Field observation of the macromorphology and analyses of micromorphology and geochemistry were conducted to the worm-shaped veins (WSVs) in the red earth of South China. The WSVs exhibit outward features of root trace...Field observation of the macromorphology and analyses of micromorphology and geochemistry were conducted to the worm-shaped veins (WSVs) in the red earth of South China. The WSVs exhibit outward features of root traces and contain the traces of stele that can be used as the definite evidence of root traces. Surrounding the worm-shaped veins there are some micro-features pressed by past root growth. Geochemical analyses indicate that the white part in the WSV was depleted in Fe content. These lines of evidence suggest the WSVs in the red earth of South China are the root traces of past forest.展开更多
Plant roots dynamics responses to elevated atmospheric CO2 concentration, increased temperature and changed precipitation can be a key link between plant growth and long-term changes in soil organic matter and ecosyst...Plant roots dynamics responses to elevated atmospheric CO2 concentration, increased temperature and changed precipitation can be a key link between plant growth and long-term changes in soil organic matter and ecosystem carbon balance. This paper reviews some experiments and hypotheses developed in this area, which mainly include plant fine roots growth, root turnover, root respiration and other root dynamics responses to elevated CO2 and global climate change. Some recent new methods of studying root systems were also discussed and summarized. It holds herein that the assemblage of information about root turnover patterns, root respiration and other dynamic responses to elevated atmospheric CO2 and global climatic change can help to better understand and explore some new research areas. In this paper, some research challenges in the plant root responses to the elevated CO2 and other environmental factors during global climate change were also demonstrated.展开更多
The trace of a Wishart matrix, either central or non-central, has important roles in various multi-variate statistical questions. We review several expressions of its distribution given in the literature, establish so...The trace of a Wishart matrix, either central or non-central, has important roles in various multi-variate statistical questions. We review several expressions of its distribution given in the literature, establish some new results and provide a discussion on computing methods on the distribution of the ratio: the largest eigenvalue to trace.展开更多
雷公藤（Tripterygium wilfordii）不仅是一种药用植物，还是一种有毒植物，在民间作为杀虫植物，有“菜虫药”之称，其主要活性成分雷公藤生物碱和雷公藤甲素既有杀虫活性又有医用活性（李琰等，2012；Brinker et al．，2005；Liu，201...雷公藤（Tripterygium wilfordii）不仅是一种药用植物，还是一种有毒植物，在民间作为杀虫植物，有“菜虫药”之称，其主要活性成分雷公藤生物碱和雷公藤甲素既有杀虫活性又有医用活性（李琰等，2012；Brinker et al．，2005；Liu，2011），临床上常用来治疗风湿性关节炎、肿瘤、免疫抑制性疾病（仲剑等，2009；Johnson et al．，2011；Huang et al．，2012）。展开更多
文摘Field observation of the macromorphology and analyses of micromorphology and geochemistry were conducted to the worm-shaped veins (WSVs) in the red earth of South China. The WSVs exhibit outward features of root traces and contain the traces of stele that can be used as the definite evidence of root traces. Surrounding the worm-shaped veins there are some micro-features pressed by past root growth. Geochemical analyses indicate that the white part in the WSV was depleted in Fe content. These lines of evidence suggest the WSVs in the red earth of South China are the root traces of past forest.
基金This research was supported by the National Natural Science Foundation of China （90502007, 30270230） the Program for New Century Excellent Talents in University, China （NCET-04-0955）the United Scholar＇s Item of Talent Training Program in West China of CAS and the Program for 0utstanding Talents in Northwest A ＆ F University.
文摘Plant roots dynamics responses to elevated atmospheric CO2 concentration, increased temperature and changed precipitation can be a key link between plant growth and long-term changes in soil organic matter and ecosystem carbon balance. This paper reviews some experiments and hypotheses developed in this area, which mainly include plant fine roots growth, root turnover, root respiration and other root dynamics responses to elevated CO2 and global climate change. Some recent new methods of studying root systems were also discussed and summarized. It holds herein that the assemblage of information about root turnover patterns, root respiration and other dynamic responses to elevated atmospheric CO2 and global climatic change can help to better understand and explore some new research areas. In this paper, some research challenges in the plant root responses to the elevated CO2 and other environmental factors during global climate change were also demonstrated.
文摘The trace of a Wishart matrix, either central or non-central, has important roles in various multi-variate statistical questions. We review several expressions of its distribution given in the literature, establish some new results and provide a discussion on computing methods on the distribution of the ratio: the largest eigenvalue to trace.
文摘雷公藤（Tripterygium wilfordii）不仅是一种药用植物，还是一种有毒植物，在民间作为杀虫植物，有“菜虫药”之称，其主要活性成分雷公藤生物碱和雷公藤甲素既有杀虫活性又有医用活性（李琰等，2012；Brinker et al．，2005；Liu，2011），临床上常用来治疗风湿性关节炎、肿瘤、免疫抑制性疾病（仲剑等，2009；Johnson et al．，2011；Huang et al．，2012）。
