共查询到20条相似文献，搜索用时 15 毫秒
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为改善成捆长秸秆输送过程中不均匀堆积与硬质颗粒夹杂问题,设计并研制一种四相曲轴步进式秸秆输送与除杂装置。将杂质颗粒简化为互不影响质点,利用动力学分析物料输送过程中夹杂杂质颗粒在筛板上受力与运动形式,利用ADAMS运动仿真分析成捆长秸秆输送与均匀化机理。试验表明,新型输送与除杂装置可实现成捆长秸秆高效输送与均匀化,有效筛分其中夹杂杂质,将筛板上秸秆垂直高度差控制在40 mm内。 相似文献
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Gilmer GH 《Science (New York, N.Y.)》1980,208(4442):355-363
Dynamic models of crystal surfaces have provided new insights into the crystal growth process. The effects of surface roughening, dislocations, and impurities have been assessed. Certain impurities have been found to cause a larger increase in the growth rate than screw dislocations. 相似文献
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Aggregation-based crystal growth and microstructure development in natural iron oxyhydroxide biomineralization products 总被引：1，自引：0，他引：1
Crystals are generally considered to grow by attachment of ions to inorganic surfaces or organic templates. High-resolution transmission electron microscopy of biomineralization products of iron-oxidizing bacteria revealed an alternative coarsening mechanism in which adjacent 2- to 3-nanometer particles aggregate and rotate so their structures adopt parallel orientations in three dimensions. Crystal growth is accomplished by eliminating water molecules at interfaces and forming iron-oxygen bonds. Self-assembly occurs at multiple sites, leading to a coarser, polycrystalline material. Point defects (from surface-adsorbed impurities), dislocations, and slabs of structurally distinct material are created as a consequence of this growth mechanism and can dramatically impact subsequent reactivity. 相似文献
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提出了一种利用图像实现颗粒粮食中异物的检测方法。该方法根据异物特征,提出了基于斑点分析的方法,一次成像2次处理,剔除比正常颗粒亮和暗的异物。并基于Mil函数库开发的图象处理系统,将黑白斑点的2次提取处理用一个函数实现,再通过数学形态学的运算和斑点分析,快速地提取杂质的大小和所在位置。该方法具有速度快、精确度高等优点,可以推广到其他领域加以利用。 相似文献
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Mocatta D Cohen G Schattner J Millo O Rabani E Banin U 《Science (New York, N.Y.)》2011,332(6025):77-81
Doping of semiconductors by impurity atoms enabled their widespread technological application in microelectronics and optoelectronics. However, doping has proven elusive for strongly confined colloidal semiconductor nanocrystals because of the synthetic challenge of how to introduce single impurities, as well as a lack of fundamental understanding of this heavily doped limit under strong quantum confinement. We developed a method to dope semiconductor nanocrystals with metal impurities, enabling control of the band gap and Fermi energy. A combination of optical measurements, scanning tunneling spectroscopy, and theory revealed the emergence of a confined impurity band and band-tailing. Our method yields n- and p-doped semiconductor nanocrystals, which have potential applications in solar cells, thin-film transistors, and optoelectronic devices. 相似文献
