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1.
贵州剑河寒武系凯里组软舌螺化石丰富、埋藏形式多样,其中以脊状单臂螺Haplophrentis carinatus化石数量最多、保存最为完整。过去有关学者对凯里组单臂螺化石的研究主要集中在化石分类学方面,对脊状单臂螺埋藏特征及与其他生物共生关系缺乏深入探讨。本文对324块脊状单臂螺化石标本进行系统研究对比后发现,凯里组脊状单臂螺口盖化石埋藏形式有四类:口盖单独保存、口盖以内模或外模化石形式保存、口盖与锥壳完全绞合保存、口盖与锥壳不完全绞合保存;附肢保存较少;锥壳多以内模化石形式保存;脊状单臂螺内模化石与印痕化石上普遍出现类似软体保存形成的三分叉结构,这类三分叉结构属于后期埋藏因素造成的次生结构。文中还对脊状单臂螺与始海百合共生关系进行探讨,并将二者共生关系归为偏害共生。  相似文献   

2.
近期在西乡化石库中发现了原始锥石类Carinachites tetrasulcatus新材料。与以往C.tetrasulcatus所不同的是,其角沟窄且浅,不但有呈现出张开状态的角沟,还发现有呈现出闭合状态的角沟化石材料。锥面具有清晰的横肋,角沟处未见横纹。最重要的是发现固着端组织结构的保存,据此推断原始锥石类可能为营固着生活的水螅型刺胞动物。其角沟的闭合、微张以便于扩大、缩小口端与中央腔,扰动海水,加快水流,加速滤食。处于梅树村阶第Ⅱ化石组合带的C.tetrasulcatus与处于第Ⅲ化石组合带的六方锥石科中的Septuconularia yanjiaheensis具有一致的闭合角沟和锥面横肋形态等特征,推断C.tetrasulcatus可能为骨状锥石类向六方锥石类演化的过渡类型。  相似文献   

3.
陕西迹(Shaanxilithes)见证了埃迪卡拉纪–寒武纪之交生物演化及生态环境的变化,是埃迪卡拉纪末期标志性的疑难化石,具有全球对比意义。本文首次报道了云南曲靖会泽县大海乡朱家箐剖面灯影组旧城段泥质灰岩中新发现的宁强陕西迹(Shaanxilithes ningqiangensis Xing, Yue and Zhang, 1984)。所采集的标本整体形态上呈条带状,边缘呈锯齿状参差不齐,可见环状体分布。通过镜下观察,可发现散落圆盘状单元。将大海乡朱家箐剖面与晋宁六街镇王家湾剖面渔户村组旧城段所产出的Shaanxilithes化石对比后发现,朱家箐剖面的标本宽度更窄,长度更长,碎片化更加明显。通过微区X射线荧光光谱仪(μ-XRF)将朱家箐剖面和王家湾剖面的标本进行对比分析后可知,前者形态在Si、Al、K的元素分布图中显示清晰,而后者的形态主要体现在Fe元素的分布图上;前者化石和围岩中Ca元素的含量远远高于后者;S元素仅在前者存在微量的分布,在后者中未有信号显示。新的化石证据表明Shaanxilithes并非只产出自碎屑岩中,还可以在灰岩中保存。化石μ-XRF的面扫描和半定量分析表明Shaanxilithes可能为伊利石矿物交代,并且说明在不同岩相背景下,风化作用程度的强弱造成两个产地化石的差异性保存。随着研究区域不断扩大, Shaanxilithes相继在华南板块滇东地区、印度西北缘、纳米比亚、华北板块西南缘等地区晚埃迪卡拉世地层中被发现。此次在滇东会泽地区发现的Shaanxilithes,进一步表明该化石分布的广泛性,可作为全球晚埃迪卡拉世地层对比的标准化石。本文结合形态学分析和微区X射线荧光光谱分析,讨论了Shaanxilithes的埋藏学信息与亲缘关系,为探索埃迪卡拉纪–寒武纪过渡时期的生物和生态特征提供了更多视角。  相似文献   

4.
陕南西乡张家沟剖面的寒武系下部岩层中发现了大量原始锥石类,根据整体形态特征和原始锥石类化石分类方案将其归属到六方锥石属Hexaconularia。前人对于六方锥石分类方案众多,本文对其进行重新厘定。本文报道的六方锥石新材料在中央锥面上具有两条不连续的角沟,这不仅丰富了种内特征,而且为六方锥石的壳体演化趋势提供了依据。前人发现的该类化石与本文描记的化石类型相同,产地不同,因而具有地层对比意义。  相似文献   

