Coniopteris was a ubiquitous plant of the Jurassic and Cretaceous periods and played an important role in the flora of the time. However, its anatomical structure is relatively poorly known. The specimens of Coniopter...Coniopteris was a ubiquitous plant of the Jurassic and Cretaceous periods and played an important role in the flora of the time. However, its anatomical structure is relatively poorly known. The specimens of Coniopteris hymenophylloides(Brongniart) Seward described here were collected from the Yaojie Formation in Gansu Province, northwestern China. The sterile fronds are characterized as being at least bipinnate with alternate arranged linear pinnae covered by thin cuticles. Fertile fronds are linear-lanceolate, with single sorus at the margin of each fertile pinnule. In situ spores are typically trilete, triangle to subcircular in polar view, cap-shaped in equatorial view, and 37 μm in average diameter. The trilete marking is straight and narrow, generally extends to 4/5 of the spore radius. The spore surface is smooth, and parts of the exine are granulated. The epidermal cells of cuticles are irregular in shape, approximately 40-60μm long and 10-20 μm wide. The elliptical stomatal complexes are paracytic,approximately 30 μm long and 19 μm wide,and irregularly distributed. On the basis of its epidermal structures and comparisons with extant ferns, we consider that Coniopteris displays combined features of the related extant genera.展开更多
As the basal group of Polypodiales, the specific taxonomy of Dicksoniaceae is still being debated. As aquantitative analysis method, numerical taxonomy has been applied to the taxonomic study of many plant families an...As the basal group of Polypodiales, the specific taxonomy of Dicksoniaceae is still being debated. As aquantitative analysis method, numerical taxonomy has been applied to the taxonomic study of many plant families andgenera in recent years due to its simplicity and high accuracy. However, the numerical analysis of the Dicksoniaceae fossilshas not been reported at present. In the present study, the pinnule morphological data of 42 Mesozoic fossil species of theDicksoniaceae were analyzed using cluster analysis, principal component analysis and correlation analysis. The resultsrevealed that 42 taxonomic units could be divided into six representative groups, which are consistent with the traditionaltaxonomy. After screening, an identification key on 28 fossil species of four genera with a definite taxonomic position wasestablished. According to the quantitative analysis, a Bayes discriminant model was established for the selected species.Lastly, the model was tested using the morphological data of the fossil pinnules in Dicksoniaceae from the YaojieFormation, suggesting that the discriminant model is accurate to a certain extent. As a result, the numerical taxonomy canbe applied to the classification of the Dicksoniaceae fossils.展开更多
介绍了清洗机的基本组成结构和工作原理,以故障树分析法(Fault Tree Analysis,FTA)为基础,通过对以往常见故障的总结和分析,建立了清洗机的故障树模型,实现了对清洗机故障的快速诊断与精准维修,有效缩短了设备故障宕机时间,提高了设备...介绍了清洗机的基本组成结构和工作原理,以故障树分析法(Fault Tree Analysis,FTA)为基础,通过对以往常见故障的总结和分析,建立了清洗机的故障树模型,实现了对清洗机故障的快速诊断与精准维修,有效缩短了设备故障宕机时间,提高了设备利用效率。展开更多
In the past few decades,the irrational use of water resources has resulted in many issues such as land subsidence in the North China Plain(NCP),hindering its socio-economic development.An accurate understanding of wat...In the past few decades,the irrational use of water resources has resulted in many issues such as land subsidence in the North China Plain(NCP),hindering its socio-economic development.An accurate understanding of water resource changes is important for the allocation of water resources in the NCP.In this study,we employed Gravity Recovery and Climate Experiment(GRACE) satellite data to monitor the total water storage(TWS) change in the NCP during 2004–2019.Evapotranspiration,precipitation,and runoff during 2004–2019 were sequentially examined,using the water balance formula(WBF),to retrieve TWS change.Furthermore,the soil moisture,snow water equivalent,and canopy water storage from the Global Land Data Assimilation System were used to calculate the natural component of the TWS variations.A comparison of these results revealed the drivers of the changes in water resources.The results showed that:(1) overall TWS retrieved by GRACE decreased substantially as a consequence of human activity,while TWS obtained by WBF fluctuated periodically around zero under the impact of three natural drivers;(2) TWS in the NCP fell at a remarkable rate of-12.39 mm/y from 2004 to 2019,and the natural part of TWS experienced two significant declines,during 2004–2010 and 2013–2016;(3) variations in runoff,precipitation,and evapotranspiration from 2004 to 2019 were not significant,but human activities contributed more to the decreasing TWS than natural factors.This study provides a reference for water resource management and groundwater exploitation across the NCP under climate change.展开更多
