳米二氧化钛，在紫外光的照射下，净化网对一氧化碳、甲醛、硫化氢等污染物的净化能力明显增强，对比实验表明，在紫外光照射下光催化剂使被吸附的污染物发生降解反应而提高活性炭的净化能力。活性 吸附作用为光催化反应浓度环境，加速反应速率。     

绕基础转动模式下刚性挡土墙主动土压力的计算

采用考虑墙体位移模式和转角的土压力计算方法,能较好地反映挡土墙实际工作条件下的位移情况,并且能计算挡土墙任意转角下的主动土压力,避免了采用库仑主动土压力理论计算得到土压力偏小而使设计安全度降低的缺点。因此,本文提出的土压力计算方法对挡土墙的设计及验算有一定的参考价值。     

Effect of dietary inclusion of various plant ingredients as an alternative for Sargassum thunbergii on growth and body composition of juvenile sea cucumber Apostichopus japonicus

Two feeding experiments were conducted to investigate the effects of dietary inclusion of different plant ingredients on growth and body composition of juvenile sea cucumber. In the first experiment, three replicate groups of the sea cucumber (average weight of 1.5 ± 0.05 g) were fed one of the seven experimental diets containing Sargassum thunbergii (CON), Undaria (UND), Laminaria (LAM), Brassica oleracea L. var. capitata (BRA), fermented soybean (FSB), distillers dried grain (DDG) and rice straw powder (RIC) for 10 weeks. After the feeding trial, survival was not significantly different among the dietary treatments. Specific growth rate (SGR) of sea cucumber fed the FSB diet (0.73) was significantly higher than that of sea cucumber fed the other diets (P < 0.05), except for the DDG diet (0.64). The lowest SGR was observed in sea cucumber fed the CON diet (0.14). Based on the result of the first experiment, the second experiment was conducted to determine the proper level of dietary DDG for growth of juvenile sea cucumber. Three replicate groups of sea cucumber (average weight of 1.6 ± 0.02 g) were fed one of the five experimental diets containing different levels (g kg^?1) of DDG (DDG0, DDG10, DDG20, DDG30 and DDG40) for 12 weeks. Survival was not significantly different among the treatments (P > 0.05). The best SGR was obtained in sea cucumber fed the DDG10 diet (10.1) and the value of sea cucumber fed the DDG40 diet (5.6) was the lowest (P < 0.05). The SGR of sea cucumber fed the DDG10 diet did not differ from that of sea cucumber fed the DDG20 diet (P > 0.05). Moisture, crude protein, crude lipid and ash contents of whole body in sea cucumber among the dietary treatments (P > 0.05) did not differ significantly at both experiments. Results of two feeding trial suggest that dietary inclusion with 100 g kg^?1 FSB or 100–200 g kg^?1 DDG may improve growth of juvenile sea cucumber, and especially DDG could be used as a good ingredient for the low‐cost feed formulation.     

低温胁迫对葡萄品种梅鹿辄和贝达活性氧代谢的影响

以抗寒性不同的2个葡萄品种梅鹿辄和贝达为材料,研究不同温度下其1年生枝条叶片的细胞膜相对透性、丙二醛(MDA)含量、超氧化物歧化酶(SOD)等抗氧化酶活性变化,并用组织化学定位方法检测氧自由基(O2·-)和H2O2水平,以期分析各指标与葡萄抗寒性之间的关系并了解其抗寒机制。结果表明,随温度降低,两个葡萄品种叶片的细胞膜相对透性、MDA、O2·-和H2O2含量显著升高,并且抗寒性弱的梅鹿辄增大幅度显著大于抗寒性强的贝达;贝达叶片中SOD、过氧化物酶(POD)和过氧化氢酶(CAT)活性随温度降低显著提高且POD和CAT活性增大幅度显著高于梅鹿辄。推测POD和CAT活性及O2·-和H2O2形成速度与葡萄品种的抗寒性关系密切。