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A new bolosaurid parareptile, Belebey chengi sp. nov., is described from Dashankou, Gansu Province, China, a Middle Permian locality which is known mostly for its therapsid
fauna. The material consists of well-preserved mandibular and anterior skull remains and currently represents the largest
and latest surviving member of Bolosauridae. Phylogenetic analysis of bolosaurid interrelationships, the first analysis of
any clade of Early Permian parareptiles, indicates that the new taxon groups consistently with the other (Russian) members
of the genus Belebey, and forms the sister clade to the genus Bolosaurus from North America. The Early Permian Eudibamus cursoris from Germany falls into the basal most position within Bolosauridae. Our analysis also shows that the split between the main
bolosaurid lineages must have occurred near or before the Permo-Carboniferous boundary and that the paleo-equatorial region
of Laurasia probably served as the center of origination for these parareptiles. A similar pattern can be found in other clades
of Paleozoic amniotes, suggesting that this may be the general trend in early amniote evolution. 相似文献
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A juvenile lizard specimen with well-preserved skin impressions from the Upper Jurassic/Lower Cretaceous of Daohugou, Inner Mongolia, China 总被引:1,自引:0,他引:1
Lizards are now relatively well known from the Yixian Formation of northeastern China. In this study, we describe a juvenile
lizard from a fossil horizon at Daohugou, Inner Mongolia. These beds predate the Yixian Formation, and are probably Late Jurassic
or earliest Cretaceous in age. The new specimen thus documents the first lizard material from the Daohugou locality and is
the earliest lizard skeleton from China. Comparisons with developmental stages of modern lizards suggest the Daohugou lizard
is a hatchling. Although tiny, the specimen is notable in preserving exquisite skin impressions showing the variation in scalation
across the body, the shape and position of the cloacal outlet, and details of the manus and pes. These are the earliest recorded
lepidosaurian skin traces. In its general proportions and the possession of paired frontals, the small Daohugou lizard resembles
both the Yixian taxon Yabeinosaurus tenuis and the questionable Jeholacerta formosa, but it differs from the latter in scalation and, based on other characters, may be distinct from both. 相似文献
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环境风险预警方法与应急成套装备的应用展望 总被引:1,自引:0,他引:1
介绍了环境风险预警方法建立的环境风险预警指标体系、环境风险源管理平台、环境风险源风险评估技术方法以及模块式应急成套装备的技术特点等;分析了环境风险预警方法与应急成套设备在危险化学品环境风险与应急管理,在区域大气环境挥发性有机污染物(VOCs)监控预警等方面的实际需求。面临现实的环境风险状况从环境风险防控与应急工程技术研究中心建设角度提出了需进一步完善、开发的环境风险预测预警技术与应急成套装备等新思路。 相似文献
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长江三角洲地下水开采的负环境效应及其防治 总被引:1,自引:0,他引:1
长江三角洲位于以上海为中心的经济发达区,是我国经济实力最强、产业规模最大的地区.但是,随着经济的高速发展和人口的高度集中,也进一步加剧了对地下水的需求,使三角洲大部分地区普遍出现地下水位大幅下降,从而引起各种环境负效应,如地面沉降、地裂缝、地面塌陷、海水入侵和水质污染等,严重影响了长江三角洲经济可持续发展和人民群众生活质量的提高.本文对长江三角洲因地下水强烈开采而出现的一系列环境地质灾害进行了总结和讨论,并初步提出了有关防治对策和建议. 相似文献
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Maeva Judith Orliac Pierre-Olivier Antoine Grégoire Métais Laurent Marivaux Jean-Yves Crochet Jean-Loup Welcomme Syed Rafiqul Hassan Baqri Ghazala Roohi 《Die Naturwissenschaften》2009,96(8):911-920
New dental remains of listriodont suids are described from the lower member of the early to middle Miocene Vihowa Formation
of the Bugti Hills, Pakistan. The material is homogeneous in terms of morphology and dimensions and referred as a whole to
Listriodon guptai Pilgrim, 1926. This species is also mentioned in coeval deposits of the Zinda Pir Dome, Pakistan, dating back to ca. 19 Ma.
The early occurrence of an advanced listriodont in Pakistan constrains the age of acquisition of several characters correlated
to lophodonty within Listriodontini, and raises major questions about the early history of the Old World Listriodontinae.
Strong morphological similarity between Listriodon guptai and the African species Listriodon akatikubas found in the late early Miocene of Maboko (Kenya, ca. 16.5 Ma) suggests that this latter is most probably a migrant originating
from Asia. 相似文献
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Soizic Le Fur Emmanuel Fara Hassane Taïsso Mackaye Patrick Vignaud Michel Brunet 《Die Naturwissenschaften》2009,96(5):565-574
Characterizing the paleoenvironmental context of the first hominids is a key issue for understanding their behavioral and
morphological evolution. The present study aims at reconstructing the paleoenvironment of the TM266 vertebrate assemblage
(Toros-Menalla, Northern Chad) that yielded the earliest known hominid Sahelanthropus tchadensis (7 Ma). For the first time, a quantitative analysis is carried out on the fossil mammal assemblage associated with that hominid.
