923 resultados para Tibetan coded character set extension B


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Phylogeny of the specialized schizothoracine fishes (Teleostei: Cypriniformes: Cyprinidae). Zoological Studies 40(2). 147-157. To elucidate phylogenetic relationships within the specialized schizothoracine fishes, we used 41 variable osteological and external characters among this groups, three species of Schizothorax, and 1 fossil species. When the 3 species of Schizothorax were designated as an outgroup and all 41 characters were set as unordered with equal weighting, the data matrix yielded a single most-parsimonious tree with a tree length of 71 steps, a consistency index of 0.6761, and a retention index of 0.7416. Meanwhile, a bootstrap test was conducted to verify the reliability of the results. The matrix was also analyzed for different conditions: all characters were ordered and the fossil species was added as an outgroup. The phylogenetic analyses presented herein support the following hypotheses. 1) All species of the specialized schizo-thoracines fishes form a monophyletic group. 2) Monophyly of the genus Ptychobarbus is not supported by the bootstrap test or when these characters are ordered. 3) The genus Gymnodiptychus forms a monophyletic group. 4) All species of Ptychobarbus and Gymnodiptychus form a monophyletic group with Diptychus as its sister group.

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The structural and photoluminescence (PL) properties of the InAs quantum dots (QDs) grown on a combined InAlAs and GaAs strained buffer layer have been investigated by AFM and PL measurements. The dependence of the critical thickness for the transition from 2D to 3D on the thickness of GaAs layer is demonstrated directly by RHEED. The effects of the introduced-InAlAs layer on the density and the aspect ratio of QDs have been discussed.

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p-type doping is a great challenge for the full utilization of ZnO as short-wavelength optoelectronic material. Due to a large electronegative characteristic of oxygen, the ionization energy of acceptors in ZnO is usually too high. By analyzing the defect wave-function character, we propose several approaches to lower the acceptor ionization energy by codoping acceptors with donor or isovalent atoms. Using the first-principles band-structure method, we show that the acceptor transition energies of V-Zn-O-O can be reduced by introducing F-O next to V-Zn to reduce electronic potential, whereas the acceptor transition energy of N-O-nZn(Zn) (n=1-4) can be reduced if we replace Zn by isovalent Mg or Be to reduce the anion and cation kinetic p-d repulsion, as well as the electronic potential.

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大气臭氧的损耗导致了地球表面具有生物学效应的紫外线-B(UV-B)辐射增强。同时,大气成分变化中除了UV-B辐射增强外,氮沉降是一个新近出现而又令人担忧的环境问题,其来源和分布正在迅速扩展到全球范围,并不断向陆地和水生生态系统沉降。本试验在四川省境内的中国科学院茂县生态站内进行,以云山、冷杉、色木槭和红椋子幼苗为模式植物,从生长形态、光合作用、抗氧化能力和矿质营养等方面研究了青藏高原东缘4种树苗对全球变化-增强UV-B辐射和氮供应(氮沉降)的响应。该试验为室外盆栽试验,包括四个处理:(1)大气UV-B辐射+无额外的氮供应(C);(2)大气UV-B辐射+额外的氮供应(N);(3)增强UV-B辐射+无额外的氮供应(UV-B);(4)增强UV-B辐射+额外的氮供应(UV-B+N)。其目的:一方面有助于丰富我国对全球变化及区域响应研究的全面认识,进一步完善在全球气候变化条件下臭氧层削减和氮沉降对陆地生态系统影响的内容;另一方面,在一定程度上有助于我们更好的理解在全球变化下森林更新的早期过程。具体结果如下: 增强的UV-B辐射在生长形态、光合、抗氧化能力、活性氧和矿质营养方面对4种幼苗都有显著的影响。UV-B辐射增强对幼苗的影响不仅与物种有关,而且,还与氮营养水平相关。