241 resultados para 310-M0009D


Relevância:

10.00% 10.00%

Publicador:

Resumo:

Two marine urostylid ciliates, Holosticha hamulata n. sp. and Holosticha heterofoissneri Hu and Song, 2001, were investigated using live observation and protargol impregnation. Both species were isolated from Korean intertidal sediments of the Yellow Sea. Holosticha hamulata measures about 150 x 25 pro in vivo, and is characterized by a tripartite body shape with a narrow head, an inflated trunk, and a tail that distally projects ventrally forming a hook-like structure. It is the characteristic body shape that distinguishes H. hamulata distinctly from congeners. Holosticha hamulata differs from H. heterofoissneri, possibly the nearest relative, also by the location of the contractile vacuole (ahead of mid-body versus near posterior body third) and the configuration of the macronucleus (on average, 33 scattered nodules assuming a Y-shape versus 17 nodules that may form a U shape). The average number of the macronuclear nodules is a pronounced feature showing great consistency in populations of each species. However, their arrangement is variable in H. heterofoissneri where the nodules are basically scattered or connected by fine fibers forming an elongate U-shape. The location of the contractile vacuole as a taxonomic feature is discussed and a dichotomous key to the species of Holosticha sensu stricto is provided.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Microsatellites were screened in a backcross family of the Pacific oyster, Crassostrea gigas. Fifteen microsatellite loci were distinguishable and polymorphic with 6 types of allele-combinations. Null alleles were detected in 46.7% of loci, accounting for 11.7% of the total alleles. Four loci did not segregate in Mendelian Ratios. Three linkage groups were identified among 7 of the 15 segregating loci. Fluorescence-based automated capillary electrophoresis (ABI 310 Genetic Analyzer) that used to detect the microsatellite loci, has been proved a fast, precise, and reliable method in microsatellite genotyping.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Three sulfated polysaccharide fractions (F1, F2, and F3) were isolated from Porphyra haitanesis, an important economic alga in China, through anion-exchange column chromatography and their in vitro antioxidant activities were investigated in this study. Galactose was the main sugar unit of the three fractions. The analytical results indicated that polysaccharide fractions from P. haitanesis had similar chemical components to porphyran from other species, but differed in their high sulfate content. The sulfate content of F1, F2 and F3 was 17.4%, 20.5% and 33.5% respectively. All three polysaccharide fractions showed antioxidant activities. They had strong scavenging effect on superoxide radical, and much weaker effect on hydroxyl free radical. Lipid peroxide in rat liver microsome was significantly inhibited, and H2O2 induced hemolysis of rat erythrocyte was partly inhibited by F1, F2 and F3. Among them, F3 showed strongest scavenging effect on superoxide radical; F2 had strongest effect on hydroxyl radical and lipid peroxide.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

A corrosion simulation device was studied using offshore long scale hanging specimens. An Ni-Cu-P steel specimen was studied by analysing its corrosion products and corrosion types. The appearance of the samples and the surface of the metallic substrate after the removal of the rust layer produced by these two methods were observed and compared after 470 days of exposure. The phase structure of the corrosion products under different marine environments were analysed and compared. It further indicated good correlation between the electrically connected hanging specimen method and the long scale hanging specimen method.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

由中国动物学会兽类学分会、中国生态学会动物生态学专业委员会、中国野生动物保护协会主办,野生动物保护协会(WCS)、国际爱护动物基金会(IFAW)协办,华东师范大学、华东师范大学生命科学学院和华东师范大学生态学国家级重点学科联合承办的"第三届全国野生动物生态与资源保护学术研讨会"于2006年10月25-29日在上海市召开.本届研讨会受到了全国广大兽类学工作者、动物生态学工作者和野生动物保护工作者的热切关注和大力支持,来自全国84个科研院所、高等院校和野生动物保护管理部门的近300多名代表参加了这次盛会.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

对江河源区人工草地群落特征、多样性及其稳定性的研究结果表明,不同处理草地植物群落的物种丰富度、多样性、均匀度指数因时间和空间的变化而有明显的差异,群落演替从5龄到6龄,各群落丰富度和多样性指数增加,生物生产量降低,群落相似性系数增大.5龄老芒麦+早熟禾混播人工草地(LP5)群落的地上生物量最高(379.6 g/m2),老芒麦单播(ES5)居中(323.4 g/m2),对照组(CKF5和CK5)最低(124.3和118.6 g/m2).6龄植物群落地上生物量依次为原生植被+封育(VP6,310.1 g/m2)>老芒麦+早熟禾混播(LP6,216.3 g/m2)>老芒麦单播(ES6,190.8 g/m2)>对照(CK6,88.7 g/m2).群落间相似性系数的变化说明,单播(ES)与混播(LP)人工草地群落有趋同演化的趋势.人工草地群落随着结构的复杂化,与对照群落间的相似性提高,说明群落处于退化演替阶段,物种丰富度和多样性增大,群落稳定性提高.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