Two complementary approaches were applied: (1) the analysis of the relative abundances of taxa and their habitat preferences;
and (2) the study of the distribution of taxa within three meaningful ecovariables: locomotion, feeding preferences, and body
mass. The resulting taxonomic and paleoecological structures are used to reconstruct the diversity and the relative extent
of the habitats in that part of northern Chad seven million years ago. The paleoenvironment was composed of open areas with
dry and humid grasslands, prevailing over wooded habitats. Water was also widely available as freshwater bodies and certainly
swamps. It appears that the high habitat diversity of the landscape is a common feature among paleoenvironments associated
with early hominids. 相似文献
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Paolo Ciavola Oscar Ferreira Piet Haerens Mark Van Koningsveld Clara Armaroli Quentin LequeuxAuthor vitae 《Environmental Science & Policy》2011,14(7):912-923
The current paper discusses the topic of marine storm impact along European coastlines, presenting results from two FP7 Projects currently focusing on this topic, one working on the physical aspects of the problem (MICORE) and the other one on the socio-economic implications (ConHaz).The MICORE Project aims to provide on-line predictions of storm-related physical hazards (hydrodynamic as well as morphodynamic). The ConHaz Project addresses the socio-economic implications should these (or other) hazards actually materialize. Together these projects aim to deliver crucial information for emergency response efforts, while realizing the practical limitations for information processing and dissemination during crisis situations.The MICORE Project has developed and demonstrated on-line tools for reliable predictions of the morphological impact of marine storm events in support of civil protection mitigation strategies. The project specifically targeted the development of early warning and information systems to support short term emergency response in case of an extreme storm event. The current paper discusses in detail the outcome of an activity of databasing historical storm data. No clear changes in storminess were observed, except for some storm proxies (e.g. surges) and only at some locations (e.g. northern Adriatic, southern Baltic, etc.).The ConHaz Project undertook a desktop study of the methods normally used for evaluating the impact of marine storms and the associated coastal hazards considering direct costs, costs due to disruption of production processes, indirect costs, intangible costs, and costs of adaptation and mitigation measures. Several methods for cost estimation were reviewed. From the review it emerged that normally end-users only evaluate direct costs after the storms, while the cost of adaptation and mitigation measures is only done strategically in the context of Integrated Coastal Zone Management plans. As there is no standardized method for cost evaluations in this field, it is suggested that clear guidelines should be produced on the basis of simplicity for use by end-users. The integration between historical databases of the physical parameters of storms and detailed cost evaluation information would support the development of a knowledge background in end-users and justify the development of adaptation strategies. 相似文献
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以石油类储存为例,通过其在固定顶罐储存、装卸的呼吸排放和工作排放的计算分析,提出控制有机液体排放的工程技术措施和管理措施。 相似文献
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本文用统计学方法,分析研究了《海洋环境科学》近5a的抽样载文及引文情况。从中析出:本刊已拥有一批热心于海洋环保事业的科研队伍,形成了以辽宁、山东等地为核心的的海洋环境科研核心地区和相对稳定的研究体系。所载论文的内容广泛,几乎覆盖了海洋环境科学研究的各处领域。引文量高,比我国行业性技术行业性技术刊物篇均引文量2.8篇高5.27篇。 相似文献
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M. R. Thomas B. Tutschek A. Frost C. H. Rodeck N. Yazdani I. Craft R. Williamson 《黑龙江环境通报》1995,15(7):641-646
A single copy Y-chromosome DNA sequence was amplified using the polymerase chain reaction (PCR) from the peripheral blood of 30 women who had achieved a pregnancy through an in vitro fertilization (IVF) programme. The time of conception was known precisely and was confirmed by serial ultrasound scans. Conceptions were dated as the number of weeks after fertilization plus 2, to give a time equivalent to the obstetric menstrual dating of the pregnancy (LMP). Y-chromosome-specific DNA was detected in all pregnancies with a male fetus (18/30). The earliest detection was at 4 weeks and 5 days, and the latest at 7 weeks and 1 day. Y-chromosome-specific sequences were no longer detected in any of the male pregnancies 8 weeks after delivery. No Y-chromosome sequences were detected in any of the pregnancies where only female babies were delivered. This demonstrates that fetal DNA appears in the maternal circulation early in the first trimester, that it can be identified in all pregnancies tested by 7 weeks, that it continues to be present throughout pregnancy, and that it has been cleared from the maternal circulation 2 months after parturition. Early non-invasive prenatal diagnosis for aneuploidies and inherited disorders will be possible in all pregnancies if fetal cells can be isolated free from maternal contamination (or identified accurately in the presence of maternal cells) without problems of contamination from previous pregnancies. 相似文献
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汽车尾气污染及其净化处理技术 总被引:1,自引:0,他引:1
本文详细阐述了汽车尾气的有害成份及其对人类健康的危害。为此 ,应该采取净化处理措施 ,减少或者消除有害气体的产生 ,为大气环境洁净而创造条件。 相似文献
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氨法烟气脱硫脱硝具有显著的技术优势:脱硫效率高,脱硫脱硝一举两得,不耗费热量不产生废渣,脱硫剂利用充分用量小,不损害设备有节能功效。脱硫剂利用率可达90%以上,脱硫效率可达90%以上、脱硝效率可达80%以上;脱硫剂用量是钙法工艺的十到二十分之一;副产物为可以直接利用的化学肥料,而非难于处置的废渣。 相似文献
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"七五"以来浑河沈阳段水质变化趋势及原因分析 总被引:2,自引:0,他引:2
"七五"至"十五"二十年的时间里,浑河沈阳段水质经历了轻污染~污染~重污染~污染的变化过程,2005年,浑河沈阳段水质由连续13年的重污染级首次降到污染级.近年来,浑河沈阳段水质改善的原因主要得益于沈阳市创建国家环境保护模范城市的过程中,对浑河城市段采取的综合整治、城镇污水处理厂建设及环境水的调配等措施;但目前浑河沈阳段由于存在着季节性自然补给水不足、部分城镇污水直接排入地表水系、城镇基础设施尚不完善等问题,全河段仍为劣Ⅴ类水质."十一"五期间,沈阳市将通过采取继续加强城镇污水处理厂建设和对污染源进行总量控制等措施,使浑河沈阳段水质持续改善. 相似文献