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Evaluating the Potential of Birch Bark Suberinic Acids for Solid Wood Impregnation
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作者 Daniela Godina Guntis Sosins +3 位作者 Aigars Paze Janis Rizikovs Raimonds Makars Andreas Treu 《Journal of Renewable Materials》 2025年第1期147-161,共15页
Instead of the traditional linear model of taking,making,and disposing,the circular bio-economy promotes a regenerative approach.Although there is potential to create valuable products like betulin,lupeol,and suberini... Instead of the traditional linear model of taking,making,and disposing,the circular bio-economy promotes a regenerative approach.Although there is potential to create valuable products like betulin,lupeol,and suberinic acids(SA)from outer birch bark,many industries,such as plywood and pulp,often choose to incinerate substan-tial amounts of leftover birch bark to meet their energy needs.This highlights the importance of obtaining valu-able products from wood.The objective of this study was to examine various fractions of SA and assess their potential for wood impregnation.The fractions included SA potassium salts in ethanol(SAK-EtOH)and water(SAK-H2O),SA suspension in water(SAS-H2O)and dried SA,which was subsequently diluted in ethanol(DSA-EtOH).There is significant potential for utilizing SA in wood treatment formulations as a sustainable alternative to harmful petroleum-derived chemicals.This approach not only addresses environmental concerns but also enhances the functionality of wood in construction applications,such as improving impregnation for moisture and fungal protection.Among the solutions tested,the ethanol solution of SA,specifically DSA-EtOH,showed the highest weight percent gain(WPG)and the greatest leaching resistance.GPC analysis showed that SA salts in ethanol(SAK-EtOH)and water(SAK-H2O)predominantly consist of low molecular fractions and each process(acidification and drying)reduces the low molecular content in the sample.This suggests that SA polymerizes after drying,making it necessary to dissolve it in ethanol to meet the requirements for impregnation.Further opti-mization,including adjustments in the concentration of the SA ethanol solution and the curing temperature,is essential to identify the optimal conditions for more in-depth impregnation studies. 展开更多
关键词 Birch bark suberinic acids solid wood impregnation
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Lipophilic extractives of the inner and outer barks from six different Pinus species grown in Indonesia 被引量:2
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作者 Masendra Tatsuya Ashitani +1 位作者 Koetsu Takahashi Ganis Lukmandaru 《Journal of Forestry Research》 SCIE CAS CSCD 2018年第5期1329-1336,共8页
