共查询到20条相似文献,搜索用时 401 毫秒
1.
在过去的30年中,中国的茶机发生了8方面的变化,在整体上促进了茶机性能的完善和能源利用率的提高。中国茶机工业已经走上规范化和标准化的进程,形成了完整的工业体系,拥有设计、制造各类茶的加工设备和茶园作业机械的能力,并具有向国内、外提供成套设备的实力。红外辐射、光谱色差、可编程控制器和工业控制器等先进技术已在茶机上应用成功。茶机的理论研究也已系统展开。 相似文献
2.
The computational fluid dynamics (CFD) has been applied to simulate heat transfer in complex and porous materials, and the
governing partial differential equation (PDE) has been used to solve this kinds of models by means of numerical approach.
The solution of the governing differential equations has been obtained using the Crank-Nicolson method. The main problem in
these methods is lack of accurate estimation of thermal diffusivity in bulk complex fibrous materials. To overcome this problem,
a novel modelling method of heat transfer in transient condition based on training of a propagation neural network has been
applied to analyze heat transfer. The neural net model has been evaluated by experimental data of polyester samples of bulky
fibrous layers. The results present that propagation neural net can estimate thermal diffusivity of samples with good accuracy. 相似文献
3.
海南不同市县旱田代表性杂草发生规律研究 总被引:1,自引:0,他引:1
为全面了解海南不同市县旱田代表性杂草全年的发生规律,从2008年至2009年,采用全年定点、定时观测的方法对海南7个市县杂草自然萌发情况进行调查。结果表明:海南不同市县定点观测样方里共有代表性杂草20科60种,其中菊科、禾本科、苋科、豆科和茜草科较多,占杂草总数的63%;外来入侵杂草有29种,占总数的48%;重要值大于5的优势种杂草有12种,占所有杂草的20%。6月是杂草种类萌发高峰,达15种。海南杂草年平均萌发量达1 060株/0.25 m2,其中万宁最高,年平均萌发量达1 559株/0.25 m2;定安最低,年平均萌发量达519株/0.25 m2。海南杂草全年发生数量有两个高峰期:一个在4月,萌发率为16%;一个在9月,萌发率为10%。全年大部分杂草在3~7月和9月萌发,萌发率为全年的70%。在海南,温度均能满足杂草萌发需要,降雨量是杂草发生的主要限制因子。 相似文献
4.
《Crop Protection》1988,7(4):273-278
A surveillance system for the brown planthopper (BPH) was set up in the Tanjung Karang Irrigation Scheme, Selangor, Malaysia after an extensive outbreak of the pest in 1977. The system has since grown to cover all major rice-growing schemes in Peninsular Malaysia. However, the Tanjung Karang Irrigation Scheme remained the most advanced area in terms of operating an early warning system for BPH. This paper describes how the data are collected, analysed and appropriate action taken to manage BPH. Information of the incidence of BPH and its natural enemies were obtained by field scouting, light trapping, and aerial net trapping. The data obtained would be supplemented by information on plant growth, farm practices and weather. A rice planthopper control committee existed in the Scheme to examine the surveillance data and using pragmatic threshold levels together with prey: predator ratios, decisions on management of the BPH would be issued for immediate implementation. As a result of the surveillance system operating in the Tanjung Karang Irrigation Scheme, the number of outbreaks of the BPH has decreased since 1977. In addition, the availability of early warning information has encouraged the implementation of integrated pest control programmes in the scheme. The incorporation of natural enemies in the collection of data and the recognition of predators in decision making has highlighted the importance of natural enemies in managing BPH and this in turn has discouraged indiscriminate use of insecticides. 相似文献
5.
中国杂交水稻白叶枯病抗性的遗传改良 总被引:21,自引:1,他引:20
20世纪80年代,中国杂交水稻抗白叶枯病育种进展迅速。在大面积种植的籼型三系和两系杂交稻中主要应用白叶枯病抗性基因Xa4,白叶枯病在生产中几乎“销声匿迹”了20年。但近年来,此病害却在长江流域一些种植新组合的稻田里又爆发了。什么原因引起它再度流行?品种的抗性是否还有效?抗病育种是否还是水稻改良的主要目标之一?通过哪些途径才能更有效地利用抗病基因培育出更为持久的抗性品种?为回答这些问题,就我国杂交水稻对白叶枯病抗性的改良,寄主与病菌群体的互动演变效应进行了分析,讨论了拓宽抗性遗传基础、白叶枯病菌毒性群体结构、基因轮换、合理利用基因等问题。 在采用了包括传统方法、分子标记辅助选择和转基因技术的综合策略后,杂交水稻抗白叶枯病育种研究将出现新的局面。 相似文献
6.
