6 resultados para G8 Summit

em Chinese Academy of Sciences Institutional Repositories Grid Portal


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通过70%冷甲醇抽提、Sephadex C i-15分子筛和反相高效液相色谱G8层析,从湖南产烙铁头蛇毒(Trineresurus muqua nwtus)冻干粉中纯化得到一个新的舒缓激肤增强肤(BPP),命名为TmF。该小肤的氨基酸序列为p(irr (iy Arg Pro, Leti (iy Pro, Pro, Ile- Pro, Pro ( pau表示焦谷氨酸)。序列结果分析表明,TmF和已经分离得到的BPPs有很高的序列同源性。MSI- MS 测定其分子量为1 .1107 kD o TmF的生物学活性和药理学活性检测的结果表明,它增强舒缓激肤(BK)(1 mg/L)诱导的离体豚 鼠回肠纵行肌收缩的活性为(1 .13士0 .3)单位(mg/ L) ; TmF (5 .0 x 10- 0 mg/ kg)可以增强约(14士2) mmHg的由BK(5 . Ox 10-' mg/ kg)诱导的舒张压下降;在抑制剂试验中,不同剂量的TmF和5x1。一zmg的血管紧张素转化酶保温30 min,结果表明大约 2.0x10一3mg的TmF表现出对ACE水解活性的半数抑制率(IQo )。

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Cubic boron nitride (c-BN) attracts widespread interest as a promising material for many potential applications because of its unique physical and chemical properties. Since the 1980's the research in c-BN thin films has been carried out, which reached its summit in the mid of 1990's, then turned into a downward period. In the past few years, however, important progress was achieved in synthesis and properties of cubic boron nitride films, such as obtaining > 1 mu m thick c-BN films, epitaxial growth of single crystalline c-BN films, and advances in mechanics properties and microstructures of the interlayer of c-BN films. The present article reviews the current status of the synthesis and properties of c-BN thin films.

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瑞香狼毒(Stellera chamaejasme L.)是瑞香科(Thymelaeaceae)狼毒属的一种多年生野草,有毒。据调查,从20 世纪60 年代开始至今,狼毒在青藏高原东缘的高寒草甸上不断蔓延、密度不断变大,在一些地段甚至成为优势物种。有关狼毒在高寒草甸蔓延的生态系统效应的研究尚未见报道。本文从系统碳、氮循环的角度,分别研究狼毒在生长和非生长季节对高寒草甸生态系统的影响。同时,从花粉化感的角度,深入研究狼毒对当地同花期物种有性繁殖的影响。系统地研究高寒草甸生态系统物质循环过程,特别是非生长季节微生物和土壤碳氮库的动态变化,有助于揭示狼毒在系统物质循环方面的“物种效应”以及这种效应的季节变化,为丰富有关高海拔生态系统,特别是其非生长季的物质循环的科学理论做出贡献。同时,碳氮循环和花粉化感的研究还有助于深刻地理解狼毒作为一种入侵性很强的杂草的特殊的蔓延机制,从而为狼毒的有效防治、高寒草甸的科学管理提供依据。 针对狼毒在青藏高原高寒草甸上蔓延的生态系统碳氮循环方面的影响,开展以下2 方面的研究:(1)在生长季,研究松潘县尕米寺附近(北纬32°53',东经103°40',海拔3190 m)的两种地形(平地和阳坡)条件下狼毒对土壤碳氮循环影响及可能的原因。狼毒和其它几个主要物种(圆穗蓼(Polygonummacrophyllum D. Don var. Macrophyllum),草地早熟禾(Poa pretensis L.),四川嵩草(Kobresia setchwanensis Hand.-Maizz.),鹅绒委陵菜(Potentilla anserina L.var. anserine)和鳞叶龙胆(Gentiana squarrosa Ledeb.)的地上凋落物产量以及地上凋落物和根的化学组成被测量。在有-无狼毒斑块下,各种土壤的库(比如,铵态氮、硝态氮、无机磷和微生物生物量)和周转率(包括净矿化、净硝化、总硝化、反硝化和微生物呼吸速率)被测量和比较。(2)在非生长季节,尤其是春季冻融交替期,选取了两个研究地点——尕米寺和卡卡沟(北纬32°59',东经103°41',海拔3400 m),分别测定有狼毒和无狼毒斑块下土壤微生物生物量碳和氮、可溶性有机碳和氮以及铵态氮和硝态氮的动态变化。同时,分别在上述两个地点有-无狼毒的样地上,研究6 个主要物种(狼毒、圆穗蓼、草地早熟禾、四川嵩草、鹅绒委陵菜和鳞叶龙胆)从秋季开始、为期1 年的凋落物分解过程。 针对狼毒花粉化感对同花期其它物种可能的花粉化感作用开展以下工作:在实验室中,用一系列浓度的狼毒花粉水浸提液对与它同花期的其它物种以及自身花粉进行测试,测定花粉萌发率;在野外自然条件下的其它物种的柱头上施用上述浓度的狼毒花粉水浸提液,观测种子结实率,同时,观察狼毒花粉的种间花粉散布数量。 生长季节的研究结果表明,狼毒地上凋落物氮含量比其它几个主要物种更高,而木质素-总氮比更低。狼毒显著地增加其斑块下表层土壤中有机质的含量,而有-无狼毒的亚表层土壤在有机碳和总磷方面没有显著差异。狼毒表土中硝态氮含量在平地和阳坡比无狼毒土壤分别高113%和90%。狼毒表土中微生物生物量碳和氮量显著高于无狼毒表土。无论是平地还是阳坡,狼毒土壤的总硝化和微生物呼吸速率显著高于无狼毒土壤;而它们的反硝化速率只在平地有显著的差异。狼毒与其它物种间地上凋落物的产量和质量的差异可能是导致有-无狼毒土壤碳氮循环差异的原因。我们假设,狼毒可能通过增加贫氮生态系统土壤中的有效氮含量提高其入侵能力。 非生长季的研究结果表明,在青藏高原东缘的高寒草甸上,土壤微生物生3物量在11 月的秋-冬过渡期达到第一个峰值;在春季的冻融交替期,微生物生物量达到第二个峰值后又迅速降低。无机氮以及可溶性有机碳氮与微生物生物量有相似的变化过程。微生物碳氮比呈现显著的季节性变化。隆冬季节的微生物生物量碳氮比显著高于生长旺季的微生物碳氮比。这种变化可能暗示冬、夏季微生物的群落组成和对资源的利用有所不同。有-无狼毒斑块下土壤微生物和土壤碳、氮库一般只在秋-冬过渡期有显著差异,有狼毒土壤微生物生物量和土壤碳、氮库显著高于无狼毒土壤;而在之后的冬季和春季没有显著差异。所有6 个物种凋落物在非生长季分解率为24%-50%,均高于生长季的10%到30%。其中在秋-冬过渡期,凋落物开始埋藏的两周时间内,分解最快,达10%-20%。不同物种凋落物全年的分解率和分解过程有显著差异。圆穗蓼在全年的分解都较缓慢(非生长季26%,生长季15%),草地早熟禾和四川嵩草等全年的分解速率比较均匀(非生长季和生长季均为30%,非生长季略高),而狼毒在非生长季分解较快(约50%),而在接下来的生长季分解变得缓慢(约12%)。所有物种的凋落物氮含量在非生长季下降,而在随后的生长季上升。 