纯电动汽车传动系参数的区间优化方法   总被引：5，自引：1，他引：5  

姬芬竹  高峰  吴志新 《农业机械学报》2006,37(3):5-7

在分析纯电动汽车传动系减速比传统优化模型的基础上,提出了区间优化方法。优化的目的是在满足电动汽车基本动力性能的前提下,求优化变量的最大可行区间,而不是一个确定的最优值。区间优化方法便于产品的系列化,可以解决传动系齿轮配齿问题。以XL2000型纯电动汽车传动系参数的优化设计为例,对所建模型进行了验证。  相似文献   

遗传神经网络在温室黄瓜霜霉病预测中的应用   总被引：5，自引：0，他引：5  

熊雪梅  姬长英 《农业机械学报》2002,33(4):69-71

在神经网络结构的优化、连续权重的训练中采用遗传算法的方法对日光温室黄瓜霜霉病进行预测，并对其发生程度进行了拟合，计算值与实际值接近，表明该模型具有良好的预测效果。  相似文献   

Effects of Dietary DHA/EPA Ratios on Fatty Acid Composition,Lipid Metabolism‐related Enzyme Activity,and Gene Expression of Juvenile Grass Carp,Ctenopharyngodon idellus          下载免费PDF全文

Hong Ji  Jie Li 《Journal of the World Aquaculture Society》2016,47(2):287-296

To determine the effects of docosahexaenoic acid/eicosapentaenoic acid (DHA/EPA) ratios on grass carp, Ctenopharyngodon idellus, a 38‐d feeding trial was conducted using six isonitrogenous and isoenergetic semi‐purified diets containing constant n‐3 long‐chain polyunsaturated fatty acid (LC‐PUFA) (0.5% of dry matter), but varying ratios of DHA to EPA and a control diet (no n‐3 LC‐PUFA was included). The results revealed higher final weight and specific growth rate in the DHA/EPA 0.21 group. The n‐3 LC‐PUFA content increased in the CK (control) groups compared with that in the control diet. Lipoprotein lipase (LPL) activity increased in the treatment groups. Malate dehydrogenase showed lower activity in the DHA/EPA 1.08 group, as well as to the change in the level of glucose‐6‐phosphate dehydrogenase (G6PDH). The gene expressions of LPL increased in the treatment groups and that of peroxisome proliferator‐activated receptor α gene showed higher expressions in DHA/EPA 1.08, 0.49, and 0.21 groups. However, no remarkable differences were found among the six groups in the peroxisome proliferator‐activated receptor γ gene expression. Our findings indicated that dietary n‐3 LC‐PUFA affected fatty acid composition and lipid metabolism of grass carp. Further, fish achieved the best effect in decreasing the lipid accumulation when dietary DHA/EPA ratio was not greater than 1.  相似文献   

攀枝花地区紫胶组分分析     

张雯雯  毕兴丹  唐勇  李继  张弘  郑华  甘瑾 《东北林业大学学报》2010,38(11)

采用溶剂分级法分析了攀枝花6个地区紫胶原胶水溶物、色素、紫胶树脂和紫胶蜡等成分的差异,并用真空直读型电感耦合等离子体原子发射光谱仪(ICP-AES)测定了不同地区紫胶原胶中的Cu、Fe、Zn、Mn、K、Ca、Mg、S、P9种元素的质量分数。结果表明,6个地区原胶中的含水率存在显著差异(p0.05);米易方田的紫胶原胶中水溶物和色素的质量分数与其他地区有显著性差异,盐源地区的紫胶原胶中紫胶红色素质量分数是12.41%,为6个地区中最高的;部分地区紫胶原胶中总树脂质量分数差异不显著,但二滩地区紫胶原胶中软树脂质量分数为27.91%,与其他地区差异显著;6个地区紫胶中紫胶蜡的质量分数差异未达到统计学显著水平;6个地区紫胶中元素S、P、K、Ca、Fe、Zn的质量分数均存在显著性差异,表明产区气候、地势等对紫胶的组成有一定的影响。  相似文献   

Comparison of physiological and yield traits between purple- and white-pericarp rice using SLs     

Zhi-Juan Ji  Xiao-Guang Wang  Yu-Xiang Zeng  Liang-Yong Ma  Xi-Ming Li  Bing-Xin Liu  Chang-Deng Yang 《Breeding Science》2012,62(1):71-77

