新疆国际客源市场时空发展变化分析研究

利用集中度和亲景度、竞争态指标,对新疆国际客源市场13个主体客源国1997～2004年统计数据进行分析,揭示国际客源时空演替规律,指出新疆主要的3个国际客源市场是日本、俄罗斯和美国,并提出了拓展国际客源市场的建议。     

Preharvest and postharvest factors related to off-odours of fresh-cut iceberg lettuce

The influence of different preharvest and postharvest factors affecting off-odour development of fresh-cut iceberg lettuce in low-O₂ modified atmospheres (MA) was investigated. Fresh-cut iceberg lettuce developed undesirable off-odours under low O₂ and elevated CO₂ atmospheres. A strong relationship between CO₂ concentration and off-odour development was observed. Significant differences in off-odour development existed among different cultivars in two harvests in consecutive years. The influence of maturity stage was evaluated, comparing fresh-cut product from immature and over-mature heads with commercial ones. Higher CO₂ concentrations and higher accumulation of ethanol and acetaldehyde were detected in the headspace of MA-packed lettuce from immature heads. Differences in respiration rate of the fresh-cut product from heads cultivated during the winter–spring seasons were around 30%. Respiration rate of fresh-cut iceberg lettuce increased when medium temperature during cultivation increased. Changes in the product weight generated different CO₂ levels which correlated with the production of ethanol and acetaldehyde and other off-odour metabolites related with the lipoxygenase (LOX) pathway such as hexanal, 1-hexanol, and cis-3-hexen-1-ol. Volatile compounds such as cis-3-hexen-1-ol, β-elemene, ethyl acetate and dimethyl sulphide increased their content more than 10 times compared with other volatiles. Moreover, differences in the initial flushed gas-mixture with or without CO₂ showed higher CO₂ concentrations and the development of stronger off-odours when samples were flushed with an enriched CO₂ gas-mixture. In summary, visual quality of fresh-cut iceberg lettuce is important but so are odour and flavour. MAP currently used for fresh-cut lettuce may need some modification to inhibit off-odours and achieve better aroma and flavour qualities for preserving “freshness” of the cut product. Screening for cultivars with low browning potential and fermentation, harvested at optimum maturity stage and with an adequate package design are recommended.     

南京市花粉浓度变化规律及预报方法研究

在花粉观测和气象观测资料的基础上,分析了南京地区花粉季节变化规律和日变化规律,以及南京地区不同种类花粉的季节分布特点,发现南京地区花粉分布呈单峰型分布,具有很强的周期性和季节性。3月中旬起,花粉数量迅速增多,到4月中旬达到顶峰,此后缓慢下降,但起伏较大。同时,根据同期气象条件分析了气象因子(温度、湿度、降水、风速)对花粉浓度的影响,建立了花粉浓度预报方程:Y=0.703X1+0.005X2+0.005X3+0.452。其中,Y为花粉浓度预报值;X1为前一日花粉实况;X2为气压差;X3为温度差。     

蛋鸡血浆极低密度脂蛋白浓度的变化规律及其选择效应研究

以雅发祖代种鸡为研究材料．用比浊法测定鸡血浆极低密度脂蛋白（ＶＬＤＬ）浓度．试验结果表明，母鸡血浆ＶＬＤＬ浓度随鸡周龄的增大而持续增加．产蛋期个体间血浆ＶＬＤＬ浓度的变异系数为１５％～６９％，２９周龄母鸡血浆ＶＤＬ浓度的遗传力为０．２４．血浆ＶＬＤＬ浓度与腹脂重、腹胀率、肝脂含量均呈正表型相关趋势．２９周龄血浆ＶＬＤＬ浓度与产蛋前期产蛋量、１８周龄体重、开产日龄、蛋黄重、蛋黄比例、蛋黄蛋白比例的遗传相关系数分别是０．２７，０．３８，－０．３３，０．２３，０．２５，０．２２．     

不同pH值和重金属浓度对水花生生根的影响

研究不同pH值和不同重金属浓度对水花生生根情况的影响。试验表明,水花生的适应性很强,在pH值为2~13范围内的溶液中均可生根。总体而言,水花生在碱性溶液中比在酸性溶液中生根情况好,当pH值在8.85左右时生根情况最好,根长为26.2 mm,根数为60根以上。随着重金属离子浓度升高,其对水花生生根的抑制作用加大,但不同重金属离子对水花生的生根影响不同。当溶液中Pb2+浓度在10 mg/L左右时,水花生生长最好,根长达22.3 mm,根数达37根;当溶液中Cr3+浓度在5 mg/L以下时,水花生生长最好,根长为39.0 mm左右,根数为40根以上。     

