定向刨花板弹性模量理论分析的试验验证     

林兰华  齐英杰等 《林业机械与木工设备》2002,30(2):7-9

介绍了定向刨花板的试验方法和过程；并应用概率设计理论求出了定向刨花板主方向的弹性模量，对定向刨花板产品进行了试验研究并与实验室产品进行了分析比较；分析了影响定向刨花板产品质量的主要因素。解决了定向刨花板弹性模量的理论求解公式的实验验证问题，论证了理论推导结果的正确性，尝试将现代设计方法和微观力学理论应用于人造板的力学性能分析和研究中，以推动定向刨花板的计算机仿真工作的开展。  相似文献   

硝酸银在水稻农杆菌转化中的作用     

王亚琴  梁承邺 《湖南农业大学学报(自然科学版)》2004,31(2)

以籼稻、粳稻两种类型的成熟种子为外植体研究了不同浓度的AgNO3在水稻农杆菌转化中的作用。结果表明，在农杆菌转化前添加AgNO3可以提高愈伤组织诱导率，最适浓度为8～10mg／L，但对愈伤组织的分化没有明显促进作用；转化后添加低浓度的AgNO3可以减轻愈伤组织的褐化，提高抗性愈伤率和绿苗分化率，最适浓度为2-8mg／L。同时发现，无论是转化前还是转化后，添加高浓度的AgNO3对水稻愈伤组织的分化均具有毒害作用。  相似文献   

Impact of pig slurry on soil properties, water salinization, nitrate leaching and crop yield in a four-year experiment in Central Spain     

J.A. Díez  P. Hernaiz  M.J. Muñoz  A. de la  Torre A. Vallejo 《Soil Use and Management》2004,20(4):444-450

Abstract. The repeated application of pig slurry to agricultural soils may result in an accumulation of salts and a risk of aquifer pollution due to nitrate leaching and salinization. Under Mediterranean conditions, a field experiment on a sandy loam soil (Typic Xerofluvent) was performed with maize (Zea mays) in 1998, 1999 and 2001 to study the effects of applying optimal (P1) and excessive rates (P3) of pig slurry on soil salinization, nitrate leaching and groundwater pollution. The rate of pig slurry was established considering the optimal N rate for maize in this soil (170, 162 and 176 kg N ha^?1 for 1998, 1999 and 2001, respectively). Pig slurry treatments were compared to an optimal N rate supplied as urea (U) and a control treatment without N fertilizer (P0). The composition of the slurries showed great variability between years. Mean NO₃^? leaching losses from 1998 to 2001 were 329, 215, 173 and 78 kg N ha^?1 for P3, P1, U and P0 treatments, respectively. The amount of total dissolved salts (TDS) added to the soil in slurry application between 1998 and 2001 was 2019 kg TDS ha^?1 for the P1 treatment and 6058 kg TDS ha^?1 for the P3 treatment. As a consequence, the electrical conductivity (EC) of the slurry‐treated soils was greater than that of the control soil. The EC correlated significantly with the sodium concentration of the soil solution. Over the entire experimental period, 2653, 2202 and 2110 kg Na ha^?1 entered the aquifer from the P3, P1 and P0 treatments, respectively. The P3 treatment did not significantly increase grain production in 1999 and 2001 compared with that achieved with the optimal N rate treatment (P1). This behaviour shows the importance of establishing application guidelines for pig slurry that will reduce the risk of soil and groundwater pollution.  相似文献   

硝酸还原酶与氮素利用的关系及其在作物遗传育种中的应用(综述)     

孙宝启  李玉京 《中国农业大学学报》1993,(3):29-34

本文综述了硝酸还原酶与氮素利用的关系及其遗传特性和在作物育种中应用的某些最新进展。氮吸收、利用等性状的生理和遗传特性极其复杂,受环境影响很大,对其进行遗传改良需考虑多种指标。对硝酸还原酶活性(NRA)与品质性状和产量的关系的争论很多,有些研究表明 NRA 可作为品质、产量性状的选择指标,有些则相反。逆境条件下 NRA 的变化非常敏感,NRA 可能与抗逆性有关。  相似文献   

Non-destructive determination of fat content in frozen and thawed mackerel by near infrared spectroscopy     

Junji  SHIMAMOTO  Kaoru  HASEGAWA  Minoru  SATO  Sumio  KAWANO 《Fisheries Science》2004,70(2):345-347

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关于我国设立刑事证据开示制度的思考     

刘晓燕 《安徽农业大学学报》2004,(1):90-92

1996年《刑事诉讼法》的修改，产生了律师阅卷难问题。为解决这一问题，真正实现控辩双方公平对抗，我国应设立刑事证据开示制度。文章对刑事证据开示制度的内涵、设立的必要性、设立的原则以及具体建议进行法律思考。  相似文献   

