999 resultados para AC-2


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以稀有鲫为材料 ,研究了应激蛋白质作为生物学指标的敏感性。结果表明 ,在无可观察效应浓度下 ,经 5d亚慢性胁迫暴露 ,以Cu2 +为胁迫因子 ,稀有鲫被诱导出约 54KDa的应激蛋白质 ;以Zn2 +为胁迫因子 ,稀有鲫被诱导出约 94KDa ,67KDa和 40KDa的应激蛋白质。应激蛋白质有可能成为一种生物学指标运用于生态风险性早期预警。

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The development of cryogenic technology and high temperature superconducting (HTS) materials has seen continued interest worldwide in the development of HTS machines since the late 1980s. In this paper, the authors present a conceptual design of a 2.5 MW class synchronous motor. The structure of the motor is specified and the motor performance is analyzed via a three-dimensional model using the finite element method (FEM). Rotor optimization is carried out to decrease the harmonic components in the air gap field generated by HTS tapes. Based on the results of this 3D simulation, the determination of the operating conditions and load angle is discussed with consideration to the HTS material properties. The economic viability of air-core and iron-core designs is compared. The results show that this type of HTS machine has the potential to achieve an economic, efficient and effective machine design, which operates at a low load angle, and this design process provides a practical way to simulate and analyze the performance of such machines.

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本文对池塘育成的一秋龄成熟中华绒螯蟹(Eriocheir sinensis)生殖行为的观察表明,其具有生殖洄游习性,当年10月是其活动高峰期.而湖泊放流育成的早熟河蟹其活动高峰在当年10月及翌年3月.在湖泊淡水水体中少数个体有交配的行为,翌年3月份发现部分雌蟹的纳精囊内有精液.在池塘中一龄成熟河蟹与未成熟河蟹一样有居洞越冬的行为,从翌年3月初开始,白天蛰伏洞里,夜晚出来活动随着温度上升,成熟河蟹完全离开洞穴,四处爬动.1995年7月上旬,作者从刚死亡的早熟河蟹剥离出形态完整的膜状新壳.但是,未发现早熟河蟹

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国家自然科学基金29607004

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用Cu2+对红豆杉(Taxuschinensis)培养细胞中紫杉醇形成的影响进行了研究。在红豆杉细胞悬浮培养20d即指数生长期末,每1L细胞悬浮培养物中加入30μmolCuCl2,Cu2+促进紫杉醇形成的作用最大。添加CuCl2对红豆杉细胞生长没有明显影响,但引起培养细胞中可溶性蛋白质含量、苯丙氨酸解氨酶活性及培养基pH值的变化。

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利用甲基格氏试剂和天然樟脑反应,合成土霉味化合物2-甲基异莰醇(MIB),并用色谱、质谱和红外光谱对其进行鉴定,然后以合成MIB作标样,测定MIB的气相色谱保留值及其在东湖水体中浓度随季节变化规律。研究结果表明,东湖水体产生土霉味的主要成份为MIB,在1995~1996年期间,1月、4月和9月为武汉东湖水体中MIB浓度的高峰期,经测定东湖水中MIB的GC保留值与合成的MIB的GC保留值完全一致。

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描述了2种枝角类:丛刺尖额氵蚤和短削盘肠氵蚤的形态鉴别特征。这2种枝角类是中国的首次记录。

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鲢、鳙放养使微型生态系统的水柱氮、磷浓度和磷的分布发生了明显的变化。至实验结束时,各实验组的水柱颗粒磷、总磷和氨氮浓度都比对照组高,而正磷酸盐浓度和沉积物磷的量均低于对照组。这种变化以鳙单养系统为最大,其次是鲢、鳙混养系统,鲢单养系统的变化最小。微型生态系统中正磷酸盐浓度同浮游动、植物密度和初级生产力显著相关,氨氮浓度同所述变量之间的相关关系则多半与正磷酸盐相反。实验观测期间浮游植物密度与总磷浓度之间存在营养级联假说所预见的下行影响,实验结束时二者之间却有上行影响的趋向。根据实验观测结果认为,微型生态系统

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为了进一步探讨我国酸沉降对水陆生态环境的影响以及典型地区生态系统对酸沉降的缓冲能力和临界负荷值,笔者对赣、鄂、湘3省具有代表性的土壤的SO吸附特性进行了研究。结果表明,红壤,待别是江西省的红壤,吸附SO的能力最强,最大吸附量达11.52mg/g士;其余依次为黄壤、棕红壤、黄褐壤和黄红壤,最大吸附量分别为11.14,8.83,6.86和6.53mg/g土;红色石灰壤对SO的吸附能力最弱,最大吸附量仅3.55mg/g土,只及红壤的30.8%。可以预计,就地区而言,以红壤为主的江西省是我国对酿沉降最敏感的地区之

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We provide experimental evidence for a vortex migration phenomenon in YBa2Cu3O7-δ (YBCO) thin film caused by travelling magnetic wave. The experiment is carried out on a 2 in. diameter YBCO thin film with a circular-type magnetic flux pump. We found that the travelling wave helps the vortices migrate into the centre of the sample: after the zero-field cooling process, the increase of the flux density in the centre is four times larger than the amplitude of the travelling wave. The reason for this massive vortex migration is probably due to the magnetic stress variation caused by the travelling wave: the magnetic stress increases locally in the crest region while decreases locally in the trough region, which could help the vortices to move locally. A comparison shows that the magnetization by standing wave can be easily predicted by Bean's model while travelling wave causes vortex migration generally much larger than the prediction of Bean's model. It is possible that travelling magnetic wave can be an effective way to magnetize a type II superconductor in considering this unusual vortex dynamics. © 2013 AIP Publishing LLC.

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<正> 在前文的基础上,用~(59)CO~2+Cl_2·6H_2O加D_2O作为样品,在200MHz谱仪上观察~1H,在400MHz谱仪上观察~(35)Cl,研究强顺磁离子~(59)Co~2+(s=3/2,I=7/2)在外加直流磁场H_0作用下,它对~1H与~(35)Cl的NMR影响。因为强顺磁离子~(59)Co~(2+)的电子自旋(s=3/2)是围绕着核旋转的,因此可以统计平均计算,

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本文在实验室批量培养,室外小池大量培养和塑料大棚大面积培养的基础上,研究了植物激素2,4-D刺激鱼腥藻增殖的效应。浓度在0.01—2.00μg/mL范围内都具有刺激鱼腥藻增殖的效果,随着浓度增加,这种效果降低。品质分析结果表明,0.01μg/mL2.4-D可提高蛋白质和叶绿素a的含量;浓度为0.05μg/mL时,二者的含量与对照相差不大;浓度达到0.1μg/mL时,二者的含量降低。本文提出,2,4-D刺激鱼腥藻增殖的应用浓度应在0.05μg/mL以下,以0.01μg/mL效果最佳。

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A critical element for the successful growth of GaN device layers on Si is accurate control of the AlGaN buffer layers used to manage strain. Here we present a method for measuring the composition of the AlGaN buffer layers in device structures which makes use of a one-dimensional x-ray detector to provide efficient measurement of a reciprocal space map which covers the full compositional range from AlN to GaN. Combining this with a suitable x-ray reflection with low strain sensitivity it is possible to accurately determine the Al fraction of the buffer layers independent of their relaxation state. © 2013 IOP Publishing Ltd.