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1.
Dedicated to Prof. Dr. H. Risler and Prof. Dr. Dr. h. c. R. K Zahn  相似文献   

2.
Bravoceratops polyphemus gen. et sp. nov. is a large chasmosaurine ceratopsid from the lowermost part of the Javelina Formation (early Maastrichtian) of Big Bend National Park, TX, USA. B. polyphemus has a distinctive narrow snout, a long fenestrate frill, and a fan-shaped median parietal bar with a midline epiparietal on its posterior margin, as well as a symmetrical depression on its dorsal surface at the nexus of the parietal rami. This depression is interpreted to be the attachment point for a second midline epiparietal. This parietal morphology is distinct from that exhibited by Anchiceratops or Pentaceratops. The posterior midline epiparietal in B. polyphemus and its bifurcated quadratojugal–squamosal joint are features shared with the most derived chasmosaurines, Torosaurus and Triceratops. The combination of primitive and derived traits exhibited by B. polyphemus, and its stratigraphic position, is compatible with the gradual transition from basal, to intermediate, to derived chasmosaurines observed throughout the western interior of North America, and with phylogenetic analysis, which suggests that Bravoceratops may be closely related to Coahuilaceratops.  相似文献   

3.
The chloroplast gene rbcL was sequenced to elucidate the evolution of the gymnosperm plant order Cycadales. In accordance with traditional systematics, the order Cycadales and the corresponding genera cluster as monophyletic clades. Among them, the genus Cycas forms a basal group. The genetic distances within the genus Encephalartos and between the sister groups Encephalartos, Lepidozamia and Macrozamia, are unexpectedly small, suggesting that the extant species are the result of Miocene and Pliocene speciation. Their distribution in Africa or Australia, respectively, may therefore rather be due to long-distance dispersal than to Cretaceous continental drift, as had previously been assumed. The rbcL sequences also indicate that the colonisation of Madagascar by Cycas thouarsii occurred only recently as the sequences of C. thouarsii and Cycas rumphii from Indonesia are identical. In contrast, the divergence of the Cycadaceae and Zamiaceae apparently occurred in the Mesozoic.  相似文献   

4.
The objectives of this work are to use gene sequence data to assess the hypothesis that the Lithodinae arose from ancestors with uncalcified abdomens in shallow waters of the North-East Pacific, investigate the monophyly and interrelationships of genera within the Lithodinae and to estimate the scale and minimum number of biogeographic transitions from the shallow environment to the deep sea and vice versa. To do this, phylogenetic analysis from three mitochondrial and three nuclear markers was conducted using minimum evolution, maximum likelihood and Bayesian methods. The Lithodinae as defined to include North Pacific genus Cryptolithodes may be paraphyletic, with the Hapalogastrinae and Cryptolithodes as sister taxa. This implies that the soft-bodied abdomen of the Hapalogastrinae might not be plesiomorphic for the Lithodidae. Paralomis, Lopholithodes, Phyllolithodes, Lithodes and Neolithodes share a common ancestor, from which the North Pacific Hapalogastrinae did not descend. Lithodid ancestors are likely to have had a north Pacific, shallow water distribution and to have had planktotrophic larvae. North Pacific genus Paralithodes is paraphyletic; P. brevipes is the most basal member of the genus (as sampled) while P. camtschaticus and P. platypus are more closely related to the genera Lithodes and Neolithodes. Genera Lithodes, Neolithodes and Paralomis (as sampled) are monophyletic if Glyptolithodes is included within Paralomis. Lopholithodes is closely related to, but not included within, the Paralomis genus. Paralomis is divided into at least two major lineages: one containing South Atlantic, West African, and Indian Ocean species, and the other containing Pacific and South American species. Several species of Paralomis do not resolve consistently with any other groups sampled, implying a complex and possibly rapid global evolution early in the history of the genus. Relationships within the Lithodes genus vary between analytical methods, suggesting that conclusions may not be stable. Consistently, however, Indian Ocean and Pacific forms—L. murrayi, L. longispina and L. nintokuae form a group separated from Atlantic species such as L. santolla, L. confundens, L. maja and L. ferox.  相似文献   

5.
源远流长的民间游戏,是我国文化宝库中的一支瑰丽奇葩,也是珍贵的文化遗产。民间游戏有一定的娱乐性、教育性、随意性。民间游戏内容丰富:有促进语言发展的,有反应传统文化的、有促进肢体动作的。只要简单材料,甚至没有材料都能随时随地组织玩。民间游戏组织形式灵活多样:有单独的,有多人的,还有能锻炼幼儿之间的协商、合作能力的。民间游戏有易学、易会、易传的特点,也符合幼儿好动、好学、好模仿、好游戏的心理特点。  相似文献   