7.
8.
我国杂交水稻的形势与战略 总被引:3,自引:0,他引:3
我国杂交水稻从开始研究至今已有30年历史,已为我国粮食生产作出了巨大贡献。要进一步发展杂交水稻,必须通过育种方法和材料的改进来提高组合的多样化、产量潜力、品质、抗性和制种产量。两系杂交稻正在走向成功,三系杂交稻在本世纪仍将是主力。杂交水稻国际开发前景可观。 相似文献
9.
10.
11.
以广东省主要种植的27个水稻品种为研究对象,通过对243份稻米样品中Cd、Pb、Cr、As、Hg等5种重金属含量的测定,分析不同品种和类型的水稻对5种重金属吸收能力的差异。研究结果表明,对广东省稻米影响最大的重金属是Cd,超标率为11.11%,Pb超标率是7.41%,Cr超标率是3.70%,As和Hg的检出量都低于国家标准。重金属对广东省稻米质量安全的影响严重程度依次为:Cd>Pb>Cr>Hg>As,3种类型品种重金属综合污染严重程度顺序是籼型常规稻>两系杂交稻>三系杂交稻。 相似文献
12.
13.
云南1998年后定植的橡胶树多数在橡胶树三等宜林地,或其边缘地区,非生产期延长,甚至10年、10年以上都不能达到投产标准,是云南天然橡胶种植业存在的一个大问题,需要尽快组织力量调查和专门研究对当前种植多年尚未投产的橡胶林的整顿、调整、巩固的重要技术和经营措施。 相似文献
14.
The aims of this study were to assess the linear relationships between agronomic and nutritional traits and identify promising traits for indirect selection in transgenic genotypes of maize. Eighteen transgenic maize genotypes were assessed in randomized blocks with three replications. The agronomic (number of days from sowing until male flowering, number of days from sowing until female flowering, plant height, ear insertion height and grain yield) and nutritional (crude protein, ether extract, crude fiber, starch and amylose) traits were measured. Analysis of variance was run for each of the 10 traits and phenotypic and genotypic correlation coefficient matrices estimated. Ridge path analysis were performed the nutritional traits were treated as main variable (dependent) and agronomic traits as explanatory variables (independents). The number of days from sowing until female flowering has a positive linear relationship to crude protein, ether extract and starch. Plant height has a positive linear relationship to crude fiber. Ear height has a positive linear relationship to amylose. Grain yield has a positive linear relationship to starch. The number of days from sowing until male flowering, plant height, ear height and grain yield can be used indirect selection in maize. 相似文献
15.
16.
17.
18.
19.
R. Murugan B. S. Dasaradan P. Karnan M. Subramanian Senthilkannan 《Fibers and Polymers》2007,8(6):665-668
The present work relates to the occurrence of fibre rupture during fibre separation in rotor spinning and also discusses the
mechanism of such rupture. The reduction in fibre length during opening has been studied at different span lengths. A correlation
has been drawn showing the influence of combing roller action on yarn tenacity and elongation. Fibre rupture has direct relationship
with opening roller speed. Fibre rupture and surface damage occurring due to action of opening roller together are found to
mar the yarn quality index. 相似文献
20.
目的探讨不同因子对黄秋葵毛状根生长的影响。方法利用增殖倍数法测定毛状根的生长.从而明确各因子对黄秋葵毛状根的影响。结果3%蔗糖浓度最适宜毛状根的生长。0.5mg/L6-BA对毛状根有一定的抑制作用,0.5mg/LNAA、IAA对毛状根有一定的促进作用。尤其是0.5mg/LIAA培养的毛状根增殖倍数更为显著。MJA对毛状根生长有抑制作用,SA对毛状根的生长没有明显的影响。结论不同因子不同程度地影响了毛状根的生长,为进一步筛选适宜的黄秋葵毛状根培养体系奠定了基础。 相似文献