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The Gaoyuzhuang Palaeobiology

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Acta Botanica sinica 2002年第5期44卷 617-627页

作者：徐兆良阿拉米克s.M. 中国科学院植物研究所北京100093 美国加州大学圣巴巴拉分校地质系克劳德研究室 ca93106

Black bedded, nodular, and lenticular chert and silicified parts of stromatolites from the approximately 1 400 - 1 600 million year-old Gaoyuzhuang Formation, North China, contain remark-ably well prep served microflora composed of diverse prokaryotic and possible eukaryotic microbes. Macroscopic algae have also been found. This Formation provides important paleobiological information from which to assess status of Mesoproterozoic life, and to evaluate paleoenvironmental conditions and pre-Phanerozoic biostratigraphy. The Gaoyuzhuang Formation has yielded over 100 taxa described by over 10 investigators. Most of the microbial taxa can be divided into three different assemblages according to their paleobiological and paleoenvironmental characteristics. I. The oscillatoriacean/chroococcacean assemblage which occurs in the first member of the Formation and this is interpreted to represent an assemblage from shallow water mat-building and mat-dwelling taxa with some possible planktonic taxa; 2. the nostocacean assemblage found only in the second member, and includes benthic mat-building or mat-dwelling taxa; and 3. the chroococcacean assemblage of the fourth member, which represents intertidal to supratidal mat-building and allochthonous taxa. Proterozoic microfossils found in chert, especially cyanobacteria, are possibly more valuable as paleoenvironmental indicators than as chronostratigraphic tools because of their morphological conservation, although trends in diversity appear to exist for cyanobacteria in the Proterozoic. The general characteristics of Gaoyuzhuang microfossils, and the fact that most nostocacean chains occur and are. preserved with the chain perpendicular to bedding indicate that: (1) the individual size of Gaoyuzhuang microfossils are part of a general trend of increase with time; (2) Gaoyuzhuang deposits are possibly in a fresh water environment and the rate of sedimentation might be equal to or less than the microbial growth rate; (3) the sedime

关键词： North China mesoproterozoic Gaoyuzhuang Formation palaeobiology

Thermal Hardening： A New seed Vigor Enhancement Tool in Rice

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Journal of Integrative Plant Biology 2005年第2期47卷 187-193页

作者： MuhammadFAROOQ s.M.A.BAsRA NazirAHMAD K.HAFEEZ DepartmentofCropPhysiology UniversityofAgricultureFaisalabad-38040Pakistan

Abstract: In a laboratory study, indica and japonica rice (Oryza sativa L.) seeds were exposed to thermal hardening (heating followed by chilling followed by heating; chilling followed by heating followed by chilling; heating followed by chilling or chilling followed by heating). In indica rice, heating followed by chilling followed by heating resulted in decreased mean germination time, time to start germination, electrical conductivity of seed leachates, and time to 50% germination, as well as increased germination index, energy of germination, radicle and plumule length, root length, root/shoot ratio, root fresh and dry weight, radicle and plumule growth rate, and shoot fresh weight. In japonica rice, chilling followed by heating followed by chilling performed better than all other treatments, including control.

关键词： germination indica rice japonica rice seedling vigor thermal hardening

A fossil-calibrated relaxed clock for Ephedra indicates an Oligocene age for the divergence of Asian and New World clades and Miocene dispersal into south America

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Journal of systematics and Evolution 2009年第5期47卷 444-456页

作者： stefanie M.ICKERT-BOND Catarina RYDIN susanne s.RENNER University of Alaska UA Museum of the North Herbarium and Institute of Arctic Biology Institute of systematic Botany University of Zurich University of Munich Systematic Botany and Mycology

Ephedra comprises approximately 50 species,which are roughly equally distributed between the Old and New World deserts,but not in the intervening regions(amphitropical range).Great heterogeneity in the substitution rates of Gnetales(Ephedra,Gnetum,and Welwitschia) has made it difficult to infer the ages of the major divergence events in Ephedra,such as the timing of the Beringian disjunction in the genus and the entry into south ***,we use data from as many Gnetales species and genes as available from GenBank and from a recent study to investigate the timing of the major divergence *** of the tradeoff between the amount of missing data and taxon/gene sampling,we reduced the initial matrix of 265 accessions and 12 loci to 95 accessions and 10 loci,and further to 42 species(and 7736 aligned nucleotides) to achieve stationary distributions in the Bayesian molecular clock *** from a relaxed clock with an uncorrelated rates model and fossil-based calibration reveal that New World species are monophyletic and diverged from their mostly Asian sister clade some 30 mya,fitting with many other Beringian *** split between the single North American and the single south American clade occurred approximately 25 mya,well before the closure of the Panamanian ***,the biogeographic history of Ephedra appears dominated by long-distance dispersal,but finer-scale studies are needed to test this hypothesis.

