There are about 9,000 species of birds living in the world. They have a more or less intimate association with human life. Birds are the only vertebrates that have dwelled throughout in the air, water and land. Unfort...There are about 9,000 species of birds living in the world. They have a more or less intimate association with human life. Birds are the only vertebrates that have dwelled throughout in the air, water and land. Unfortunately, little do we understand of their origins and evolutionary history. This is largely due to the poor preservation of the fossil ancestry. Like their modem descendants, the early ancestors had both an extensive range of life spans and very thin skeletons.展开更多
目的建立高效液相色谱-高分辨飞行时间质谱联用技术(high performance liquid chromatography tandem triple-time-of-flight mass spectrometry,HPLC-Triple-TOF MS)筛选中国和俄罗斯人参中人参皂苷差异化合物的分析方法。方法采用HPLC...目的建立高效液相色谱-高分辨飞行时间质谱联用技术(high performance liquid chromatography tandem triple-time-of-flight mass spectrometry,HPLC-Triple-TOF MS)筛选中国和俄罗斯人参中人参皂苷差异化合物的分析方法。方法采用HPLC-Triple-TOF MS对来源于中国和俄罗斯的48例人参样品进行测定,通过高分辨飞行时间质谱分析,对48例样品的特征峰质谱信息进行提取,通过得到的一级质谱精确质荷比和二级质谱碎片信息,结合软件数据库进行成分鉴别后,采用主成分分析(principal component analysis,PCA)和偏最小二乘判别分析(partial least squares discrimination analysis,PLS-DA)对得到的数据进行处理,筛选差异组分。结果经上述方法进行处理和分析后,中国和俄罗斯人参样品间的组分得到明显区分,初步筛选并鉴定出了中国和俄罗斯人参间14种差异显著的人参皂苷类化学成分。结论本研究成功建立了基于高效液相色谱-高分辨飞行时间质谱联用技术鉴别中国和俄罗斯人参的分析方法,建立的方法准确、可靠,可用于中国和俄罗斯人参的产地鉴别和溯源。展开更多
Study of fossil birds in China was first conducted by western scholars in last century, and extensive study of Cenozoic birds by Chinese scholars since the 1970s. However, it is the finding of Mesozoic birds, mostly f...Study of fossil birds in China was first conducted by western scholars in last century, and extensive study of Cenozoic birds by Chinese scholars since the 1970s. However, it is the finding of Mesozoic birds, mostly from northeast China since the 1990s, that has become the focus and highlight of paleornithology of China. Enantiornithine birds from the Late Jurassic-Early Cretaceous of China provide the most complete record of the early evolution of this展开更多
In September 1990, two well-preserved articulated specimens of bird were discovered by the first author from the Mesozoic Jiufotang Formation in Liaoning Province, China. Based on one of them, a nearly complete specim...In September 1990, two well-preserved articulated specimens of bird were discovered by the first author from the Mesozoic Jiufotang Formation in Liaoning Province, China. Based on one of them, a nearly complete specimen, a new avian order including a single genus展开更多
文摘There are about 9,000 species of birds living in the world. They have a more or less intimate association with human life. Birds are the only vertebrates that have dwelled throughout in the air, water and land. Unfortunately, little do we understand of their origins and evolutionary history. This is largely due to the poor preservation of the fossil ancestry. Like their modem descendants, the early ancestors had both an extensive range of life spans and very thin skeletons.
文摘Study of fossil birds in China was first conducted by western scholars in last century, and extensive study of Cenozoic birds by Chinese scholars since the 1970s. However, it is the finding of Mesozoic birds, mostly from northeast China since the 1990s, that has become the focus and highlight of paleornithology of China. Enantiornithine birds from the Late Jurassic-Early Cretaceous of China provide the most complete record of the early evolution of this
文摘In September 1990, two well-preserved articulated specimens of bird were discovered by the first author from the Mesozoic Jiufotang Formation in Liaoning Province, China. Based on one of them, a nearly complete specimen, a new avian order including a single genus
