Inhibitory effect of yuzu essential oil on the formation of N-nitrosodimethylamine in vegetables

The inhibitory effect of yuzu (Citrus junos Tanaka) essential oil on the formation of N-nitrosodimethylamine (NDMA) in the presence of vegetables (31 species) or saliva was investigated by HPLC. Most vegetable extracts enhanced the formation of NDMA. However, the formation ratio of NDMA in vegetable extracts was decreased by yuzu oil in the range of 59 to 22%. In the presence of yuzu oil and saliva, its ratio ranged between 62 and 24%. These results indicated that yuzu oil inhibited the formation of NDMA even in vegetables and saliva. The contents of ascorbic acid, nitrate, and nitrite in the 31 vegetable species were 0.3-65 mg/100 g, 3-581 mg/100 g, and 10-750 microg/100 g, respectively. Ascorbic acid and nitrite had little effect on the inhibition or formation of NDMA at their intact levels. Nitrate accelerated the formation of NDMA, and the addition of saliva further enhanced it. The mechanism of inhibition of NDMA formation by alpha-terpinene was studied. It was assumed from the results of LC-MS that a new compound formed by the reaction of alpha-terpinene with nitrite would be a derivative of alpha-terpinene with dinitroso groups. The molecular weight of this compound was 194. It is suggested that terpene hydrocarbons in citrus essential oils would contribute to the decrease of NDMA formation.     

虎鲨饥饿后的补偿生长及淀粉酶活性研究

在28℃左右的条件下，对虎鲨分别进行了饥饿Od(对照组)、饥饿4d、饥饿6d、饥饿8d、饥饿4d-摄食4d-饥饿4d、饥饿4d-摄食8d-饥饿4d 6个处理，并将每个组饥饿过程中的身体组分与淀粉酶变化作了测定，结果表明：虎鲨的恢复生长属于部分补偿生长；饥饿过程中蛋白质含量、脂肪含量、能值下降，含水量增加，灰份变化规律不明显；淀粉酶活力在饥饿时间较短时呈现下降趋势，持续饥饿时间增加后则开始上升，恢复生长后酶活力均上升。     

池塘和水库养殖鱼类营养成分分析与比较

随机取水库养殖和池塘养殖鳙鱼、鲢鱼和鲤鱼各8条,分别测定各鱼肌肉中粗蛋白、粗脂肪、粗灰分、钙和磷占鲜鱼重的百分比。结果表明,水库与池塘养殖方式3种鱼的粗蛋白含量由高至低均为,鲢鱼、鳙鱼、鲤鱼,鲢鱼高于鲤鱼(P<0.05);2种养殖模式3种鱼的粗脂肪含量由高至低均为,鲤鱼、鳙鱼、鲢鱼,鲤鱼高于鲢鱼(P<0.01);2种养殖方式3种鱼的粗灰分、磷、钙含量的高低趋势却不同。2种养殖模式中,同品种鱼粗蛋白含量差异不显著(P>0.05),而池塘养殖模式鱼的粗脂肪含量均高于水库养殖模式的鱼。3种鱼的粗灰分含量,池塘养殖模式均显著低于水库养殖模式(P<0.01),而磷、钙的含量3种鱼在2种养殖模式下表现的高低趋势却不同。     

科技期刊影响力的实证研究——以《中国农学通报》为例

以<中国农学通报>为例,从历史积淀、办刊宗旨、主办单位、编辑水平、办刊理念等方面分析了科技期刊影响力的基础;论述了增强科技期刊影响力的途径,包括提高稿源水平、办刊质量、编审效率、加强管理与编辑队伍建设,加快与国际接轨;并从栽文量、影响因子、即年指标变化、被引频次、基金资助论文率、网络影响力等方面实证分析了其对<中国农学通报>影响力的作用.     

不同激素浓度对食用菊花组织培养的影响

以盆栽食用菊花的茎尖为外植体,通过调节激素浓度诱导愈伤形成、芽体萌发、继代增殖以及生根壮苗,快速扩繁食用菊花组培苗。研究结果表明：愈伤分化和芽诱导的最适培养基为MS+ 1 mg/L 6-BA+ 0.1 mg/L NAA,芽的诱导率可达到55%;不定芽增殖的最适培养基为MS+ 1 mg/L 6-BA+ 0.3 mg/L NAA+ 0.1 mg/L KT,平均每株芽数4.9个;生根的最适培养基为1/2MS+ 0.1 mg/L NAA,根数最多可达11根。     

Key Parameters in Urban Form Layout for Weakening Urban Heat Island Intensity and Its Response Mechanism

