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根据拉萨市呈带状布局的现状，结合拉萨市城市规划和铁路线路引入方向及路网规划等具体情况，提出拉萨地区铁路按客货分设的思路进行方案比选，对拉萨铁路地区总图规划研究，提出了总图规划方案，主要站段位置的构想，肝对近期工程的实施方案作了简要的论述。 相似文献
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根据拉萨市呈带状布局的现状, 结合拉萨市城市规划和铁路线路引入方向及路网规划等具体情况, 提出拉萨地区铁路按客货分设的思路进行方案比选. 对拉萨铁路地区总图规划研究, 提出了总图规划方案, 主要站段位置的构想, 并对近期工程的实施方案作了简要的论述. 相似文献
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西安都市圈道路网络化对景观格局的影响 总被引：1，自引：0，他引：1
在快速城市化过程中,道路网络快速扩张对区域生态景观的分割、隔离、破坏等是导致生态景观过程与格局演变的重要原因。研究道路网络化对景观格局的影响可为快速城市化地区生态、道路建设和区域可持续发展规划提供参考。本文以西安都市圈为例,利用GIS和RS技术,基于西安都市圈TM遥感影像和Arcgis 10.1、Fragstats 4.2软件平台,通过构建道路网空间指数,定量评价了路网空间结构和景观格局变化,并从空间上分析了道路网络化对景观格局的影响。结果表明:1)1985—2015年,西安都市圈路网发育不断成熟,基本呈现以西安市区为中心、空间指数向四周递减(除杨陵区和阎良区外)且东高西低的趋势。2)随着城市化进程的不断推进,西安都市圈景观呈现多样化、复杂化和破碎化。其中:园地、林地和建设用地规模扩大,景观聚集度上升;耕地、水域及滩涂景观破碎化程度不断加深。3)30年间,高等级道路的修建、低等级道路的不断完善以及市内环路打通等,使得西安都市圈路网逐渐完善,景观优势度下降,破碎化程度上升,形状趋于规则化。此外,路网发育的程度不同对不同地类的影响各不相同:路网成熟的区域,建设用地面积较多,形状较规则,呈聚集状态,林地面积较少,且零星分布,破碎化程度较高;道路结构简单的区域,林地聚集成片,聚集度较高,耕地、水域及滩涂在路网空间指数各等级影响域内均呈现破碎化状态,且形状较不规则。 相似文献
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贵阳地区下三叠统安顺组中的遗迹化石是研究P-T生物大灭绝后古环境、古生态的良好材料,在研究区发现、描述了8个遗迹属,9个遗迹种。安顺组中遗迹化石的垂向分布表明:安顺组一段以结构单一、个体较小的遗迹化石Planolites montanus,Palaeophycus curvatus和Phycodes palmatus为主;二、三段中遗迹化石属种增多、生物扰动增强,除了一段的3个遗迹种外还发现有6个遗迹种:Beaconichnus darwinum,Chondrites recurvus, Thalassinoides paradoxicus,Thalassinoides horizontalis,Arenicolites isp.,Rhizocorallium commune,在三段出现的复杂遗迹化石Rhizocorallium commune和Thalassinoides paradoxicus代表了本地区海洋环境在早三叠世晚期的重大改善。岩性特征和生物化石特征表明安顺组一段上部为台缘浅滩环境,二段为碳酸盐岩台地边缘斜坡环境,三段为靠近台地边缘的潮间-潮下环境,在一至三段沉积期,海水含氧条件有所改善,研究区处于浅海“宜居带”上。安顺组四段沉积于半局限台地内的潮间-潮上环境,处于“宜居带”之外,在此区域遗迹化石不发育,生物活动相对较弱。早三叠世奥伦尼克期遗迹化石发育特征表明生物复苏活动在碳酸盐岩台地边缘带相对活跃。 相似文献
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O. A. Ershova V. M. Lipunov E. S. Gorbovskoy N. V. Tyurina V. G. Kornilov D. S. Zimnukhov A. Gabovich O. A. Gress N. M. Budnev V. V. Yurkov V. V. Vladimirov A. S. Kuznetsov P. V. Balanutsa R. Rebolo M. Serra-Ricart D. Buckley R. Podesta H. Levato C. Lopez F. Podesta C. Francile C. Mallamaci S. A. Yazev D. M. Vlasenko A. Tlatov V. Senik V. Grinshpun A. Chasovnikov V. Topolev A. Pozdnyakov K. Zhirkov D. Kuvshinov F. Balakin 《Astronomy Reports》2020,64(2):126-158
We present the results of early observations for 130 error-boxes of gamma-ray bursts performed with the Mobile Astronomical System of TElescope-Robots (MASTER) global network of robotic telescopes from Moscow State University in fully automatic mode (2011–2017). Among them, GRB 130907A, GRB 120811C, GRB 110801A, GRB 120404A, GRB 140129B, GRB140311B, and GRB 160227A are considered in details. Among these 130 gamma-ray bursts, in the first 60 s after the trigger with the Swift, Fermi, INTEGRAL, MAXI, Lomonosov, and Konus-Wind orbital observatories, the MASTER was pointed on 51 gamma-ray bursts, being the leader in terms of the first pointing. Full observation automation and MASTER own real-time image processing software allowed us to obtain unique data on early optical emission that accompanied 44 gamma-ray bursts (GRB 110801A, GRB120106A, GRB 120404A, GRB 120811C, GRB 120907A, GRB 121011A, GRB 130122A, GRB 130907A, GRB 131030A, GRB 131125A, GRB 140103A, GRB 140108A, GRB 140129B, GRB 140206A, GRB 140304A, GRB 140311B, GRB 