云南松不同部位木材乙醚提取物含量差异的研究

以云南松的一个试验点和两个天然优良林分为对象,研究了云南松个体不同部位乙醚提取物含量的特点.云南松个体内不同部位木材的乙醚提取物含量差异显著,其树干上部值大于树干下部值,树干值大于侧枝值;4年生材值为(11±1)年生材值的1.75倍;同株同部位不同生长期的木材乙醚提取物含量差异显著,4年生材的含量比5～12年生材高达4倍.同株不同部位同生长期木材的乙醚提取物含量相同.通过实验建立了用木芯法测定活立木乙醚提取物含量的方法.高1.3m、1.0m木芯混合样与(11±1)年生圆盘木粉样测定值的相关系数r=0.671 2＞r0.001.22=0.6304,呈极显著正相关.木芯法是鉴定活立木乙醚提取物含量的较佳选择,其不必砍树,既保留了采样活立木--良种选择基因的样木,又降低了取样、制样成本.改进的恒重乙醚提取物的方法精度符合国家标准要求,省时、降低分析成本.     

Clinicopathologic findings, sensitivity to house dust mites and efficacy of milbemycin oxime treatment of dogs with Cheyletiella sp. infestation

Twenty-three dogs with positive skin scrapings for Cheyletiella sp. were treated with milbemycin oxime using a protocol approximating 2 mg kg⁻¹ orally once weekly for three weeks. Nineteen of these dogs belonged to a household of 41 dogs and two dogs were in households with one other dog. All in-contact dogs were treated. Pre-treatment intradermal skin tests showed positive reactions to D. farinae in 13 dogs and to D. pteronyssinus in 12 dogs; these became negative post-treatment in four and seven dogs, respectively. All dogs showed a dramatic reduction in clinical signs one week after the third treatment. Eighteen dogs no longer had mites on skin scrapings, three had dead mites and two had deformed eggs. Recurrence of clinical signs necessitated two additional courses of the protocol in the multiple dog household and for a dog receiving immunosuppressive treatment for pemphigus foliaceus. Possible adverse reactions to the milbemycin (vomiting, lethargy) were noted once in two dogs.     

烘烤干筋阶段恒定温度及持续时间对烤烟香吃味的影响

试验采用二因素回归最优设计,研究了贵烟4号烘烤干筋恒定温度及持续时间对烤后烟叶香吃味评分及石油醚提取物含量的影响。结果表明:在干筋阶段当温度稳定在50℃-60℃持续时间5-20h时,烟叶香吃味评分和石油醚提取物含量表现出先增后降的抛物线曲线,最佳香吃味得分出现在温度54.3℃-57.0℃,持续时间为12.5-15.5h:最高石油醚提取物含量出现在温度54.3℃-56.3℃、持续时间5-12.5h时,二者具有较好的相关性。     

Effect of level and source of nutrients in late gestation on subsequent milk yield and composition and fertility of dairy cows

The effect of level and source of nutrients in late gestation on food intake, milk yield, milk composition and fertility in the subsequent lactation were evaluated in a randomized block design experiment involving 76 cows. Four experimental diets, based on grass silage, were offered to provide two levels of metabolizable energy (ME) intake (80 and 125 MJ/cow/day) either from 100:0 or 40:60 forage:concentrate (F:C) ratios for the last 28 days of gestation. Post-calving all cows were offered the same grass silage supplemented with 7 kg/day concentrates. For treatments 80 ME, 125 ME and 100:0 F:C, 40:60 F:C total dry matter (DM) intakes were 6.8, 10.5, 9.0 and 8.4 kg DM/day and ME intakes were 80, 126, 102 and 104 MJ/day, respectively, during the last 4 weeks of gestation. For weeks 1-16 of the subsequent lactation, treatment 125 ME increased milk fat content and yield but had no effect on food intake, milk protein content or onset of cyclicity. Treatment 125 ME increased condition score and live weight at calving. Altering the F:C ratio of the diets in late gestation had no effect on food intake, milk yield, milk composition or on the onset of cyclicity in the subsequent lactation. Cow parity and level of nutrient intake in late gestation provided the best fit relationships for the yields of fat and fat plus protein (R² relationships=0.49 and 0.52, respectively) during weeks 1-16 of lactation. It is concluded that increasing nutrient intake in late gestation increased milk fat content and yield but had no effect on milk protein concentration. The improved milk fat content and yield observed in a previous study was due to increased nutrient intake rather than altering the F:C ratio. Furthermore there was no measurable benefit in food intake or animal performance in the subsequent lactation through feeding concentrates in late gestation.     