6.
Toothless pterosaurs played a key role in broadening the taxonomic, morphological and ecological diversity of Cretaceous pterosaurs. Here we report a complete, articulated skeleton of a 1.4-m-wingspan pterosaur from the Lower Cretaceous Jiufotang Formation of Liaoning Province, China which is identified as a new genus and species, Shenzhoupterus chaoyangensis gen. et sp. nov. The new taxon is edentulous, with a relatively large skull and a remarkably large, tall nasoantorbital fenestra that extends well above the main part of the braincase. Phylogenetic analysis shows that Shenzhoupterus gen. nov. belongs in a distinct clade of azhdarchoid pterosaurs, formally recognised here as a new family, Chaoyangopteridae, that also includes Chaoyangopterus, Jidapterus and Eoazhdarcho from the Jiufotang Formation and Eopteranodon from the Yixian Formation. These new data clarify recent confusion surrounding the systematics of these Lower Cretaceous taxa and provide new insights into the evolutionary history of pterosaurs.  相似文献   

7.
A temnospondyl ilium from the uppermost Toutunhe Formation (Middle Jurassic, Callovian) of the southern Junggar Basin is described. Among the known temnospondyls it is very unusual in morphology because of its very long and slender shaft. It compares closely only to the ilium of one of the latest known trematosaurids from the Ladinian of southern Germany. The Toutunhe Formation has also yielded vertebrae and skull fragments of temnospondyls which belong to the brachyopid Gobiops from the Upper Jurassic of Mongolia. Brachyopoid ilia do not, however, display a morphology similar to that of the new specimen. It is therefore concluded that this specimen represents a second taxon of temnospondyl from the Toutunhe Formation, which probably represents the latest surviving trematosauroid. The Trematosauroidea, which was hitherto exclusively known from the Lower to early Upper Triassic, therefore joins the Brachyopoidea – and possibly the Capitosauroidea – as another group of temnospondyls which survived the end-Triassic mass extinction.  相似文献   

8.
The NMEP programme consists of 29 sites at which samples of stone and metals are being exposed for a minimum of 4 years to determine rates of decay in the current pollution climate. The sites were chosen to cover a wide range of environmental conditions, climate and topography. Information on meteorological conditions and atmospheric pollutants is being collected from all the sites. Four of the sites also form part of an international programme that is operating concurrently for the United Nations Economic Commission for Europe (UNECE).The stone tablets are 50 × 50 × 8 mm and are exposed on freely rotating carousels in sheltered and unsheltered positions which represent the washed and unwashed areas of buildings. Tablets of Portland limestone and White Mansfield dolomitic sandstone are exposed at all sites and in addition Monks Park limestone is exposed at the nine sites. Prior to exposure the tablets were cleaned and weighed, and in some cases the surface roughness was measured using an oblique light source and image analysis system.Tablets have been retrieved after 1 and 2 years of exposure and re-weighed following drying. Samples of powder have been removed from the surface of pristine, sheltered and unsheltered tablets and analysed using ion-chromatography for soluble ionic species (Ca2+, Mg2+, Na+, NH4+, SO4−4, NO3, Cl). The results showed the expected increases in acid species and soluble calcium in the sheltered tablets and increases in chlorides in tablets exposed near to the coast. Tablet surfaces have also been studied to obtain further diagnostic detail.The results from the analysis of the stone tablets and from the monitoring of pollutant concentrations and meteorological variables have been used to identify empirical relationships and as a basis for mathematical modelling. Preliminary findings from these studies are presented in this paper.  相似文献   

9.
As part of a U.K. National Materials Exposure Programme, samples of stone and metals are being exposed at 29 sites for a minimum of 4 years. The sites were chosen to cover a wide range of environmental conditions, climate and topography. Information on meteorological conditions and atmospheric pollutants are being collected from all the sites. Four of the sites also form part of an international programme that is operating concurrently for the United Nations Economic Commission for Europe (UNECE).Results are reported from the exposure test on bare mild steel, galvanized steel, painted steel, copper and aluminium. Rates of corrosion in industrial areas are well below those reported for similar sites in 1930–1960, mainly because of the large fall in sulphur dioxide concentrations, and in many cases the scale is becoming increasingly protective. Rates for aluminium are extremely low.The measured mass losses have been fitted to a variety of simple multivariate correlation functions. Work using continuous corrosion monitors suggests (in agreement with the mass-loss data) that:
  1. 1.(i) the rate of corrosion of steel is controlled in British conditions mainly by the long-term average sulphur dioxide concentration, and scarcely responds to short-term SO2 episodes;
  2. 2.(ii) nitrogen oxide concentrations have little effect on the rate of corrosion;
  3. 3.(iii) the chloride content of rain is not a very important factor for steel corrosion rates except at a few coastal sites.
  相似文献   