The relationship between urban form layout and Urban Heat Island (UHI) intensity response mechanism was quantified and the parameter curves was studied. Large-scale analysis and calculation software such as ArcGIS and MATLAB are used and extract Urban Form and inversed UHI, based on the seven times summer TM images of Tianjin between 1992 and 2013. The results show that: Firstly, the double indicators measure for the UHI intensity was proposed, that is, highest UHI temperature value and total UHI warming. Secondly, the UHI intensity increases with the expansion of urban form area; and in general, gross area of urban form is positively correlated with highest UHI temperature value and total UHI warming.Thirdly, dispersion of the urban form and contagion index are not apparently involved with highest UHI temperature, but correlated with total UHI warming.Fourthly, plague area has a positive relationship with UHI intensity; with a single plague over 50 km 2, highest UHI temperature value will grow rapidly by the linear along with the increase of plague and a quadric curve correlation between plague area and total UHI warming is obtained. Fifthly, there was a negative relationship between perimeter-to-area ratio of the plaque and UHI intensity and a S curve correlation between perimeter-to-area ratio of the plaque and highest UHI temperature value. When the ratio is between 0.005 to 0.04, a quadric curve correlation will be formed between perimeter-to-area ratio and highest UHI temperature value. Finally, urban form fractal dimension is positively relevant with UHI intensity and in a linear relationship with highest UHI temperature and a cubic curve relationship with Total UHI warming.     

高密度城区公园降温效应与模拟预测研究——以天津中心城区为例

研究了不同水胶比条件下,NaOH预处理方式和橡胶掺量对混凝土吸水性、毛细孔隙率、干燥收缩及力学性能的影响。结果表明,掺加经NaOH预处理的橡胶所配混凝土具有更低的吸水率、毛细孔隙率、脆性和更高的抗折强度,预处理对橡胶混凝土上述性能的改性作用与水胶比有关,水胶比较高时改性效果较好。     

不同抗蒸腾剂对月季切花保鲜的影响

本文对几种抗蒸腾剂应用于月季切花保鲜的保鲜效果进行了研究,结果表明：抗蒸腾剂Vaporgard稀释至1：70浓度后喷洒在月季切花表面,可延长月季切花的保鲜期;抗蒸腾剂wiltpruf易导致白色花系的月季切花产生花朵变色,因而不适用于白色花系的月季切花保鲜;在实验设定的浓度内,抗蒸腾剂Transfilm未找寻到合适的适用于月季切花保鲜的浓度,其最适浓度有待下一步继续实验确定;外源ABA做为月季切花保鲜剂使用时,其最佳的喷施浓度为0.01g/L。     

天然植物饲料对育肥猪生长性能、血液指标及肉质的影响

为研究天然植物饲料对育肥猪生长性能、血液生化指标、抗氧化指标及肉质的影响,试验选取25kg左右的生长育肥猪152头,随机分为2组,每组4个重复,每个重复19头猪。对照组饲喂基础日粮,试验组饲喂添加500g/t天然植物饲料的日粮,试验期110d。结果表明:天然植物饲料可促进育肥猪的生长发育;试验组育肥猪血清中白蛋白(ALB)和碱性磷酸酶(ALP)水平显著高于对照组(P<0.05);与对照组相比,试验组血清总抗氧化能力(T-AOC)提高了3.19%(P<0.05),血清丙二醛(MDA)降低了6.43%(P<0.05);与对照组相比,试验组育肥猪肉pH24、肉色红度值和熟肉率分别提高了3.30%、10.99%和4.16%(P<0.05)。试验结果表明,天然植物饲料可促进育肥猪的生长,提高血清生化指标及抗氧化能力,显著改善肉质。     

草履蚧的生活史及越冬卵在土壤中的分布调查

草履蚧在陕西１ 年发生１ 代,一般情况下越冬卵孵化盛期为２ 月中下旬,若虫２ 月中旬至３月下旬上树危害,雌成虫４ 月下旬至６ 月中旬下树,下树雌虫在树干周围的地面杂物下、土缝、疏松土层内产卵越夏和过冬。蚧虫卵在树冠下土壤中的分布规律、分布量与距树干的距离远近有关,集中分布于距离树干６０ ｃｍ 范围内地面以下０～５、６～１０ ｃｍ 的土层中。以土壤中草履蚧的卵量作为该虫的防治指标时,指标值确定为树冠下在离树干６０ ｃｍ 范围内、０～１５ ｃｍ 土层中１００ ｃｍ ２ 面积下有卵（８～１０）±２ 粒