实验室的花粉萌发试验证明,狼毒花粉对自身花粉萌发没有自毒作用,而其它受试的所有物种(圆穗蓼,秦艽(Gentiana macrophylla Pall. var. fetissowii),湿生扁蕾(Gentianopsis paludosa (Hook. f.) Ma var. paludosa),鳞叶龙胆,椭圆叶花锚(Halenia elliptica D. Don var. elliptica),蓝钟花(Cyananthus hookeri C. B.Cl. var. grandiflorus Marq.),小米草(Euphrasia pectinata Ten.),川西翠雀花(Delphinium tongolense Franch.),高原毛茛(Ranunculus tanguticus (Maxim.)Ovcz. var. tanguticus)和鹅绒委陵菜)的花粉萌发率随着狼毒花粉浸提液浓度的增加呈显著的非线性降低。大约3 个狼毒花粉的浸提液就可以抑制受试的多数物种的50%的花粉萌发。在鳞叶龙胆和小米草柱头上狼毒花粉的数量分别为5.76 个和3.35 个。狼毒花粉散布数量的差异最可能的原因在于是否有共同的传粉昆虫。花的形状(辐射对称VS 左右对称)、植株或花的密度以及花期重叠性可以部分解释这种差异。在野外试验中,我们发现6 个物种(秦艽、湿生扁蕾、鳞叶龙胆、椭圆叶花锚、蓝钟花和小米草)的种子结实率随狼毒花粉浸提液浓度的增加呈显著的非线性降低。鳞叶龙胆和小米草柱头上狼毒花粉的数量(分别是5.76 个和3.35 个)分别达到了抑制它们63%和55%种子结实率的水平。因此,狼毒对鳞叶龙胆和小米草可能存在明显的花粉化感抑制作用。狼毒周围的物种可能通过花期在季节或昼夜上的分异避免受到狼毒花粉化感的影响或者通过无性繁殖来维持种群繁衍,因此狼毒通过花粉化感作用对其周围物种繁殖的影响程度还需要进一步地研究。如果狼毒的花粉化感抑制作用确实存在,那么它可能成为一种自然选择压力,进而影响物种的进化。 Stellera chamaejasme L., a perennial toxic weed, has emerged and quicklydominated and spread in the high-frigid meadow on the eastern Tibetan Plateau ofChina since the 1960s. In the present study, effects of S. chamaejasme on carbon andnitrogen cycles on the high-frigid meadow on the eastern Qinghai-Tibetan Plateau ingrowing and non-growing season, and its pollen allelopathic effects on the sympatricspecies were determined. The present study that focused on carbon and nitrogencycles, especially on microbial biomass and pools of carbon and nitrogen innon-growing season, could profoundly illuminate plant-species effects on carbon andnutrient cycles and its seasonal pattern and help to understand spread mechanism ofS. chamaejasme as an aggressive weed. The present study also contributed to furtherunderstand carbon and nutrient cycles on alpine regions in non-growing season andprovide a basis on weed control of S. chamaejasme and scientific management in thehigh-frigid ecosystem. Effects of S. chamaejasme on carbon and nitrogen cycles on the high-frigidmeadow on the eastern Qinghai-Tibetan Plateau were determined. The study couldbe divided into two parts. (1) In the growing season, we quantified the effects of S.chamaejasme on carbon and nitrogen cycles in two types of topographic habitats, theflat valley and the south-facing slope, where S. chamaejasme was favored to spreadlitter and root were measured to explain the likely effects of S. chamaejasme on soilcarbon and nutrient cycles. The sizes of various soil pools, e.g. nitrite, ammonium,inorganic phosphorus and microbial biomass, and turnover rates including netmineralization, gross nitrification, denitrification and microbial respiration weredetermined. (2) In the non-growing season study, microbial biomass carbon andnitrogen, soluble organic carbon and nitrogen, ammonium and nitrate weredetermined through the non-growing season, especially in the processes offreeze-thaw of spring in two high-frigid sites, i.e. Kaka valley and Gami temple, onthe eastern Qinghai-Tibetan Plateau. Meanwhile, litter decomposition of six commonspecies, including Stellera chamaejasme L., Polygonum macrophyllum D. Don var.Macrophyllum, Poa pretensis L., Kobresia setchwanensis L., Potentilla anserina L.var. anserine and Gentiana squarrosa Ledeb., were also examined under theabove-mentioned experimental design through one whole-year, which began in theautumn in 2006. In the study of pollen allelopathy, several work, including in vitro study oneffects of extract of pollen from S. chamaejasme on sympatric species and pollenfrom itself, field experiments on effects of pollen extract with the same regime ofconcentrations on seed set and field observation on heterospecific pollen transfer ofS. chamaejasme