The chemical compositions of the dichloromethane extracts of inner and outer barks from six Pinus species(P.elliotii,P.oocarpa,P.caribeae,P.merkusii,P.montezumae,and P.insularis) grown in Indonesia were investigated... The chemical compositions of the dichloromethane extracts of inner and outer barks from six Pinus species(P.elliotii,P.oocarpa,P.caribeae,P.merkusii,P.montezumae,and P.insularis) grown in Indonesia were investigated by GC and GC–MS.Generally,the amounts of extractive contents were higher in the inner bark than in the outer bark except for P.merksuii.Fatty acids,monoterpenes,sesquiterpenes,resin acids,triterpenoids,and steroids were detected and quantified.Inner and outer barks differed not only in content of these compounds but also in their composition.Fatty acids and alcohols were the major classes of lipophilic compounds in the outer bark of P.caribeae, P.insularis,and P.montezumae.Steroids and triterpenoids were the dominant compounds identified in the inner bark of P.elliotii,P.insularis,and P.merkusii.Resin acids were the most abundant group in the inner bark of P.oocarpa whereas monoterpenes and sesquiterpenes were recorded in minor quantities in both bark layers of all species. 展开更多
关键词 bark extractive LIPOPHILIC Inner bark Outer bark Pinus spp
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基于听觉掩蔽效应和Bark子波变换的语音增强 被引量:39
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作者 陶智 赵鹤鸣 龚呈卉 《声学学报》 EI CSCD 北大核心 2005年第4期367-372,共6页
提出了一种适用于低信噪比下的提高语音的听觉效果的语音增强方法。该方法在谱减法的基础上有两个特点:首先减参数是根据人耳听觉掩蔽效应提出的且是自适应的;其次采用了与人耳听觉系统特性更为适应的Bark子波变换方法对增强前后的语音... 提出了一种适用于低信噪比下的提高语音的听觉效果的语音增强方法。该方法在谱减法的基础上有两个特点:首先减参数是根据人耳听觉掩蔽效应提出的且是自适应的;其次采用了与人耳听觉系统特性更为适应的Bark子波变换方法对增强前后的语音进行分析。对该算法进行了客观和主观测试,结果表明:与谱减法相比对低信噪比的语音信号,(1)能更好地抑制残留噪声和背景噪声,(2)增强后的语音具有更好的清晰度和可懂度。 展开更多
关键词 听觉掩蔽效应 bark子波变换 语音增强 宽带噪声 谱减法
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一种基于Bark域能量分布的噪声分类方法 被引量:5
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作者 袁文浩 林家骏 +1 位作者 陈宁 王雨 《华东理工大学学报(自然科学版)》 CAS CSCD 北大核心 2013年第4期472-476,共5页
对不同种类噪声的分类处理,可以提高噪声环境下语音信号处理的性能。为了能够准确地区分各类噪声,提出了一种基于Bark域噪声能量分布特性的噪声分类方法。通过将噪声能量从均匀时频空间映射到Bark空间,构造了一个能够有效区分各种噪声... 对不同种类噪声的分类处理,可以提高噪声环境下语音信号处理的性能。为了能够准确地区分各类噪声,提出了一种基于Bark域噪声能量分布特性的噪声分类方法。通过将噪声能量从均匀时频空间映射到Bark空间,构造了一个能够有效区分各种噪声的22维特征向量,并使用支持向量机(SVM)进行模型训练和噪声分类。实验结果表明:所提出的噪声分类方法具有非常高的分类准确率,对用于实验的两种噪声数据集的平均分类准确率分别为99.50%和93.44%。 展开更多
关键词 噪声分类 支持向量机 bark 能量分布特性
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基于Bark域噪声估计及掩蔽效应的语音增强 被引量:6
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作者 赵欢 熊敏 侯卫国 《计算机工程》 CAS CSCD 北大核心 2009年第12期261-263,共3页
针对非平稳环境下噪声估计和语音增强性能降低的特点,提出一种基于Bark域的快速自适应噪声谱估计算法。它基于听觉模型,将带噪信号变换到Bark域,并在Bark域内实现基于人耳掩蔽的语音增强。仿真实验表明该算法能充分利用Bark带内频带间... 针对非平稳环境下噪声估计和语音增强性能降低的特点,提出一种基于Bark域的快速自适应噪声谱估计算法。它基于听觉模型,将带噪信号变换到Bark域,并在Bark域内实现基于人耳掩蔽的语音增强。仿真实验表明该算法能充分利用Bark带内频带间的相关性,跟踪快变的背景噪声,提高语音增强性能,减少运算量和复杂度。 展开更多
关键词 语音增强 噪声估计 bark 掩蔽效应
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基于Fisher比的Bark小波包变换的语音特征提取算法 被引量:6
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作者 王晓华 屈雷 +1 位作者 张超 蒋细伟 《西安工程大学学报》 CAS 2016年第4期452-457,共6页
为解决MFCC特征参数在噪声环境中识别率低的问题,提出一种基于Fisher比的Bark小波包变换特征提取算法.首先采用小波包变换构造Bark滤波器代替三角形的Mel滤波器.其次采用Fisher对Bark滤波后的特征参数进行选择,去除大量干扰信息,节省特... 为解决MFCC特征参数在噪声环境中识别率低的问题,提出一种基于Fisher比的Bark小波包变换特征提取算法.首先采用小波包变换构造Bark滤波器代替三角形的Mel滤波器.其次采用Fisher对Bark滤波后的特征参数进行选择,去除大量干扰信息,节省特征匹配的时间.仿真实验表明,该算法明显提高系统的识别率和鲁棒性. 展开更多
关键词 FISHER bark 小波包变换 MFCC 说话人识别
