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31.
Du, W., Wang, X.L., Komiya, T., Zhao, R. & Wang, Y., April 2016. Dendroid multicellular thallophytes preserved in a Neoproterozoic black phosphorite in southern China. Alcheringa 40, xxx–xxx. ISSN 0311-5518.

A new form of dendroid multicellular thallophyte is documented in the Ediacaran Doushantuo phosphorite at Weng’an, Guizhou Province, southern China. The dendroid thallophytes have variable forms, possibly owing to heteromorphic variation. Many lateral branches extend from the upper portions of the main axes; the lateral branches bear terminal vegetative vesicles, reproductive vesicles, monosporangium-like discoidal vesicles and urn-shaped pseudoparenchymatous structures. The vegetative vesicles give rise to clavate pseudoparenchymatous structures, characterized by differentiation of the thallus medulla/cortex, which might represent an early stage of thallus development. An oogamous conceptacle arising from one carpogonial vesicle forms a highly specialized goblet-shaped conceptacle. The discovery of the new dendroid multicellular thallophytes provides not only the first fossil-based evidence of the morphological complexity and tissue differentiation in the Precambrian organisms but also insights into the life cycle of the Precambrian red algae.

Wei Du* [], School of Earth Sciences and Resources, China University of Geosciences, Beijing, PR China; Xun Lian Wang [], School of Earth Sciences and Resources, China University of Geosciences, Beijing, 100083, PR China; Tsuyoshi Komiya [], Graduate School of Arts and Sciences, University of Tokyo, Tokyo 153-8902, Japan. Ran Zhao [], Department of Earth and Planetary Science, University of Tokyo, Tokyo 113-0033, Japan. Yue Wang [], School of Resources and Environments, Guizhou University, Guiyang, 550025, PR China. *Also affiliated with Graduate School of Arts and Sciences, University of Tokyo, Tokyo 153-8902, Japan.  相似文献   

