土壤条件对挖坑机动态力学参数的影响     

刘会敏  茅也冰  王乃康 《北京林业大学学报》2003,25(4):64-69

为研究土壤条件 (土壤类型、土壤湿度、土壤硬度 )对挖坑机动态力学参数 (扭矩、进给阻力 )的影响 .该试验采用模拟生产条件的方法 ,在自行研制的试验台上实现动态实时记录 .通过数据分析 ,得出各影响因素与钻头动态力学参数间的数学关系 ,做出曲线拟合方程 ,从而找到最佳值 ,为挖坑机的设计、选择及运用 ,提供理论依据 .  相似文献   

床垫软硬度对不同体型人群体压分布的影响     

方菲  申黎明  郭园 《安徽农业大学学报》2016,43(2):319-324

人体体型特征和床垫的软硬度是影响床垫使用舒适性的重要因素。运用人体体压分布测试系统,探究不同软硬度的床垫对仰侧卧姿势下瘦型、中等体型和胖型3种体型受试者体压分布的影响。结果发现,仰侧卧时,瘦型、中等体型和胖型体型受试者肩部、腰部和臀部的接触面积变化趋势一致,均呈现增大趋势。且仰卧下三体型受试者各部位的平均压力的整体变化趋势大致相同,侧卧时仅瘦型和中等体型受试者三部位的平均压力变化趋势大体一致。另外仰卧时床垫硬度的变化对胖型受试者腰部和臀部平均压力影响较大,对瘦型受试者的体压分布面积指数影响较大,对中等体型受试者腰部平均压力影响最小。侧卧时,床垫硬度的变化对胖型受试者腰部的平均压力影响较为显著,对中等体型受试者的三部位平均压力影响最小。  相似文献   

Calcium chloride sprays decrease physiological disorders following long-term cold storage of apple   总被引：3，自引：0，他引：3  

Dris R  Niskanen R 《Plant foods for human nutrition (Dordrecht, Netherlands)》1999,54(2):159-171

Field experiments were carried out at the Horticultural Research Institute, and in five commercial apple orchards, located in southwest Finland including the Åland Islands during 1994 and 1995. The experimental cultivars were Melba, Raike, Red Atlas, Åkerö, Aroma, and Lobo. The treatments were untreated control and preharvest calcium chloride (CaCl₂) sprays at Ca 2.0 g/l. Fruit samples were stored for two to six months at 2–4 °C and 85–95% RH. The percentage of the incidence of physiological disorders of stored apples was scored. Fruit macronutrients, firmness, diameter and juice titratable acidity and percentage of soluble solids were determined. Only a few nutrient effects in the flesh of the apple cultivars were a result of CaCl₂ sprayings. Preharvest CaCl₂sprays increased fruit firmness and the titratable acidity but decreased soluble solids, soluble solids/titratable acidity ratio, and the incidence of physiological storage disorders of some cultivars. When looking at the mean of all cultivars, CaCl₂ sprayings increased titratable acidity and decreased soluble solids/titratable acidity ratio after four months of storage during 1995 and reduced the incidence of physiological disorders after three months of storage during 1994 and after four months of storage in 1995.  相似文献   

Peach ripening: Segregation at harvest and postharvest flesh softening     

《Postharvest Biology and Technology》2013

The peach melting flesh cultivars ‘Ryan Sun’ and ‘Sweet September’ and the non-melting, ‘Kakamas’ were harvested according to their visually assessed ground color and divided into four, ripeness classes (M1, M2, M3, and M4). The following aspects were determined: fruit mass, soluble, solids content (SSC), ground skin hue angle (h°) and chroma (C*), the absorbance difference at 670 nm and, 720 nm index (I_AD), and the texture (fruit firmness measured with a needle, flesh firmness measured, with a 7.9 mm plunger, and uniaxial compression strength). Considering that in peaches, the h° of the, ground color and the I_AD are maturity indicators closely associated with ripeness and particularly with, flesh firmness, the texture parameters and their relationship to h° and I_AD were examined. The visual, assessment of the ground color was validated as the criterion for sorting the ripeness levels in peaches, as confirmed by h° and I_AD. Fruit firmness assessed with the needle and that with the 7.9 mm plunger, were highly correlated with each other and with the h° and I_AD, whereas the compression strength, exhibited less correlation with the optical properties of the skin. The non-melting ‘Kakamas’ showed, the poorest correlation between texture and h° and I_AD. Comparing both optical properties, the I_AD, showed a higher correlation with texture features than the h°. In a second experiment, fruit from the M3 ripeness class was maintained in a ripening chamber (20 °C, and 80% RH) until the flesh was softened for consumption. During postharvest, the first two principal, components of a principal component analysis explained 85% of the total variance of the texture, components and the optical properties of the skin. PC1 (67.2%) was defined positively by the texture, parameters and I_AD. The h° of the ground color was negatively related to all texture parameters, and, I_AD. PC2 (17.8%) was associated positively with the juice content, and this parameter proved to be, independent of all others.  相似文献   

Fruit Quality and Flavor Compounds Before and After Commercial Harvest of the Late-Ripening ‘Fairtime’ Peach Cultivar     

《International Journal of Fruit Science》2013,13(1):25-36

ABSTRACT

In this work quality of tree ripe and commercial ripe ‘Fairtime’ peach fruit was evaluated during fruit maturation and storage. Quality parameters and volatile fraction were monitored at intervals of 7-15 days from pit hardening until 10 days after commercial harvest and after 7, 17 and 24 days of refrigeration. In fruit on the tree, weight increased quadratically, diameter and peel color increased linearly, whereas flesh firmness decreased linearly. Soluble solids (SS) reached maximum levels at commercial harvest, whereas acidity started declining after commercial harvest. In the peel, esters and alcohols showed opposite trends. In the flesh, alcohols decreased quadratically and disappeared in tree ripe fruit. In refrigerated fruit, there were no significant weight changes, flesh firmness decreased linearly, SS reached a minimum around the 10th day, and acidity decreased quadratically. A three day harvest delay followed by two weeks of refrigeration may represent a chance to further extend marketing of optimum flavor ‘Fairtime’ peaches into late fall.  相似文献   