总体表现为,高的UV-B辐射导致了色木槭和红椋子幼苗叶片的皱缩和卷曲,并降低了色木槭幼苗的叶片数和叶重,在额外的氮供应下,云杉、冷杉和红椋子的叶重也显著地降低了;色木槭和红椋子幼苗叶片的解剖结构受到了增强的UV-B辐射的影响,增强的UV-B辐射显著地降低了色木槭叶片的栅栏组织厚度,提高了红椋子叶片的厚度;增强的UV-B辐射显著地降低了4种幼苗的单株总生物量、植物地下部分的生长、总叶绿素含量 [Chl (a + b)]、净光合速率和最大量子产量(Fv/Fm),提高了4种幼苗叶片的膜脂过氧化(MDA含量),改变了植物体不同器官中的矿质元素含量;增强的UV-B辐射提高了冷杉、色木槭和红椋子叶片中的过氧化氢含量(H2O2)、超氧负离子(O2-)生成速率,在额外的氮供应下,云杉叶片中的活性氧含量也显著地提高了;在无额外的氮供应条件下,增强的UV-B辐射显著地提高了4种幼苗叶片中的UV-B吸收物质、脯氨酸含量和抗氧化酶的活性(SOD、POD、CAT、GR和APX)。在额外的氮供应条件下,UV-B辐射的增强却显著地降低了冷杉叶片中脯氨酸含量和红椋子叶片中UV-B吸收物质含量,但是,在4种幼苗叶片中,5种抗氧化酶的活性对UV-B辐射的增强没有明显的规律性,增强的UV-B辐射显著地提高了云杉叶片中的POD、SOD和GR的活性,提高了冷杉叶片中的POD和GR活性,提高了色木槭叶片中的POD、SOD和CAT活性和红椋子幼苗叶片中的POD和SOD活性。从这些结果可知,植物在遭受高的UV-B辐射导致的过氧化胁迫时,植物体内形成了一定的保护机制,但是,这种保护不能抵抗高的UV-B辐射对植物的伤害。 额外的氮供应在生长形态、光合、抗氧化能力、活性氧和矿质营养方面对4种幼苗都有一定的影响,不同幼苗对额外的氮供应响应不同,并且受到UV-B辐射水平的影响。在当地现有的UV-B辐射水平下,额外的氮供应显著地提高了幼苗的单株总生物量、植物地下部分的生长、Chl (a + b)、净光合速率(红椋子除外)、UV-B吸收物质(冷杉除外)、脯氨酸含量(红椋子除外)和部分抗氧化酶的活性,降低了H2O2的含量、O2-的生成速率和MDA含量(红椋子除外),改变了植物体内部分矿质元素含量,显著地提高了云杉和冷杉叶片中的Fv/Fm。这些指标总体表明,在当地现有大气UV-B辐射水平下,额外的氮供应对植物的生长和发育是有利的。在增强的UV-B辐射水平下,4种幼苗的生长形态和光合大部分指标都没有受到额外氮供应的影响,额外的氮供应提高了红椋子幼苗的单株总生物量和Chl (a + b)含量,提高了冷杉和色木槭叶片中的活性氧含量和MDA含量,却降低了红椋子叶片中的活性氧含量;额外的氮供应也提高了云杉、色木槭和红椋子叶片中UV-B吸收物质和脯氨酸含量,降低了冷杉叶片中UV-B吸收物质和脯氨酸含量;在抗氧化酶活性方面,额外的氮供应降低了云杉、冷杉叶片中5种抗氧化酶的活性和红椋子叶片中POD和GR的活性,提高了色木槭叶片中的POD和SOD的活性;4种幼苗植物体内的矿质元素含量对额外的氮供应没有显著的规律性。从这些结果可知,在高的UV-B辐射下,额外的氮供应提高了云杉、冷杉和色木槭幼苗对高的UV-B辐射的敏感性,然而,额外的氮供应却促进了红椋子幼苗的生长,原因可能是,在高的UV-B辐射下,额外的氮供应增加了红椋子叶片的厚度、叶重和叶片数,降低了叶片中活性氧含量的结果。表明在高的UV-B辐射水平下,额外的氮供应降低了红椋子幼苗对高的UV-B辐射的敏感性。 在全球变化的趋势下,UV-B辐射增强和氮沉降可能同时存在,我们的研究表明,与大气UV-B辐射+无额外的氮供应处理相比,增强UV-B辐射+额外的氮供应处理显著地降低了幼苗的单株总生物量(红椋子除外)、Chl (a + b)、净光合速率、Fv/Fm(冷杉除外)和MDA含量(红椋子除外),提高了活性氧含量 (云杉除外)、UV-B紫外吸收物质含量(冷杉除外)、脯氨酸含量和部分抗氧化酶的活性,改变了植物体不同器官中的矿质元素含量。结果表明,在当地现有条件下,全球变化(UV-B辐射增强和氮沉降)对云杉、冷杉和色木槭幼苗的生长是不利,尽管植物体内一些抗氧化性指标提高了,然而,却对红椋子幼苗的单株总生物量的累积没有显著的影响。 The depletion of the ozone led to the increase of ultraviolet-B (UV-B) with biological effects in the earth’s surface. At the same time, except for enhanced UV-B radiation, nitrogen deposition was an anxious environmental problem at present, rapidly expanding to the global scope and continuously depositing to land and aquatic ecosystem. The experiment was conducted in Maoxian Ecological Station of Chinese Academy of Sciences, Sichuan province, China. Picea asperata, Abies faxoniana, Acer mono Maxim and Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings were selected as model plants to assess the effects of enhanced UV-B radiation and supplemental nitrogen supply on growth, morphological, photosynthesis, antioxidant and mineral nutrient traits of 4 species seedlings in east Qinghai-Tibetan Plateau. The experiment was potted outdoor, including 4 treatments: (1) ambient UV-B without supplemental nitrogen (control, C); (2) ambient UV-B with supplemental nitrogen (N); (3) enhanced UV-B without supplemental nitrogen (UV-B); (4) enhanced UV-B with supplemental nitrogen (UV-B+N). One hand, it was helpful for enriching our country to comprehensive understanding of the researches in the global change and the region response, further perfecting the effects of the depleted ozone layer and nitrogen deposition on land ecosystem under the global change; the other hand, it was favorable for us to better understanding of the early process of forest renews under the global change. The results were as follows: Enhanced UV-B radiation had significant effects on 4 species seedlings in growth, morphological, photosynthesis, antioxidant and mineral nutrient traits of 4 species seedlings. The effects of enhanced UV-B on plants were not only related with