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71.
采用梯度校正的密度泛函理论方法,计算了云南松松塔中分离的2种新木脂素的绝对结构为7S,8R的手性结构、电子吸收光谱、电子圆二色谱、红外振动光谱和振动圆二色谱,计算值与实验值相符. 分子轨道和振动模式分析,两种新木质素具有相似的手性光谱. 电荷密度转移对电子圆二色谱具有主要贡献;而振动圆二色谱主要源于分子骨架运动.  相似文献   
72.
The fire retarding performance of 28 different inorganic chemical substances was tested by measuring the relative particle fire hazard properties of Pinus halepensis needles treated with these chemicals. The tests were performed using a new method, based on a specifically designed apparatus for monitoring the forest species temperature, under precisely controlled temperature and static air atmosphere conditions. The relative ignition and smoldering combustion properties determined were: the ignition delay time, the combustion rate, the heat content and the mass residue of forest samples. The key elements for the effectiveness of fire retardants were the delay of ignition and the reduction of heat and combustion rate. The chemicals examined were: Cu, Fe, Al2O3, Fe2O3, SiO2·H2O, NaHCO3, KI, KBr, KCl, NaCl, CaCO3, MnSO4·5H2O, CuSO4·5H2O, MgCl2·6H2O, Na2B4O7·10H2O, Na2HPO4, Na2CO3, Na2SiO3, ZnSO4·7H2O, Zn3(PO4)2·2H2O, NH4Br, NH4Cl, NH4HCO3, (NH4)2CO3, NH4H2PO4 (MAP), (NH4)2SO4 (AS), (NH4)2HPO4 (DAP) and a commercial retardant containing both DAP and AS. Among them the best performance was exhibited by ammoniac phosphates, followed by ammoniac sulfates and silica.  相似文献   
73.
The use of precipitation followed by acetylation procedures and preparative TLC purification allowed a facile isolation of four carbohydrates from the methanol extract of Pinus halepensis seeds. The isolated oligosaccharides exhibited high degree of purity. They were identified as α-D-galactosyl-(1→1)-myo-inositol nonaacetate (1), α-D-glucosyl-(1→2)-β-D-fructosyl octaacetate (2), α-D-galactosyl-(1→6)-α-D-glucosyl-(1→2)-β-D-frutosyl undecaacetate (3), and α-D-galactosyl-(1→6)-α-D-galactosyl-(1→6)-α-D-glucosyl-(1→2)-β-D-frutosyl tetradecaacetate (4) and were isolated for the first time from this plant. The 1H and 13C NMR assignments for compounds 2, 3, and 4 were detailed herein for the first time.  相似文献   
74.
The removal of methyl green (MG) dye from aqueous solutions using acid- or alkali-treated Pinus brutia cones (PBH and PBN) waste was investigated in this work. Adsorption removal of MG was conducted at natural pH, namely, 4.5 ± 0.10 for PBH and near 4.8 ± 0.10 for PBN. The pseudo-second-order model appeared to be the most appropriate to describe the adsorption process of MG on both PBN and PBH with a correlation coefficient R2 > 0.999. Among the tested isotherm models, the Langmuir isotherm was found to be the most relevant to describe MG sorption onto modified P. brutia cones with a correlation factor R2 > 0.999. The ionic strength (presence of other ions: Cl?, Na+, and SO42?) also influences the adsorption due to the change in the surface properties; it had a negative impact on the adsorption of MG on these two supports. A reduction of 68.5% of the adsorption capacity for an equilibrium dye concentration Ce of 30 mg/L was found for the PBH; while with PBN no significant influence of the ionic strength on adsorption was observed, especially in the presence of NaCl for dye concentrations superior to 120 mg L?1.  相似文献   
75.