5.
北京十三陵地区位于燕山的中段,是华北晚前寒武纪地层发育良好的地区之一。本区雾迷山组厚两千余米,主要分布在萃花山,小宫门东山及卧虎山一带。数年前,笔者在本区萃花山雾迷山组一段采集到一批微小的柱状叠层石与层纹状藻席相互共生的标本,其中一些标本是由黑色燧石组成的。通过切片方法研究,我们发现在一些由黑色燧石组成的叠层石和藻席中保存有多种形态的微化石。作者扼要记述了这些微化石的形态特征,并将这一微化石群与世界其它地区的前寒武纪微生物组合进行比较,并探讨了这一微化石群的生态环境。  相似文献   

6.
叠锥石     
倪国平 《化石》2003,(2):22-22
叠锥石是藻类生物长期沉积作用形成的特殊构造体 ,为叠层石中之一种。其所具有的形态特征与真正的生物化石有区别 ,又和沉积岩的层纹状构造不同 ,为一特殊观赏石石种。该石的基本层相互叠合形成锥柱体 ,柱体的不同形态及石体的分叉情况是对叠层石的分类与鉴定的重要依据。该类石由于受成岩作用的破坏较大 ,完整的生物遗体难于保存。笔者获得的叠锥石 ,主要产于二叠纪峨眉山玄武岩顶部与侏罗纪相交的过度带的喷出岩碎屑层中。其底层叠层与柱体完好 ,层理形态清晰 ,集合体为黑黄色。该石具有美丽的造型 ,完好的生物遗迹 ,别具一格的锰铁与泥质…  相似文献   

7.
贵州剑河革东寒武纪凯里生物群中水母状化石属种单调,仅发现1属1种贵州拟轮盘水母钵Pararotadiscus guizhouensis(Zhao et Zhu,1994),但却有丰富的生态现象.近40%的标本与腕足类、三叶虫、金臂虫、棘皮动物或遗迹化石Gnrdia共存,是目前全球水母状化石中罕见的丰富生态现象.其中65件贵州拟轮盘水母钵盘体上、下或周围出现了背、腹壳分散保存的腕足类,说明腕足类与贵州拟轮盘水母钵共同埋藏;1块标本的丛状触手中还包裹有腕足类,说明丛状触手不是类似于植物根系的固着器.这种现象还证实贵州拟轮盘水母钵不是固着而是浮游生活的,其与腕足类壳瓣共存,主要是浮游的贵州拟轮盘水母钵死亡后沉落海底与腕足类壳瓣重叠的结果.  相似文献   

8.
Hiemalora stellaris是湖北宜昌三峡地区埃迪卡拉系灯影组石板滩生物群中数量最为丰富的化石类型之一,由位于中心位置的圆盘和围绕盘缘向外伸出的似触手状结构组成,似触手状结构长度与圆盘直径具有较好相关性。同时也发现少量Hiemalora与茎干相连,其中一枚产自石板滩段底部的标本保存完整,与茎干连接有叶状体。叶状体呈卵形,可见一级分枝与二级分枝,顶部有呈"牛角状"的尖刺,叶状体形态与Charniodiscus spinosus相似。结合纽芬兰地区发现的Primocandelabrum hiemaloranum,表明Hiemalora作为生物体的固着器官,起到抵御水流冲刷、支撑和固定整个生物体的作用,但与其相连的叶状体表现出不同的形态类型,表明Hiemalora化石可能具有较为多样的生物来源。根据化石的形态特征和埋藏状态分析,Hiemalora在生物生活时位于藻席层之下的沉积物内,常呈正凸起保存于岩层顶面,而茎干和叶状体位于水体中,生物死亡后,叶状体倒伏在藻席层之上,当岩层沿藻席层劈开后,在顶面保存为凹陷的印痕。  相似文献   