species, but also related with nitrogen nutrient level. Generally, the increase of UV-B radiation led to the shrinkage and curl of leaves in Acer mono Maxim and Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings, and reduced the number of leaf and leaf weight of Acer mono Maxim seedlings, under supplemental nitrogen supply, leaf weight of Picea asperata, Abies faxoniana and Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings significantly also reduced; the anatomical features of leaf in Acer mono Maxim and Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings affected by enhanced UV-B radiation, the increase of UV-B radiation markedly reduced the palisade tissue thickness of Acer mono Maxim leaf and enhanced the leaf thickness of Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings; the enhanced UV-B radiation significantly reduced total biomass per plant of 4 species seedlings, the growth of the underground parts, Chl (a + b), net photosynthetic rate and maximum potential quantum yield of photosynthesis (Fv/Fm), and increased the degree of lipid peroxidation (MDA content) and changed the content of mineral elements in different parts of plants; the enhanced UV-B radiation also increased the rate of superoxide radical (O2-) production and hydrogen peroxide (H2O2) content in leaves of Abies faxoniana, Acer mono Maxim, Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings, under supplemental nitrogen supply, the reactive oxygen species in leaves of Picea asperata seedlings also significantly increased by enhanced UV-B radiation; under without supplemental nitrogen supply, enhanced UV-B radiation evidently induced an increase in UV-B absorbing compounds, proline content and the activities of antioxidant enzymes (SOD, POD, CAT, GR and APX) of leaves in 4 species seedlings. Under supplemental nitrogen supply, enhanced UV-B radiation induced a decrease in proline content of leaves in Abies faxoniana seedlings and UV-B absorbing compounds of leaves in Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings, but, there were no obvious rules in the activities of five antioxidant enzymes of 4 species seedling leaves to enhanced UV-B radiation, enhanced UV-B radiation significantly increased the activities of POD, SOD and GR in Picea asperata leaves, the activities of POD and GR in Abies faxoniana leaves and the activities of POD, SOD and CAT in Acer mono Maxim leaves. The results indicated that some protective mechanism was formed when plants were exposed to enhanced UV-B radiation, but the protection could not counteract the harm of high UV-B radiation on plants. Supplemental nitrogen supply had some effects on 4 species seedlings in growth, morphological, photosynthesis, antioxidant and mineral nutrient traits. The response of 4 species seedlings was different to supplemental nitrogen supply, and was affected by UV-B levels. Under local ambient UV-B radiation, supplemental nitrogen supply significantly increased the total biomass per plant, the growth of underground parts, Chl (a + b), net photosynthetic rate (except for Acer mono Maxim seedlings), UV-B absorbing compounds (except for Abies faxoniana seedlings), proline content (except for Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings) and the activities of some antioxidant enzymes, and reduced H2O2 content, the rate of O2- production and MDA content (except for Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings) and