140512A, GRB 140629A, GRB 140801A, GRB140907A, GRB 140930B, GRB141028A, GRB 141225A, GRB 150210A, GRB 150211A, GRB 150301B, GRB 150323C, GRB 150404A/Fermi trigger 449861706, GRB 150403A, GRB 150413A, GRB 150518A, GRB 150627A, GRB 151021A, GRB 151215A, GRB 160104A, GRB 160117B, GRB 160131A, GRB 160227A, GRB 160425A, GRB 160611A, GRB 160625B, GRB 160804A, GRB 160910A, GRB 161017A, GRB 161117A, GRB 161119A). We obtain light curves for 13 gamma-ray bursts among the above listed ones and compare the data in the optical (MASTER), X-ray (Swift-XRT), and hard X-ray (Swift-BAT) ranges. 相似文献
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Nazire
zgen-Erdem Mehmet Akyaz&#x; Asl&#x; Karabaolu 《Journal of Asian Earth Sciences》2007,29(5-6):911-927
The Ilerdian–Middle Cuisian sedimentary succession of the Seyitgazi region, southern Eskişehir (Central Anatolia, Turkey) is composed of claystones, limestones and clayey limestones. It contains abundant benthic foraminifera, particularly species of Alveolina. From this succession, 28 species of Alveolina d’Orbigny are described and their comparative stratigraphic distribution with the Alveolina species in the Tethyan Eocene is documented. Generally, Ilerdian–Cuisian Alveolina assemblages of the Seyitgazi region have close affinities with coeval Alveolina assemblages described in different studies from the Tethyan Province. The Ilerdian unit of the study area is characterized by Alveolina species such as Glomalveolina lepidula, Glomalveolina minutula, G. karsica, Alveolina vredenburgi, A. ellipsoidalis, A. avellana, A. aff. minervensis, A. dedolia, A. moussoulensis, A. subpyrenaica, A. laxa, A. aragonensis, A. varians, A. ilerdensis, A. trempina, A. citrea, A. pisella and A. decipiens. Likewise, the Early Middle Cuisian unit is represented by G. minutula, A. oblonga, A. schwageri, A. haymanensis, A. canavarii, A. aff. coudurensis, A. ruetimeyeri, A. muscatensis, A. cremae, A. bayburtensis and A. lehneri. 相似文献
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本文利用《辽史》中“帝王纪”、“游幸表”、“食货志”和同时代“宋人使辽语录”中所记载的有关旱、涝、冻灾记录,对928～1109年共182年间燕北地区的历史气候进行了复原。研究结果表明,辽代燕北地区的干湿变化过程中,早期以干为主,中、晚期以湿为主。1080年前后为一气温剧烈下降时期,比黄淮海地区的同期变化要早约30年。 相似文献
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The Neoproterozoic Katangan R.A.T. (“Roches Argilo-Talqueuses”) Subgroup is a sedimentary sequence composed of red massive to irregularly bedded terrigenous-dolomitic rocks occurring at the base of the Katangan succession in Congo. Red R.A.T. is rarely exposed in a continuous section because it was affected by a major layer-parallel décollement during the Lufilian thrusting. However, in a number of thrust sheets, Red R.A.T. is in conformable sedimentary contact with Grey R.A.T which forms the base of the Mines Subgroup. Apart from the colour difference reflecting distinct depositional redox conditions, lithological, petrographical and geochemical features of Red and Grey R.A.T. are similar. A continuous sedimentary transition between these two lithological units is shown by the occurrence of variegated to yellowish R.A.T. The D. Strat. “Dolomies Stratifiées” formation of the Mines Subgroup conformably overlies the Grey R.A.T. In addition, a transitional gradation between Grey R.A.T. and D. Strat. occurs in most Cu–Co mines in Katanga and is marked by interbedding of Grey R.A.T.