9.
三叶虫是寒武纪海洋中的常见动物,其受伤愈合现象的化石记录可以反映生态系统内物种之间竞争关系。中国华南寒武纪早期澄江化石生物群因保存软躯体构造化石而成为研究寒武纪大爆发时期古海洋生态群落的绝佳窗口,然而,澄江生物群中三叶虫受伤愈合现象的化石至今未见报道。中间型始莱德利基虫(Eoredlichia intermedia Lu,1940)是澄江生物群的常见物种,也是我国寒武系第二个三叶虫化石带的标准带化石。在2 000余枚中间型始莱德利基虫标本中,发现两枚成体标本的头甲侧边缘、颊刺和胸甲肋节保存了不同程度的残缺。据此推测,Eoredlichia intermedia在生命活动过程中曾受到碎壳型捕食动物的攻击或其他伤害而形成伤口。伤口部位边缘加厚且光滑,显示了明显的愈合痕迹。这些特征表明始莱德利基虫在受到非致死的伤害后,具备自身修复损伤的能力。这是迄今所知最为古老的,也是在澄江生物群中首次发现的三叶虫受伤并且愈合的标本,反映了寒武纪第二世第三期底栖生态系统中碎壳型捕食者和三叶虫猎物之间的军备竞赛生态关系。  相似文献   

10.
早寒武世最早期梅树村期处于“寒武纪大爆发”序幕阶段。在这一时期,生物类群发生了大规模辐射演化及其身体构型的快速革新,形成与前寒武纪生物群明显不同的生物组合面貌。最近在陕南宽川铺地区早寒武世早期灯影组宽川铺段地层中发现了数十枚呈三维立体精美保存的磷酸盐化奇异星状生物化石标本,通过形态功能分析及与其共生的Punctatus的口盘类比表明,该奇异星状生物很可能属于腔肠动物Punctatus的口盘,星状体的中心为该生物的口部。而腔肠动物的出现标志着真后生动物的开始,在生物起源演化历程上占据着极其关键的位置。本文报道的奇异星状生物可能代表了初具原始触手的腔肠动物早期演化类型,为研究真后生动物起源演化、功能进化提供了新的实证材料。  相似文献   

11.
A new polynitro cage compound 2, 4, 6, 8, 10, 12, 13, 14, 15-nonanitro-2, 4, 6, 8, 10, 12, 13, 14, 15-nonaazaheptcyclo [5.5.1.1(3,11).1(5,9)] pentadecane (NNNAHP) was designed in the present work. Its molecular structure was optimized at the B3LYP/6-31 G(d,p) level of density functional theory (DFT) and crystal structure was predicted using the Compass and Dreiding force fields and refined by DFT GGA-RPBE method. The obtained crystal structure of NNNAHP belongs to the P-1 space group and the lattice parameters are a = 9.99 ?, b = 10.78 ?, c = 9.99 ?, α = 90.01°, β = 120.01°, γ = 90.00°, and Z = 2, respectively. Based on the optimized crystal structure, the band gap, density of state, thermodynamic properties, infrared spectrum, strain energy, detonation characteristics, and thermal stability were predicted. Calculation results show that NNNAHP has detonation properties close to those of CL-20 and is a high energy density compound with moderate stability.  相似文献   

12.
13.
The variation with age of the 18 trace element mass fractions and some histological characteristics of intact prostate glands of 50 subjects aged 0–30 years was investigated by instrumental neutron activation analysis, inductively coupled plasma atomic emission spectrometry, and a quantitative morphometric analysis. Mean values ± standard error of the mean (M ± SΕΜ) for the mass fractions (in milligrams per kilogram wet tissue) of these trace elements in pre-puberty were: Al 28.5 ± 9.0, B 0.40 ± 0.11, Ba 1.48 ± 0.44, Br 10.5 ± 1.5, Ca 241 ± 30, Cl 3,203 ± 278, Cu 3.51 ± 0.89, Fe 33.7 ± 4.1, K 2,364 ± 145, Li 0.020 ± 0.004, Mg 153 ± 23, Mn 0.46 ± 0.06, Na 2,286 ± 130, P 1,391 ± 100, S 1,698 ± 132, Si 62 ± 11, Sr 0.38 ± 0.08, and Zn 27.6 ± 2.3. During puberty and postpuberty, when there is a significant increase in circulating androgens, the mean values were: Al 7.2 ± 1.4, B 0.21 ± 0.05, Ba 0.25 ± 0.06, Br 5.8 ± 1.0, Ca 433 ± 81, Cl 2,314 ± 201, Cu 1.77 ± 0.13, Fe 20.9 ± 1.6, K 2,585 ± 118, Li 0.0088 ± 0.0014, Mg 232 ± 27, Mn 0.34 ± 0.04, Na 1,875 ± 107, P 1,403 ± 98, S 1,673 ± 73, Si 22.2 ± 3.1, Sr 0.22 ± 0.03, and Zn 93.3 ± 8.9. Mean values (M ± SΕΜ) of percent volumes (%) of the stroma, epithelium and lumen in the prostate before puberty were 73.4 ± 2.6, 20.4 ± 1.7, and 4.45 ± 0.94, respectively, versus 46.5 ± 2.5, 38.5 ± 1.9, and 14.9 ± 1.2 during puberty and postpuberty. This work’s results confirm that the Zn mass fraction in prostate tissue is an androgen-dependent parameter. For the first time it has been demonstrated that the glandular lumen is a main pool of Ca, Mg, and Zn accumulation and that the stroma is a main pool of Al, B, Ba, Br, Cl, Cu, Fe, Mn, Na, and Si accumulation in the normal human prostate, for the age range 0–30 years. It was concluded that the Ca, Mg, and Zn binds tightly within the prostatic fluid, because the volume of glandular lumen reflects the volume of prostatic fluid.  相似文献   