changed the content of mineral elemental in different parts; supplemental nitrogen supply also evidently increased Fv/Fm in Picea asperata and Abies faxoniana seedlings. These results indicated that supplemental nitrogen supply was favorable for the growth of plants under local ambient UV-B radiation. Under enhanced UV-B radiation, mostly parameters in growth and morphology of 4 species seedlings were not affected by supplemental nitrogen supply. Supplemental nitrogen supply increased the total biomass per plant and Chl (a + b) of Swida hemsleyi (Schneid. et Wanger.) Sojak seedling, increased the reactive oxygen species and MDA content in Abies faxoniana and Acer mono Maxim leaves, and reduced the reactive oxygen species in Swida hemsleyi (Schneid. et Wanger.) Sojak leaves; supplemental nitrogen supply also increased UV-B absorbing compounds and proline content in Picea asperata, Acer mono Maxim and Swida hemsleyi (Schneid. et Wanger.) Sojak leaves, decreased UV-B absorbing compounds and proline content in Abies faxoniana leaves; in the activities of antioxidant enzymes, supplemental nitrogen supply significantly reduced the activities of antioxidant enzymes in Picea asperata and Abies faxoniana leaves and the activities of POD and GR in Swida hemsleyi (Schneid. et Wanger.) Sojak leaves, and increased the activities of POD and SOD in Acer mono Maxim leaves; the content of mineral elements in 4 species seedlings was no significantly rule to supplemental nitrogen supply. We knew from the results, under enhanced UV-B radiation, supplemental nitrogen supply made Picea asperata, Acer faxoniana and Acer mono Maxim seedlings more sensitivity to enhanced UV-B radiation, however, accelerated the growth of Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings. The reason was probably that supplemental nitrogen supply increased the leaf thickness, leaf weight and leaf number, reduced the reactive oxygen content of leaf in Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings grown under high UV-B radiation. This showed that supplemental nitrogen supply reduced the sensitivity of Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings to high UV-B radiation. Under the tendency of the global change, enhanced UV-B radiation and nitrogen deposition may probably coexist. The results showed, compared with the treatment of ambient UV-B radiation without supplemental nitrogen supply, the treatment of enhanced UV-B radiation with supplemental nitrogen supply significantly reduced the total biomass per plants (except for Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings), Chl (a + b), net photosynthetic rate, Fv/Fm and MDA content (except for Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings), and increased reactive oxygen content (except for Picea asperata seedlings), UV-B absorbing compounds (except for Abies faxoniana seedlings), proline content and part antioxidant enzymes, and changed the content of mineral elements of different parts. The results indicated that the global change (enhanced UV-B and nitrogen deposition) were not favorable for the growth of plants under local ambient UV-B radiation and nitrogen nutrient level,, though increased some antioxidant indexes, however, the treatment of enhanced UV-B with supplement nitrogen supply did not significantly affect on the biomass accumulation of Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings.

