990 resultados para 173


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HIRFL-CSR工程对CSRe冷却装置电子冷却部分的控制系统在实时性和可靠性方面提出了非常高的要求。电子冷却工作环境复杂,各种干扰难以预测。从电子冷却的控制系统改进出发,以实现电子冷却的自动调束为目标,以高端FPGA和ARM嵌入式系统为基础,采用P2P通讯技术和神经元网络算法来实现对电子冷却的自动控制。该控制系统对电子冷却控制的完善提供了先进的硬件平台和软件实现方案。

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The high-spin level structure of Au-188 has been investigated via the Yb-173(F-19,4n gamma) reaction at beam energies of 86 and 90 MeV. The previously reported level scheme has been modified and extended significantly. A new I-pi = 20(+) state associated with pi h(11/2)(-1) circle times nu i(13/2)(-2)h(9/2)(-1) configuration and two new rotational bands, one of which is built on the pi h(9/2) circle times nu i(13/2) configuration, have been identified. The prolate-to-oblate shape transition through triaxial shape has been proposed to occur around Au-188 for the pi h(9/2) circle times nu i(13/2) bands in odd-odd Au isotopes. Evidence for pi h(11/2)(-1) circle times nu i(13/2)(-1) structure of nonaxial shape with gamma < -70 degrees has been obtained by comparison with total Routhian surface and cranked-shell-model calculations.

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Low temperature heat capacities of N-(p-methylphenyl)-N'-(2-pyridyl)urea were determined by adiabatic calorimetry method in the temperature range from 80 to 370 K. It was found that there was not any heat anomaly in this temperature region. Based on the experimental data, some thermodynamic function results were obtained. Thermal stability and decomposition characteristics analysis of N-(p-methylphenyl)-N'-(2-pyridyl)urea were carried out by DSC and TG. The results indicated that N-(p-methylphenyl)-N'-(2-pyridyl)urea started to melt at ca. 426 K (153degreesC) and the melting peak located at 447.01 K (173.86degreesC). The melting enthalpy was 204.445 kJ mol(-1) (899.6 J g(-1)). The decomposition peak of N-(p-methylphenyl)-N'-(2-pyridyl)urea was found at 499.26 K (226.11degreesC) from DSC curve. This result was similar with that from TG and DTG experiment, in which the mass loss peak was determined as 500.4 K (227.2degreesC).

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A high quality pure hydroxy-sodalite zeolite membrane was successfully synthesized on an alpha-Al2O3 support by a novel microwave-assisted hydrothermal synthesis (MARS) method. Influence of synthesis conditions, such as synthesis time, synthesis procedure, etc., on the formation of hydroxy-sodalite zeolite membrane by MAHS method was studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and gas permeation measurements. The synthesis of hydroxy-sodalite zeolite membrane by MAHS method only needed 45 min and synthesis was more than 8 times faster than by the conventional hydrothermal synthesis (CHS) method. A pure hydroxy-sodalite zeolite membrane was easily synthesized by MAHS method, while a zeolite membrane, which consisted of NaX zeolite, NaA zeolite and hydroxy-sodalite zeolite, was usually synthesized by CHS method. The effect of preparation procedures had a dramatic impact on the formation of hydroxy-sodalite zeolite membrane and a single-stage synthesis procedure produced a pure hydroxy-sodalite zeolite membrane. The pure hydroxy-sodalite zeolite membrane synthesized by MARS method was found to be well inter-grown and the thickness of the membrane was 6-7 mum. Gas permeation results showed that the hydrogen/n-butane permselectivity of the hydroxy-sodalite zeolite membrane was larger than 1000. (C) 2004 Elsevier Inc. All rights reserved.

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荒漠化土地荒漠化(沙漠化)是发生在干旱、半干旱和亚湿润干旱地区,由于气候变化和人类活动所造成的土地退化过程。近半个世纪以来,由于人类过度耕种、过分放牧和狂砍滥伐森林,使得土地贫瘠、植被破坏、水土流失,从而加剧了沙漠化对人类的威胁。我国是世界上受沙漠化危害较严重的国家之一,沙化土地有173.97万平方公里,占国土陆地面积的18.12%,每年由沙化造成的直接经济损失超过540亿元。土地沙漠化已成为严重威胁中华民族生存空间、制约我国经济社会发展的巨大挑战。

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利用地统计学和地理信息系统相结合的方法研究了沈阳市郊耕地土壤(0~20cm)交换性镁含量的空间变异性特征 ,绘制了交换性镁含量的空间分布图。结果表明 :土壤交换性镁含量符合正态分布 ,变异函数的最佳理论模型为球状模型 ,交换性镁含量具有中等的空间相关性(C0 与C0+C比值为55.0 %) ,但空间自相关距离较大(73.1km) ,影响其空间变异的结构性因子主要是成土母质、河流走向以及土壤类型。

