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四维画法几何中的垂直问题 被引量:5
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作者 董培蓓 刘黎 《工程图学学报》 CSCD 1996年第1期34-36,共3页
本文用形、数结合的观点,以两线垂直数性积为零作为基础,直线与三维空间垂直的投影特征作为图解问题的依据,系统地论述了四维空间里的所有垂直问题,且各种情况均有明确的结论。
关键词 四维空间 数性积 画法几何 垂直
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Variability of leaf functional traits of invasive tree Rhus typhina L. in North China 被引量:5
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作者 WEI Mei WANG Shu +3 位作者 WU Bing-de JIANG Kun ZHOU Jia-wei WANG Cong-yan 《Journal of Central South University》 SCIE EI CAS CSCD 2020年第1期155-163,共9页
Functional traits, specifically leaf functional traits, are core-topics to explore importance to the invasion success of invasive plant species. This study aims to address the differences in leaf functional traits and... Functional traits, specifically leaf functional traits, are core-topics to explore importance to the invasion success of invasive plant species. This study aims to address the differences in leaf functional traits and their corresponding variability of the invasive tree staghorn sumac Rhus typhina L. with different invasion success, including lower and higher invasion success, in two climatic regions in North China, including a warm temperate region and a cold temperate region. No significant differences were found for leaf functional traits of staghorn sumac across different invasion success. However, the variability of leaf chlorophyll and nitrogen concentrations of staghorn sumac under higher invasion success were approximately 66.023% and 68.615% higher than those under lower invasion success, respectively. The leaf chlorophyll and nitrogen concentrations of staghorn sumac in the warm temperate region were approximately 18.432% and 16.337% higher than those in cold temperate region, respectively. The variability of specific leaf area of staghorn sumac in warm temperate region was approximately 59.802% higher than that in cold temperate region. Accordingly, leaf chlorophyll and N concentrations as well as specific leaf area of staghorn sumac and their corresponding variability may play an essential role in shaping ecological success of studied invader along a climatic gradient. 展开更多
关键词 climatic region invasive tree coefficient of variation VARIABILITY specific leaf area Rhus typhina L.
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Elasticity under pressure and thermal property of Mg2La from first-principles calculations
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作者 牛晓峰 黄志伟 +2 位作者 胡磊 王涵 王宝健 《Journal of Central South University》 SCIE EI CAS CSCD 2017年第8期1713-1719,共7页
The elastic properties, thermodynamic and electronic structures of Mg_2La were investigated by using first-principles. The calculated results show that pressure affects the elastic constants of C_(11) more than that o... The elastic properties, thermodynamic and electronic structures of Mg_2La were investigated by using first-principles. The calculated results show that pressure affects the elastic constants of C_(11) more than that of C_(12) and C_(44). Specifically, higher pressure leads to greater bulk modulus(B), shear modulus(G), and elastic modulus(E). We predict B/G and anisotropy factor A based on the calculated elastic constants. The Debye temperature also increases with increasing pressure. Based on the quasi-harmonic Debye model, we examined the thermodynamic properties. These properties include the normalized volume(V/V_0), bulk modulus(B), heat capacity(C_v), thermal expansion coefficient(α), and Debye temperature(■). Finally, the electronic structures associated with the density of states(DOS) and Mulliken population are analyzed. 展开更多
关键词 first-principles elastic properties thermodynamics properties electronic structure
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