to six of those sympatric species has been done. The results in the growing season showed that aboveground litter of S.chamaejasme had higher tissue nitrogen and lower lignin: nitrogen ratio than thoseco-occurring species. S. chamaejasme significantly increased topsoil organic matter,whereas no significant differences were found for organic C and total P in subsoilbetween under-Stellera and away-Stellera locations. The nitrate in Stellera topsoilwas 113% and 90% higher on the flat valley and on the south-facing slope,respectively. Both microbial biomass C and N were significantly higher in Stelleratopsoil. Gross nitrification and microbial respiration were significantly higher inStellera topsoil both on the flat valley and on the south-facing slope, whereassignificant differences of denitrification were found only on the flat valley. Thedifferences in the quantity and quality of aboveground litter are a likely mechanismresponsible for the changes of soil variables. We assumed that S. chamaejasme couldenhance their spread by increasing nutrient availability in N-deficient ecosystems. The results in the non-growing season showed that microbial biomass achievedthe first summit in late autumn and early winter on the eastern Qinghai-TibetanPlateau. In the stages of freeze-thaw of spring, microbial biomass firstly achieved thesecond summit and subsequently sharply decreased. Inorganic nitrogen, solubleorganic carbon and nitrogen had a similar dynamics with that of microbial biomass.Ratio of microbial biomass carbon and nitrogen had an obviously seasonal pattern.The highest microbial C: N were in the non-growing season, which weresignificantly higher than those in the growing season. The seasonal pattern inmicrobial biomass C: N suggested that large changes in composition of microbialpopulation and in resources those used by microbes between summer and winter.Generally, microbial biomass and pools size of carbon and nitrogen in Stellera soilwere significantly higher than those under adjacent locations in late autumn andearly winter, but there were not significant differences in winter and in spring. Litterof all the focal species (Stellera chamaejasme L., Polygonum macrophyllum D. Donvar. Macrophyllum, Poa pretensis L., Kobresia setchwanensis Hand.-Maizz.,Potentilla anserina L. var. anserine and G. squarrosa Ledeb.) decomposed about24%-50% in the non-growing season, which were higher than those in the growingseason (ranged from 10% to 30%). Litter decomposed 10%-20% within the first twoweeks in late autumn and early winter. Significant differences in the whole-yeardecomposition rate and in the processes of decomposition were found among species.Polygonum macrophyllum decomposed slowly through the whole year (26% and15% in the non-growing season and in the growing season, respectively). Certainspecies, such as P. pretensis L. and K. setchwanensis, decomposed at a similar rate(30% both in the non-growing and in the growing season, slightly higher in the8growing season than those in the growing season), whereas S. chamaejasmedecomposed more rapidly (about 50%) in the non-growing season and subsequentlydecomposition became slow (about 12%) in the growing season. Litter nitrogencontents of all the focal species firstly decreased in the non-growing season and thenincreased in the growing season. In vitro experiments of pollen allelopathy, the results showed that pollen from S.chamaejasme was not autotoxic, whereas pollen germination in all the sympatricspecies (Polygonum macrophyllum D. Don