按提交时间
按主题分类
按作者
按机构
  • Transformation among precipitation, surface water, groundwater, and mine water in the Hailiutu River Basin under mining activity

    分类: 地球科学 >> 水文学 提交时间: 2022-06-17 合作期刊: 《干旱区科学》

    摘要:

    Abstract: Coal mining has changed the hydrogeological conditions of river basins, and studying how the relationship among different types of water body has changed under the influence of coal mining is of great significance for understanding the regional hydrological cycle. We analyzed the temporal and spatial distribution of hydrochemical properties and environmental isotopes in the Hailiutu River Basin (HRB), China with a mixed model. The results showed that: (1) human activity (e.g., coal mining and agricultural production) causes considerable changes in the hydrochemical properties of surface water in and around the mining areas, and leads to significant increases in the concentrations of Na+ and SO2– 4; (2) precipitation is the main source of water vapour in the HRB. The transformation between surface water and groundwater in the natural watershed is mainly affected by precipitation; and (3) in the mining areas, the average contribution rates of precipitation to the recharge of surface water and groundwater increased by 2.6%–7.9% and 2.7%–9.9%, respectively. Groundwater in the Salawusu Formation constitutes up to 61.3%–72.4% of mine water. Overall, this study is beneficial for quantifying the effects of coal mining on local hydrological cycles. The research results can provide a reference for local water resources management and ecological environment improvement.

  • Spatial-temporal characteristics and influencing factors of relative humidity in arid region of Northwest China during 1966–2017

    分类: 地球科学 >> 地球科学史 提交时间: 2020-10-20 合作期刊: 《干旱区科学》

    摘要:Playing an important role in global warming and plant growth, relative humidity (RH) has profound impacts on production and living, and can be used as an integrated indicator for evaluating the wet-dry conditions in the arid and semi-arid area. However, information on the spatial-temporal variation and the influencing factors of RH in these regions is still limited. This study attempted to use daily meteorological data during 1966–2017 to reveal the spatial-temporal characteristics of RH in the arid region of Northwest China through rotated empirical orthogonal function and statistical analysis method, and the path analysis was used to clarify the impact of temperature (T), precipitation (P), actual evapotranspiration (ETa), wind speed (W) and sunshine duration (S) on RH. The results demonstrated that climatic conditions in North Xinjiang (NXJ) was more humid than those in Hexi Corridor (HXC) and South Xinjiang (SXJ). RH had a less significant downtrend in NXJ than that in HXC, but an increasingly rising trend was observed in SXJ during the last five decades, implying that HXC and NXJ were under the process of droughts, while SXJ was getting wetter. There was a turning point for the trend of RH in Xinjiang, which occurred in 2000. Path analysis indicated that RH was negatively correlated to T, ETa, W and S, but it increased with increase of P. S, T and W had the greatest direct effects on RH in HXC, NXJ and SXJ, respectively. ETa was the factor which had the greatest indirect effect on RH in HXC and NXJ, while T was the dominant factor in SXJ.

  • Additional tsaganomyid, cylindrodontid and ctenodactyloid rodent materials from the Erden Obo section, Erlian Basin (Nei Mongol, China)

    分类: 生物学 >> 动物学 提交时间: 2020-08-02 合作期刊: 《古脊椎动物学报》

    摘要:To improve the Paleogene biochronological framework of the Erlian Basin, Nei Mongol and clarify the diversity of fossil rodents in this region, new tsaganomyids (Cyclomylus lohensis,Coelodontomys asiaticus) from the “Upper White” beds, cylindrodontids (Gobiocylindrodon sp.,Proardynomys sp., and Cylindrodontidae gen. et sp. indet.) from the “Middle Red” and “Lower Red” beds, and ctenodactyloids (Yuomys sp.) from the “Lower White” beds of the Erden Obo section are reported. The appearance of C. lohensis and Co. asiaticus from the Erden Obo section confirms that the age of the “Upper White” beds is Early Oligocene. The “Upper White” beds of the Erden Obo section and the top bed of the Nom Khong Obo are confirmed to belong to the same formation by both lithofacies and mammalian fossils. The different kinds of cylindrodontids found from the different horizons of the Erden Obo section show that the cylindrodontids had a high diversity and a relative continuous evolution in Eocene Asia.

  • Transfer Learning for Scientific Data Chain Extraction in Small Chemical Corpus with BERT-CRF Model

    分类: 计算机科学 >> 自然语言理解与机器翻译 提交时间: 2019-05-12

    摘要: Abstract. Computational chemistry develops fast in recent years due to the rapid growth and breakthroughs in AI. Thanks for the progress in natural language processing, researchers can extract more fine-grained knowledge in publications to stimulate the development in computational chemistry. While the works and corpora in chemical entity extraction have been restricted in the biomedicine or life science field instead of the chemistry field, we build a new corpus in chemical bond field anno- tated for 7 types of entities: compound, solvent, method, bond, reaction, pKa and pKa value. This paper presents a novel BERT-CRF model to build scientific chemical data chains by extracting 7 chemical entities and relations from publications. And we propose a joint model to ex- tract the entities and relations simultaneously. Experimental results on our Chemical Special Corpus demonstrate that we achieve state-of-art and competitive NER performance.

