检索结果-南通市图书馆

国外医学（军事医学分册） 1989年第1期6卷 34-36页

作者： mark.,pb 周景春

Structure-function studies of the influenza virus RNA polymerase PA subunit

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China(Life Sciences) 2009年第5期52卷 450-458页

作者： mark.BARTLAM College of Life Sciences and Tianjin State Laboratory of Protein Science Nankai University

The influenza virus RNA-dependent RNA polymerase is a heterotrimeric complex (PA, pb1 and pb2) with multiple enzymatic activities for catalyzing viral RNA transcription and replication. The roles of pb1 and pb2 have been clearly defined, but PA is less well understood. The critical role of the polymerase complex in the influenza virus life cycle and high sequence conservation suggest it should be a major target for therapeutic intervention. However, until very recently, functional studies and drug discovery targeting the influenza polymerase have been hampered by the lack of three-dimensional structural information. We will review the recent progress in the structure and function of the PA subunit of influenza polymerase, and discuss prospects for the development of anti-influenza therapeutics based on available structures.

关键词： influenza polymerase PA subunit crystal structure endonuclease protein-protein interaction

Atmospheric deposition of 7Be,210pb and 210Po during typhoons and thunderstorm in Shanghai, China and global data synthesis

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2020年第4期63卷 602-614页

作者： Juan DU mark.BASKARAN Jinzhou DU State Key Laboratory of Estuarine and Coastal Research East China Normal UniversityShanghai 200241China Department of Geology Wayne State UniversityDetroit 48202USA

Atmospherically-delivered ~7Be,^(210)Po and ^(210)pb in bulk precipitation and air samples collected around the globe have provided valuable quantification on the rates of removal, as well as proportional mixing of attendant air masses;however, such studies during thunderstorm and typhoon events are limited. We report the first continuous time-series rainwater sampling and analysis of ~7Be,^(210)pb and ^(210)Po from two typhoons and one thunderstorm during 2015 summer in Shanghai. The depositional fluxes within individual rain events of typhoons and thunderstorms varied by a factor of 10 for ~7Be, 5.7 for ^(210)pb, 7.4 for ^(210)Po,and 7.0 for ~7Be/^(210)pb activity ratios(AR). Such large observed variations in the depositional fluxes of ~7Be,^(210)pb,^(210)Po and ~7Be/^(210)pb activity ratios were attributed to air masses injected from surrounding high pressure system adjoining the typhoon to low pressure system within the typhoon. Based on ~7Be/^(210)pb activity ratios, we estimated the variations in the fraction of maritime and continental air masses into the typhoon. Observed constancy in the ^(210)Po/^(210)pb AR indicates that the residence times of air masses contributing to the typhoon during heavy rain are similar. From a synthesis of global fallout of ~7Be and ^(210)pb during pulse events(precipitation≥50 mm from single rainout event), we quantify the importance of pulse events in the atmospheric fallout of these radionuclides.

关键词： 7Be 210pb 210Po Typhoon Thunderstorm Air masses intrusions

清醒狗与开胸麻醉狗心肌顿抑氧自由基作用的研究

在线全文

学校读者我要写书评

暂无评论

中国病理生理杂志 1995年第2期11卷 143-147页

作者：李小鹰 McCay pb 解放军总医院

本实验应用自旋捕捉剂ＰＢＮ证实了开胸麻醉狗与清醒狗心肌顿抑模型的主要区别。冠状动脉阻闭１５ｍｉｎ后再灌注头３小时ＰＢＮ加合物释放总量开胸麻醉狗明显高于清醒狗（约为５倍），而且心肌顿抑的恢复开胸狗明显差于清醒狗。这种区... 详细信息

本实验应用自旋捕捉剂ＰＢＮ证实了开胸麻醉狗与清醒狗心肌顿抑模型的主要区别。冠状动脉阻闭１５ｍｉｎ后再灌注头３小时ＰＢＮ加合物释放总量开胸麻醉狗明显高于清醒狗（约为５倍），而且心肌顿抑的恢复开胸狗明显差于清醒狗。这种区别的主要原因推测是开胸创伤本身以及肾上腺素能神经过度兴奋引起，从而提示在心肌顿抑氧自由基产生的研究中应用清醒动物模型的重要性。