根据天然草地退化程度的差异,采用松耙+补播+施肥+封育(退化较严重的草地)、封育+施肥(轻度退化草地)等措施,植物群落物种组成、多样性等特征值及其植被盖度发生明显变化.研究第2年结果表明,物种数封育+施肥处理最高(32种),对照居中(26种),补播+施肥处理最低(13种);多样性指数大小依次为封育+施肥(3.126)、对照(2.819)、补播+施肥(1.494);均匀度指数大小依次为封育+施肥(0.902)、对照(0.865)、补播+施肥(0.582);群落总盖度大小依次为封育+施肥(85.9%)、补播+施肥(79.7%)、对照(72.9%);补播+施肥+封育处理后地上生物量最大(460.65 g/m2),原生植被+封育+施肥处理居中(310.14 g/m2),对照最低(178.96 g/m2);地下生物量大小依次为封育+施肥(6 920.37 g/m2)、补播+施肥(1 458.96 g/m2)、对照(828.91 g/m2);补播+施肥+封育处理优良牧草较对照提高近50倍,杂草类减少82.81%,封育+施肥处理较对照良牧草比例提高48倍,杂草类比例减少80.46%.半人工草地通过灭除杂草和施肥相结合的示范试验表明:单纯进行灭杂,地上生物量减少,灭杂和施肥相结合不仅可提高地上生物量,而且可提高优良牧草的比例;不同处理区土壤养分含量各不相同,其中封育+施肥处理全氮、全碳、有机碳最高,对照居中,补播+施肥较低.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

We measured the stable carbon isotope ratios for muscle of the upland buzzards (Buteo hemilasius), plateau pika (Ochotoma curzoniae), root vole (Microtus oeconomus), plateau zokor (Myospalax fontanierii) and passerine bird species at the Haibei Alpine Meadow Ecosystem Research Station (HAMERS), and provided diet information of upland buzzards with the measurement of stable carbon isotopes in tissues of these consumers. The results showed that δ~(13)C values of small mammals and passerine bird species ranged from -25.57‰ to -25.78‰ (n = 12), and from -24.81‰ to -22.51% (n = 43), respectively, δ~(13)C values of the upland buzzards ranged from -22.60‰ to -23.10‰ when food was not available. The difference in δ~(13)C values (2.88‰±0.31‰) between upland buzzards and small mammals was much larger than the differences reported previously, 1‰-2‰, and showed significant difference, while 1.31‰±0.34‰ between upland buzzard and passerine bird species did not differ from the previously reported trophic fractionation difference of 1‰-2‰. Estimation of trophic position indicated that upland buzzards stand at trophic position 4.23, far from that of small mammals, i.e., upland buzzards scarcely captured small mammals as food at the duration of food shortage. According to isotope mass balance model, small mammals contributed 7.89% to 35.04% of carbon to the food source of the upland buzzards, while passerine bird species contributed 64.96% to 92.11%. Upland buzzards turned to passerine bird species as food during times of shortage of small mammals. δ~(13)C value, a useful indicator of diet, indicates that the upland buzzards feed mainly on passerine bird species rather than small mammals due to "you are what you eat" when small mammal preys are becoming scarce.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

对青藏高原东北部高山冰缘地区和相邻低海拔地区59种多年生草本被子植物进行了染色体计数。其中,45个种的染色体记数为首次报道,并确定其信性.对分布于高山冰缘地区和冰缘以下不同海拔地区植物染色体的多倍性进行分析研究,结果如下:(1)多年生草本被子植物多倍体频率随海拔高度上升而增加:海拔2000-3000m,多倍体频率为29.4%-47.1%.3000-3800(4000)m(高寒灌丛-草甸区),多倍体频率为33.3%-53.3%;4000-5200m以上的高山冰缘地区,多倍体频率达55.6%-70.4%.(2)高山冰缘地区新多倍体较多,并且与青藏高原上特有的植物类群(特有属、亚属或特有种)相关联。(3)分布在冰缘地区的多倍体广布种,通常都是较原始类群的古多倍体,它们可能在青藏高原强烈隆升以前就已经形成,并分化出许多生态型,在高原强烈隆升并出现高山冰缘环境以后,某些生态型突出繁殖适应机制(r型选择机制),能开拓新生境而在新出现的严酷而不稳定的冰缘地区繁衍,其它一些生态型则依靠营养生长优势(K型选择机制)广泛分布在其稳定、成熟的生境中。(4)冰缘以下地区的多倍体特有种多数属于古多倍体或次生多倍体。它们多数可能是由西南山地或秦岭、华北森林区系产生,然后扩散至青藏高原边缘。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Adaptation to hypoxia is regulated by hypoxia-inducible factor 1 (HIF-1), a heterodimeric transcription factor consisting of an oxygen-regulated a-subunit and a constitutively expressed beta-subunit. How animals living on Qinghai-Tibetan plateau adapt to the extreme hypoxia environment is known indistinctly. In this study, the Qinghai yak which has been living at 3000-5000 m attitude for at least two millions of years was selected as the model of high hypoxia-tolerant adaptation species. The HIF-1 alpha ORFs (open reading frames) encoding for two isoforms of HIF-1 alpha have been cloned from the brain of the domestic yak. Its expression of HIF-1 alpha was analyzed at both mRNA and protein levels in various tissues. Both its HIF-1 alpha mRNA and protein are tissue specific expression. Its HIF-1 alpha protein's high expression in the brain, lung, and kidney showed us that HIF-1 alpha protein may play an important role in the adaptation to hypoxia environment. (c) 2006 Elsevier Inc. All rights reserved.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