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对发光光状杆菌(Photorhabdus luminescens)5个菌株的生长速度、抗药性、晶体蛋白量和电转化条件进行了比较研究。结果表明:5菌株生长速度基本一致,对几种抗生素的抗药性不一致。5菌株晶体蛋白cipA和cipB主要在细胞内表达且不分泌到胞外,培养时间对晶体蛋白cipA和cipB的产量影响较大,其随培养时间的延长而增加,菌株DSM15138、DSM15139、DSM3368中晶体蛋白cipA和cipB产量高于DSM12190和DSM3369。分别将DSM15138和DSM15139的30μL过夜菌分别接种于1.4 mL LB中,30℃下1 050 r/min振摇3 h后,采用缓冲液(10%甘油+2 mmol/L HEPES)制备感受态细胞,在1 100 V/cm条件下转化效果最好,且相同条件下DSM15138转化效率高于DSM15139。 相似文献
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颗粒粮食中异物的视觉检测算法与实现 总被引：1，自引：0，他引：1
提出了一种利用图像实现颗粒粮食中异物的检测方法。该方法根据异物特征,提出了基于斑点分析的方法,一次成像2次处理,剔除比正常颗粒亮和暗的异物。设计包括输送系统、照明系统、成像系统、处理系统、结果存储和输出系统5个部分的异物检测系统,将粮食颗粒放到输送带上,在指定位置由成像系统获取图像,并将数据传人计算机进行分析处理,之后选用合适的算法进行图像处理。比较后发现,与Halcon库相比,Mil库设置的特征参数更多,使用者可以在较短时间内获取试验结果,并且Mil图像函数库的使用非常方便,故笔者选用Mil库提取绿豆颗粒中的异物杂质。利用Mil函数库开发的图像处理系统,把黑白斑点的2次提取处理,用一个函数实现,再通过数学形态学的运算和斑点分析,快速地提取杂质的大小和所在位置。该方法具有速度快、精确度高等优点,可以推广到其他领域加以应用。 相似文献
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一、车辆对柴油的要求 柴油发动机对柴油的洁净程度要求十分严格。高压泵是很精密的柱塞泵,高压油泵的柱塞间隙很小,约在0.0025mm以下。高压泵一般可将油压提高到9.8～49MPa或更高,以保证柴油喷入燃烧室雾化良好。喷油器的构造也非常精密,喷雾针与座配合间隙约0.003～0.005mm,喷嘴喷孔直径为0.25～0.35mm,由于高压泵和喷油器都是很精密的机 相似文献
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笔者按我国农村燃油净化现况与需求进行了柴油沉淀净化试验。用非线性回归法,在试验条件下得出了机械杂质沉淀规律的数学模型,并提出了机械杂质理论沉降量的计算方法。据此,导出理论净化效率,同时分析了实际的与理论的净化规律。 相似文献
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以大孔吸附树脂提取的大豆皂苷粗提物为研究对象,利用阳离子交换树脂进行纯化。以HPLC分析方法,苷元显色法等多种分析手段,检测树脂纯化的除杂和脱色能力,验证此方法的可行性。通过实验研究,确定了最佳纯化条件:选用50%甲醇水溶液,最佳pH为6.0。本法除杂率达33.01%,脱色率达52.36%。此法不仅有效地去除了样品中的色素等杂质,还可以去除部分大豆异黄酮类物质。 相似文献
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REVIEW The role of defects as essential entities in semiconductor materials is reviewed. Early experiments with semiconductors were hampered by the extreme sensitivity of the electronic properties to minute concentrations of impurities. Semiconductors were viewed as a family of solids with irreproducible properties. Scientific efforts overcame this idiosyncrasy and turned the art of impurity doping into today's exceedingly useful and reproducible technology that is used to control precisely electrical conductivity, composition, and minority-carrier lifetimes over wide ranges. Native defects such as vacancies and self-interstitials control basic processes, foremost self- and dopant diffusion. The structural properties of dislocations and higher dimensional defects have been studied with atomic resolution, but a thorough theoretical understanding of their electronic properties is incomplete. Reactions between defects within the host lattices are increasingly better understood and are used for gettering and electrical passivation of unwanted impurities. Metastable defects such as DX centers and the EL2-related arsenic antisite are briefly discussed. The recent development of isotopically controlled semiconductors has created new research opportunities in this field. 相似文献
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分析4LZ-1.0型联合收割机的清选效果及脱粒后混合物的组成,可有针对性地对清选装置进行创新设计,为此在田间试验过程中,对排出物进行取样,并分类进行测量与统计。统计分析结果表明,在脱粒后的混合物中,成熟谷粒质量约占90%,经过清选后,轻杂物全部得到清除,清选损失小于1%,但含杂率达4.9%;通过对千粒重的测量分析,在脱粒后的混合物中,谷粒、瘪谷及短茎秆数量比例为793∶205∶2。因此,对4LZ-1.0联合收割机的改进设计时,要在保证较小值的清选损失前提下,把降低含杂率作为主要设计目标,所测定的清选前混合物的数量比例关系可为运用离散单元法进行清选力学分析提供依据。 相似文献