关键词：狗氧自由基心肌顿抑心肌缺血

Cambro-Silurian magmatisms at the northern Gondwana margin(Penninic basement of the Ligurian Alps)

在线全文

学校读者我要写书评

暂无评论

Geoscience Frontiers 2019年第1期10卷 315-330页

作者： Matteo Maino Laura Gaggero Antonio Langone Silvio Seno mark.Fanning Department of Earth and Environmental Sciences University of Pavia Department of Earth Environment and Life Sciences University of Genoa CNRd Institute of Geosciences and Earth Resources U.O.S. Research School of Earth Sciences The Australian National University

The Early Paleozoic evolution of the northern margin of Gondwana is characterized by several episodes of bimodal magmatism intruded or outpoured within thick sedimentary basins. These processes are well recorded in the Variscan blocks incorporated in the Ligurian Alps because they experienced low temperature Alpine metamorphism. During the Paleozoic, these blocks, together with the other Alpine basements, were placed between the Corsica-Sardinia and the Bohemian Massif along the northern margin of Gondwana. In this framework, they host several a variegated lithostratigraphy forming two main complexes(Complexs I and II) that can be distinguished by both the protoliths and their crosscutting relationships, which indicate that the acidic and mafic intrusives of Complex II cut an already folded sequence made of sediments, basalts and granitoids of Complex I. Both complexes were involved in the Variscan orogenic phases as highlighted by the pervasive eclogite-amphibolite facies schistosity(foliation II). However, rare relicts of a metamorphic foliation at amphibolite facies conditions(foliation I)is locally preserved only in the rocks of Complex I. It is debatable if this schistosity was produced during the early folding event e occurred between the emplacement of Complex I and II e rather than during an early stage of the Variscan metamorphic *** SHRIMP and LA ICP-MS Ue pb zircon dating integrated with literature data, provide emplacement ages of the several volcanic or intrusive bodies of both complexes. The igneous activity of Complex I is dated between 507 ± 15 Ma and 494 ± 5 Ma, while Complex II between 467 ± 12 Ma and 445.5 ± 12 *** folding event recorded only by the Complex I should therefore have occurred between 494 ± 5 Ma and 467 ± 12 Ma. The Variscan eclogite-amphibolite facies metamorphism is instead constrained between ~420 Ma and ~300 Ma. These ages and the geochemical signature of these rocks allow constraining the Early Paleozoic tectono-magmatic

关键词： U-pb zircon dating Early Paleozoic magmatism Pre-Alpine basements Gondwana margin Ligurian Alps

Provenance of the Permo-Carboniferous sediments in the northern Alxa and its tectonic implications for the southernmost Central Asian Orogenic Belt

在线全文

学校读者我要写书评

暂无评论

Geoscience Frontiers 2020年第4期11卷 1415-1429页

作者： Yan Chen Tairan Wu Zhicheng Zhang C.mark.Fanning Mingming Zhang Mingming Zhang Institute for Peat and Mire Research State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation RestorationNortheast Normal UniversityChangchun 130024China Key Laboratory of Geographical Processes and Ecological Security in Changbai Mountains Ministry of EducationSchool of Geographical SciencesNortheast Normal UniversityChangchun 130024China The Key Laboratory of Orogenic Belts and Crustal Evolution Ministry of EducationSchool of Earth and Space SciencesPeking UniversityBeijing 100871China Research School of Earth Sciences Australian National UniversityMills RoadCanberraACT0200Australia

As the southernmost segment of the Central Asian Orogenic Belt(CAOB),the northern Alxa orogenic belt(NAOB)connects the southeastern and southwestern segments of the *** NAOB amalgamated with the closure of the Paleo-Asian Ocean;however,the closure time of the Paleo-Asian Ocean is still on great *** this study,we reported new detrital zircon U-pb geochronology and Hf-O isotopes for the Permo-Carboniferous sediments in the northern Alxa to constrain the provenance and its tectonic *** Permo-Carbonifereous Amushan Formation is composed of volcanic-carbonite-clastic rocks and was deposited in a shallow marine *** on the zircon U-pb geochronology,the Amushan Formation was deposited in the late Carboniferous to early Permian,but some outcrops of volcanic and clastic rocks in the Quaganqulu area were likely formed in the middle to late *** integrated zircon age spectrum for the clastic rocks shows a wide range from late Archean to Paleoproterozoic,Mesoproterozoic(with a peak age at 1458 Ma),early Neoproterozoic(with peak ages of 988 Ma and 929 Ma),early Paleozoic(with a peak age at 447 Ma) and late Paleozoic(with a peak age at 294 Ma).Combined with the zircon Hf-O isotopes,the provenance was considered to be the Alxa Block,the Shalazhashan terrane and the Zhusileng-Hangwula block(and the southern Beishan orogenic belt).The multiple source regions to the south and north of the Paleo-Asian Ocean indicate the closure of this ocean before the late *** absence or small proportion of depositional age-approximated zircons in most samples makes their age spectra similar to extensional *** with the intra-plate volcanism,the deposits were considered to be formed in extensional ***,after the closure of the Paleo-Asian Ocean,the NAOB stepped into an extensional stage.