-type and D. Strat.-type layers or by a progressive petrographic and lithologic transition from R.A.T. to D. Strat. Thus, there is an unquestionable sedimentary transition between Grey R.A.T. and D. Strat. and between Grey R.A.T. and Red R.A.T.The R.A.T. Subgroup stratigraphically underlies the Mines Subgroup and therefore R.A.T. cannot be comprised of syn-orogenic sediments deposited upon the Kundelungu (formerly “Upper Kundelungu”) Group as suggested by Wendorff (2000). As a consequence, the Grey R.A.T. Cu–Co mineralisation definitely is part of the Mines Subgroup Lower Orebody, and does not represent a distinct generation of stratiform Cu–Co sulphide mineralisation younger than the Roan orebodies. 相似文献
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1987年8月王宁等报道具有八次对称轴准晶的高分辨图象,呈现出正八边形相嵌的图案。本文认为从配位多面体理论上对八次对称存在的可能性加以研究是有必要的,为此提出了具有十次配位的等腰三角十六面体和一系列带帽反棱柱,精确地求出了这些十六面体的顶点间的夹角、棱长和晶面法线与四次轴间的夹角等几何参数,作为应用对于Cr—V—Ni—Si八次对称准晶,设Ni原子（简称原子A）位于多面体中心,而V,Cr,Si原子（简称原子B）位于顶点上,原子A和B之半径分别为1.24（?）和1.32（?）,间隙0≤（?）（?）≤0.6（?）.则:（1）若原子A和B按等腰三角十六面体配位且A,B的键长为（2.56+δ）（?）,则原子B间的键长为1.08（2.56+δ）（?）或1.29（2.56+δ）（?）;（2）若原子A和B按带帽反棱柱配位且呈“紧密堆积”,则原子A和B之间的键长为（2.56+δ）（?）或（2.56+δ）(0.511+（0.261+[0.08/（2.56+δ）]n）1/2（?） 相似文献
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Permo-Carboniferous Radiolarians from the Wupata''''erkan Group,Western South Tianshan, Xinjiang, China 总被引：3，自引：0，他引：3
LI Yuejun SUN Longde WU Haoruo ZHANG Guangya WANG Guolin HUANG Zhibin Institute of Geology Geophysics Chinese Academy of Sciences Beijing Tarim Oilfield Company PetroChina Korla Xinjiang 《《地质学报》英文版》2005,(1)
1 IntroductionThe Wupata'erkan Group, also called Wupata'erkanFormation (Wang et al., 1990), in the western SouthTianshan, China (Fig. 1), mainly comprises gray and darkgray fine-grained clastic rocks, interlayered with medium-acidic volcanic rocks (andesite and quartz porphyry),carbonates, cherts and variegated tuffaceousconglomerates. The chert in the formation was firstly foundin our field trip along sections of the Qiqi'erjianakesu Riverand Kekebiele Daban. Deformation of the group is… 相似文献
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LI Yuejun SUN Longde WU Haoruo ZHANG Guangy WANG Guolin HUANG Zhibin Institute of Geology Geophysics Chinese Academy of Sciences Beijing Tarim Oilfield Company PetroChin Korl Xinjiang 《《地质学报》英文版》2005,79(1)
1 IntroductionThe Wupata'erkan Group, also called Wupata'erkanFormation (Wang et al., 1990), in the western SouthTianshan, China (Fig. 1), mainly comprises gray and darkgray fine-grained clastic rocks, interlayered with medium-acidic volcanic rocks (andesite and quartz porphyry),carbonates, cherts and variegated tuffaceousconglomerates. The chert in the formation was firstly foundin our field trip along sections of the Qiqi'erjianakesu Riverand Kekebiele Daban. Deformation of the group is… 相似文献