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基于BARK子波变换的语音增强方法研究 被引量:2
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作者 李野 吴亚锋 刘雪飞 《计算机工程与应用》 CSCD 北大核心 2009年第33期128-131,共4页
在Bark子波的构造的基础上,提出一种改进的Bark子波变换构造方法,即直接由临界带中心频率确定Bark子波的中心频率,保证了其通带和临界带的对应一致性,并与人耳的听觉系统十分吻合。采用Bark子波对带噪语音进行分解,在语音信号的子带层... 在Bark子波的构造的基础上,提出一种改进的Bark子波变换构造方法,即直接由临界带中心频率确定Bark子波的中心频率,保证了其通带和临界带的对应一致性,并与人耳的听觉系统十分吻合。采用Bark子波对带噪语音进行分解,在语音信号的子带层次上用一种类似于软阈值的无穷阶可导的函数进行阈值处理,并应用谱减法进行二次增强。仿真实验表明,构建Bark子波与增强算法使信噪比和PESQ得分都有较大提高,特别是在信噪比较高时,语音具有很好的清晰度和可懂度。 展开更多
关键词 bark子波 语音增强 阈值
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Acidity and conductivity of Pinus massoniana bark as indicators to atmospheric acid deposition in Guangdong, China 被引量:2
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作者 KUANG Yuan-wen ZHOU Guo-yi +1 位作者 WEN Da-zhi LIU Shi-zhong 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2006年第5期916-920,共5页
Barks of Pinus massoniana collected from two polluted sites, Qujiang and Xiqiaoshan, and from the relatively clean site Dinghushan were used to evaluate the pollution indication by the determination of their acidity a... Barks of Pinus massoniana collected from two polluted sites, Qujiang and Xiqiaoshan, and from the relatively clean site Dinghushan were used to evaluate the pollution indication by the determination of their acidity and conductivity. The acidity of the inner and outer barks from the polluted sites was significantly higher than those from the clean site, suggesting that the acidity of the bark occurred in concurrent with the air pollution. The significant lower pH values of the outer bark than the inner bark collected from all sites indicated that the outer bark was more sensitive than the inner bark in response to acid pollution, implying that the outer bark is more preferable when used as indication of atmospheric acid pollution. The conductivities of the inner barks differed significantly among the three sites, with higher values at the clean site. However, the significant differences were not observed among these sites. Furthermore, the pH values for the inner and outer barks were not correlated with the conductivity, which did not coincide with some other studies. 展开更多
关键词 ACIDITY CONDUCTIVITY inner bark outer bark Pinus massoniana
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基于Bark子波变换和RAS-MFCC特征的语音识别系统研究 被引量:1
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作者 刘菁华 《电声技术》 2011年第9期47-48,54,共3页
提出了一种适用于低信噪比下的语音识别算法。该算法在前端利用人耳听觉掩蔽效应进行语音增强,然后提取一种在不需要噪声先验知识,能避免大量计算的情况下能较好地消除系统加性噪声的自相关MFCC(RAS-MFCC)参数,作为语音特征参数进行识别。
关键词 语音识别 听觉特性 bark子波 MFCC自相关系数
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基于小波包Bark子带方差的端点检测算法 被引量:2
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作者 李娟 《洛阳师范学院学报》 2019年第2期23-26,共4页
传统的端点检测方法大多数抗噪性不好,基于能量和短时过零率的双参数双门限端点检测在静音状态下效果较好,但是在噪声环境中性能下降.针对这个问题,使用小波包变换把信号分解成17个Bark子带,求出平均方差值,然后采用单参数双门限方法进... 传统的端点检测方法大多数抗噪性不好,基于能量和短时过零率的双参数双门限端点检测在静音状态下效果较好,但是在噪声环境中性能下降.针对这个问题,使用小波包变换把信号分解成17个Bark子带,求出平均方差值,然后采用单参数双门限方法进行端点检测.实验证明,即使在-2dB的噪声环境下,该方法仍然能取得较好的端点检测效果. 展开更多
关键词 端点检测 小波包 单参数双门限检测 bark子带方差