超临界CO2流体与技术配合相结合开辟了重金属萃取的新途径。本文介绍了超临界CO2流体萃取重金属的研究现状,总结了影响萃取的因素,并对未来的发展趋势作了展望。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

利用三维荧光光谱研究了太阳辐射对溶解有机质(DOM)荧光光谱特征的影响。实验结果表明,太阳辐射使DOM的荧光发射光谱强度减弱。在三维荧光光谱图中,红枫湖样品的荧光峰A,C,南明河样品的荧光峰A,B,C,尤其是荧光峰C的λExmax/λEmmax位置随着太阳辐射时间的延长而逐渐向短波长移动。从腐殖酸样品的三维荧光光谱图中则发现,原始样品荧光峰位置出现在λEx/λEm=275/500nm处,光照作用后出现两个荧光峰λEx/λEm=245/450nm和310/450nm。太阳辐射对DOM中不同荧光组分的光降解速率存在差异,从荧光峰A和C的比值r(A,C)随太阳辐射时间的变化趋势得知,荧光峰C比荧光

Relevância:

10.00% 10.00%

Publicador:

Resumo:

贵州省赫章县的土法炼锌不仅导致植被的破坏,而且使附近土壤和溪流沉积物中重金属有不同程度的积累,土壤中w(Pb)达到37.24×lO^-6~30100×lO^-6,w(Zn)为162.23×lO^-6~31625×lO^6。,w(Cd)为O.50×lO^-6~113×lO^-6,大大超过了当地的土壤背景值;沉积物中w(Pb)达到325.00×lO^-6~21850×lO^-6,w(Zn)为1250.00×10^-6~30425×10^-6,w(Cd)为25×10^-6~97×10^-6。土壤和沉积物中Pb、Zn含量与Al2O3有极显著的正相关性;土壤中重金属Pb、压含量与A12O3有极显著的正相关性,而沉积物中Pb、压含量与Al2O3则没有相关性。土壤和沉积物中铁矿物(铁氧化物和氢氧化物)对重金属的强烈固定作用。连续提取法对化学形态研究表明,Pb、办在土壤中主要表现为铁锰氧化物结合态与残渣态,而在沉积物中则主要为碳酸盐结合态、残渣态和铁锰氧化物结合态。土壤中可交换态Pb、压所占的比例很小,但其绝对含量变化较大,w(Pb)从最低2.75×lO^-6到最高310.4l×l0^-6,w(Zn)4.94×lO^-6~321.10×lO^-6。沉积物中w(Pb)7.42×lO^-6~98.9l×lO^-6;w(zn))9.97×lO^-6~72.67×lO^-6。土壤中重金属Pb、压的有效性程度明显高于溪流沉积物,对生态环境的潜在危害更大.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

“三江”地区是我国主要的火山岩型块状硫化物矿床成矿区域之一,产于赠科-乡城矿带的呷村矿床是我国典型的含金富银的块状硫化物矿床。矿床位于义敦古岛弧主弧带北段的昌台火山-沉积盆地中。该盆地上三叠统自下而上分为根隆组、呷村组和勉戈组,相应形成三个火山旋回,成矿作用发生在每个火山旋回末期。在呷村旋回的流纹质火山活动末期,形成呷村、嘎衣穷、夏塞等银多金属矿床。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

近年来地质证据和少量的实验研究证实,相当量的铜可以在气相中迁移,人们认识到铜在气相中迁移是一种重要的地球化学过程,但目前关于铜在气相中溶解反应机理的研究还相当缺乏.本文通过溶解度法,在310~350℃,压力为4.2~10 MPa的条件范围内,实验研究了铜在不饱和水蒸气相中的溶解度.结果表明:水蒸气的存在大大增强了铜在气相中的溶解度;恒定温度下,铜在气相中的溶解度随着水蒸气压的增加而增大;气相中铜可能以水合物的形式存在,铜在气相中的溶解可由以下反应表述:CuClm^solid +nH2O^gas=CuClm·(H2O)n^gas(m=1,2),其中水合数随着温度升高而下降,温度为310℃水合数n为~6,330℃为~5,350℃为~4.研究结果明确显示,气体溶剂H2O与铜之间的反应可大大增强铜在气相中的溶解和迁移能力。