14.
The effect of age and gender on major, minor, and trace element contents in the intact rib bone of 80 relatively healthy 15–55-year-old women and men was investigated. Contents or upper limit of contents of 16 chemical elements in the rib bone were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). Mean values (M?±?SΕΜ) for the mass fraction of Ba, Ca, Cu, Fe, K, Li, Mg, Na, P, S, Sr, and Zn (milligram per kilogram of dry bone) were as follows: 2.54?±?0.16, 171,400?±?4,050, 1.35?±?0.22, 140?±?11, 1,874?±?71, 0.049?±?0.011, 2,139?±?38, 5,378?±?88, 75,140?±?1,660, 1,881?±?51, 291?±?20, and 92.8?±?1.5, respectively. The upper limits of contents of Al, B, Mn, and V were <7.20, <0.65, <0.36, and <0.03, respectively. Statistically significant tendency for the Ca, Mg, and P content to decrease with age was found in the human rib bone, regardless of gender. The mass fraction of Fe in the male rib bone increases with age. It was shown that higher Ca, Mg, Na, P, and Sr mass fractions as well as lower Fe content were typical of female ribs as compared to those in male ribs.  相似文献   

15.
The goal of this article was to establish reference ranges of the concentration of trace elements in human serum and to compare these results with those reported by other authors. We describe the sample preparation and measurement conditions that allow the rapid, precise, and accurate determination of Al, As, B, Be, Cd, Co, Cu, Fe, Li, Mn, Mo, Ni, Rb, Se, Sr, and Zn in human serum samples (n=110) by inductively coupled plasma-mass spectrometry (ICP-MS). Accuracy and precision were determined by analyzing three reconstituted reference serum samples by comparison with other methods and by the standard addition procedure. The advantages of the ICP-MS method include short time of analysis of the elements mentioned, low detection limit, high precision, and high accuracy. Disadventages include a high risk of contamination due to the presence of some of the elements of interest in the environment, the relatively delicate sample handling, and the high cost of the equipment.  相似文献   

16.
Summary Concentration of N, P, K, Ca, Mg and S in summer groundnut crop was higher than in kharif while Zn, Fe, Mn and Cu contents were higher in summer crop. Kernel's N, P and Zn; Leaflet's Ca and Mn; Stem's K and Fe; Root's S and Cu and Petiole's Mg contents were highest. Shell's N, P, K, Mg, S, Zn and Cu; Kernel's Ca, Fe and Mn contents were the least. N, P, K, S, Zn and Cu concentrations decreased linearly as the crop grew. Ca, Mg, Fe and Mn concentrations did not display any distinct pattern. Ca concentration was positively correlated with pod yield in both the seasons.  相似文献   