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基于Bark小波的语音端点检测算法 被引量:5
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作者 尹晨晓 郭英 +1 位作者 张碧锋 刘霞 《计算机工程》 CAS CSCD 北大核心 2011年第12期276-278,共3页
为提高噪声环境下端点检测算法的性能,提出一种基于Bark小波变换的语音端点检测算法。在Bark小波变换的非线性映射中引入伸缩尺度参数,提取不同子带上信号的小波变换系数,利用Bark小波的奇异性构造端点检测参数,并通过仿真验证得到有效... 为提高噪声环境下端点检测算法的性能,提出一种基于Bark小波变换的语音端点检测算法。在Bark小波变换的非线性映射中引入伸缩尺度参数,提取不同子带上信号的小波变换系数,利用Bark小波的奇异性构造端点检测参数,并通过仿真验证得到有效的阈值选择规则。实验结果表明,与传统的短时能量法和倒谱距离测度法相比,该算法的检测准确率明显提高,具有较强的噪声鲁棒性。 展开更多
关键词 语音端点检测 bark小波变换 伸缩尺度参数 参数提取
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一种Bark子波变换的电子耳蜗语音增强算法 被引量:3
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作者 黄雅婷 顾济华 +2 位作者 陶智 赵鹤鸣 吴迪 《计算机工程与应用》 CSCD 北大核心 2008年第5期215-217,231,共4页
提出了一种Bark子波变换的电子耳蜗语音增强算法。该算法首先引入与人耳听觉系统更为适应的Bark子波变换来进行电子耳蜗CIS语音信号处理,然后在每个Bark通道中利用非线性谱减法对其进行语音增强,谱减法的参数由人耳隐蔽阈值来控制。结... 提出了一种Bark子波变换的电子耳蜗语音增强算法。该算法首先引入与人耳听觉系统更为适应的Bark子波变换来进行电子耳蜗CIS语音信号处理,然后在每个Bark通道中利用非线性谱减法对其进行语音增强,谱减法的参数由人耳隐蔽阈值来控制。结果表明:即使在低信噪比的情况下,信噪比也能提高16dB左右,合成的语音对于电子耳蜗使用者具有较好的清晰度和可懂度。 展开更多
关键词 bark子波 电子耳蜗 语音增强
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Properties of Bark Particleboard Bonded with Demethylated Lignin Adhesives Derived from Leucaena leucocephala Bark
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作者 Rafidah Md Salim Jahimin Asik Mohd Sani Sarjadi 《Journal of Renewable Materials》 EI CAS 2024年第4期737-769,共33页
Lignin extraction from bark can maximize the utilization of biomass waste,offer cost-effectiveness,and promote environmental friendliness when employed as an adhesive material in bark particleboard production.Particle... Lignin extraction from bark can maximize the utilization of biomass waste,offer cost-effectiveness,and promote environmental friendliness when employed as an adhesive material in bark particleboard production.Particles of fine(0.2 to 1.0 mm),medium(1.0 to 2.5 mm),and coarse(2.5 to 12.0 mm)sizes,derived from the bark of Leucaena leucocephala,were hot-pressed using a heating plate at 175℃for 7 min to create single-layer particleboards measuring 320 mm×320 mm×10 mm,targeting a density of 700 kg/m^(3).Subsequently,the samples were trimmed and conditioned at 20℃and 65%relative humidity.In this study,we compared bark particleboard bonded with urea formaldehyde(UF)adhesive to fine-sized particleboard bonded with demethylated lignin adhesive.The results indicated that bark particleboards utilizing demethylated lignin and UF adhesives exhibited similar qualities.Coarse particleboard showed differences in modulus of elasticity(MOE)and modulus of rupture(MOR),while medium-sized particles exhibited significant variations in moisture content(MC)and water absorption(WA).Furthermore,the thickness swelling of coarse and medium-sized particles under wet and oven-dried conditions exhibited notable distinctions.Overall,the demethylated lignin adhesive extracted from L.leucocephala bark demonstrated similar quality to UF adhesive,with particle size correlating inversely to the strength of the bark particleboard. 展开更多
关键词 bark particleboard properties demethylated lignin lignin adhesives Leucaena leucocephala bark particles
