共查询到20条相似文献，搜索用时 140 毫秒
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基于多分类器融合的玉米叶部病害识别 总被引：5，自引：6，他引：5
针对单分类器识别的局限性和玉米叶部病害的复杂性,该文提出了一种基于自适应加权的多分类器融合的玉米叶部病害识别方法。首先,对采集的玉米叶部病害图像的病害区域分别提取颜色、颜色共生矩阵和颜色完全局部二值模式3种特征,并相应地构建3个基于支持向量机的单分类器;然后,利用K近邻和聚类分析的方法计算各单分类器的自适应动态权值;最后,通过线性加权的方式进行融合判决,得到最终的分类结果。利用该方法对7种常见的玉米叶部病害图片进行了试验,平均识别率达94.71%。结果表明,其性能优于目前常见的单一特征或特征组合构建的同类分类器及多分类器融合方法。研究结果为其他农作物病害诊断提供了借鉴和参考。 相似文献
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基于最优二叉树支持向量机的蜜柚叶部病害识别 总被引：7，自引：7，他引：0
为了提高蜜柚叶部中晚期病害的识别准确率,确保蜜柚叶部病害对症施药与病害防治的效果,该文提出了一种基于最优二叉树支持向量机(support vector machine,SVM)的蜜柚叶部病害识别方法,该方法首先将蜜柚叶部病害图像转换为B分量、2G-R-B分量、(G+R+B)/3分量以及YIQ颜色模型中的Q分量的4个灰度图像,再利用5尺度8方向的Gabor小波分别与4个分量灰度图像进行卷积运算,获得5个尺度下不同方向的幅值均值作为病害的特征向量,并结合提出的最优二叉树支持向量机病害识别模型,对黄斑病、炭疽病、疮痂病、煤烟病等4种蜜柚叶部病害进行分类识别。通过交叉验证的方法进行分类识别测试,结果表明:黄斑病、炭疽病、疮痂病、煤烟病识别准确率分别为90%、96.66%、93.33%、96.66%,平均识别率达到94.16%,并将该方法与BP神经网络、一对一SVM与一对多SVM进行比较,试验结果表明该方法可有效识别4种蜜柚叶部病害,在训练时间和识别精度上都优于其他3种方法。该方法可为蜜柚病害准确识别与防治提供有效的技术支持。 相似文献
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基于改进Multi-Scale AlexNet的番茄叶部病害图像识别 总被引：13，自引：11，他引：2
番茄同种病害在不同发病阶段表征差异明显,不同病害又表现出一定的相似性,传统模式识别方法不能体现病害病理表征的动态变化,实用性较差。针对该问题,基于卷积神经网络提出一种适用于移动平台的多尺度识别模型,并基于此模型开发了面向农业生产人员的番茄叶部病害图像识别系统。该文详细描述了AlexNet的结构,分析其不足,结合番茄病害叶片图像特点,去除局部响应归一化层、修改全连接层、设置不同尺度卷积核提取特征,设计了基于AlexNet的多感受野识别模型,并基于Android实现了使用此模型的番茄叶部病害图像识别系统。Multi-ScaleAlexNet模型运行所耗内存为29.9MB,比原始AlexNet的内存需求652MB降低了95.4%,该模型对番茄叶部病害及每种病害早中晚期的平均识别准确率达到92.7%,基于此模型的Andriod端识别系统在田间的识别率达到89.2%,能够满足生产实践中移动平台下的病害图像识别需求。研究结果可为基于卷积神经网络的作物病害图像识别提供参考,为作物病害的自动化识别和工程化应用参考。 相似文献
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改进Faster R-CNN的田间苦瓜叶部病害检测 总被引：11，自引：9，他引：2
为实现在自然环境条件下对苦瓜叶部病害的目标检测,该研究提出了一种基于改进的更快速区域卷积神经网络(Faster Region with Convolutional Neural Network Features,Faster R-CNN)的苦瓜叶部病害目标检测方法。Faster R-CNN以残差结构卷积神经网络Res Net-50作为该次试验的特征提取网络,将其所得特征图输入到区域建议网络提取区域建议框,并且结合苦瓜叶部病害尺寸小的特点,对原始的Faster R-CNN进行修改,增加区域建议框的尺寸个数,并在ResNet-50的基础下融入了特征金字塔网络(Feature Pyramid Networks,FPN)。结果表明,该方法训练所得的深度学习网络模型具有良好的鲁棒性,平均精度均值(Mean Average Precision,MAP)值为78.85%;融入特征金字塔网络后,所得模型的平均精度均值为86.39%,提高了7.54%,苦瓜健康叶片、白粉病、灰斑病、蔓枯病、斑点病的平均精确率(Average Precision,AP)分别为89.24%、81.48%、83.31%、88.62%和89.28%,在灰斑病检测精度上比之前可提高了16.56%,每幅图像的检测时间达0.322s,保证检测的实时性。该方法对复杂的自然环境下的苦瓜叶部病害检测具有较好的鲁棒性和较高的精度,对瓜果类疾病预防有重要的研究意义。 相似文献
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采用盆栽模拟试验,研究了澳大利亚蕨类植物粉叶蕨对砷的耐性及吸收富集砷的特征,同时比较了澳大利亚粉叶蕨(Pityrogramma calomelanos(L.)Link var.austroamericana(Domin)Farw)和中国蜈蚣草(Pteris vit-tats L.)在澳大利亚的Kurosol土壤上对As的吸收积累差异及植物修复效率.研究结果表明,在As投加浓度为2 400 μmol/kg时,虽然粉叶蕨的生长受到一定抑制,但仍维持了较高的地上部生物量;地上部As含量达到2438.33 mg/kg DW时,超过了砷超积累植物的临界含量标准(1 000 mg/kg);地上部As积累量为21.6 mg/株DW时,地上部对As的生物富集系数为18.6,地上部As含量大于根系As含量,基本符合As超积累植物的基本特征.与As超积累植物蜈蚣草相比较,暴露在As浓度为2 400 μmol/kg环境时,中国蜈蚣草对砷的耐性、地上部As含量及生物富集等方面均明显优于澳大利亚粉叶蕨,其地上部As含量和积累量分别为2 936.13 mg/kgDW和41.1 mg/株DW. 相似文献
