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991.
使用亚大气压下介质阻挡放电低温等离子体,对水稻糙米种子进行处理,不同气体、功率、处理时间下观测低温等离子体对糙米生长活力的影响;采用近红外光谱技术对处理后的糙米进行初步的理化性质分析.结果显示:空气等离子体放电对糙米生长活力的促进要优于氮气等离子体放电,空气实验组的最佳处理条件为(360W,5min),而氮气实验组的最佳处理条件为(360W,10min).另外,近红外光谱的主成分分析结果显示空气实验组(360W,5min)和氮气实验组(360W,10min)的糙米光谱与对照组光谱均存在明显差异.低温等离子体对水稻糙米种子的生长活力具有促进作用,能利用近红外光谱技术对作用效果进行初步评估. 相似文献
992.
基于治理理论和委托—代理模型,本研究以35 个国际单项体育联合会善治
评价为对象,设计了以透明度、程序民主、制衡、团结等维度作为关键维度的指标体系,
并使用文献资料法、问卷调查法和访谈法等方法,对数据进行搜集整理。研究发现,国
际单项体育联合会平均得分为45.5(满分100),善治状况评价为“一般”,决策和工作
机制不透明、选举和工作程序失范、利益相关者参与不足等,导致组织内部投机主义盛
行,国际单项体育联合会合法性面临危机。研究建议:1)严格执行选举程序,健全主席
和高管资格审查机制;2)完善信息公开制度,提升组织透明度;3)规范工作流程,充
实组织行政程序正当性;4)多元主体参与,健全组织内外部审查制度;5)明确最长任
期,保证组织官员积极性。 相似文献
993.
Selective functionalization of mesoporous silica nanospheres (MSNs) is crucial for nanoengineering of MSNs.
Herein, we have combined “surface-protected etching strategy” and “cationic surfactant assisted etching
strategy” to prepare functionalized MSNs with externally attached amino groups. The externally attached NH2
groups endow the catalysts with excellent catalytic performance for nitroaldol reaction between nitromethane
and benzaldehyde. In addition, those NH2-MSNs can also be used to support gold nanoparticles, which display
very good catalytic performance for reduction of 4-nitrophenol. It can be envisioned that the synthesis protocol
developed in this work could also be extended to nanoengineered MSNs, which provides opportunities for nanoreactors
design. 相似文献
994.
Yan M Zhaoxin Du Xiaoming Cui Jun Cheng Guolong Liu Tianhao Gong Huimin Liu Xiaopeng Wang Yuyong Chen 《自然科学进展(英文版)》2018,28(6):711-717
The microstructure and mechanical properties of Ti-3.5Al-5Mo-6V-3Cr-2Sn-0.5Fe high strength titanium alloy sheets prepared by unidirectional cold rolling and two-step cross cold rolling were investigated. Results showed that the β phase grains were refined significantly by cold rolling followed by solution treatment for a short time.Compared to unidirectional cold rolling, the short time solution treatment after two-step cross rolling could significantly reduce the non-uniformity of the microstructure of the alloy sheets. After aging treatment at 550 ℃,the anisotropy of the mechanical properties still existed in the unidirectional rolled sheets, and the tensile strength was highest along the rolling direction. After solution and aging treatment, the anisotropy of the mechanical properties of the two-step cross rolling process sheet was not obvious than unidirectional cold rolling,and alloy had good strength and plasticity matching. 相似文献
995.
The pedigrees of three sequenced rice cultivars were analyzed to show that a majority of the genetic composition of 'Nipponbare' originates from japonica cultivars while the minority originates from indica cultivars. In contrast, '93-11' is derived mainly from indica cultivars with a smaller contribution from japonica cultivars. All ancestors of 'Guang lu ai 4' appeared to be indica lines. A set of molecular markers (46 InDels and 53 SSRs) polymorphic between 'Nipponbare' and '93-11' were examined in 46 typical indica and 47 typical japonica cultivars selected from 443 accessions according to Cheng's index. All cultivars were divided into indica and japonica groups without overlapping when clustered by Cheng's index, InDels and SSRs. Much higher InDel and SSR diversity between groups than within groups implies that the marker polymorphisms between 'Nipponbare' and '93-11' represent a large proportion of inter-subspecific diversity. About 85% of indica cultivars and more than 90% of japonica cultivars were confirmed to have the same PCR banding patterns as '93-11' and 'Nipponbare', respectively. Some polymorphic loci between 'Nipponbare' and '93-11' cannot be validated in other indica and japonica cultivars, either as subspecies-specific but not predominant alleles, or alleles not specific between the two groups. It was concluded that molecular markers developed from sequence polymorphism between 'Nipponbare' and '93-11' often represent inter-subspecific diversity, although some exceptions were sensitive to either particular marker loci or particular cultivars. 相似文献
996.
一类食饵捕食者模型的渐近性态 总被引:3,自引:1,他引:3
研究了一类带周期系数的阶段结构的食饵-捕食者模型的渐近性态。利用比较原理和泛函数微分方程定理建立了种群一致持续生存的条件,并得到了正周期解的存在性。 相似文献
997.
Lateral gene transfer and the nature of bacterial innovation 总被引:119,自引:0,他引:119
Unlike eukaryotes, which evolve principally through the modification of existing genetic information, bacteria have obtained a significant proportion of their genetic diversity through the acquisition of sequences from distantly related organisms. Horizontal gene transfer produces extremely dynamic genomes in which substantial amounts of DNA are introduced into and deleted from the chromosome. These lateral transfers have effectively changed the ecological and pathogenic character of bacterial species. 相似文献
998.
变数据窗阻抗算法的频域分析方法研究 总被引:1,自引:1,他引:0
分析典型变数据窗阻抗算法的估计原理和特点 ,提出了一种适用于不同阻抗估计算法的新型频率响应计算方法 ,为不同算法的频域特性分析和比较提供了共同的基础 .该方法也可用于对算法抑制非周期分量的性能进行分析研究 相似文献
999.
1000.
Pt nanoparticles were prepared by the chemical reduction method.The average diameter of Pt nanoparticles was determined to be 2.5nm by TEM.The electrochemical propertis of Pt nanoparticles were studied by cyclic voltammetry,In comparison with massive Pt,the oxidation current peak of CO adsorbed on Pt nanoparticles in broader.Twin adsorbates of CO on Pt nanoparticles were determined by in situ FTIRS for the first time.It has revealed that the linear and twin-bonded CO can be converted into bridge-bonded CO with the variation of electrode potential.A series of special properties of Pt nanoparticles,such as enhanced IR absorption of CO adsorbates,were also observed. 相似文献