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基于Bark子波变换的MFCC特征提取 被引量:5
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作者 尹许梅 何选森 《计算机工程》 CAS CSCD 北大核心 2011年第11期192-194,共3页
为提高低信噪比环境下语音的鲁棒性,提出一种改进的Mel频率倒谱系数(MFCC)特征提取方法。在传统MFCC特征提取的基础上,引入更适应人耳听觉系统的Bark子波变换,在快速傅里叶变换之前对语音进行预处理,并在MFCC提取方法中代替离散余弦变换... 为提高低信噪比环境下语音的鲁棒性,提出一种改进的Mel频率倒谱系数(MFCC)特征提取方法。在传统MFCC特征提取的基础上,引入更适应人耳听觉系统的Bark子波变换,在快速傅里叶变换之前对语音进行预处理,并在MFCC提取方法中代替离散余弦变换;在语音预处理阶段,利用改进的Lanczos窗函数抑制旁瓣以提高语音鲁棒性。实验表明,与传统MFCC方法相比,在噪声环境下,改进方法具有更高的说话人识别率。 展开更多
关键词 说话人识别 MEL频率倒谱系数 bark子波 窗函数
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FrFT-Bark域特征提取与CNN残差收缩网络心音分类算法 被引量:3
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作者 樊庆玲 杨宏波 +2 位作者 郭涛 张伟 王威廉 《云南大学学报(自然科学版)》 CAS CSCD 北大核心 2023年第3期564-574,共11页
为充分挖掘心音信号的生理、病理信息,提高心音自动分类的准确率,提出一种不依赖于分割和去噪的心音自动分类新算法.首先提取心音信号Bark域分数傅里叶变换的时频特征,然后将深度残差收缩网络引入卷积神经网络中构建新的分类模型,该模... 为充分挖掘心音信号的生理、病理信息,提高心音自动分类的准确率,提出一种不依赖于分割和去噪的心音自动分类新算法.首先提取心音信号Bark域分数傅里叶变换的时频特征,然后将深度残差收缩网络引入卷积神经网络中构建新的分类模型,该模型能够自动去除与当前任务无关的特征信息,提高模型预测的准确率及稳定性.研究所用心音样本5000例,其中1000例用于测试.实验结果表明,提出算法的准确率、灵敏度、特异度分别为0.925、0.902、0.948,F1值为0.923.该方法整体性能较以往方法有明显提升,具有较强的鲁棒性和泛化能力,有望应用于先心病的临床筛查. 展开更多
关键词 心音分类 bark域分数傅里叶变换 卷积神经网络 深度残差收缩网络
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Protective effects of Foeniculum vulgare root bark extract against carbon tetrachloride-induced hepatic fibrosis in mice 被引量:10
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作者 cai zhang xing tian +3 位作者 ke zhang guo-yu li hang-yu wang jin-hui wang 《World Journal of Gastroenterology》 SCIE CAS 2017年第31期5722-5731,共10页
AIM To investigate the protective effects of Foeniculum vulgare root bark (FVRB), a traditional Uyghur medicine, against carbon tetrachloride (CCl4)-induced hepatic fibrosis in mice. METHODS Mice were randomly divided... AIM To investigate the protective effects of Foeniculum vulgare root bark (FVRB), a traditional Uyghur medicine, against carbon tetrachloride (CCl4)-induced hepatic fibrosis in mice. METHODS Mice were randomly divided into eight groups (n = 20 each). Except for the normal control group, mice in the rest groups were intraperitoneally injected (i.p.) with 0.1% CCl4-olive oil mixture at 10 mL/kg twice a week to induce liver fibrosis. After 4 wk, mice were treated concurrently with the 70% ethanol extract of FVRB (88, 176, 352 and 704 mg/kg, respectively) daily by oral gavage for 4 wk to evaluate its protective effects. Serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), triglyceride (TG), hexadecenoic acid (HA), laminin (LN), glutathione (GSH), superoxide dismutase (SOD), and malondialdehyde (MDA) in liver tissues were measured. Hematoxylin-eosin (H and E) staining and Masson trichrome (MT) staining were performed to assess histopathological changes in the liver. The expression of transforming growth factor beta 1 (TGF-beta 1), matrix metalloprotein 9 (MMP-9) and metallopeptidase inhibitor 1 (TIMP-1) was detected by immunohistochemical analysis. Additionally, TGF-beta 1 and alpha-smooth muscle actin (alpha-SMA) protein expression was measured by Western blot. RESULTS A significant