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1.
本文介绍了碱金属硼酸盐的一些基本知识,主要回顾了其中Li2O—B2O3体系的研究历史,讨论了该体系结构与性质的关系并总结了Li2O-B2O3晶态及非晶态物质作为新型功能材料的研究进展。  相似文献   
2.
Thirteen new species referable to four genera, of which one is new, from the Cretaceous of Russia and Mongolia are established herein and assigned to the family Pelecinidae. Among the four genera, Protopelecinus gen. nov., including four new species, is referred to the subfamily Pelecininae, while Iscopinus Kozlov, including three new species, Eopelecinus Zhang, Rasnitsyn and Zhang, including five new species, and Scorpiopelecinus laetus sp. nov. are assigned to the subfamily Iscopininae. Of these new taxa, eight, namely Protopelecinus regularis, P. furtivus, Iscopinus simplex, ?I. suspectus, Eopelecinus exquisitus, E. scorpioideus, E. rudis and Scorpiopelecinus laetus, are from the Lower Cretaceous Zaza Formation of Baissa, Transbaikalia, Russia; two, E. minutus and E. fragilis, are from the basal Lower Cretaceous Tsagan-Tsab Formation of Khutel-Khara, Mongolia; two, P. dubius and P. deformis, are from the Lower Cretaceous (Aptian?) of Bon Tsagan, Mongolia; and one, I. separatus, is from the Upper Cretaceous (Cenomanian) Ola Formation of Obeshchayushchiy, Russia. A key to fossil pelecinid wasps is provided and a morphological analysis shows that the Pelecinidae might be paraphyletic with respect to the Proctotrupidae. The Chinese insect fauna from both the Yixian and Laiyang formations is dominated by Eopelecinus and Sinopelecinus whereas the Siberian + Mongolian fauna from the Zaza and Tsagan-Tsab formations is dominated by Eopelecinus and Iscopinus. Hence, Eopelecinus is common to both. The differences between the two faunas are likely to be the result of geographical variation in populations.  相似文献   
3.
正Objective The Cretaceous–Paleogene boundary(K–Pg boundary)marks the beginning of the Cenozoic,and is one of the most important geological boundaries.Charophytes are usually very abundant in the non-marine strata near the K–Pg boundary,and the change in the charophyte flora can help to recognize the K–Pg boundary.The position of K–  相似文献   
4.
A planthopper originally assigned to the genus Boreocixius in Surijokocixiidae (Surijokocixioidea, Fulgoromorpha) from the Ladinian (Middle Triassic) of Tongchuan in Shaanxi, northwestern China is described as Boreocixius tongchuanensis Zhang et al. sp. nov. As the third species ascribed to the genus, it differs from its congeners in having the much larger tegmen with postnodal veinlets and pigmented bands, providing new morphological information for Boreocixius. The establishment of the new species further increases the diversity of Boreocixius and Surijokocixiidae as well.  相似文献   
5.
用NMR和XPS技术研究了Li2S─B2O3(─LiBr)体系硫氧化物玻璃的结构,结果指出,4─配位硼分数N4仅仅由玻璃Li2S/B2O3摩尔比决定.而与LiBr含量无关,这表明Li2S作为变形剂参与了玻璃网络形成,而LiBr仅作为参杂剂溶解于玻璃基体中,并进入网络间隙。含LiBr玻璃7LiNMR谱运动变窄说明Li+离子是移迁离子.S2p的XPS解析谱证实了玻璃中桥硫和非桥硫的存在.Lils结合能值显示出Li+离了迁移的化学环境。  相似文献   
6.
以溶胶-凝胶-酯化法在220℃即可得到纯相的LixMn2O4(0.762<x<1.139)尖晶石粉体材料。它在880℃时发生立方相向四方相的转变:900℃-1000℃间,四方相渐变为正交相LiMnO2,过程中有Li2MnO3生成。应用SEM、TEM观测了材料的粘度及形貌,其粒度10-40nm,粒子间极易团聚成为1-206μm的团块。以BET法测其比表面为3.6m2/g。  相似文献   
7.
针对现有全球卫星导航系统性能评估无规范的评估标准问题,该文提出了以统一模型和算法为评估体系的方法,较详细的评估了全球卫星导航系统公开服务信号的基本性能,主要评估了空间信号误差、广播电离层模型改正效率及伪距单点定位精度等。结果表明:空间信号误差方面,伽利略最优、GPS和北斗三号相当;广播电离层模型方面,北斗全球广播电离层模型改正效果最优,GPSK8与NeQuick模型在低中纬度改正效果相当,北斗区域电离层模型在其服务区内具有较高改正效果;定位方面,北斗、GPS和伽利略静态伪距单点定位的三维位置均方根误差优于5m,格洛纳斯优于10 m;动态伪距单点定位方面,北斗在中国境内定位精度最高;基于统一评估体系下,可以直观对比得到目前各卫星导航系统的性能差异,同时也为后续的建设提供相应的参考。  相似文献   
8.
