| 1 | 3个小型高原湖泊水陆交错带中植物叶片pH值变异及其潜在影响因素显示文摘陆生植物叶片pH值是与植物生理功能和养分利用状况息息相关的重要植物属性,并随植物功能型和环境的变化而变化。然而,水生植物叶片pH值的变异特征及其与陆生植物间的差异性仍不清楚。在3个自然形成的小型高原湖泊的湖滨植物群落中,我们采集植物、土壤和湖水样品,检测了植物叶片pH值与碳、氮含量以及环境条件(水或土壤pH值、土壤水位状况)。从植物功能型和群落两个水平分析了湖滨植物叶pH值沿水分梯度的变化及其潜在影响因素。研究结果表明,不同类型的水生植物,以及水生、沼生和陆生环境中生长的植物的叶pH存在较大差异;浮叶植物叶片pH值(4.21±0.05)显著低于挺水植物(5.71±0.07)和沉水植物(5.82±0.06);水生草本植物叶片pH值(5.43±0.10)显著低于沼生草本植物(6.12±0.07)和陆生草本植物(5.74±0.05);陆生草本植物叶片pH值显著高于木本植物。植物功能群间叶片pH值的变异可能与叶片的结构、光利用特性和养分特性有关。群落水平的结果与植物功能型水平相一致:水生群落叶片pH值显著低于陆生群落。群落水平叶片pH值可能主要受物种组成、水分条件和环境pH值的影响。本研究首次探索了水生植物的pH值,并且在景观尺度上对比了不同功能型植物的叶片pH值,为深入探索植物pH值变异机制以及其在水生和湿地生态系统中的生态意义提供参考。 | Sining Liu Shenqun An Zhengbing Yan Junpeng Ren Xiaoqian Lu Feiyang Ge Wenxuan Han | 2021 | Journal of Plant Ecology2021，14，3： | 1 |
| 2 | A Novel Synchronization Method in Terahertz Large-Scale Antenna Array System显示文摘We focus on the problems of the accurate time delay estimation,the design of training pilots,and hybrid matrix optimization within the large-scale antenna array Terahertz(THz)broadband communication system.In contrast to the existing researches based on narrow-band arrays,we hereby shed light on the time delay estimation of broadband arrays.In THz broadband communication systems,the data symbol duration is relatively short when comparing with the dimension of the antenna array.In large-scale antenna systems,signals received in each antenna are no longer different phase-shifted copies of the same symbol,but completely different symbols in which occasion traditional narrowband structure is no longer suitable.Based on the above conclusion,firstly,we put forward a system model based on large-scale antenna arrays and Time delay line(TDL)structure.Secondly,we deduce the Cramer-Rao lower bound(CRLB)of the time delay estimation,and present a time delay estimation algorithm that could reach the CRLB.Thirdly,by minimizing the CRLB,we address the design of the training pilot and optimized TDL structure under the condition of constant envelope training pilot and modulus TDL structure.Finally,we disclose the numerical simulation results.According to the simulation results,the aforementioned method is workable in reaching the CRLB,the TDL structure can significantly surpass that of the traditional model,and the optimal pilot design method outperforms the pseudo-random pilot structure. | ZHENG Chen DING Xuhui LIU Dekang BU Xiangyuan AN Sining | 2021 | Chinese Journal of Electronics2021，30，5： | 0 |
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