米尔贝肟的研究进展

米尔贝肟是一种新型的半合成大环内酯类驱虫药,对体内外寄生虫均具有驱杀作用,是公认的具有广谱、高效、安全的驱虫药,特别是对一些伊维菌素敏感的犬相对更为安全。对其产生,理化性质,作用机理,临床应用,安全性及其常见的联合用药等方面进行了综述。     

液液萃取/气相色谱法测定废水中的三氯甲烷

建立了液液萃取/气相色谱法测定水中三氯甲烷的分析方法。选取石油醚、四氯化碳、环己烷、二硫化碳四种有机溶剂作为三氯甲烷萃取剂,确定了萃取方法和萃取次数,配制4种标准系列溶液,并对标准溶液和萃取溶液进行色谱分析。结果表明:4条标准曲线相关系数>0.9950,标准偏差<4%,加标回收率>75%。其中,石油醚的萃取效果最好为5.88 mg/ml,标准偏差为1.09%,加标回收率最高为99.21%,最低检出限为5.56×10-3mg/L。二硫化碳萃取效果最差为3.15 mg/ml,标准偏差为3.89%,加标回收率75.63%,最低检出限为9.58×10-2mg/L。环己烷和四氯化碳介于两者之间。该方法具有重现性好、准确度高、快速、简便的特点,为三氯甲烷的萃取研究提供一定的参考价值。     

二甲醚作为汽车代用燃料的应用前景

介绍了新型燃料二甲醚的应用优点,提出了其应用中存在的问题,并展望了其应用前景。     

八氯二丙醚在不同类型土壤中的降解

建立了土壤中八氯二丙醚(OCDPE)残留分析方法,进行八氯二丙醚在土壤中室内残留降解以及田间残留消解动态研究。土壤样品用乙酸乙酯超声波振荡提取,气相色谱法(GC-ECD)测定。添加回收试验结果表明(添加浓度为0.01～1.0 mg.kg-1),土壤中八氯二丙醚的添加回收率为82.3%～101.5%,变异系数为7.4%～9.9%。八氯二丙醚在不同土壤类型中的降解符合一级动力学模型。八氯二丙醚起始浓度为1.0 mg.kg-1时,其在红壤、黄褐土、砂姜黑土等3种供试土壤中室内降解半衰期分别为24.40 d、38.50 d和21.93 d;起始浓度为10.0 mg.kg-1时,半衰期分别为23.41 d、39.15 d和24.06 d。供试土壤含水量分别为田间持水量的40%、60%和80%时,八氯二丙醚的降解半衰期分别为49.15 d、38.50 d和35.91 d。八氯二丙醚在茶园土壤田间残留消解动态研究结果表明,其消解动态方程为Ct=4.152 4e-0.1198t,半衰期为5.78 d。研究结果对于研究八氯二丙醚在土壤中的环境行为及其安全性评价具有重要的指导意义。     

定色前期稳温点对烟叶石油醚提取物和多酚含量的影响

通过两种取样方式研究定色前期不同稳温点对三明烤烟CB-1中上部烟叶烤后石油醚提取物和多酚类物质含量的影响。结果表明:中部烟叶以48℃稳温,上部烟叶以46℃稳温,有利于提高烤后烟叶石油醚提取物和多酚类物质含量。方差分析表明,混合取样时处理间统计分析差异较大,定级取样(C3F或B2F)时差异较小。     

冠醚化合物为载体的PVC膜新型铝离子选择电极研究

研究了基于氮杂冠醚为中性载体的阳离子选择性电极,该电极在pH为3．0的硝酸缓冲介质中对铝离子有近能斯特响应,其线性范围为8．0×10^-5～1．0×10^-1mol／L,检测限为4．0×10^-5mol／L,斜率为20．0mV／dec．响应时间为20．0S．该电极用于EDTA的电位滴定,结果令人满意．