<正>The classification and phytogeny of the basal Vespina(=Orussoidea+Apocrita)are reconsidered based primarily on rich and well preserved material from the Middle Jurassic of Daohugou in Inner Mongolia,China. Comparatively smooth morphological transitions are traced from a Xiphydriidae-like ancestor toward Orussoidea via the Jurassic family Karatavitidae,and through Karatavitidae and the Jurassic and Early Cretaceous family Ephialtitidae independently to Stephanidae,to Evanioidea,and,via the extinct Jurassic Kuafuidae fam.nov.to the remaining Apocrita.New hypothesis is proposed concerning development of the characteristic wasp-waist of Apocrita,which is supposed to appear independently and in different ways in Evanioidea and in the rest of Apocrita.As a result,six infraorders are proposed for the suborder Vespina with the following taxonomic structure:infraorder Orussomorpha including the only superfamily Orussoidea(Karatavitidae+Paroryssidae + Orussidae),infraorder Stephanomorpha with the only superfamily Stephanoidea(Ephialtitidae+Stephanidae), infraorder Evaniomorpha with the only superfamily Evanioidea of traditional composition,infraorder Ceraphronomorpha with the superfamilies Ceraphronoidea s.str.and monotypical Megalyroidea and Trigonaloidea,and the infraorders Proctotrupomorpha,Ichneumonomorpha,and Vespomorpha of traditional composition.The family Kuafuidae is unplaced to infraorder because it is putatively paraphyletic with respect to Ceraphronomorpha,Proctotrupomorpha,Ichneumonomorpha and Vespomorpha.Described as new are Karatavites junfengi sp.nov,Praeratavites wuhuaensis sp.nov.,P.perspicuus sp.nov.,Postxiphydria daohugouensis gen.et sp.nov.,P.ningchengensis gen.et sp.nov.,Postxiphydroides strenuus gen.et sp.nov.,Praeratavitoides amabilis gen.et sp.nov.,Proapocrtius densipediculus sp.nov.,P.sculptus sp.nov.,P.longantennatus sp.nov., P.formosus sp.nov.,P.atropus sp.nov.,P.elegans sp.nov.,Stephanogaster pristinus sp.nov.,Asiephialtites lini sp. nov.,Praeproapocritus vulgatus gen.et sp.nov.,Sinaulacogastrinus solidus gen.et sp.nov.,Sinevania speciosa gen. et sp.nov.,Eonevania robusta gen.et sp.nov.,Kuafua polyneura gen.et sp.nov.(all from the Middle Jurassic of Daohugou),as well as Kuafuidae fam.nov.including Kuafua gen.nov.as well as Arthrogaster Rasnitsyn,1975,and Leptogastrella Rasnitsyn,1975 from the Upper Jurassic of Karatau in Kazakhstan.  相似文献   
9.
最新一些研究结果强调了全新世期间的长期增温趋势,综合全球平均海平面、大陆冰盖面积、大气温室气体和太阳辐射证据来看,这比传统观点所认为的全新世期间的长期降温趋势,更具有合理性。回顾历史,结合最新的一些研究进展,发现支持“中全新世大暖期”和“晚全新世降温趋势”的证据存在明显的不确定性,最核心的问题为晚全新世加强的人类活动对代用指标或者证据的强烈扰动,使得其不能准确地反映真实的气候变化过程。鉴于目前全新世温度历史争论的核心关键在于晚全新世,因此有必要加强晚全新世温度变化研究。在人类活动影响较小的地区,或者利用对人类活动不敏感的代用指标开展研究,有望可以获得更可靠的晚全新世温度历史重建结果,为准确认识中华数千年文明的长期温度变化背景,进而理解期间的“人地关系”演化历史,并最终客观认识现今面临的以全球变暖为主要特征的气候环境问题,提供一定的科学基础。  相似文献   
10.
This paper expounds the features of the buildings and analyzes the seismic disaster characteristics of the Jiuzhaigou M_S7. 0 earthquake in the area between Songpan and Jiuzhaigou. New buildings (especially the frame structure) had good anti-seismic performance,but brick-wood structures and brick-concrete structures sustained large amounts of damage in the earthquake. By computing the seismic damage index,we found that the seismic damage index of the frame structure was far less than that of civil structures and brick-wood structures. The seismic damage index of frame structures were all zero in the Ⅵ area,and increased rapidly with the increase of intensity,but the increasing range was reduced. We also discussed how to evaluate the intensity in areas where there was a lack of buildings or there was only one structure type,which can be referenced in future field work.  相似文献   
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