臭氧和紫外线对冰箱消毒的研究     

罗方妮  李湘鸣 《扬州大学学报(农业与生命科学版)》1995,(4)

家用冰箱存在着不同程度的细菌污染，必需对冰箱进行定期或不定期的消毒。经用载体法和平皿法研究发现，用紫外线对冰箱进行消毒是可行的，其对大肠杆菌、金黄色葡萄球菌和枯草杆菌黑色变种芽胞有较强的杀灭作用，而且不会引起冰箱内温度升高。同时还可产生少量Ｑ，除去冰箱内异味，因此具有杀菌、抑菌、除臭保鲜的作用。  相似文献   

Sectioned pelvic fin ray ageing of muskellunge Esox masquinongy from a Virginia river: comparisons among readers, with cleithrum estimates, and with tag–recapture growth data     

T. O. BRENDEN  E. M. HALLERMAN  & B. R. MURPHY 《Fisheries Management and Ecology》2006,13(1):31-37

Abstract  The potential utility of pelvic fin rays as ageing structures was evaluated for southern US muskellunge Esox masquinongy Mitchill populations by comparing age estimates among three readers and against cleithrum estimates, and by comparing observed length changes of tagged fish with changes predicted from growth equations based on pelvic fin ray age estimates. Mean coefficient of variation in age estimates among all readers and between the two readers with prior ageing experience was 17.8% and 5.6%, respectively. Exact and within 1-year agreement rates between pelvic fin rays and cleithra were 76% and 100%, respectively. Mean (± 2 SE) estimated absolute error between observed and predicted length changes for 13 tagged muskellunge was 30 ± 14 mm. This evaluation indicated that pelvic fin rays may prove to be a useful, non-lethal method for ageing muskellunge in southern US waters. Validation studies are still needed to ensure that growth rings form consistently throughout fish's life span.  相似文献   

自由曲面前照灯近光配光的防眩目研究     

谷正气  贺平 《湖南农业大学学报(自然科学版)》2004,31(6)

从驾驶员心理学和生理学角度探讨了汽车夜间会车时眩目的机理．由于传统的前照灯配光设计停留在二维的层面上，设计周期长，且配光效果差，很难达到防眩目的要求．本文通过Reflector CAD软件反求出了符合ECE法规配光要求的自由曲面前照灯反射镜的三维模型，该模型可以直接用于数控程序的编制，减小了前照灯的设计成本和设计周期，利用TracePro软件对模型进行近光配光的仿真实验，通过光线追踪的方法避免了实际配光实验时调整反射镜配光所需的反复制造过程，同时又保证了前照灯防眩目的效果。  相似文献   

Food intake and energy expenditure in growing cats with and without a predisposition to overweight          下载免费PDF全文

Vivien Ghielmetti  Brigitta Wichert  Simon Rüegg  Diana Frey  Annette Liesegang 《Journal of animal physiology and animal nutrition》2018,102(5):1401-1410

Overweight and obesity are multifactorial diseases caused by an imbalance in energy metabolism. An underlying genetic predisposition is often a factor in these conditions. In the cat breeding family of the Institute of Animal Nutrition at the Vetsuisse Faculty, University of Zurich, a segregating overweight phenotype with a genetic contribution was observed. From this breeding family, 26 kittens were followed from birth up to 8 months of age. During this time, food intake was measured using an automatic feeding station, and energy expenditure was investigated using indirect calorimetry at the ages of 4 and 6 months. Dual‐energy X‐ray absorptiometry (DEXA) was performed and blood glucose, leptin and insulin were measured at the ages of 4, 6 and 8 months. The kittens were also weighed daily for the first 2 weeks of life, every second day until weaning and once per week until 8 months of age. The body condition score (BCS) was evaluated monthly between 2 and 8 months of age. The main finding of this study is that a predisposition to overweight is connected to a higher food intake early in life, with no significant alterations in energy expenditure. The leptin blood levels were related to body fat percentage, and insulin sensitivity did not seem to be affected.  相似文献   