10.
Harvestmen (Arachnida: Opiliones) are familiar animals in most terrestrial habitats but are rare as fossils, with only a handful of species known from each of the Palaeozoic, Mesozoic, and Cenozoic eras. Fossil harvestmen from Middle Jurassic (ca. 165 Ma) strata of Daohugou, Inner Mongolia, China, are described as Mesobunus martensi gen. et sp. nov. and Daohugopilio sheari gen. et sp. nov.; the two genera differ primarily in the relative length of their legs and details of the pedipalps. Jurassic arachnids are extremely rare and these fossils represent the first Jurassic, and only the fourth Mesozoic, record of Opiliones. These remarkably well-preserved and modern-looking fossils are assigned to the Eupnoi, whereby M. martensi demonstrably belongs in Sclerosomatidae. It thus represents the oldest record of a modern harvestman family and implies a high degree of evolutionary stasis among one of the most widespread and abundant groups of long-legged, round-bodied harvestmen.  相似文献   

11.
Post-Triassic theropod, sauropodomorph, and ornithischian dinosaurs are readily recognized based on the set of traits that typically characterize each of these groups. On the contrary, most of the early members of those lineages lack such specializations, but share a range of generalized traits also seen in more basal dinosauromorphs. Here, we report on a new Late Triassic dinosaur from the Santa Maria Formation of Rio Grande do Sul, southern Brazil. The specimen comprises the disarticulated partial skeleton of a single individual, including most of the skull bones. Based on four phylogenetic analyses, the new dinosaur fits consistently on the sauropodomorph stem, but lacks several typical features of sauropodomorphs, showing dinosaur plesiomorphies together with some neotheropod traits. This is not an exception among basal dinosaurs, the early radiation of which is characterized by a mosaic pattern of character acquisition, resulting in the uncertain phylogenetic placement of various early members of the group.  相似文献   

12.
13.
陈子方  李琴  赵勇胜 《中国环境科学》2015,35(12):3628-3633
通过批实验研究了Al(III)对糖浆溶液化学还原六价铬反应的影响,揭示了不同条件下Al(III)对六价铬还原反应动力学的影响.结果表明:Al(III)能够促进糖浆溶液还原六价铬反应进行;其作用机制是Al(III)与糖浆溶液中有机还原物质及Cr(VI)反应形成三者的络合物,降低糖浆中多酚等有机还原物质还原Cr(VI)的反应活化能,提高六价铬还原反应速率.Al(III)存在时,该六价铬还原反应符合准一级动力学反应; pH 2.0,2.5,3.0,3.5时,添加Al(III)的实验组中六价铬反应速率常数比对应的空白对照组中反应速率常数分别增加了0.0251,0.0139,0.0058, 0.0048h-1.添加Al(III)前后反应体系中六价铬还原的反应活化能(Eа)分别为66.38,62.80kJ/mol.当糖浆浓度不足时,Al(III)能够提高糖浆溶液还原六价铬的反应去除率.  相似文献   

14.
15.
We report on the earliest modern mongooses of Africa, from the late Miocene (ca. 7 Ma) of the hominid locality TM 266, Toros-Menalla, Chad. The material is based on fragmentary dentitions of three individuals. The main diagnostic feature of the Chadian species is the great development of the shear in the carnassials, which distinguishes the Chadian specimens from all extant herpestids except Herpestes and Galerella. In comparison with most extinct and extant Herpestes, the species from Toros-Menalla differs by a markedly smaller size and, depending on the species, relatively more elongated carnassials, more transversely elongated M1 and more reduced p4. On the basis of a great morphological similarity and the absence of significant differences, we assign our material to Galerella sanguinea; the Chadian finding therefore represents the earliest appearance of an extant species of Herpestidae. This record ties the first appearance of the genus to a minimum age of ca. 7 Ma, which is consistent with the estimated divergence date of 11.4 Ma known from the literature for the species of Galerella.  相似文献   

