基于MDT的双翼翻土防漏耕犁的犁体曲面展开     

陈翠英  陈利刚 《农业机械学报》2002,33(5):38-39,43

介绍一种基于MDT的犁壁曲面双样板曲线近似展开法，在MDT平台上直接用直线投影法求样板曲线，并直接将正视图投影到三维犁曲面上求各元线实长，减少了计算工作量，具有快捷方便的优点，该方法已用于双翼翻土防漏耕犁的设计，效果良好。  相似文献   

福建沿海水域互花米草蔓延的动态监测分析     

潘卫华  陈家金  张春桂  林晶 《中国农业气象》2011,(Z1)

利用1999/2000年和2006/2007年2个不同时相的遥感影像对福建省沿海水域的互花米草进行解译提取,并结合地理信息数据和社会统计数据进行变化分析。研究表明:基于专家决策树的福建省互花米草信息提取法具有较高的解译精度,动态监测结果显示,7a来福建沿海水域互花米草蔓延迅速,已侵占了大片的养殖水域和滩涂资源,研究旨在为引起有关部门的高度重视并采取必要的治理措施提供理论依据。  相似文献   

Biological characteristics of JAK2 transduced CD34⁺ cells from cord blood during ex vivo expansion     

ZHAO Sheng-ming  GU Xi-chun  CHANG Nai-bai  XU Xiao-dong  PEI Lei 《园艺学报》2007,23(12):2460-2464

AIM: To explore the feasibility and biological characterization of long-term regulated expansion of JAK2 transduced human CD34⁺ cord blood cells in vitro.METHODS: A retrovirus (RV) vector which contains JAK2 catalytic domain and two binding sites for a chemical inducer,dimerization (AP20187),was cloned (designated MGI-F₂JAK2).CD34⁺cells were enriched from cord blood with a MiniMACS system.The purified CD34⁺ cells were transfected with supernatant from the retrovirus packaging cell line that expressed JAK2.Following transduction,cells were expanded into four groups: AP20187 alone,FL alone,TPO,alone,AP20187+FL+TPO,respectively.The expanded cells were monitored by GFP expression,immunophenotyping,progenitor colony assay,karyotype analysis as well as tumorigenesis in nude mice.RESULTS: The purity of selected CD34⁺ cells was over 91% and gene transfer rate was 49.32%±6.21%.Only the group of AP20187 +FL+ TPO was obtained a significant sustained outgrowth of the transduced CD34⁺ cord blood cells.The percentage of GFP+ cells consistently produced a rise to the 90% peak level by the end of 8th week of culture.Flow cytometry analysis showed that the phenotype of the expanded cells was CD33⁺,CD61⁺ and Gly-A⁺ partial positive;CD38⁺ and HLA-DR⁺ strong positive,while CD2,CD7 and CD19 were almost negative.Colony assays performed in methycelluos,which can give rise to BFU-E,CFU-GM and CFU-Mix,the CFU-GM was predominantly in all colonies.The tumor was not observed in nude mice and the karyotype analysis was normal from expanded cells.CONCLUSION: The results demonstrate that AP20187-mediated activation of JAK2 signaling is capable of stimulating expansion JAK2 transduced CB CD34⁺ cells in combination with FL and TPO.This system may have applications for studies in signaling transduction,hematopoiesis,and for gene and cell therapy.  相似文献   

The genetic structure of populations of <Emphasis Type="Italic">Turnip mosaic virus</Emphasis> in Kyushu and central Honshu,Japan     

Yasuhiro Tomitaka  Tohru Yamashita  Kazusato Ohshima 《Journal of General Plant Pathology》2007,73(3):197-208