冲击法检测马铃薯坚实度的试验研究   总被引：1，自引：0，他引：1  

王娇  张本华  赵利军 《沈阳农业大学学报》2009,40(6)

应用自制的冲击摆对马铃薯的坚实度进行了检测研究.利用3种不同形状的冲击针头(圆柱型、圆锥型和三棱锥型)作为工作部件,采用电测方法对摆锤摆动角度进行检测,并以此来衡量马铃薯的坚实度.试验所得数据经过spss软件分析,分别得出不同针型的描述性统计分析结果,经过柯尔莫哥洛夫检验,方差榆验及利用Scheffe方法进行多重比较.结果表明:利用冲击的试验方法来检测马铃薯的坚实度原理可行,三棱锥型的针头更能真实地反映马铃薯的坚实度,可为其他果蔬产品的坚实度检测提供参考.  相似文献   

不同耐贮性辣椒贮藏期间的生理生化特性   总被引：4，自引：0，他引：4  

杨瑞平  陈儒钢  巩振辉  李大伟  黄炜  逯明辉 《西北农业学报》2009,18(6):221-225

以P18-2、P98、P129为试材,研究不同耐贮性辣椒在贮藏期间的生理生化变化.结果表明,在10℃下贮藏21 d,随着贮藏时间的延长,不同耐贮性辣椒的生理生化变化趋势相同,果实硬度不断下降,可溶性果胶含量增加, 聚半乳糖醛酸酶活性下降,纤维素酶活性上升,可溶性糖含量减少,vC含量降低,含水量下降;但耐贮品种比不耐贮品种的变化趋势平稳.  相似文献   

番茄叶面喷施硅和钙对果实硬度及相关生理代谢的影响   总被引：1，自引：0，他引：1  

苏敬  乜兰春  齐迎斌  王苗苗 《园艺学报》2016,43(4):789-795

以番茄品种‘红双喜’为试材,研究了生长期叶面喷施硅、钙对果实硬度、细胞壁组成物质以及细胞壁代谢相关酶活性的影响。结果表明：叶面喷施7 mmol ? L-1 H4SiO4、7 mmol ? L-1 K2SiO3、7 mmol ? L-1 H4SiO4 + 45 mmol ? L-1 CaCl2和7 mmol ? L-1 K2SiO3 + 45 mmol ? L-1 CaCl2均显著提高了番茄采收当天和采后7 d的果实硬度,4个处理的果实在采收当天和采后7 d原果胶和纤维素含量显著高于对照,可溶性果胶含量以及多聚半乳糖醛酸酶（polygalacturonase,PG）活性、果胶甲酯酶（pectin methylesterase,PME）活性、纤维素酶（cellulose enzyme,Cx）活性显著低于对照。在各处理中,以7 mmol ? L-1 H4SiO4和7 mmol ? L-1 K2SiO3处理的效果最好,采后7 d,果实硬度分别比对照高14.31%和13.84%,原果胶含量分别比对照高75.00%和68.10%,纤维素含量分别比对照高68.66%和80.60%,可溶性果胶含量分别比对照低28.41%和29.55%,PG酶活性分别比对照低18.70%和20.87%,PME酶活性分别比对照低13.61%和17.66%,Cx酶活性分别比对照低31.42%和31.38%。  相似文献   

桃果实果胶、可溶性糖、可滴定酸含量和果实大小与果实硬度关系的研究   总被引：11，自引：2，他引：9  

马之胜  王越辉  贾云云  宣立锋 《江西农业学报》2008,20(10):45-46

以普通桃、油桃和蟠桃为试材,研究了桃果实果胶、可溶性糖、可滴定酸含量、果实大小与果实硬度之间的关系。结果表明,果实原果胶和可溶性果胶含量分别与果实带皮硬度呈显著正相关和极显著负相关,总果胶含量、可溶性糖、可滴定酸含量及果实大小与果实硬度之间均没有显著的相关性。  相似文献   

Photosynthetic reaction,mineral uptake,and fruit quality of strawberry affected by different levels of macronutrients     

Rouhi Shirko  Mozafari Ali Akbar  Ghaderi Naser 《Journal of plant nutrition》2018,41(14):1807-1820

This experiment was conducted to evaluate the effects of three nutrient recipes containing different concentrations of macronutrients in the vegetative stage [Vegetative Nutrient Solution: (VNS-I, VNS-II, and VNS-III)] and two nutrient recipes in reproductive stage [Reproductive Nutrient Solution: (RNS-I and RNS-II)], on physiological and biochemical parameters of strawberry ‘Paros’ in a soilless system. The results indicated the significant effects of nutrient solution on the photosynthetic capacity, yield, minerals uptake and titratable acidity of strawberry fruits. In the other hand fruit total soluble solids affected by vegetative nutrient solution. The highest yield was obtained under application of lowest level of minerals. Vegetative growth including leaf number and leaf area, as well as total chlorophyll were the highest as potassium (K⁺), calcium (Ca²⁺), and nitrogen (N) concentrations were increased. The highest content of N and Ca²⁺ uptake were in VNS-III × RNS-I formulation. Additionally, the highest vitamin C was in VNS-I formulation. Moreover, the most firmed fruits and the highest post-harvest shelf life of fruits were produced in VNS-III × RNS-I formulation.  相似文献