X射线荧光光谱法快速测定稻谷中的镉     

李梅 《粮食储藏》2016,(1):46-48

探索了一种对稻谷中重金属镉的快速、直接的测定方法,以适用稻谷集中收购、存储和流通过程中快速检测的的需要。样品无需前处理,直接磨成粉状即可上机测定。该方法采用X射线荧光光谱分析的原理,样品中的待测元素受激产生特征X射线,并由高性能探测器接收,得到镉元素的信号强度,然后根据信号强度与浓度的比例关系,经过软件处理自动计算样品中镉的含量,20min内完成精确定量。检出限可达到0.034mg/kg,实物标样标准偏差为0.016。此方法简单快速,并且准确性高,重现性好,可广泛应用于稻谷中镉的快速检测。  相似文献   

Pedotransfer functions to assess adsorbed phosphate using iron oxide content and magnetic susceptibility in an Oxisol          下载免费PDF全文

L. A. Camargo  J. Marques Jr.  G. T. Pereira  L. R. F. Alleoni  A. S. R. de S. Bahia  D. De B. Teixeira 《Soil Use and Management》2016,32(2):172-182

Adsorbed phosphate in soils can be chemically extracted; however, this process is both time‐consuming and not cost‐effective if large numbers of samples have to be analysed. Indirect assessment of adsorbed phosphate by pedotransfer functions (PTFs) can help optimize fertilizer strategies. This study aimed to evaluate the spatial variability of adsorbed phosphate (P_ads), iron oxides and magnetic susceptibility (MS) in oxisols and to calibrate PTFs to predict P_ads. A total of 308 soil samples were collected from Hapludox and Eutrudox soils formed from sandstone in Brazil. The contents of clay (196–607 g/kg), iron oxides (40–165 g/kg), MS (1.2–29 × 10^?6 m³/kg) and P_ads (327–842 mg/kg) were in the range of typical values for these highly weathered soils. This study showed that the attributes studied were spatially dependent. Geomorphic surfaces enabled understanding of spatial variability and helped to develop a more efficient sampling scheme to calibrate PTFs. Moreover, the adsorbed phosphate in these oxisols could be predicted by a PTF using iron oxides and MS as predictors. The MS attribute enabled the most accurate prediction (concordance coefficient = 0.95, root‐mean‐square error = 46 mg/kg and relative improvement in root‐mean‐square error = ?4.12) of spatial variability through PTF compared to other predictors.  相似文献   

低雷诺数工况下锯齿型翅片性能的参数化研究     

郭丽华  覃峰  陈江平  夏立峰  陈芝久 《农业机械学报》2007,38(7):168-171

基于田口方法,结合均匀设计法对低雷诺数工况下错列锯齿型翅片进行三维参数化数值研究。以单层翅片组件为测试对象,对6种试件的试验表明,仿真结果与试验数据的趋势吻合良好,而存在差异的主要原因是试件加工工艺引起翅片表面存在毛刺。按照均匀设计法得到6因子5水平的11种仿真方案,引入田口方法的信噪比和贡献率,研究各几何参数对翅片性能的影响程度,依次为齿距、齿高、齿型角、错齿距、齿开窗宽度和齿厚。根据各水平下各可控因子的信噪比分布得到翅片的优化模型,并通过仿真验证了优化模型的有效性。  相似文献   

Method to Analyze and Evaluate the Depth Profile of the Three Dimensional Residual Stresses State with X-ray   总被引：1，自引：0，他引：1  

CHEN Yu an  ZHOU Shang qi  HAN Xian bing 《保鲜与加工》2002,(1):40-43

  相似文献   

Analysis of Heat Transfer and Optimal Parameters of Multi-louvered Fin Condenser     

LI Kui-ning  ZHAO Jian-gang  LUO Hong 《保鲜与加工》2005,(6):41-43

The authors conduct the experimental study and optimal computing for the condenser of automobile air conditioner. The especially the properties of heat transfer and flow at the side of air when using shutter fin. The authors the influence of several combinations of fin's geometry parameter to heat transfer and flow resistance. The maximal heat transfer is used as a criterion relation to select the fin's geometry parameters in the same facing air area of condenser. Furthermore, a program is designed to conduct optimal computing, and the computing results are basically consistent with experimental results. It shows that the optimal method is reasonable and the results can be applied to engineering practice.  相似文献   

原木截面形状扫描参数的计算     

张晗  冯衡滨 《林业机械与木工设备》2012,(8):33-35

利用激光扫描技术得到原木截面的基本参数,通过计算得到比较精确的原木截面形状,在整根原木上进行周期扫描从而得到整根原木的形状参数。  相似文献