  • The incisor enamel microstructure of Mina hui (Mammalia, Glires) and its implication for the taxonomy of basal Glires

    分类: 生物学 >> 动物学 提交时间: 2017-11-07 合作期刊: 《古脊椎动物学报》

    摘要:The incisor enamel microstructure of Mina hui Li et al., 2016 from the upper Wanghudun Formation, Middle Paleogene of Qianshan, Anhui is described following the hierarchical system ranging from crystallites to Schmelzmuster. The enamel sample was taken from the upper incisor of the holotype. The enamel consists of a very thin prismless external layer, a relatively thick outer layer (PE) with radial enamel and an inner layer (PI) with multilayered Hunter-Schreger bands (HSB). The thickness of HSB is irregular and the inclination has a small angle; no transition zones between the HSB; prism cross sections are irregularly round; interprismatic matrix is very thick with crystallites in the PE running parallel to the prism long axes. These characters resemble pauciserial HSB in rodents. Ribbon-like prism seams and convergent crystallite discontinuities are consistent in different portions of the enamel, which are interpreted as a primitive feature for Glires, or even placental mammals. Compared with known enamel structure of basal Glires, the enamel of Mina stands for the earliest known evidence of double-layered enamel of the group. It indicates that the early evolution of Glires and placental mammals is complex and adds more details to the enamel microstructure of the earliest Glires.

  • A synopsis of Paleocene stratigraphy and vertebrate paleontology in the Qianshan Basin, Anhui, China

    分类: 生物学 >> 动物学 提交时间: 2017-11-07 合作期刊: 《古脊椎动物学报》

    摘要:The Mesozoic and Cenozoic redbeds in the Qianshan Basin comprise a set of monocline clastic rocks and are subdivided into the Late Cretaceous Gaohebu Formation, the Paleocene Wanghudun Formation (including the Lower, Middle, and Upper members) and Doumu Formation (including the Lower and Upper members). Continuous investigations in the Qianshan Basin since 1970 have resulted in discovery of a lot of vertebrate specimens. Up to date, 61 species (including 9 unnamed ones) in 45 genera of vertebrates, representing reptiles, birds and mammals, have been reported from the Paleocene of the Qianshan Basin. Among them, mammals are most diverse and have been classified into 46 species (7 unnamed) of 33 genera, representing 16 families in 10 orders. According to their stratigraphic occurrence, seven fossiliferous horizons can be recognized in the Qianshan Paleocene. Based on the evidence of mammalian biostratigraphy, the strata from the Lower Member through the lower part of the Upper Member of Wanghudun Formation could be roughly correlated to the Shanghu Formation of the Nanxiong Basin (Guangdong Province) and the Shizikou Formation of the Chijiang Basin (Jiangxi Province), corresponding to the Shanghuan Asian Land Mammal Age (ALMA). Both the upper part of the Upper Member of Wanghudun Formation and the Doumu Formation could be correlated to the Nongshan Formation of the Nanxiong Basin and the Chijiang Formation of the Chijiang Basin, corresponding to the Nongshanian ALMA. Paleomagnetic results from several Chinese Paleocene basins suggest that the Shanghuan is roughly correlative to the Puercan and Torrejonian North American Land Mammal Ages (NALMA), while the Nongshanian correlative to the early to middle Tiffanian (Ti1–4a). The Shanghuan and the Nongshanian are probably correlated to the Danian and the Selandian of the Global Geologic Time Scale. Therefore, all the fossil vertebrates collected in the Qianshan Basin are the Early and Middle Paleocene in age.

  • Introduction to terminologies of tooth enamel microstructures and a proposal for their standard Chinese translations

    分类: 地球科学 >> 地质学 提交时间: 2017-09-28 合作期刊: 《古脊椎动物学报》

    摘要:Tooth enamel is composed of elongated, hexagonal crystallites of hydroxyapatite. Some crystallites are arranged into various regual structures and futher formed a composite structure in a hierarchical manner. The hierarchical system can provide a basis for analysis different levels of structural complexity from varitaiton of particular crystallite strucutes to variation of structural types throughout a individual’s dentition. The size, orientation, distribution and the packing patterns of crystallites are gene-comtrolled and have limited range of intraspecific variability. Thus, these microstructures provide considerable and reliable morphological characters that help understanding of external dental morphology in context of both phylogeny and function in vertebrates. Because teeth are highly resistant to weathering, mainly owing to their enamel covering, so that they were commonly preserved as fossils. This organic system, particularly their microstructures, has attracted more and more attention from vertebrate paleontologists and other morphologists. However, as already recognized by many previous studies, some terminologies of the enamel microstructures have been complex and used inconsistently. Although considerable effort has been made to study enamel microstructures in China during the last few decades, a standard terminology of enamel microstructures in Chinese has not be formally brought into line with that in English literatures. Here we intend to introduce and systematize the relevant terminology used in the study of enamel microstructures and translate them into Chinese, in hoping that this systematic effort will enhance researches of enamel microstructures in China. 脊椎动物牙齿釉质显微结构具丰富的形态学特征,承载着系统发育和生物力学等方面的信息。本文在前人的研究基础上,试图系统地介绍牙釉质显微结构的基本内容,提出牙釉质研究中相关术语的中文译名建议,并对一些重要术语做了简要解释,供相关研究者参考,以期促进牙釉质显微结构研究的进一步发展。