关键词： CAOB Alxa Provenance Permo-Carboniferous Detrital zircon

Assessing availability, phytotoxicity and bioaccumulation of lead to ryegrass and millet based on 0.1 mol/L Ca(NO_3)_2 extraction

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2006年第5期18卷 958-963页

作者： SI Ji-tao TIAN Bao-guo WANG Hong-tao Nicholas Basta Jackie Schroder mark.Casillas Department of Environmental Science and Engineering Tsinghua University Beijing 100084 China School of Natural Resources The Ohio State University Columbus OH 43210 USA Department of Plant and Soil Sciences Oklahoma State University Stillwater Oklahoma 74078 USA

This study was conducted to assess availability, phytotoxicity and bioaccumulation of lead （pb） to ryegrass （Lolium perenne L.） and millet （Echinochloa crusgalli） based on the 0.1 mol/L Ca（NO3）2 extraction. Effect of soil properties on availability, phytotoxicity and bioaccumulation of pb to the two plants was also evaluated. Five soils with pH values varying from 3.8 to 7.3, organic carbon （OC） contents from 0.7% to 2.4%, and clay contents from 11.6% to 35.6% were selected. Soils were spiked with pb to achieve a range of concentrations： 250, 500, 1000, 3000 and 5000 mg/kg. pb availability in the spiked soils was estimated by extracting soil with 0.1 mol/L Ca（NO3）2. The results indicate that plants yield decreased with decreasing soil pH and increased with increasing soil clay and OC content. Negative relationship between available pb and the relative dry matter growth （RDMG） of the two plants were significantly related. Available pb used to assess EC20 （20% effective concentration） and EC50 （50% effective concentration） of millet was 119 and 300 mg/kg, respectively. Available pb used to assess EC20 and EC50 of ryegrass was 63 and 157 mg/kg, respectively. Bioaccumulation, expressed as bioconcentration factors of pb, was inversely related to soil pH, soil OC and clay content. Strong relationships were found between available lead and uptake by the two plants （P was 0.92 and 0.95 respectively）. In general, 0.1 mol/L Ca（NO3）2 available pb may be used to assess the availability, phytotoxicity and bioaccumulation of lead to the two plants tested.

关键词： heavy metals bioconcentration factor spike extraction lead (pb)

Central Asian aridification during the late Eocene to early Miocene inferred from preliminary study of shallow marine-eolian sedimentary rocks from northeastern Tajik Basin

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2016年第6期59卷 1242-1257页

作者： WANG Xin Brian KRAATZ Jin MENG Barbara CARRAPA Peter DECELLES mark.CLEMENTZ Sherzod ABDULOV CHEN FaHu Key Laboratory of Western China's Environmental Systems(Ministry of Education) College of Earth and Environmental Sciences Lanzhou UniversityLanzhou 730000China Western University of Health Sciences Pomona 91766USA American Museum of Natural History New York 10024USA Department of Geosciences University of ArizonaTucson 85721USA Department of Geology and Geophysics University of WyomingLaramie 82071USA Institute of Geology Earthquake Engineering and Seismology of the Academy of SciencesTajikistan CAS Center for Excellence in Tibetan Plateau Earth Sciences Beijing 100101China