reduction in serum levels of AST, ALT, TG, HA and LN was observed in the FVRB-treated groups, suggesting that FVRB displayed hepatoprotective effects. Also, the depletion of GSH, SOD, and MDA accumulation in liver tissues was suppressed by FVRB. The expression of TGF-beta 1, MMP-9 and TIMP-1 determined by immunohistochemistry was markedly reduced in a dose-dependent manner by FVRB treatment. Furthermore, protective effects of FVRB against CCl4-induced liver injury were confirmed by histopathological studies. Protein expression of TGF-beta 1 and alpha-SMA detected by Western blot was decreased by FVRB treatment. CONCLUSION Our results indicate that FVRB may be a promising agent against hepatic fibrosis and its possible mechanisms are inhibiting lipid peroxidation and reducing collagen formation in liver tissue of liver fibrosis mice. 展开更多
关键词 Hepatic fibrosis Foeniculum vulgare root bark HISTOPATHOLOGY Carbon tetrachloride TGF-beta 1
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Inhibition of Ehrlich ascites carcinoma by Manilkara zapota L.stem bark in Swiss albino mice 被引量:5
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作者 M Abu Osman M Mamunur Rasbid +2 位作者 M Abdul Aziz M Rowshahul Habib M Rezaul karim 《Asian Pacific Journal of Tropical Biomedicine》 SCIE CAS 2011年第6期448-451,共4页
Objective:To evaluate the antitumor activity of Manilkara zapota(M.zapota) L.stem bark against Ehrlich ascites carcinoma(EAC) in Swiss albino mice.Methods:The in vivo antitumour activity of the ethyl acetate extract o... Objective:To evaluate the antitumor activity of Manilkara zapota(M.zapota) L.stem bark against Ehrlich ascites carcinoma(EAC) in Swiss albino mice.Methods:The in vivo antitumour activity of the ethyl acetate extract of stem bark of M.zapota L.(EASM) was evaluated at 50,100 and 200 mg/kg bw against EAC using mean survival time.After administration of the extract of M.zapota,viable EAC cell count and body weight in the EAC tumour hosts were observed.The animal was also observed for improvement in the haematological parameters(e.g.,heamoglobin content,red and white blood cells count and differential cell count) after EASM treatment. Results:Intraperitoneal administration of EASM reduced viable EAC cells,increased the survival lime,and restored altered haematological parameters.Significant efficacy was observed for EASM at 100 mg/kg dose(P<0.05).Conclusions:It can be concluded that the elhyl acetate extract of stem bark of M.zapota L.possesses significant antitumour activity. 展开更多
关键词 Manilkara zapota ANTITUMOUR activity Stem bark Ehrlich ASCITES CARCINOMA Haematological parameter
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Heartwood, sapwood and bark content of teak trees grown in Karnataka, India 被引量:5
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作者 Vindhya Prasad Tewari K.M.Mariswamy 《Journal of Forestry Research》 SCIE CAS CSCD 2013年第4期721-725,共5页