关键词： biogeography Ephedra relaxed molecular clock dating uncorrelated rates model.

Evaluation of the Electroslag Remelting Process in Medical Grade of 316LC stainless steel

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Journal of Materials science & Technology 2009年第5期25卷 592-596页

作者： s.Ahmadi H.Arabi A.shokuhfar A.Rezaei Institute of Advanced Technologies for Metallic Materials Tarbiat Modares University Center of Excellence of Advanced Materials and Processing(CEAMP) Department of Metallurgy and Materials Science and EngineeringIran University of Science&Technology(IUST) Department of Material science Faculty of Mechanical EngineeringK.N.Toosi University of Technology

This study is focused on the effects of electroslag remelting by prefused slag （CaO, Al2O3, and CaF2） on macrostructure and reduction of inclusions in the medical grade of 316LC （316LVM） stainless steel. Analysis of the obtained results indicated that for production of a uniform ingot structure during electroslag remelting, shape and depth of the molten pool should be carefully controlled. High melting rates led to deeper pool depth and interior radial solidification characteristics, while decrease in the melting rates caused more reduction of nonmetallic inclusions. Large shrinkage cavities formed during the conventional casting process in the primary ingots were found to be the cause of the fluctuation in the melting rate, pool depth and extension of equiaxed crystals zone.

关键词： Ultra clean steel Electroslag Radial solidification remelting Prefused slag Vertical solidification

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赑屃:力拔山兮驮功德

艺术品鉴 2024年第1期 50-53页

作者： s-Rong 不详

六子霸下,又名赑屃(bì xì),似龟有齿,喜欢负重,是碑下龟。墓碑文化在中国历史悠久,源远流长。现今遗留下来的很多古代墓碑都是“螭首龟趺”的形制,碑额雕刻蛟龙,碑底压着一只“龟趺”,比如有名的《徐达墓》《德明墓碑》《樊敏碑》等... 详细信息

六子霸下,又名赑屃(bì xì),似龟有齿,喜欢负重,是碑下龟。墓碑文化在中国历史悠久,源远流长。现今遗留下来的很多古代墓碑都是“螭首龟趺”的形制,碑额雕刻蛟龙,碑底压着一只“龟趺”,比如有名的《徐达墓》《德明墓碑》《樊敏碑》等。故而民谚有“王八驮石碑”一语。

关键词：樊敏碑赑屃螭首墓碑石碑龟

Diaspore characteristics and ecological adaptation of Bromus tectorum *** different distribution regions

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Journal of Arid Land 2013年第3期5卷 310-323页

作者： YaoBin LIU YuanMing ZHANG Robert s NOWAK Liliya DIMEYEVA Key Laboratory of Biogeography and Bioresource in Arid Land Xinjiang Institute of Ecology and GeographyChinese Academy of Sciences Graduate University of Chinese Academy of sciences Department of Natural Resources and Environmental science University of Nevada-RenoRenoNevada 89557USA Institute of Botany and Phytointroduction Almaty 050040Kazakhstan

The invasion of nonnative plants is considered one of the main threats to the structure and function of North American ecosystems. Moreover, they can alter ecosystem processes and reduce biodiversity. In arid and semi-arid region of North America, the species of European annual grass Bromus tectorum L. is an outstanding example of these problems, which not only increase the fire density and change the fire regime, but replace native communities. Therefore, there are amount of researches on B. tectorum, including resource acquisition, water use efficiency and growth. Whereas the relevant research on the morphology of diaspore is scare. Diaspores have a fundamental role in seed germination and seedling establishment. Besides, as an important link between different generations, diaspores have a vital significance on individual reproduction and population extension. Hence, dias- pores under selection for studying have an important implication. This study compares differences in seed mor- phology for Bromus tectorum collected from the United states, Kazakhstan, and Xinjiang of China. The following indices of B. tectorum diaspores were analyzed： size, thickness of covering layers, and micromorphological char- acteristics of the base, middle and transition area of diaspores as well as of the awn. Micromorphology of the lemma and the cross-section of the diaspore were observed by scanning electron microscopy. Results showed that thick- ness of the lemma and the palea of diaspores from B. tectorum-infested grasslands in the United states were re- duced （P〈0.05）, likely because of environmental influences. This reduction facilitated the germination of diaspores and lowered the resistance of B. tectorum to adverse environmental conditions. The length of the awn also in- creased significantly （P〈0.05）, which helped in dispersal and anchoring of diaspores. Therefore, B. tectorum adapted ecologically to its new environment in the United states by strengthening its establishment a