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根据2006年8月QuickBird卫星影像数据,利用GIS技术和景观格局分析软件FRAGSTATS,分别从斑块组成、类型水平与景观水平分析了沈阳城市绿地景观格局。结果表明:沈阳三环内绿地斑块18261个,绿地面积173.71km2;斑块数目主要以中型斑块为主,占总数的62.25%,面积上以大型斑块为主,占总面积的85.59%;绿地总体呈现绿地斑块分布不均衡,绿地结构不合理。农业用地占面积最大,斑块聚集程度最高;居住绿地与附属绿地破碎化程度高,分布分散;整体景观多样性指数适中,为1.6,斑块类型丰富,均匀度较高,达0.73,蔓延度指数较高为0.83,存在着少数类型控制整个景观的现象。建议调整城市绿地空间布局与结构,提高中小型绿地斑块如居住绿地在城市绿地景观中的比重。

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利用树木径向生长仪研究了黄土丘陵区6年生油松(Pinus tabulaef ormis)、山杨(Populus davidiana)和辽东栎(Quercus liaotungensis)及林下灌木胡颓子(Elaegnus umbellata)4种林木整个生长季茎干的径向变化,发现4种林木的径向变化表现为膨胀收缩旋回增长的模式。在整个生长季中,山杨从5月到10月径向持续增长,增长时间最长;而油松和胡颓子的径向生长主要发生在7月份,从8月份开始其增长速率变缓;辽东栎在整个生长季节的径向生长最小。在整个生长季内,山杨径向增长了2.63 mm,胡颓子为0.64 mm,油松和辽东栎则分别为0.40 mm和0.26 mm。辽东栎日收缩量与膨胀量明显大于其他树种。通过对影响林木径向生长的15种环境因子进行主成分分析后,将主要环境因子归结为温度影响因子、湿度影响因子和降水影响因子3个主成分,并提取了影响该区几种林木生长的主要环境因子:日大于0℃的积温、最低6 h相对湿度和日降雨量。采用线性逐步回归方法,建立了日膨胀量与日收缩量与3个主要环境因子之间的关系。发现日收缩量与日大于0℃的积温成正相关,而与最低6 h相对湿度和日降雨...

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Tongji Univ, Inst Dev Study, Syst Engn Soc China, Comm Syst Dynam, Syst Dynam Soc, China Chapter, Shanghai Inst Foreign Trade, Syst Dynam Soc, Chapters Asia Pacific Area

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辽宁沿海养殖对虾爆发性病害的病因分析国际翔,王丽霞,李文清,刘丹孙伯伦(中国科学院沈阳应用生态研究所,沈阳110015)(阳锦州水产所)93年辽宁沿海养殖对虾发生了爆发性流行性病害,受害面积之大,损失之严重,是养虾史上前所未有的。作者对辽宁沿海6市、...

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采用 3 12 D最优饱和设计和二次通用旋转组合设计 ,通过 8年连续试验 ,对辽西半干旱区影响农业生产的水、肥因素的耦合作用进行了田间试验 .讨论分析了N、P、水及其耦合作用对作物产量的影响 .施N、施P、灌水和覆盖秸秆的合理匹配能够明显提高作物产量 ,否则 ,不仅增加成本 ,而且由于加重作物的水分或养分胁迫 ,造成减产 .根据试验结果进行了生产要素的产量效益分析 ,提出了该地区小麦、玉米生产的水肥最佳经济配比 :小麦为生育期供水 12 0 .2mm ,N 5 8.5kg·hm-2 ,P2 O512 3 .0kg·hm-2 ;玉米为生育期灌水 173 .3mm ,N 2 5 6.5kg·hm-2 ,P2 O585 .5kg·hm-2 ,覆秸秆 85 0 9.5kg·hm-2 .

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采用生长速率法和孢子萌发法测定了辽细辛根的不同溶剂(石油醚、氯仿、乙酸乙酯、乙醇)粗提取物和精油对引起黄瓜灰霉病的灰葡萄孢菌菌丝生长和孢子萌发的作用。结果表明,细辛不同溶剂提取物和精油对灰葡萄孢菌的菌丝生长和孢子萌发均有一定的抑制作用,且对孢子萌发的抑制效果好于对其菌丝生长的抑制效果;石油醚提取物和精油的抑菌效果较好,对菌丝生长的EC50分别为177.44 mg/L和159.98 mg/L,对孢子萌发的EC50分别为173.23 mg/L和125.29 mg/L;试验还显示细辛所含的主要抑菌活性成分易被极性小的有机溶剂所提取。

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可持续发展作为一种理论概念,包容着十分丰富的思想内涵。其思想已上升为一种哲学高度的当代伦理观,因此其可以渗透到人类意识和理念之中,并指导人们的思维和行动。本文通过对旅游景区存在的问题进行分析,提出了旅游景区要坚持走可持续发展道路。文章深刻分析了可持续发展理论渊源,并根据可持续发展理论要求提出了旅游景区可持续发展对策。

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本文在长期定位施肥试验基础上研究了黄土高原旱地不同施肥条件下冬小麦对水分的利用。结果表明 :旱地不同施肥连续 15年种植冬小麦后对土壤剖面含水量影响显著 ,施N或NP配合处理与CK和单施P处理剖面含水量差异均达显著或极显著水平 ,冬小麦对土壤储水的利用深度超过 2 0 0cm ,最大施肥处理N180kg/hm2 P2 O5180kg/hm2 小麦收获后 0~ 40 0cm剖面储水量比CK少 173 .89mm ,高N肥投入产量与生育年降水量显著相关 ,旱地土壤深层储水利用有很大的抗旱增产潜力