var. Macrophyllum, Gentianamacrophylla Pall. var. fetissowii, Gentianopsis paludosa (Hook. f.) Ma var. paludosa,Gentiana squarrosa Ledeb., Halenia elliptica D. Don var. elliptica, Cyananthushookeri C. B. Cl. var. grandiflorus Marq., Euphrasia pectinata Ten., Delphiniumtongolense Franch., Ranunculus tanguticus (Maxim.) Ovcz. var. tanguticus andPotentilla anserina L. var. anserina) decreased nonlinearly as the increasingconcentrations of extract of pollen from S. chamaejasme. Pollen Extract of threepollens from S. chamaejasme generally inhibited 50% pollen germination of most ofthe focal species. 5.76 and 3.35 pollens from S. chamaejasme were observed in fieldon stigmas of G. squarrosa and E. pectinata, respectively. Differences inheterospecific pollen transfer of S. chamaejasme could be attributed to the primaryreason whether they shared common pollinators. Flower morphology (e.g.zygomorphic or actinomorphic), plant or floral density and concurrence in floweringphonologies could explain, in part, the differences in heterospecific pollen transfer.In field experiments, the results showed that seed set in six sympatric species(Gentiana macrophylla Pall. var. fetissowii, Gentianopsis paludosa (Hook. f.) Mavar. paludosa, Gentiana squarrosa Ledeb., Halenia elliptica D. Don var. elliptica,Cyananthus hookeri C. B. Cl. var. grandiflorus Marq. and Euphrasia pectinata Ten.)decreased nonlinearly as the increasing concentrations of extract of pollen from S.chamaejasme. According to the nonlinear curves, the amounts of pollens from S.chamaejasme on stigmas of G. squarrosa and of E. pectinata (i.e. 5.76 grains and3.35 grains, respectively) could reduce 63% and 55% seed set of G. squarrosa and ofE. pectinata, respectively. Thus, allelopathic effects of S. chamaejasme on G.squarrosa and E. pectinata could be realistic. The sympatric species of S.chamaejasme could avoid pollen allelopathy of S. chamaejasme to sustainthemselves. This highlights the need to study how much pollen allelopathy in S.chamaejasme influences the sympatric species through divergence in seasonal ordiurnal flowering phonologies or through asexual reproduction. If pollen allelopathyin S. chamaejasme was confirmed, it could be as a pressure of natural selection andthus play an important role in species evolution.

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Agenda 21, the 40-chapter action plan, agreed to by all nations participating in the 1992 Earth Summit represents an ambitious effort to provide policy guidance across the entire spectrum of environment, development, and social issues confronting mankind. In the area of oceans and coasts (Chapter 17 of Agenda 21), the Earth Summit underscored that the management of oceans and coasts should be ‘integrated in content and anticipatory in ambit.’ To assist those responsible for implementing the Earth Summit guidelines on ocean and coastal management, this article first reviews the fundamental shift in paradigm reflected in the Earth Summit agreements as well as the specific recommendations contained in Chapter 17. Next, the article examines the central concept of ‘integrated management,’ noting both its importance and its limits. A general or ‘synthesis’ model of ‘integrated coastal management’ is then presented, addressing such questions as management goals, what is being managed, where, how, and by whom. In a concluding section, methods are proposed whereby the general or ‘synthesis model’ can be tailored to diverse national contexts, involving varying physical, socio-economic, and political conditions.