Five physiological and eleven yield traits of two pairs of sister lines generated from a high generation with similar genetic background (SLs) for purple pericarp were investigated to explore the reasons behind low-yield production of colored rice. Of the five physiological traits examined, except grain anthocyanin content, there were generally similar trends between the P (purple-pericarp) lines and the corresponding W (white-pericarp) lines over two seasons (in the year 2009 and 2010 separately). The results demonstrated that the chlorophyll content of flag leaves, the net photosynthetic rate of flag leaves, and the grain anthocyanin content could be easily influenced by the environment. The physiological functions of the traits for the P lines were more active than those of the corresponding W lines in the year 2010. The grain anthocyanin content of the P lines was much greater in the year 2010 than in the year 2009 during the growth period. The investigation of yield traits revealed that the P lines had reduced 1000-grain weight, yield per plot and grain/brown rice thickness compared to the W lines. A difference comparison of these traits and a source-sink and transportation relationship analysis for these SLs suggested that small sink size was a key reason behind yield reduction of purple pericarp rice.  相似文献   

The Possible Effects of Global Warming on Cropping Systems in China Ⅹ. The Possible Impacts of Climate Change on Climatic Suitability of Spring Maize in the Three Provinces of Northeast China   总被引：1，自引：0，他引：1  

ZHAO Jin  YANG Xiao-guang  LIU Zhi-Juan  LV Shuo  WANG Jing  CHEN Fu 《中国农业科学》2014,47(16):3143-3156

  相似文献   

树形结构对果树生产能力的影响分析   总被引：1，自引：0，他引：1  

杨飞  卢桂宾  杜俊杰  季兰 《山西林业科技》2012,41(1):46-49

果树树形与结构是影响果树产量的重要因素,笔者结合国内外的研究状况,综述了不同树形结构对光能利用率、营养与生殖、抗逆性、产量品质、实际生产的影响,指出适宜的栽植密度、合理的树形结构是保证果园光照良好,产量和品质提高的重要措施。  相似文献   

对38名自然保护区周边村民野生动植物保护问题的调查报告     

张毅  张艺  岳清洪  侯文婕  贾英田  普元祖  蓝海波  冀静 《北京农业》2010,(21)

为了解四川省平武县水晶镇大坪村村民对野生动植物保护的活动现状,采取随机问卷调查形式。调查结果显示村民具有对野生动植物保护的常识,认识较好,有具体行动。需进一步加强野生动植物保护的宣传力度、改变宣传方式。  相似文献   

Molecular divergence and application of the ITS-5.8S rDNA and RUBISCO spacer in <Emphasis Type="Italic">Porphyra haitanensis</Emphasis> Chang et Zheng (Bangiales,Rhodophyta)     

Changsheng Chen  Chaotian Xie  Dehua Ji  Yan Liang  Lingmin Zhao 《Aquaculture International》2010,18(6):1045-1060

To select a reliable and sensitive method for discriminating strains of Porphyra haitanensis, the nucleotide sequence of the internal transcribed spacer 1 to internal transcribed spacer 2 regions (ITS-5.8S) of nuclear ribosomal DNA and the intergenic spacer region of RUBISCO were compared in five wild and five cultivated Porphyra haitanensis strains. Based on molecular analyses, sequences of ITS-5.8S (about 1,210 bp) could be divided into three regions: ITS1, 5.8S, and ITS2. The ITS1 and ITS2 sequences of each strain differed, even between individuals collected from the same site. In contrast, 5.8S rDNA and RUBISCO spacer sequences were identical among the ten P. haitanensis strains, although differences were found among different Porphyra species. Phylogenetic analysis also supported these conclusions. These sequence features of highly conserved regions and diversified regions that occurred repeatedly in ITS-5.8S could be useful in discriminating germplasm of P. haitanensis strains or Porphyra species. In contrast, the RUBISCO spacer is only suitable for identifying Porphyra species. New coupled primers were designed to amplify only the 5.8S rDNA and ITS2 region of Porphyra. The sequences of these amplified fragments can be readily used to identify germplasm or to perform phylogenetic analysis of Porphyra spp.  相似文献   

论犬子宫破裂     

王艳红  杨荣  纪海青 《北京农业》2012,(15):121-122

犬的子宫体部或子宫角在妊娠期、分娩期或子宫发生异常病变时,发生破裂称为子宫破裂。子宫破裂为生殖系统最严重并发症之一,常引起母体和胎儿的死亡。  相似文献