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目前,石油开采过程中常会出现杂质随钻井液直接喷出井口的情况,即常说"返渣"现象。针对此现象,设计了石油井口排污装置。将解决钻采"返渣"作为研究目的,应用Pro/E优化/动态仿真,建立装置三维模型,对主要几何尺寸参数进行优化设计,在此基础上进行动态仿真分析。结果表明,此装置能够引导钻井液及杂质流入规定管道中,且安全性能好、操作方便快捷,解决了钻采时任其自喷的现象。 相似文献
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几种提取乌苏里貉毛囊核酸方法的比较(英文) 总被引：1，自引：0，他引：1
[目的]该研究旨在探讨提取乌苏里貉毛囊核酸的可靠方法。[方法]本实验分别利用改进的有机酚法,chelex-100法,PCR缓冲液法和试剂盒法,从乌苏里貉毛发中提取核酸DNA,对所提核酸进行PCR扩增及电泳分析,并且对四种方法进行比较。[结果]经分光光度计测定和凝胶电泳检测,本实验研究结果表明chelex-100提取的核酸有蛋白质等杂质,PCR缓冲液法提取核酸浓度低有机酚法和试剂盒法提取的DNA浓度高,且没有杂带。[结论]本研究为进一步探索高效,简便的提取乌苏里貉毛囊核酸DNA提供了有力的科学理论基础。 相似文献
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为了提取纯净的鸭疫里氏杆菌赘生物,比较了4种培养基培养RAⅡ型菌和4种提取赘生物试验的方法,结果表明,马丁琼脂培养的RA菌赘生物含量较高,杂质少,适宜于作为提取赘生物用的培养基;差速离心结合滤膜过滤法能有效地把细菌和赘生物分离开来,提取到较纯的赘生物.赘生物的核酸检测和蛋白质电泳分析表明,赘生物无核酸存在,蛋白质电泳图谱与菌体相似形态学观察表明,提取的赘生物可分为大、中、小三类,大的和中等的赘生物外层为一层厚的壁,中央为三角形或四边形样的核物质;小的赘生物为圆形,有一层很薄的外膜,中央为点状或星状的核.研究结果为该菌的分类提供了一定的科学依据. 相似文献
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采用乙醇发酵去除酶法合成α-熊果苷反应液中大部分糖类杂质,以活性炭纤维吸附分离α-熊果苷,选择甲醇-乙酸乙酯混合溶剂重结晶精制。结果表明,50%乙醇溶液洗脱部分α-熊果苷含量最高,此部分经甲醇-乙酸乙酯混合溶剂反复重结晶精制,可制备得到α-熊果苷无色针状结晶,HPLC检测纯度达到99%以上,收率达到80%。该工艺简单可行,稳定性高、重复性好,适合大规模制备高纯度α-熊果苷。 相似文献
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Lu-lu LI Bo MING Jun XUE Shang GAO Ke-ru WANG Rui-zhi XIE Peng HOU Shao-kun LI 《农业科学学报》2021,20(7):1775-1782
The harvest method of shelling corn(Zea mays L.) kernels in the field decreases labor costs associated with transporting, drying and threshing the crop. However, it was previously found that the kernel moisture content increased after field harvest, which decreased the value of corn kernels. To identify the reasons underlying the increase, we conducted a multiyear and-area trial in the Huang-Huai-Hai Plain, China and performed a staged-harvest test at several phases of kernel dry-down. The test investigated a range of parameters such as the kernel moisture content pre-and post-harvest, the kernel breakage rate, the amount of impurities, and the moisture content of various other plant tissues. An analysis of 411 pairs of pre-and post-harvest samples found that kernel moisture content after harvest was 2.2% higher than that before harvest. In the staged-harvest test, however, a significant increase was only observed when the kernel moisture content before harvest was higher than 23.9%. The increase in post-harvest kernel moisture content was positively associated with the pre-harvest kernel moisture content, breakage rate and impurity rate. Typically, at harvest time in this region, there is a significant fraction of immature crops with a high moisture content, resulting in kernels that are prone to breakage or impurities that ultimately lead to increases in water content after harvest. Therefore, we suggest using hybrids that quickly wither late in the growing stage. Additionally, farmers should delay harvest in order to minimize the pre-harvest kernel moisture content and thus reduce breakages and impurities, thereby improving the quality of kernels after harvest and the efficiency of corn kernel farming in China. 相似文献