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We propose another possible mechanism of synchronized flow, i,e. that a time headway dependent randomization can exhibit synchronized flow. Based on this assumption, we present a new cellular automaton (CA) model for traffic flow, in which randomization effect is enhanced with the decrease of time headway. We study fundamental diagram and spatial-temporal diagrams of the model and perform microscopic analysis of time series data, which shows the model could reproduce synchronized flow as expected. It is also shown that a spontaneous transition from synchronized flow to jam could be observed by incorporating slow-to-start effect into the model. We expect that our work could contribute to the understanding of the real origin of synchronized flow. 相似文献
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吲哚二酮哌嗪生物碱是一种内生真菌次生代谢产物,多提取自曲霉属Aspergillus和青霉属Penicillium,是由不同氨基酸结合衍生而来的,在自然界分布广泛。该类化合物含有吲哚和二酮哌嗪两个母核,具有良好而广泛的生物活性,可为药物研发提供先导化合物,其新颖的结构和显著的生物活性也受到了化学全合成领域内学者的日益关注。本文主要从该类化合物的发现和化合物的结构以及化合物抗癌与抗肿瘤、抑菌、免疫调节、抗氧化及杀虫等生物活性方面对这类化合物的相关研究予以回顾,并对其结构与生物活性之间的活性构效关系进行了简要分析,为该类化合物的发现、合成及生物活性研究提供参考,并为药物研发提供借鉴。 相似文献
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应用Fe/Mo/Al2O3载体载入式催化剂,以CO为碳源,分别通过火焰热解法和电加热热解法合成了碳纳米管.为了探究导致两种方法合成产物异同的原因,分别对两种方法中对应的实验操作和参数进行了对比分析.分析表明:(1)由于热解形式不同-火焰热解形式的剧烈性和电加热热解形式的缓和性,导致两种方法热解区气流扰动强度存在巨大差别,极大影响了产物的产量和质量;(2)由于合成温度不同,火焰热解法合成温度为830℃,可以合成单壁碳纳米管,而电加热热解法合成温度为790℃,仅能合成双壁、三壁碳纳米管. 相似文献
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In this paper, a new lattice hydrodynamic model based on
Nagatani's model [Nagatani T 1998 Physica A 261 599] is
presented by introducing the flow difference effect. The stability
condition for the new model is obtained by using the linear
stability theory. The result shows that considering the flow
difference effect leads to stabilization of the system compared
with the original lattice hydrodynamic model. The jamming
transitions among the freely moving phase, the coexisting phase, and
the uniform congested phase are studied by nonlinear analysis.
The modified KdV equation near the critical point is derived to
describe the traffic jam, and kink--antikink soliton solutions
related to the traffic density waves are obtained. The simulation
results are consistent with the theoretical analysis for the new
model. 相似文献
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为了了解规模化栽培后富硒香菇的产量(生物学效率)及富硒规律,本实验通过香菇栽培基质添加模式,采取规模化生产进行富硒香菇栽培试验,选取不同浓度硒营养强化剂对香菇品种“向阳二号”和“9608”进行添加,测定相对应的香菇生物学效率以及第一潮次和第二潮次的总硒及硒代氨基酸的含量。实验发现向阳二号香菇,在硒添加量较低(0-6mg/kg)时香菇的生物转化率基本不随硒添加量的增加而改变,当硒添加量继续增加(10-60mg/kg)时,香菇的生物转化率整体低于低添加量;9608香菇,随着硒添加量的增加(0~60mg/kg),香菇的生物转化率表现出微弱的增加趋势,但差异性不显著;而两种不同品种、潮次香菇的总硒及硒代氨基酸含量均随着硒添加量的增加而提高,但硒代氨基酸占总硒的比例变化趋势却有所不同,在66.7-85.4%范围内。此外,对于不同品种的香菇,其第一潮次总硒含量在硒的添加量在0~20 mg/kg的范围内呈现良好的规律性,总硒是基质(风干)中硒含量的约4-5倍。可见,按照该规模化栽培模式进行生产栽培,可以得到总硒含量稳定、硒代氨基酸占总硒比>65%的富硒香菇产品,对富硒香菇产业的发展有一定的指导意义。 相似文献