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Afrobolivina afra, a Late Cretaceous bolivinid foraminifer, became extinct in the Early Paleocene. It was succeeded by the smaller, morphologically similar species Afrobolivina africana. Morphological variation in A. afra was in part correlated with environmental factors showing a pattern of random fluctuations about long-term ecological trends. A gradual, persistent and unbroken environmental trend, related to a eustatic fall in sea-level, is significantly correlated with the morphological evolution of the species. The micro-biogeography of A. afra at the time it was approaching extinction is consistent with its having given rise to A. afracana allopatrically in a manner which can be described by a fold-catastrophe adaptive model. This mode predicts that A. afra should undergo quantum evolution to A. africana in a restricted area in a near-shore environment.However, detailed study of borehole material reveals an apparent parabolic increase in the overall size of A. afra prior to extinction and it is argued that as a result, A. africana cannot be the direct descendant of A. afra without there having been some “discontinuity” in the environment or evolutionary process. This suggests that the sudden replacement of a species by a smaller, morphologically similar form may not be a straightforward succession. The apparent parabolic increase in size of A. afra can be modelled by the fold catastrophe of Thom theory if interpreted as representing the initial phase of a form of adaptive quantum evolution in which a gradual environmental change causes a fitness peak to be absorbed into the flank of a higher peak.In terms of such a model, the absence of a larger descendant species suggests that A. afra could have been replaced by A. africana before the quantum threshold had been reached. A possible cause for this could be that the changes in the environment might have lowered the height of the fitness function in the vicinity of the peak for A. afra to below that of the peak for A. africana, or vice versa. 相似文献
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Rajeev?SARASWAT Manumalenki?MANASA Thejasino?SUOKHRIE Mohammad?Syed?SAALIM Rajiv?NIGAM 《《地质学报》英文版》2017,91(6):2268-2282
A total of 97 surface sediment samples were collected from the continental shelf and slope of the western Bay of Bengal to assess the potential application of Asterorotalia trispinosa as a paleomonsoon proxy. The relative abundance of living as well as total (living and dead) A. trispinosa ranges from being absent to a maximum of ~31%. The highest abundance of A. trispinosa is close to the outfall region of the Ganga-Brahmaputra Rivers and decreases away from the river mouths. Contrary to that, A. trispinosa is rare in front of both the Cauvery and Pennar river outfall regions, in the central part of the western Bay of Bengal. The living A. trispinosa abundance is the lowest in between two major river systems, viz. Ganga-Brahmaputra-Mahanadi and Krishna-Godavari. The relative abundance of both the total and living A. trispinosa is strongly positively correlated with ambient seawater temperature, and negatively correlated with %Corg and salinity. Based on the spatial distribution, we conclude that A. trispinosa is stenohaline in nature, rather than euryhaline, and further that the increased relative abundance of A. trispinosa indicates warmer and only marginally hyposaline environment. Even though the ecological preference of A. trispinosa suggests it as a potential paleomonsoon proxy, the restricted distribution implies limited application. 相似文献