基金project received financial support from the National Natural Science Foundation of China (No. 41262001)the Science and Technology Support Fund of Gansu Province (No. 1104FKCA116)
文摘Coniopteris was a ubiquitous plant of the Jurassic and Cretaceous periods and played an important role in the flora of the time. However, its anatomical structure is relatively poorly known. The specimens of Coniopteris hymenophylloides(Brongniart) Seward described here were collected from the Yaojie Formation in Gansu Province, northwestern China. The sterile fronds are characterized as being at least bipinnate with alternate arranged linear pinnae covered by thin cuticles. Fertile fronds are linear-lanceolate, with single sorus at the margin of each fertile pinnule. In situ spores are typically trilete, triangle to subcircular in polar view, cap-shaped in equatorial view, and 37 μm in average diameter. The trilete marking is straight and narrow, generally extends to 4/5 of the spore radius. The spore surface is smooth, and parts of the exine are granulated. The epidermal cells of cuticles are irregular in shape, approximately 40-60μm long and 10-20 μm wide. The elliptical stomatal complexes are paracytic,approximately 30 μm long and 19 μm wide,and irregularly distributed. On the basis of its epidermal structures and comparisons with extant ferns, we consider that Coniopteris displays combined features of the related extant genera.
基金support from the National Natural Science Foundation of China(Grant No41262001)the Science and Technology Support Fund of Gansu Province(Grant No.1104FKCA116)
文摘As the basal group of Polypodiales, the specific taxonomy of Dicksoniaceae is still being debated. As aquantitative analysis method, numerical taxonomy has been applied to the taxonomic study of many plant families andgenera in recent years due to its simplicity and high accuracy. However, the numerical analysis of the Dicksoniaceae fossilshas not been reported at present. In the present study, the pinnule morphological data of 42 Mesozoic fossil species of theDicksoniaceae were analyzed using cluster analysis, principal component analysis and correlation analysis. The resultsrevealed that 42 taxonomic units could be divided into six representative groups, which are consistent with the traditionaltaxonomy. After screening, an identification key on 28 fossil species of four genera with a definite taxonomic position wasestablished. According to the quantitative analysis, a Bayes discriminant model was established for the selected species.Lastly, the model was tested using the morphological data of the fossil pinnules in Dicksoniaceae from the YaojieFormation, suggesting that the discriminant model is accurate to a certain extent. As a result, the numerical taxonomy canbe applied to the classification of the Dicksoniaceae fossils.
基金supported by the National Key Research and Development Program of China (Grant No.2022YFF0711603)the Fundamental Research Funds for the Central Universities (Grant Nos.0209-14380093 and0209-14380097)+2 种基金the Frontiers Science Center for Critical Earth Material Cycling Fund (Grant No.JBGS2102)the National Natural Science Foundation of China (Grant No.41671423)the Ministry Science and Technology Development of China-Data Sharing Infrastructure of Earth System Science (Grant No.2005DKA32300)。
文摘In the past few decades,the irrational use of water resources has resulted in many issues such as land subsidence in the North China Plain(NCP),hindering its socio-economic development.An accurate understanding of water resource changes is important for the allocation of water resources in the NCP.In this study,we employed Gravity Recovery and Climate Experiment(GRACE) satellite data to monitor the total water storage(TWS) change in the NCP during 2004–2019.Evapotranspiration,precipitation,and runoff during 2004–2019 were sequentially examined,using the water balance formula(WBF),to retrieve TWS change.Furthermore,the soil moisture,snow water equivalent,and canopy water storage from the Global Land Data Assimilation System were used to calculate the natural component of the TWS variations.A comparison of these results revealed the drivers of the changes in water resources.The results showed that:(1) overall TWS retrieved by GRACE decreased substantially as a consequence of human activity,while TWS obtained by WBF fluctuated periodically around zero under the impact of three natural drivers;(2) TWS in the NCP fell at a remarkable rate of-12.39 mm/y from 2004 to 2019,and the natural part of TWS experienced two significant declines,during 2004–2010 and 2013–2016;(3) variations in runoff,precipitation,and evapotranspiration from 2004 to 2019 were not significant,but human activities contributed more to the decreasing TWS than natural factors.This study provides a reference for water resource management and groundwater exploitation across the NCP under climate change.