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[目的]通过开展不同钙肥施用量对乌拉尔甘草(Glycyrrhiza uralensis.)产量及品质的影响研究,为甘草的优质高产栽培提供依据。[方法]采用田间小区试验方法,比较不同钙肥施用量对乌拉尔甘草株高、药用成分以及地上和地下部生物量的作用。[结果]钙肥施用量为450~600kg/hm2时,甘草的产量和植株甘草酸及总黄酮的总量最大,过量的施用钙肥对乌拉尔甘草的生长以及有效成分的含量具有抑制作用。[结论]适量的钙肥供应有利于乌拉尔甘草的生长以及乌拉尔甘草中有效成分含量的提高。 相似文献
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固沙植物甘草与土地荒漠化探析 总被引：12，自引：0，他引：12
阐述了我国甘草资源分布现状以及甘草在干旱荒漠区的生态作用 ,指出实行围栏护育和人工种植 ,是保护甘草资源 ,恢复干旱半干旱荒漠地区生态平衡 ,防止土壤荒漠化的有效途径 相似文献
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钼、硼、锰和锌对人工种植乌拉尔甘草品质的影响 总被引：2，自引：2，他引：0
在大田条件下,采用叶面喷施的方法,研究了Mo、B、Mn和Zn 4种微量元素不同浓度（0,0.5g/L,1g/L和1.5g/L）对人工种植乌拉尔甘草几种主要次生代谢成分积累的影响。结果表明,乌拉尔甘草根中甘草酸含量、甘草苷含量与Mn、Zn和Mo供应水平密切相关。其中Mn、Zn元素的低、中、高浓度处理和Mo元素的中、高浓度处理可以显著提高乌拉尔甘草根中的甘草酸含量;Mo和Zn元素的低、中、高浓度处理及Mn元素的高浓度处理则可以显著提高乌拉尔甘草根中的甘草苷含量;Mn元素的中、高浓度处理及Zn元素的中浓度处理可以显著提高乌拉尔甘草根中的甘草多糖含量。4种微量元素的低、中、高浓度叶面喷施均可以显著提高乌拉尔甘草根中的总黄酮含量。由此认为,以上4种微量元素对改善人工种植乌拉尔甘草的品质具有一定的作用。 相似文献
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Isolation and identification of flavonoids in licorice and a study of their inhibitory effects on tyrosinase 总被引：5，自引：0，他引：5
Five different flavonoids were isolated from licorice after multistep chromatographic fractionation. The aim was to identify and characterize active components in licorice responsible for antibrowning activities and to seek new tyrosinase inhibitors for applications as antibrowning and depigmenting agents in the food and cosmetic industries. The isolated flavonoids were identified as liquiritin, licuraside, isoliquiritin, liquiritigenin (from Glycyrrhiza uralensis Fisch.), and licochalcone A (from Glycyrrhiza inflate Bat.) by UV, MS, (1)H NMR, and (13)C NMR analyses. The inhibitory potencies and capacities of these flavonoids toward monophenolase activity of mushroom tyrosinase were investigated. The IC(50) values of licuraside, isoliquiritin, and licochalcone A for monophenolase activity were 0.072, 0.038, and 0.0258 mM, respectively. A study of the mechanisms of monophenolase inhibition by these flavonoids indicated that they are all competitive inhibitors. Different from the above flavonoids, no inhibitory activity was observed for liquiritin, whereas liquiritigenin activated the monophenolase activity as a cofactor. The inhibitory effect of licuraside, isoliquiritin, and licochalcone A on diphenolase activity with l-DOPA as the substrate was much lower than those with l-tyrosine. Results suggest that licuraside, isoliquiritin, and licochalcone A have the high potential to be further developed into effective antibrowning and depigmenting agents. 相似文献
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本文研究了NaCl和Na2SO4不同浓度下两种中性盐胁迫对乌拉尔甘草种子萌发的效应。结果表明:≤280 mmol/L浓度的NaCl和≤240 mmol/L浓度的Na2SO4处理时,发芽率高于60%,高浓度的Na2SO4抑制种子发芽强于NaCl;不同浓度Na2SO4处理的发芽高峰期出现比对照早3～5天,比NaCl处理的早2～6天;Na2SO4处理种子的发芽势小于相同浓度的NaCl;中性盐胁迫浓度大于200 mmol/L时,种子发芽指数小于对照,NaCl溶液各梯度处理下的发芽指数均高于相应浓度的Na2SO4处理。发芽率、发芽势和发芽指数都与NaCl和Na2SO4浓度呈极显著负相关,发芽高峰期出现的天数与NaCl浓度呈正相关,与Na2SO4浓度呈负相关。 相似文献