The genetic structure of the populations of Turnip mosaic virus in Kyushu and central Honshu, Japan was assessed. The host specificity of isolates was determined, and their gene sequences compared utilizing a population genetic approach. Phylogenetic analysis of partial sequences revealed that 32 of 49 Honshu isolates (65%) collected during 1997–2001 belonged to the basal-BR group as did 23 of 64 isolates from Kyushu. All these basal-BR isolates infected both Brassica and Raphanus plants. However, analyses of the positions of recombination sites in five regions of the genome (one third of the full sequence) showed that at least four intra-lineage recombinants were present in these populations. These analyses showed that Kyushu and Honshu shared none of these subpopulations, and genetically distinct basal-BR populations were present in the two districts. We conclude that different basal-BR subpopulations had expanded into those districts. The nucleotide sequences are deposited in the DDBJ/EMBL/GenBank databases under accession numbers AB267281-AB267376.  相似文献   

不同香型烤烟CO_2膨胀前后品质的比较研究     

范自众 《安徽农业科学》2012,40(34):16803-16805,16808

[目的]比较不同香型烤烟CO2膨胀前后品质变化。[方法]开展了3种主要香型烟叶CO2膨胀试验,对各样品烟丝膨胀前后的物理性能、化学成分、烟气指标和内在质量进行检测分析。[结果]清香型烟叶经过CO2膨胀,还原糖、挥发酸、焦油和烟碱含量平均降幅最大,香气质、香气量和柔细度改善或保持最佳;浓香型烟叶的平均膨胀效果最明显,总糖、总氮含量平均变化最大,杂气、刺激性、透发性和浓度改善或保持最佳;中间香型烟叶CO2膨胀后总植物碱、氯和蛋白质含量平均变化明显,重量、口数、总粒相物以及CO 4项指标降幅最大,甜度、余味指标有更好提升。[结论]不同香型烤烟各项理化、感官指标受膨胀影响程度有所差别,烤烟香型与CO2膨胀具有一定的关联性。  相似文献   

水泥混凝土路面与工程结构用软木伸缩缝填料   总被引：4，自引：0，他引：4  

李大年 《林产化学与工业》1990,10(2):107-115

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Oviposition and larval performance of Monochamus alternatus (Coleoptera: Cerambycidae) on the Japanese cedar Cryptomeria japonica     

Zu-Ji Zhou  Katsumi Togashi 《Journal of Forest Research》2006,11(1):35-40

To determine whether Monochamus alternatus can use the Japanese cedar (Cryptomeria japonica) as a host tree, experiments were conducted in a laboratory using three insect populations of different localities. Adult females chose Pinus densiflora bolts as oviposition substrate when supplied with cedar and pine bolts simultaneously, whereas some females from one locality oviposited on cedar bolts when supplied with them exclusively. Seventy-three percent of 40 eggs hatched in cedar bolts. When the first instar larvae were inoculated on cedar bolts, the development was stunted greatly and all died during the larval stage. Two of 20 larvae that were inoculated on cedar bolts at the third instar entered the diapause and one larva developed into an adult female, which produced viable eggs but was much smaller than those obtained from pine bolts. The results did not exclude the possibility that M. alternatus can use recently killed C. japonica trees as a host.  相似文献   

关于桥梁伸缩缝的研究     

阎治理  陆书斋 《森林工程》1996,12(2):52-53

本文通过对几种桥梁伸缩缝的测试,并分析了测试的数据,认为最新生产的江苏毛勒伸缩缝既可满足桥梁梁端变形需要,又可起到防水作用,同时还具有良好的舒适性和耐用性。  相似文献   

旅华欧洲游客旅游决策行为模式研究——以西安入境欧洲游客为例     

姚媛 《安徽农业科学》2010,38(23):12871-12872,12879

研究以国家自然科学基金项目支持的入境旅游市场调查数据为基础,以入境游客旅游决策行为为切入点,通过对西安入境欧洲游客的问卷调查,对其旅游决策行为及其影响因素进行分析研究,对西安欧洲旅游客源市场的拓展提出针对性的建议和对策。  相似文献   

年产1.5万m~3中纤板生产线的扩产改造     

邝孔唐 《木材工业》2001,15(1)

简要介绍了年产 1.5万 m3中纤板生产线改造前的情况 ,重点论述了关键设备和工艺的改造过程 ,以及改造后的情况。结果表明 :改造后生产线的生产能力可以达到 3万 m3/ a的预期目标  相似文献