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臭氧层损耗导致的地球表面UV-B辐射增强以及温室气体增多引起的气候变暖是当今两大全球环境问题。UV-B辐射增强和气候变暖对陆地植物和生态系统产生深远影响,并已成为全球变化研究的重要议题。作为世界第三极的青藏高原,UV-B 辐射增强以及气候变暖现象尤为突出。本试验所在林区是青藏高原东缘的主要林区,具有大面积的亚高山人工针叶成熟林,在全球变化背景下该森林的天然更新潜力如何是急待回答的重要问题。基于此,本研究围绕森林树种的种子和幼苗这一更新的重要阶段,开展了气候变暖、UV-B辐射增强和联合胁迫对云杉种子萌发及幼苗定居影响的研究,旨在全球变化背景下,探讨全球变暖、UV-B 辐射增强和联合胁迫是否对西南地区大面积人工亚高山针叶林更新的种子萌发和幼苗定居阶段产生影响。 本文以青藏高原东缘亚高山针叶林主要树种云杉为研究对象,研究云杉种子萌发及幼苗的生长和生理对UV-B辐射增强与气候变暖的响应。采用UV-B荧光灯(UV-lamp)来模拟增强的UV-B 辐射,此外,采用开顶式有机玻璃罩(OTCs)来模拟气候变暖。本试验包括四个处理:(1)大气UV-B 辐射+大气温度(C);(2)大气UV-B 辐射+模拟气候变暖(W);(3)增强的UV-B辐射+大气温度(U);(4)增强的UV-B辐射+模拟气候变暖(U+W)。 根据本试验结果,UV-B辐射增强对云杉种子萌发没有显著影响,它对萌发云杉幼苗的影响主要体现在幼叶展开以后。根据两年的试验结果,增强的UV-B辐射降低了云杉幼苗抗氧化酶活性,降低了抗氧化物质的含量,此外,造成了膜质的过氧化,表现为MDA在针叶中的积累。增强的UV-B照射处理萌发云杉幼苗两年后,幼苗的生长受到显著抑制。我们的结果显示,OTCs分别提高了空气(10 cm)和土壤(5 cm)温度1.74℃和0.94 ℃。增温显著地促进了云杉种子提前萌发,提高了萌发速率和萌发比率,而且,明显地促进了幼苗的生长,表现为株高和生物量累积的显著增长。此外增温还有利于云杉幼苗根的伸长生长以及生物量的累积,这可以使云杉幼苗更好地利用土壤中的水分和营养元素。 根据本试验结果,温度升高显著地促进了增强UV-B辐射下云杉萌发幼苗的生长,这说明,温度升高缓解了UV-B辐射增强对云杉萌发幼苗的负面影响。这种缓解作用可能是温度升高对UV-B辐射增强处理下幼苗的抗氧化系统活性改善的结果。温度升高还缓解了高UV-B辐射对云杉幼苗根生长的抑制作用,这也可能是增温缓解伤害的原因之一。此外,根据我们的试验结果,增温与UV-B辐射增强联合作用(U+W)下云杉萌发幼苗的生长状况好于大气温度与大气UV-B辐射联合(C)处理,表现为株高、地径、根长和生物量积累均高于C处理,因此可以推断,UV-B辐射增强与气候变暖同时存在对萌发幼苗在两年之内的生长没有产生抑制作用,也就是说,气候变暖的缓解作用完全弥补了UV-B辐射增强的有害作用。 同样,增强的UV-B辐射显著影响了云杉幼苗的光合作用,表现为净光合速率(Pn)和表观量子效率(Φ)的提高,此外,根据我们的试验结果,它还造成了PSII的光抑制。增强的UV-B辐射显著抑制了云杉幼苗对营养元素的吸收,表现为大量营养元素、碳、钙、镁和锌含量的降低,但是,它却显著促进了铁在植株体内的积累。增温显著地提高了净光合速率,但是,它对光系统II(PSII)的光化学效率影响不大。温度升高缓解了UV-B增强对云杉幼苗光合作用的伤害,表现为净光合速率、表观量子效率以及PSII光化学效率的提高。此外,温度升高还缓解了UV-B辐射增强对离子吸收的抑制作用。 Enhanced UV-B radiation due to the reduction of O3 layer and global warming induced by increased greenhouse gases in the air have become the two pressing aspects of global climate changes. Moreover, enhanced UV-B radiation and warming have profound and long-term impacts on terrestrial plants and ecosystems, and the studies focusing on the two factors have attracted many attentions. Qinghai-Tibetan Plateau is the third in elevation in the world, and enhanced UV-B radiation and climate warming are especially prominent in this region. Our research located in the main forest belt in the eastern Qinghai-Tibetan Plateau where large areas of subalpine coniferous forests distributed. Based on that, we carried out a research to study the effects of enhanced UV-B radiation and climate warming on seed germination and seedlings growth of seedlings which are the important basic stage in forest regeneration. This research was arranged by a complete factorial design and included two factors (UV-B radiation and temperature) with two levels. The UV-lamps were used to manipulate the supplemental UV-B radiation and open-top chambers (OTCs) were adopted to increase temperature. The four treatments were: (1) C, ambient UV-B without warming; (2) U, enhanced UV-B without warming; (3) W, ambient UV-B with OTCs warming; (4) U+W, enhanced UV-B with OTCs warming. The main results were exhibited as follows: 1. Based on our results in this research, OTCs increased temperature on average 1.74℃ in air (10 cm above ground) and 0.92 ℃ in soil (5 cm beneath ground). Furthermore, OTCs also slightly reduced soil moisture and relative air humidity, however, the differences was not statistically significant. 