关键词： Bromus tectorum diaspore micromorphology lemma Kazakhstan United states Xinjiang of China

MULTIPLE sOLUTIONs FOR NONAUTONOMOUs sECOND ORDER PERIODIC sYsTEMs

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Acta Mathematica scientia 2010年第1期30卷 350-358页

作者： Zdzislaw Denkowski Leszek Gasiński Nikolaos s.Papageorgiou Institute of Computer science Jagiellonian University Department of Mathematics National Technical UniversityZografou CampusAthens 15780Greece

We study nonautonomonus second order periodic systems with a nonslnooth potential. Using the nonsmooth critical theory, we establish the existence of at least two nontrivial solutions. Our framework incorporates large... 详细信息

关键词： locally Lipschitz potential generalized subdifferentiM coercive functional critical point local linking theorem nonsmooth Palais-smale condition multiple nontrivial solutions

Xyloglucans of Monocotyledons Have Diverse structures

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Molecular Plant 2009年第5期2卷 943-965页

作者： Yves s.Y. Hsieh Philip J. Harris school of Biological sciences The University of Auckland Private Bag 92019 Auckland New Zealand

Except in the Poaceae, little is known about the structures of the xyloglucans in the primary walls of monocotyledons. Xyloglucan structures in a range of monocotyledon species were examined. Wall preparations were isolated, extracted with 6 M sodium hydroxide, and the extracts treated with a xyloglucan-specific endo-（1→4）-β-glucanase preparation. The oligosaccharides released were analyzed by high-performance anion-exchange chromatography and by matrix-assisted laser-desorption ionization time-of-flight mass spectrometry. Oligosaccharide profiles of the non-commelinid monocotyledons were similar to those of most eudicotyledons, indicating the xyloglucans were fucogalactoxyloglucans, with a XXXG a core motif and the fucosylated units XXFG and XLFG. An exception was Lemna minor （Araceae）, which yielded no fucosylated oligosaccharides and had both XXXG and XXGn core motifs. Except for the Arecales （palms） and the Dasypogonaceae, which had fucogalactoxyloglucans, the xyloglucans of the commelinid monocotyledons were structurally different. The Zingiberales and Commelinales had xyloglucans with both XXGn and XXXG core motifs; small proportions of XXFG units, but no XLFG units, were present. In the Poales, the Poaceae had xyloglucans with a XXGn core motif and no fucosylated units. In the other Poales families, some had both XXXG and XXGn core motifs, others had only XXXG; XXFG units were present, but XLFG units were not.

关键词： Commelinid monocotyledons non-commelinid monocotyledons plant cell walls Poaceae xyloglucans xyloglucan-specific endo-(1→4)-β-glucanase.

Cellular reprogramming in farm animals： an overview of iPsC generation in the mammalian farm animal species

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Journal of Animal science and Biotechnology 2016年第4期7卷 459-467页

作者： J. Ogorevc s. Orehek P. DovcC Department of Animal science Biotechnical Faculty University of LjubljanaDomzale Slovenia

Establishment of embryonic stem cell （EsC） lines has been successful in mouse and human, but not in farm animals. Development of direct reprogramming technology offers an alternative approach for generation of pluripotent stem cells, applicable also in farm animals. Induced pluripotent stem cells （iPsCs） represent practically limitless, ethically acceptable, individuum-specific source of pluripotent cells that can be generated from different types of somatic cells, iPsCs can differentiate to all cell types of an organism＇s body and have a tremendous potential for numerous applications in medicine, agriculture, and biotechnology. However, molecular mechanisms behind the reprogramming process remain largely unknown and hamper generation of bona fide iPsCs and their use in human clinical practice. Large animal models are essential to expand the knowledge obtained on rodents and facilitate development and validation of transplantation therapies in preclinical studies. Additionally, transgenic animals with special traits could be generated from genetically modified pluripotent cells, using advanced reproduction techniques. Despite their applicative potential, it seems that iPsCs in farm animals haven＇t received the deserved attention. The aim of this review was to provide a systematic overview on iPsC generation in the most important mammalian farm animal species （cattle, pig, horse, sheep, goat, and rabbit）, compare protein sequence similarity of pluripotency-related transcription factors in different species, and discuss potential uses of farm animal iPsCs. Literature mining revealed 32 studies, describing iPsC generation in pig （13 studies）, cattle （5） horse （5）, sheep （4）, goat （3）, and rabbit （2） that are summarized in a concise, tabular format.

关键词： Cellular reprogramming Farm animals Induced pluripotent stem cells Pluripotency