The tempo-spatial development of the Cenozoic Asian aridification across the Eocene-Oligocene and its controlling factors are important scientific topics in Earth Sciences, which are pertinent to regional and global tectonic and climatic events. However, sedimentary rocks preserving the record of aridification during this time from central Asia(ACA) are rare. Here we present a preliminary analysis of sedimentary facies of the lower Paleogene in the northeastern Tajik Basin, which reveals that: the lower part of the studied section is dominated by shallow marine deposits of the Paratethys, the middle part is typical of alternations of eolian dune and fluvial deposits, the upper part is represented by eolian loess-sandy loess(L&SL) like facies, and the top exhibits alternations of fluvial-lacustrine and loess like facies. Based on a chronological framework derived from preliminary magnetostratigraphy, published U-pb dating of a volcanic ash, and regional litho-stratigraphic correlations, we determine that eolian and L&SL facies accumulated in the northeastern Tajik Basin during the Late Eocene and through most of the Oligocene. These sedimentary units indicate that semi-arid to arid environments of ACA had developed at least since the late Eocene. This initial aridification is closely linked to the westward retreat of the Paratethys that was likely driven by a combination of tectonic activity and sea level changes.

关键词： Northeastern Tajik Basin Paleogene Eolian deposits Paratethys Aridification

Currawang Cu-pb-Zn massive sulfide deposits in basic volcanics, New South Wales, Australia

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 1999年第S2期44卷 54-55页

作者： Brian Marshall mark.Bouffler T.HO Department of Applied Geology University of Technology Sydney New South Wales 2007 Australia Woodlawn Mines PO Box 141 Goulburn NSW 2580 Australia

1 Geology THE Currawang deposit is situated in the Canberra-Goulburn district, near the Woodlawn deposit, and isone of a large number of the massive sulfide deposits of base metal located in the late Silurian volcanics,New South Wales. The Currawang deposit is a vein type deposit in basic volcanics, different from otherdeposits in the Canberra-Goulburn district which are the felsic-volcanics-hosted deposits and belong toVMS. The Currawang deposit as two lenses (the south lens and the north lens) that occurred in the basicvolcanics consisted of pillow basalt, massive basalt, with agglomerate, tuff and dolerite. The constituentsof the basalt are amphibole, chlorite, feldspar, pyroxene, epidote, leucoxene, ilmenite, magnetite,

关键词： Currawang Cw-pb-Zn deposit massive sulfide deposit basic volcanics New South Wales.

Natural and anthropogenic sources of lead, zinc, and nickel in sediments of Lake Izabal, Guatemala

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2020年第10期32卷 117-126页

作者： Elisandra Hernandez Jonathan Obrist-Farner mark.Brenner William F.Kenney Jason H.Curtis Edward Duarte Geosciences and Geological and Petroleum Engineering Department Missouri Uniuersity of Science and Technology.RollaMO 65409USA. Department of Geological Sciences University of FloridaGainesvilleFL 32611USA Land Use and Enuironmental Change Institute Uniuersity of FloridaGainesvilleFL 32611USA Escuela de Quimica Universidad de San Carlos de Guatemala01012Guatermala

Sediments in Lake Izabal,Guatemala,contain substantial lead (pb),zinc (Zn),and nickel (Ni).The lack of historical data for heavy metal concentrations in the sediments makes it difficult to determine the sources or evaluate whether inputs of metals to the lake have changed through *** measured the relative abundances and concentrations of pb,Zn,and Ni by X-Ray Fluorescence core scanning and by Inductively Coupled Plasma Optical Emission Spectrometry in three sediment cores to explore stratigraphic distributions of metals in the lake *** amounts of pb and Zn in the core taken near the Polochic Delta suggest that galena and sphalerite mining increased pb and Zn delivery to Lake Izabal between ~1945 and 1965 *** up-core Ni increase in the core taken near a different mine on the north shore of Lake Izabal suggests that recent nickel mining operations led to an increase in Ni concentrations in the local sediments,but amounts in the other cores indicate that Ni is not widely distributed throughout the *** cores from Lake Izabal are reliable recorders of heavy metal input to the lake,and were measured to establish background metal levels,which would otherwise be *** of pb,Zn,and Ni in older,pre-20th-century Lake Izabal sediments reflect input from natural erosion of *** results provide previously unavailable estimates of background metal concentrations in Lake Izabal before the onset of *** results are necessary for future monitoring related to mining contamination of the lake ecosystem.

关键词： Lake Izabal Heavy metals Lead contamination Anthropogenic impacts Mining Guatemala