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在大田不同供肥条件下 ,于小麦灌浆后期对小麦旗叶光合特性参数进行了连续测定。结果表明 ,小麦叶片气体交换参数均有明显的日变化趋势 ,肥力条件对其日变化进程具有明显的调控作用。不施肥处理小麦叶片 Pn有明显午休现象 ,而低肥处理第一高峰不明显 ,没有明显午休现象 ;高肥处理的 Pn呈单峰曲线 ,峰值来得也较晚。养分条件可改善小麦叶片水分利用效率

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Directed by the theory of "Collision Tectonic Facies", the tectonic setting and dynamic mechanism of the formation of Songliao basin in late Mesozoic (J_3-K_1) are studied in the present thesis with the methods of petrology, petrochemistry, geochemistry and isotopic geochronology. The research contents in this paper include as followings. Firstly, the general tectonic frame is made up of different tectonic facies formed from Mid-late Proterozoic to Mesozoic, which are Huabei plate, the Chengde-Siziwangqi melange (Pz_1), the Wenduermiao magmatic arc (Pz_1), the Hegenshan-Chaogenshan melange (Pz_2), the accretion arec (Pz_1-P), the Raohe-Hulin melange (Mz), the magmatic arc (Mz) and the pull-apart basin on the magmatic arc (Mz). Secondly, the volcanic rock assemblages of Songliao basin and its adjacent area in late Mesozoic is the typical calc-alkaline of the magmatic arc. The types of volcanic rocks in the study area include basalts, basaltic andesites, andesites, dacites and rhyolites, and basic-intermediate volcanic rocks have higher alkalinity. The volcanic rock series in this area is the high-K calc-alkaline series. Thirdly, the total REE of volcanic rocks in Songliao basin and its adjacent area is higher than that of the chondrite. The pattern of the REE normalized by the chondrite shows the characteristics similar to that of the typical island arcs or the active continental margins in the earth, that is enrichment of LREE and depletion of Eu. The spider-diagram of the trace element normalized by the primitive mantle also expresses the similar features to that of the typical island arcs or the active continental margins, it has distinctive valleies of Nb, Ta, Sr, P, and Ti, as well as the peaks of La, Ce, Th, U, and K. The incompatible elements show that the high field strength elements, such as Nb, Ta, Ti, and P, are depletion while the low field strength elements, such as K, U, Pb, and Ba, are enrichment. These features are similar to those of orogenic volcanic rocks and imply the formation of the volcanic rocks in this area is related to the subduction. The degrees of both the enrichment of the HFS elements and depletion of the LFS elements become more obvious from basic to acid volcanic rocks, which suggests crustal contamination enhances with the magmatic crystallization and fractionation. The concentration of the compatible elements is W-shape, and anomalies in Cr and Ni suggest there is the contamination during the magmatic crystallization and fractionation. Fourthly, the isotopic age data prove the volcanic activity in the Songliao basin and its adjacent area started in the early-middle Jurassic, and ended in the end of the early Cretaceous-the beginning of the Cretaceous. The volcanism summit was the late Jurassic-the early Cretaceous (100 - 150Ma). Finally, the tectonic setting of volcanism in the late Mesozoic was magmatic arc, which originated the subduction of Raohe-Hulin trench to the northwest Asian plate. The subduction began in the middle Jurassic, and the collision orogenesis between the Sikhote-Alin arc and Asian continent was completed in the end of the early Cretaceous-the beginning of the late Cretaceous. The results of above tectonic processes were finally to format Nadanhada orogenic belt symbolized by the Raohe-Hulin suture or melange belt. The violently oblique movement of the Izanagi plate toward Asian plate in the late Mesozoic was the dynamic mechanism of above tectonic processes. At the same tome, the left-lateral strike-slip shear caused by the oblique movement of the Izanagi plate produced a series of strike-slip faults in east Asian margin, and the large scale displacements of these strike-slip faults then produced the pull-apart basing or grabens on the magmatic arc. Conclusively, the tectonic setting during the formation of the grabens of Songliao basin in the late Mesozoic was magmatic arc, and its dynamic mechanism was the pull-apart. In a word, there was a good coupling relation among the oblique subduction of the oceanic plate, collisional orogene between island arc and continental plate, strike-slip shear of the faults and the formation of the grabens in Songliao basin and its adjacent area in late Mesozoic. These tectonic processes were completed in the unoin dynamic setting and mechanism as above description.