We evaluated heartwood, sapwood and bark content in teak trees. A total of 27 sample plots were laid out in teak plantations raised by State Forest Department in Kamataka covering different age groups (11-36 years),... We evaluated heartwood, sapwood and bark content in teak trees. A total of 27 sample plots were laid out in teak plantations raised by State Forest Department in Kamataka covering different age groups (11-36 years), density (516-2061 trees/ha) and sites. From these planta- tions, a total of 130 trees were felled for estimating the yield and bark content in relation to diameter at breast height (DBH), age and density. Bark content ranged from 22.2%-54.3%. Heartwood and sapwood con- tent were analyzed by sampling five trees each from two different planta- tions, one 30 years old at 553 trees.ha-1 and the other 32 years old at 911 trees.ha-1. The highest heartwood proportion of stem wood volume (over-bark) was 56.3% and the lowest was 37.1%. 展开更多
关键词 diameter at breast height (DBH) age stand density heart-wood SAPWOOD bark TEAK INDIA
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Cytotoxicity and anti-inflammatory effects of root bark extracts of Acanthopanax henryi 被引量:5
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作者 KIM Jong-Hwan LIU Xiang-Qian +2 位作者 DAI Ling YOOK Chang-Soo LEE Kyung-Tae 《Chinese Journal of Natural Medicines》 SCIE CAS CSCD 2014年第2期121-125,共5页
AIM: To investigate the cytotoxicity, anti-inflammatory activity, and action mechanism of root bark extracts of Acanthopanax henryi. METHOD: The hot methanol extract of the root bark of A. henryi was subjected to XAD-... AIM: To investigate the cytotoxicity, anti-inflammatory activity, and action mechanism of root bark extracts of Acanthopanax henryi. METHOD: The hot methanol extract of the root bark of A. henryi was subjected to XAD-4 column chromatography eluting with a gradient of methanol in water. The cytotoxicity and anti-inflammatory effects of the MeOH fractions were evaluated on the inhibition on lipopolysaccharide(LPS)-induced nitric oxide, prostaglandin E2, interleukin-1β, and interleukin-6 production in RAW 264.7 macrophages. RESULTS: The 80% MeOH fraction was a better inhibitor of LPS-induced NO, PGE2, IL-1β, and IL-6 production, and expression of inducible nitric oxide synthase(iNOS) at the protein levels in a concentration-dependent manner. CONCLUSION: The 80% MeOH fraction of A. henryi root bark has significant anti-inflammatory activity. This provides a pharmacological basis for clinical application for the treatment of inflammation. 展开更多
关键词 Acanthopanax henryi(Oliv.) Harms Root bark extract Cytotoxic activity Anti-inflammatory activity
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基于Bark尺度小波包和Teager能量算子的语音去噪方法
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作者 王静 张晨 李双田 《信号处理》 CSCD 北大核心 2005年第z1期44-47,共4页
针对小波包分解的高频混叠和频带顺序混乱,采取了一种改进小波包算法,采用一种更精细的Bark尺度小波包对带噪语音进行分解,以模拟人耳的听觉特性.对分解系数计算Teager能量算子(TEO),并使用一种简单的随TEO变化而调节的自适应阈值门限... 针对小波包分解的高频混叠和频带顺序混乱,采取了一种改进小波包算法,采用一种更精细的Bark尺度小波包对带噪语音进行分解,以模拟人耳的听觉特性.对分解系数计算Teager能量算子(TEO),并使用一种简单的随TEO变化而调节的自适应阈值门限对带噪语音进行阈值去噪,不需要判别清浊音和无声段,实验证明,该方法在多种噪声下都能取得较好语音增强效果,特别是在有色噪声和非平稳噪声下.对于较低信噪比的语音也能获得一定改善. 展开更多
关键词 bark尺度 小波包变换 语音去噪 TEAGER能量算子 混频
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