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Modulations of the Bcl-2/Bax family were involved in the chemopreventive effects of licorice root (Glycyrrhiza uralensis Fisch) in MCF-7 human breast cancer cell 总被引：10，自引：0，他引：10
Jo EH Hong HD Ahn NC Jung JW Yang SR Park JS Kim SH Lee YS Kang KS 《Journal of agricultural and food chemistry》2004,52(6):1715-1719
Recently, cancer chemoprevention with strategies using foods and medicinal herbs has been regarded as one of the most visible fields for cancer control. Genistein in soy, American ginseng, and resveratrol are well-known to have antiproliferative properties in human breast cancer. Licorice root is a botanical, a shrub native to southern Europe and Asia, which primarily has desirable qualities in sweetening and herbal medicine. In this study, licorice (Glycyrrhiza uralensis Fisch) root also inhibits cell proliferation in human breast cancer cell. The cell proliferation study demonstrated that licorice root reduced the proliferation of MCF-7 cells in a dose- and time-dependent manner. The extracts were fractionated in CHCl(3), EtOAc, C(6)H(14), and CH(3)OH-H(2)O (70:30), and these extracts of licorice root (50 microg/mL) induced DNA fragmentation demonstrated by Hoechst 33258 staining. Apoptosis also determined the sub-G1 accumulation by flow cytometry analysis. These results were consistent with specific cleavage of PARP and antiapoptotic protein Bcl-2 and up-regulation of proapoptotic protein Bax demonstrated by Western blotting. Our findings suggest that licorice root may have chemopreventive effects against human breast cancer through the modulation of the expression of the Bcl-2/Bax family of apoptotic regulatory factors. 相似文献
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荒漠草原典型植物群落枯落物蓄积量及其持水性能 总被引：1，自引：0，他引：1
通过对荒漠草原4种典型植物群落(蒙古冰草群落、甘草群落、赖草群落、沙蒿群落)枯落物蓄积量的调查,结合室内持水试验,运用数理统计的方法分别得到4种典型植物群落枯落物的蓄积量、最大持水量、吸水速率等水文特征参数.结果表明:荒漠草原不同植物群落枯落物蓄积量在50.8～396.2 g/m2,其蓄积量由大到小为蒙古冰革群落>甘草群落>赖草群落>沙蒿群落,与植物群落地上生物量变化是一致的;4种植物群落枯落物最大持水量存在一定差异,蒙古冰草群落、甘草群落、赖草群落、沙蒿群落桔落物最大持水量分别相当于0.934,0.737,0.656,0.230 mm的降雨.这4种枯落物最大可吸收其自身重量2.45～3.71倍的降雨;4种植物群落枯落物的持水量与时间呈线性相关,在浸水的前2 h枯落物吸水速率最快,随着时间的延长,趋势逐渐变缓,当枯落物在水中浸泡12 h时,其持水量基本达到最大值;4种植物群落枯落物吸水速率与时间呈指数相关,在浸水的前2 h吸水速率较快,4～12 h后逐步减缓.荒漠草原桔落物蓄积、覆盖所引起的水分蓄存与运移已经成为荒漠草原生态系统最为关键的生态过程之一. 相似文献