A new abietatrienoid, 15‐methoxydidehydroabietic acid ( 1 ), a new ring B‐seco abietatrienoid, 10‐hydroxy‐9,10‐secoabieta‐8,11,13‐trien‐18‐oic acid ( 2 ), and a new tetracyclic triterpenoid, pinusyunnanol ( 3 ), together with five known compounds, were obtained from the twigs and needles of Pinus yunnanensis. The structures of the new compounds were elucidated by means of extensive spectroscopic analyses.  相似文献   
76.
采用动态顶空吸附/手性毛细管气相色潜-质谱(GC—MS)法,首次分析研究了马尾松(Pinus massoniana Lamb)、湿地松(Pinus elliottii Engelm)、油松(Pinus tabulaeformis Carr.)针叶挥发性化合物中主要手性单萜(α-蒎烯、莰烯、β-蒎烯、β-水芹烯、柠檬烯)的组成与相对含量,结果表明其在种间相差较大。马尾松中的(-)-α-蒎烯的含量(55.50%)最高,而其对映异构体(+)-α/-蒎烯在油松中含量(16.86%)最高,(-)β-蒎烯在湿地松中含量(43.38%)最高。马尾松手性单萜的组成和含量在树与树间差异也较大。  相似文献   
77.
The needle oils of Pinus sylvestris L. were analyzed by GC and GC-MS. The results showed some qualitative and quantitative variations. Forty-three components were identified in the oils of P. sylvestris. All the samples of essential oils contained α-pinene, camphene, and β-pinene as major constituents. Chemical variations of P. sylvestris samples were discussed. Published in Khimiya Prirodnykh Soedinenii, No. 1, pp. 22–25, January–February, 2006.  相似文献   
78.
云南松枝梢营养成分分析   总被引:6,自引:0,他引:6  
对云南松健康树和纵坑切梢小蠹蛀害树枝梢营养成分进行了分析,在健康树和蛀害树松梢中分别检测出11种氨基酸和14种氨基酸。健康树松梢中元素含量变化趋势由高到低为Ca,Mg,Al,Mn,Fe,B,Zn,Sr,Ni,蛀害树松梢中无机元素含量变化趋势由高到低为Ca,Mg,Al,Fe,Mn,B,Zn,Sr,Ni,为查找纵坑切梢小蠹蛀害的原因提供依据和数据。  相似文献   
79.
探究了应用激光诱导击穿光谱(LIBS)结合化学计量学方法鉴别硫熏浙贝母的可行性。采集了未经硫熏、轻度硫熏和重度硫熏的浙贝母样本的LIBS光谱,使用小波变换和归一化对原始光谱进行预处理后,分别建立了基于全波段(400.41~871.65 nm)和基于特征波段(400.41~600.02 nm)的支持向量机(SVM)、极限学习机(ELM)和随机森林(RF)的鉴别模型。结果表明:基于特征波段建立的三类模型的性能均与基于全波段建立的模型保持一致或更优,说明特征波段的提取是有效的。基于特征波段建立的模型中,SVM模型性能最优,建模准确率和预测准确率分别达到了100%和95.83%。综上所述,应用LIBS技术结合特征波段提取和化学计量学方法鉴别不同程度硫熏的浙贝母是可行的,且具有快速、简便、多元素同时分析的优势,可为鉴别硫熏中药材提供依据,有助于建立中药材质量检测与分级评定系统。  相似文献   
80.
离子注入对黑松花粉粒和花粉管内骨架系统的损伤效应   总被引:2,自引:2,他引:0  
以黑松花粉粒和花粉管为试验材料, 研究了离子注入对细胞骨架系统的损伤效应。研究结果表明, 离子注入会不同程度地破坏花粉管内微管网络的完整性, 花粉管形态的异常状态与其微管骨架结构的异常状态密切相关。离子注入对黑松花粉管内的微管骨架系统的正常结构有明显的效应, 这种效应的明显程度与离子注入剂量有一定的相关性, 即随着离子注入剂量的增加, 微管骨架系统受到破坏的程度更加明显。离子注入对黑松花粉管内微丝骨架系统的分布状态有明显的影响, 其程度也与离子注入剂量的大小存在一定的相关性。  相似文献   
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