2. Our results showed that enhanced UV-B had no significant effects on the seeds germination of P. asperata. Enhanced UV-B affected sprouts of P. asperata until the needles unfolded. During two years, enhanced UV-B inhibited the efficiency of the antioxidant defense systems, and as a result, it induced oxidant stress and the accumulation of MDA in needles. After two years of exposure to enhanced UV-B, the growth of P. asperata sprouts was markedly restrained compared with those under ambient UV-B radiation and temperature (C). Warming significantly stimulated the germination speed and increased the germination rate of P. asperata seeds. In the next place, it prominently facilitated the growth of P. asperata sprouts, represented as improvements in stem elongation and biomass accumulation. Furthermore, warming also increased root growth of P. asperata sprouts, which could made sprouts more efficient to use water and nutrient elements in soil. In this research, warming alleviated the deleterious effects of enhanced UV-B on P. asperata sprouts. It markedly stimulated the growth of P. asperata sprouts exposed to enhanced UV-B. The ease effects of warming on the abilities of the antioxidant defense systems might account for its amending effects on growth. After two years of exposure to enhanced UV-B radiation and warming, the growth of P. asperata sprouts was better than those under ambient UV-B radiation without warming (C), which could be seen from the higher plant height, basal diameter, root length and total biomass accumulation compared with C. 3. Enhanced UV-B radiation significantly influenced the photosynthesis processes of two-year old P. asperata seedlings. Our results showed that enhanced UV-B reduced the net photosynthetic rate (Pn) and the apparent quantum efficiency (Φ), and induced photoinhibition of photosynthetic system II (PSII). Enhanced UV-B significantly decreased the concentration of nitrogen (N), phosphorous (P), potassium (K), calcium (Ca), magnesium (Mg) and zinc (Zn), however, it increased the accumulation of iron (Fe) in the whole plant of P. asperata seedlings. Warming significantly stimulated Pn of P. asperata seedlings but it had no prominent impacts on the photochemical efficiency of PSII. In our research, warming also alleviated the harmful effects of enhanced UV-B on photosynthesis and absorption of ions of P. asperata seedlings. It increased Pn, Φ and the photochemical efficiency of PSII in seedlings exposed to enhanced UV-B. Moreover, warming also increased the absorption of ions of the seedlings exposed to enhanced UV-B radiation.