冬季家庭居室内PM_(10)浓度的影响因素

[目的]为了探讨家庭居室内PM10污染物的来源,对人体的危害及影响因素。[方法]在丹东市的三个区选择了14个家庭,对其厨房、卧室和客厅进行PM10浓度的测试,并对室内的PM10污染物来源进行了分析。[结果]室内空气PM10浓度主要受吸烟、烹饪时的燃料、不同清洁方式、室外颗粒物浓度、室内人员多少和活动频繁程度、通风量7个因素的影响,被测14户家庭中有7户所有的房间均超标。[结论]丹东市家庭室内PM10浓度超标不容乐观,应引起有关部门的重视。     

锰对公鸡乳酸脱氢酶活性和精子密度的影响

本文就日粮锰对公鸡乳酸脱氢酶(LDH)活性及生殖功能的影响进行了研究。结果表明日粮中锰缺乏或过多引起血清、肝脏和睾丸 LDH 活性同步下降。精子数/睾丸Ⅰ组(添加 Mn 0ppm)、Ⅳ组(添加 Mn 300ppm)比Ⅲ组(添加 Mn100ppm)分别降低了35.06%和31.55%,表明精子生成过程对锰的需要量有一定的范围。睾丸 LDH 活性和精子数/睾丸之间 r=0.6791(P<0.05),提示锰缺乏或过多造成睾丸生精功能下降的重要原因之一是由于锰影响了睾丸 LDH 活性。     

苜蓿提取液抑菌活性研究

[目的]研究苜蓿提取液对4种常见菌绿脓杆菌、停乳链球菌、大肠杆菌和金黄色葡萄球菌的抑菌活性。[方法]采用二倍稀释法和血平板鉴定相结合的方法测定其最低抑菌浓度(MIC)。[结果]苜蓿提取液对绿脓杆菌和停乳链球菌的MIC分别为0.674和1.347mg/ml;对大肠杆菌和金黄色葡萄球菌的MIC均为2.695 mg/ml。[结论]苜蓿提取液对绿脓杆菌和停乳链球菌有较好的抑菌活性,对大肠杆菌和金黄色葡萄球菌的抑菌效果一般。     

小麦全蚀病拮抗微生物的分离及其拮抗性能研究

从开封北郊的麦田土壤中分离筛选出11株对小麦全蚀病菌(Gaeumannomyces graminis var.tritici)有拮抗作用的细菌,通过对它们进行生理生化检验,确定为4个种,即:巨大芽孢杆菌(Bacillus megaterium)、蜡样芽孢杆菌(Bacillus cereus)、苏云金芽孢杆菌(Bacillus thuringien-sis)、凝结芽孢杆菌(Bacillus coagulans)。分别利用平板拮抗和小麦活体拮抗对分离到的11株拮抗菌株的拮抗能力进行检测。结果表明,菌株的平板拮抗能力较强,在活体试验中,可以降低病害的发病强度。     

番茄灰霉病高效拮抗菌株鉴定及抗菌活性研究

采用形态特征观察、生理生化特性测定以及16S rDNA序列分析,对分离于淄博感染灰霉病的大棚番茄土壤样品中的6株拮抗细菌进行了分类鉴定和拮抗活性分析。结果显示,6株细菌形态均为直的杆状,有鞭毛能运动,能生成抗热的芽孢,芽孢椭圆形,革兰氏染色均为阳性,通过对菌株16S rDNA序列进行测定和同源性比对,发现与芽孢杆菌同源性达99%,结合生理生化特性确定B-01、B-02、B-03、B-04为蜡样芽孢杆菌(Bacillus cereus),B-06为枯草芽孢杆菌(Bacillus subtilis),B-07为短小芽孢杆菌(Bacillus pumilus)。通过滤液抑菌活性测定,B-02、B-06滤液对病原菌有很强的抑制作用,并且在稀释不同倍数时均能抑制灰霉病菌的生长。