Correlated Responses in Two Traits when Selection is Practised on their Ratio     

M. Hühn 《Plant Breeding》1992,109(1):28-34

In many fields of application in plant breeding and crop science, ratios of two component traits X and Y are of interest (harvest index in cereals, leaf-to-stem ratio in forage legumes, height-to-diameter ratio in forest trees etc.). When selection is practised on the ratio X/Y of two traits X and Y, the experimenter may be interested in the resulting changes of both trait means. Based on improved approximations for the covariances between X and X/Y and between Y and X/Y and for the variance of X/Y the changes in the means of X and Y can be predicted by applying the regression approach from conventional selection theory. Explicit expressions for these correlated responses in X and Y when selection is practised on their ratio X/Y are derived and discussed. The different outcomes (decrease, zero change or increase) for the selection pressures on X and Y are characterized by phenotypic coefficients of variation of X and Y, phenotypic and genotypic correlations between X and Y and heritabilities of X and Y.  相似文献   

水分对硝酸磷肥中氮的扩散及其肥效的影响     

黄瑞珍  张胜 《中国农业大学学报》1989,(2):193-200

国产硝酸磷肥含氮27%,磷13.5%。所含速效氮中硝态氮均占一半。研究麦田不同水分对硝酸磷肥中硝态氮在土壤中扩散结果显示,硝态氮在土壤中下移深度与土壤湿润峰的深度基本一致,在小麦越冬期有表聚现象。当灌水量为田间持水量时,硝态氮移动深度为40～50cm,是在主要根系活动层内,这对小麦吸收有利,不会产生氮的流失。等氮磷条件下,硝酸磷肥与磷铵加尿素在北方地区有同样肥效。  相似文献   

法氏囊活性肽对鸡体增重及饲料转化率的影响   总被引：3，自引：0，他引：3  

侯艳红  钱建飞  张焕铃  郝勤宗  裘孝良  凌雯  李银  张则斌  陈溥言  杨奎 《畜牧与兽医》2002,34(9):8-10

把不同剂量的法氏囊活性肽 (BS)冻干粉与传染性法氏囊病 (IBD)活苗混合后 ,对 2 1日龄SPF鸡滴鼻点眼 ,同时另选一批同样生长状态的鸡 ,在颈部皮下接种IBD细胞毒油苗 ,同时肌肉注射上述不同剂量法氏囊活性肽 ,观察法氏囊活性肽对鸡生长性能的影响。结果发现 :免疫后7d ,活苗 0 2mLBS组增长最快 ,比免疫对照组多增 82 5 % ,并且饲料报酬高。但从整个试验期看 ,0 4mLBS组增重效果较好 ,比免疫对照组多增 1 9 8% ,并且有较高的饲料转化率。而肌肉注射BS组中 ,高剂量 (0 8mL)BS组的增重效果一直很好 ,比对照组总增重平均多增 7 2 3 % ,并有较高的饲料报酬。这说明滴鼻点眼或是肌肉注射 ,BS都有促生长的作用  相似文献   

赖氨酸占蛋白质及饲粮的比例对杜洛克猪生长肥育性能及胴体品质的影响   总被引：1，自引：0，他引：1  

吴梅芳  彭健  邓昌彦  熊远著  王振骅  童光照  吴东明 《中国畜牧杂志》1993,(2)

杜洛克猪48头,体重27kg左右,分6组。试验前期(27～60kg)日粮的消化能均为13.67MJ)/kg,后期(60～90kg)均为13.44MJ/kg。粗蛋白1、2、3组前期均为18％,后期均为16％;4、5、6组前期均为16％,后期均为14％。同时配合3种赖蛋比水平6.6～6.9％,6.1～6.25％及5％。试验结果表明:4、5、6组平均日增重、饲料利用率及胴体瘦肉率都略高于1、2、3组,但差异不显著(P>0.05)。在前期,以第5组平均日增重最高(达782克),极显著高于其他各组(P<0.01);饲料利用率2.41,极显著好于其他各组(P<0.01)。后期以第5组平均日增重最高(875克)。试验前期,第5组获得最佳的日增重(822克),极显著高于其他各组(P<0.01),饲料利用率2.98,胴体瘦肉率65.79％,与其他各组差异不显著(P>0.05)。在两种粗蛋白水平组内,均以赖蛋比6.1～6.25％的第5组和第2组生长速度最快(822克和778克)。说明在相同的能量水平下,赖蛋比是影响生长速度的主要因素。  相似文献