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A hydroponic experiment with six treatments, i.e., 0% seawater （control）, 10% seawater, 25% seawater, 0% seawater ＋ N （7.5 mmol L-1 NaNO3）, 10% seawater ＋ N （7.5 mmol L-1 NaO3）, and 25% seawater ＋ N （7.5 mmol L-1 NaNO3）, was carried out to study the effect of nitrogen addition on the growth and physiological and biochemical characteristics of Jerusalem artichoke （Helianthus tuberosus） seedlings under seawater stress. The 10% seawater stress treatment had the least effect on plant growth while at 25% seawater growth was significantly inhibited. The malondialdehyde content and electrolyte leakage in leaves under 10% seawater were similar to those of the control, but significantly higher under the 25% seawater stress. The activities of superoxide dismutase, peroxidase and catalase in the leaves increased concomitantly with increasing seawater concentration and time. Proline and soluble-sugars in the leaves and Na^＋, K^＋, and Cl- contents in shoots and roots increased significantly with the concentration of seawater increasing. Nitrogen addition resulted in increasing fresh and dry weights of shoots and roots compared with seawater treatment without N. Nitrogen supplementation also significantly enhanced the activities of antioxidant enzymes in leaves. Addition of N to seawater enhanced the contents of proline and soluble-sugars in the leaves and K^＋ and total-N in the aerial parts and roots of H. tuberosus, but it resulted in declined concentrations of Na^＋ and Cl- in the aerial parts and roots. Nitrogen addition ameliorated the toxicity of seawater by improving the antioxidative enzymes, accumulating of proiine and soluble-sugars, and altering the distribution of inorganic ions in H. tuberosus. 相似文献
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Kim HJ Lim SS Park IS Lim JS Seo JY Kim JS 《Journal of agricultural and food chemistry》2012,60(22):5583-5589
Licorice, the root of the Glycyrrhiza species ( Glycyrrhiza uralensis Fisher), is known to have antioxidant, anti-inflammatory, antiviral, and antitumor properties. The objective of this study is to explore the neuroprotective effect of dehydroglyasperin C (DGC) against glutamate-induced oxidative stress in mouse hippocampal HT22 cells. DGC significantly reduced cytotoxicity and reactive oxygen species (ROS) generation induced by glutamate in HT22 cells, whereas DGC did not restore glutathione depletion caused by glutamate. In addition, it was further investigated whether DGC affected the expression of heme oxygenase (HO)-1, one of the major cellular antioxidant defense systems, and it was found that DGC dose-dependently increased HO-1 expression. DGC-mediated cytoprotection of HT22 neuronal cells from glutamate insult was abrogated by either HO-1 inhibitor (Tin protoporphyrin, SnPP) or AKT inhibitor (LY294002). In conclusion, the present results demonstrate for the first time that DGC protects neuronal cells against glutamate-induced oxidative injury through the induction of HO-1 expression, which is, in turn, activated maybe through Nrf2-Keap1 and PI3K/AKT signaling pathways. 相似文献