16.
以TEOS为硅源的聚硅氯化铝絮凝剂的制备及其物化特征   总被引:7,自引:0,他引:7  
采用TEOS为硅源合成制备了新型的聚硅氯化铝PASC(A),并与传统方法合成的聚硅氯化铝PASC(B) 做了比较,探讨了产品的pH值和Zeta电位随B值和Si/Al摩尔比的变化关系,并利用酸解反应和27Al NMR研究了硅引入对PASC分子结构和铝形态的影响.结果表明,由于采用了特殊的合成方法,与PASC(B)相比,PASC(A)具有更高的聚合度,分子量分布并且分子中铝硅分布均匀,不易被酸解聚,而且有利于Al13形态稳定性.  相似文献   

17.
18.
The Xijiang River is the major source of water for about 4.5 millions of urban population and 28.7 millions of rural population. The water quality is very important for the health of the rural population. The concentration and distribution of chlorobenzenes (CBs) in both water and waterweeds collected from 4 stations in the Xijiang River (Gangdong section) of the Pearl River in April and November were determined. The result showed that nearly every congener of CBs was detected. The total contents of CBs (∑CBs) in the river water ranged from 111.1 to 360.0 ng/L in April and from 151.9 to 481.7 ng/L in November, respectively. The pollution level of CBs in the water in April was higher than that in November. The contents of ∑ CBs in waterweeds ranged from 13.53×102 μg/g to 38.27×102μg/g dry weight (dw). There was no significant difference between April and November in waterweeds. The distribution of CBs in roots, caulis, and leaves of Vallisneria spiralis L. showed different patterns. The leaves mainly contained low-molecular-weight CBs(DCBs), whereas the roots accumulated more PCBs and HCBs. The average lgBCFlip (bioconcentration factor) of CBs ranged from 0.64 to 3.57 in the waterweeds. The spatial distribution character of CBs in the Xijiang River was: Fengkai County < Yunan County <Yun'an County < Gaoyao County according to the ∑CBs, and the pollution deteriorated from the upstream to the downstream of the Xijiang River. Further analysis demonstrated that the discharge of waste containing CBs may be the main source of CBs pollution in the Xijiang River.  相似文献   

19.
电压对电动修复Cr(Ⅵ)污染高岭土的影响研究   总被引:2,自引:0,他引:2  
试验选用重铬酸钾作为污染物,配制高岭土中Cr(Ⅵ)初始质量分数为500mg·kg-1.试验研究了不同电压下的电动修复效率和单位能耗,并结合经济效益找出合适的电压范围.试验结果表明:当电压为20V时,去除效率达到89.9%,单位能耗仅为93.04KW·h·g-1.当电压再增大的时候,去除效率提高较小,单位能耗增大迅速,不符合经济效益的要求.由于适宜的施加电压和土壤本身性质有很大联系,如何通过简单的方法确定适宜的施加电压,还需进一步研究.  相似文献   

20.
Per-and polyfluoroalkyl substances(PFASs) are ubiquitous in sludge and water from waste water treatment plants, as a result of their incorporation in everyday products and industrial processes. In this study, we measured several classes of persistent PFASs,precursors, transformation intermediates, and newly identified PFASs in influent and effluent sewage water and sludge from three municipal waste water treatment plants in Sweden, sampled in 2015. For sludge, samples from 2012 and 2014 were analyzed as well.Levels of precursors in sludge exceeded those of perfluoroalkyl acids and sulfonic acids(PFCAs and PFSAs), in 2015 the sum of polyfluoroalkyl phosphoric acid esters(PAPs) were 15–20 ng/g dry weight, the sum of fluorotelomer sulfonic acids(FTSAs) was 0.8–1.3 ng/g,and the sum of perfluorooctane sulfonamides and ethanols ranged from non-detected to 3.2 ng/g. Persistent PFSAs and PFCAs were detected at 1.9–3.9 ng/g and 2.4–7.3 ng/g dry weight, respectively. The influence of precursor compounds was further demonstrated by an observed substantial increase for a majority of the persistent PFCAs and PFSAs in water after waste water treatment. Perfluorohexanoic acid(PFHxA), perfluorooctanoic acid(PFOA), perfluorohexane sulfonic acid(PFHxS), and perfluorooctane sulfonic acid(PFOS)had a net mass increase in all WWTPs, with mean values of 83%, 28%, 37% and 58%,respectively. The load of precursors and intermediates in influent water and sludge combined with net mass increase support the hypothesis that degradation of precursor compounds is a significant contributor to PFAS contamination in the environment.  相似文献   

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