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黄瑞梅 《信阳农业高等专科学校学报》2014,(3):88-91
白居易继承陈子昂、杜甫的兼济思想,创作了170余首优秀"讽谕"诗篇。这些讽喻诗多用散文化句式,诗中多杂以议论,还善于运用虚字虚词。这些创作手法具有以文为诗的特点,对宋诗特点的形成也起到了重要作用。 相似文献
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Simon Bilodeau-Gauthier Daniel Houle Christian GagnonBenoît Côté Christian Messier 《Forest Ecology and Management》2011,261(1):95-104
Partitioning of elements in tree xylem is being increasingly studied, as it suggests that elements are potentially mobile within the xylem long after their uptake. A recent study revealed that only the most mobile xylem fraction (water-soluble) of base cations (calcium [Ca], magnesium [Mg], and potassium [K]) increased at higher soil acidity, while the two mobile fractions (water- and acid-soluble) of acidic metals—potentially phytotoxic aluminium (Al), cadmium (Cd) and manganese (Mn)—were significantly enhanced on very acid soils. The current paper presents an investigation of soil-wood chemistry relationships with basal area tree growth. It was hypothesized that the growth of sugar maple would be reduced by low base cation and high acidic metal concentrations in the xylem mobile fractions. Sugar maple trees (n = 55) from six watersheds in southern Quebec, Canada were analysed by sequential chemical extractions for the water-soluble, acid-soluble and residual fractions of base cations (Ca, K, Mg) and acidic metals (Al, Cd, Mn) in xylem. Generally, tree growth was positively correlated to concentrations of base cations in wood (ρ = 0.27-0.50) and soil (ρ = 0.41-0.67), and negatively correlated to concentrations of acidic metals in wood (ρ = −0.33 to −0.52) and soil (ρ = −0.67). However, these relations differed depending on the element fraction considered. Water- and acid-soluble xylem concentrations of base cations and Al were among the best predictors of growth trends (R2 = 0.46-0.51). The relationship between acidic metals and tree growth is further discussed. 相似文献
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陕西省主要粮食作物比较优势分析 总被引:2,自引:0,他引:2
根据比较优势理论,利用改进的综合比较优势指数法,对陕西省小麦、稻谷、玉米3种主要粮食作物在1990~2009年间的比较优势变动趋势进行了分析,其结果表明:3种作物的综合比较优势指数都处于劣势,其中小麦和玉米具有规模优势但是效率和效益指数较低,稻谷具有效率和效益优势但是规模太小,并在此基础上提出了陕西省主要粮食作物结构调整的对策和建议。 相似文献
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本文通过田间试验法研究生物有机肥、腐植酸有机肥及水溶性有机肥3种施肥处理对土壤pH值、有机质及小麦对镉的转运及富集规律的影响。结果表明,3种施肥处理均可以降低碱性土壤小麦不同生育期土壤pH值、有效提高土壤有机质含量,且腐植酸有机肥处理土壤pH值与空白对照相比在拔节期达极显著水平;生物有机肥、腐植酸有机肥处理可降低小麦根到籽粒的转运系数及根部镉的富集。 相似文献
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Shuang–Huang–Lian (SHL), a traditional Chinese formula containing Lonicerae japonicae flos (LJF), Scutellariae radix (SR) and Forsythiae fructus (FF), is commonly used to treat acute upper respiratory tract infection, acute bronchitis and light pneumonia. Forsythoside A is one of the main active ingredients in Forsythiae fructus, a key herb in SHL. In the present study, effects of different compositions in SHL on the in vitro metabolism in Sprague–Dawley rat liver microsomes of forsythoside A were investigated. The observations from Sprague–Dawley rat liver microsomes in the presence of β-NADPH or UDPGA that forsythoside A may be the substrates of CYP3A4, CYP2C9, CYP1A2, UGT1A6, UGT1A3, UGT1A1 and UGT1A9; Chlorogenic acid may be the substrates of CYP3A4, CYP2C9, CYP1A2, CYP2C19, UGT1A6, UGT1A3 and UGT1A1; Baicalin may be the substrates of CYP3A4, CYP2C19, CYP1A2, UGT1A9, UGT1A1 and UGT1A3; Baicalein may be the substrates of CYP3A4, CYP2E1 and UGT1A6. It was also found that the residue of forsythoside A in SHL, FF + LJF and FF + SR was greatly increased compared with that in FF in Sprague–Dawley rat liver microsomes in the presence of β-NADPH or UDPGA, which indicated that the metabolism of forsythoside A in SHL may be influenced by chlorogenic acid in LJF acting on the CYP3A4, CYP2C9, CYP1A2, UGT1A6, UGT1A3 and UGT1A1; baicalin in SR acting on the CYP3A4, CYP1A2, UGT1A9, UGT1A1 and UGT1A3; baicalein acting on the CYP3A4 and UGT1A6 respectively. 相似文献
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