17.
《Ibis》1894,36(3):447-460
  相似文献   

18.
This report attempts to formulate reference ranges of elemental concentrations for 15 trace elements in selected human tissues and body fluids. A set of samples consisting of whole blood, blood serum, urine, milk, liver, and hair were chosen and considered for 15 elements of biological significance: As, Cd, Co, Cr, Cu, F, Fe, I, Hg, Mn, Mo, Ni, Pb, Se, and Zn. The results represent wholly or partially data received from 40 countries of the global regions of Africa, Asia, Europe, North, South, and Central America, Australia, and New Zealand. This survey, even if qualitative, has been useful in demonstrating certain trends of trace-element scenarios around the world. It is of course recognized that both diet and environment exert a strong influence on the distribution pattern of several elements, such as As, Cd, Mn, Pb, Se, and Zn. A limited comparison of the available information on soil status of different countries reflected some interesting associations for elements, such as Mn and Zn. Importantly, this study revealed that only a few countries were in a position to identify a reasonable amount of data on samples requested for this project. Regretably, for a number of countries, any dependable data for even such essential elements as Cu, Fe, and Zn were not available. In view of the nutritional importance of many elements, the time is ripe for concerted efforts by intergovernmental agencies to initiate investigations or commission task forces/projects to generate reliable reference data for selected global regions, which sadly lack data of any kind at present.  相似文献   

19.
Oral cancer is one of the main causes of cancer-related deaths in South-Asian countries. There are very limited treatment options available for oral cancer. Research endeavors focused on discovery and development of novel therapies for oral cancer, is necessary to control the ever rising oral cancer related mortalities. We mined the large pool of compounds from the publicly available compound databases, to identify potential therapeutic compounds for oral cancer. Over 84 million compounds were screened for the possible anti-cancer activity by custom build SVM classifier. The molecular targets of the predicted anti-cancer compounds were mined from reliable sources like experimental bioassays studies associated with the compound, and from protein-compound interaction databases. Therapeutic compounds from DrugBank, and a list of natural anti-cancer compounds derived from literature mining of published studies, were used for building partial least squares regression model. The regression model thus built, was used for the estimation of oral cancer specific weights based on the molecular targets. These weights were used to compute scores for screening the predicted anti-cancer compounds for their potential to treat oral cancer. The list of potential compounds was annotated with corresponding physicochemical properties, cancer specific bioactivity evidences, and literature evidences. In all, 288 compounds with the potential to treat oral cancer were identified in the current study. The majority of the compounds in this list are natural products, which are well-tolerated and have minimal side-effects compared to the synthetic counterparts. Some of the potential therapeutic compounds identified in the current study are resveratrol, nimbolide, lovastatin, bortezomib, vorinostat, berberine, pterostilbene, deguelin, andrographolide, and colchicine.  相似文献   

20.
We report 19 new species records for the faunal list of Coleoptera in New Brunswick, Canada, six of which are new records for the Maritime provinces, and one of which is new Canadian record. We also provide the first recent records for five additional species in New Brunswick. One new species of Stenotrachelidae, Cephaloon ungulare LeConte, is added to the New Brunswick faunal list. Additional records are provided for Cephaloon lepturides Newman, as well the first recent record of Nematoplus collaris LeConte. Two species of Oedemeridae, Asclera puncticollis (Say) and Asclera ruficollis (Say), are newly reported for New Brunswick, and additional locality and bionomic data are provided for Calopus angustus LeConte and Ditylus caeruleus (Randall). The records of Ditylus caerulus are the first recent records for the province. Three species of Meloidae, Epicauta pestifera Werner, Lytta sayi LeConte, and Meloe augustcollis Say are reported the first time for New Brunswick; Epicauta pestifera is newly recorded in Canada. Lacconotus punctatus LeConte and the family Mycteridaeis newly recorded for New Brunswick. The first recent records of Borus unicolor Say (Boridae) are reported from the province. One new species of Pythidae, Pytho siedlitzi Blair, and the first recent records of Pytho niger Kirby are added to the faunal list of New Brunswick. Three species of Pyrochroidae are newly reported for the province, including Pedilus canaliculatus (LeConte) and Pedilus elegans (Hentz), which are new for the Maritime provinces. Five species of Anthicidae and the first recent record of Anthicus cervinus LaFerté-Sénectére are newly reported for New Brunswick. Anthicus melancholicus LaFerté-Sénectère, Sapintus pubescens (LaFerté-Sénectère), Notoxus bifasciatus (LeConte), and Stereopalpus rufipes Casey are new to the Maritime provinces faunal list. Ambyderus granularis (LeConte) is removed from the faunal list of the province. Three species of Aderidae, Vanonus huronicus Casey, Zonantes fasciatus (Melsheimer), and Zonantes pallidusWerner, are newly recorded for New Brunswick; Zonantes fasciatus and Vanonus huronicus are new for the Maritime provinces' faunal list. Collection data, bionomic data, and distribution maps are presented for all these species.  相似文献   

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