32.
周少明 《民俗研究》2000,(3):135-142
1988年,Evelyn s.Rawski曾提到历史学家与人类学家研究中国丧葬习俗的方法及由此引起的一些争论。Rawski指出,历史学家和人类学家研究中国丧葬仪式的方法是不同的。就人类学家而言,他们关心  相似文献   
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34.
早期上海小校场木版年画,深受苏州桃花坞年画影响,店铺多为仿冒桃花坞的作品。清末民初,小校场石印年画以其题材新颖、色彩艳丽、物美价廉而盛极一时,木版年画开始走向尾声。而月份牌年画的出现,又开创了中国年画史上一个特殊的辉煌时期。正是近代西方印刷技术的传入,彻底改变了中国年画的命运。上海小校场年画的嬗变,清晰地呈现了传统年画消亡的历程。  相似文献   
35.
This paper focuses on the study of simulations for spatially variable seismic underground motions in U-shaped canyons. First, a canyon ground cross-coherence function based on commonly used coherence function models of flat terrain, is deduced and presented. To further obtain the underground cross-coherence function, a mathematical expression, including its specific deduction process for describing the relationship between coherence functions of multi-support ground and underground motions, is also given in detail and adopted. Then, the key factors (i.e. canyon underground power spectrum density and canyon underground coherence function) for simulating the spatially variable seismic underground motions are obtained by a two-step transferring method from flat-ground to underground soil. Furthermore, a program is coded for generating the spatially variable seismic underground motions. The effectiveness of the generated seismic motions is further verified. Finally, two numerical examples are taken to validate the proposed simulation approach, illustrating the specific characteristics of canyon coherence function. The analysis results show the apparent differences of the simulated seismic motions using the canyon coherence function from those using conventional coherence function models of flat terrain. The proposed approach provides some insights for anti-earthquake analysis of soil-structure interaction or underground structures in canyon topography.  相似文献   
36.
研究木质文物中的细菌对木材腐蚀性影响,筛选防腐剂抑制腐蚀性强细菌的腐蚀作用,是延长木质文物保存期的一种有效的生物保护措施。为研究饱水木漆器F455及其水环境中细菌的种类,以及对木材的腐蚀程度,采用16S rRNA基因序列分析方法及生理生化试验,对饱水木漆器F455及水环境中细菌进行鉴定,并选取典型菌按5×10~8个/瓶菌量接种马尾松心材(悬于无菌自来水中),37℃培养120d,测试木材的损失率。结果发现,从F455文物挑选的32株细菌中,有29株菌鉴定为芽孢杆菌属(Bacillus),为优势菌属,其余为短杆菌属(Brevibacterium)、短波单胞菌属(Brevundimonas)和产碱杆菌属(Alcaligenes)各1株。水样样品中细菌菌属较F455文物样品中丰富,27株菌有9个属,其中短杆菌属(Brevibacterium)有9株,为优势菌属,其余交替赤细菌属(Altererythrobacter)有5株,短波单胞菌属(Brevundimonas)有4株,产碱杆菌属(Alcaligenes)有3株,黄杆菌属(Flavobacterium)有2株,芽孢杆菌属(Bacillus sp.)、白色杆菌属(Leucobacter)、类芽孢杆菌属(Paenibacillus)、苍白杆菌属(Ochrobactrum)各1株。从2种样品材料的分离菌中共挑选出14株典型菌进行木块腐蚀试验,与对照组比较,其中有9株菌差异极显著。说明这些菌对马尾松木材有一定的腐蚀作用,但是腐蚀率非常低,最高仅1.56%。表明这些细菌对试验木材马尾松腐蚀并不严重。该研究分析了饱水木漆器长期保存在水槽中细菌对木漆器的影响,丰富了饱水木漆器文物生物影响的理论依据。  相似文献   
37.
18世纪英国上流社会性道德问题突出,豢养情妇、通奸、嫖妓不一而足,在双重道德标准下,人们对这些问题见怪不怪。这些问题的存在是社会转型期道德价值体系混乱与缺失、上流社会婚姻制度缺陷、王室成员不良影响、欧陆尤其是法国影响等因素使然。这些问题的存在带坏了社会道德风气,对上流社会的家庭生活带来不利影响,引发政治腐败,损害了上流社会的声誉与威望,也引发了有识之士的批判与道德整肃运动的出现。  相似文献   
38.
The completeness of the complex response spectrum method for both formally underdamped and overdamped modes is theoretically proved, and the physical meanings of the decoupled modes as well as involved parameters are recognized and clarified in this paper. For the system with relatively large non-classical damping, the eigenvalue pairs generated by the complex mode decomposition method are real and the so-called modal damping ratios are larger than unity. In this paper, we firstly clarified that the decoupled modes are virtual and the so-called modal frequency and damping ratio are mathematical parameters that have no physical meaning. Then, the completeness of the complex response spectrum method for both formally underdamped and overdamped modes is rigorously proved by allowing the “damping frequency” to be an imaginary number. For the virtually overdamped modes, Duhamel integral involved in the calculation for formally underdamped modes automatically convert to hyperbolic Duhamel integral. A numerical example taken from the published literature is given to verify this method. Structural responses for the system with coupled damping under multi-support seismic excitations are further analyzed and numerical results indicate the accuracy of complex response spectrum method.  相似文献   
39.
本文主要研究了殷墟卜辞中一些与"火"有关的内容.例如"好火",凡对人类有益的自然现象称为"好",《尚书》中有"好风"、"好雨"."火"是阳精,古人认为阳气盛会降雨.卜辞中还有"执火",与祭祀活动有关."火"也会给人类造成极大危害,商王曾占卜火灾.  相似文献   
40.
对上海博物馆馆藏新品王件春秋早期的铜一铁复合兵器中铁的类型、制成方法、机械性能和材料组织进行了分析,以判明铁刃的原料来源和制作工艺。结果表明:铁刃基体成分为较纯的铁,没有发现镍元素,铁刃组织呈层状分布,结构疏松,合较多夹杂物和孔洞,夹杂物由硅酸盐类复相组成,证实了三件铜一铁复合兵器的铁刃是由人工冶铁锻制而麻  相似文献   
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