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压缩真空场中非简并双光子过程中系统约化密度主方程 被引量:1
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作者 何林生 冯勋立 +4 位作者 季广德 张伟 吴世雄 张智明 夏宇兴 《量子光学学报》 CSCD 1997年第2期90-96,共7页
在本文中我们利用投影算符技巧通过刘维方程推导了系统约化密度主方程,这种方法特别适合于赝非马尔可夫的库场情况。所得结果和改进的路易塞尔方法的结果一致。这种方法能正确地在各种库的情况下给出单光子过程和双光子过程的系统的主... 在本文中我们利用投影算符技巧通过刘维方程推导了系统约化密度主方程,这种方法特别适合于赝非马尔可夫的库场情况。所得结果和改进的路易塞尔方法的结果一致。这种方法能正确地在各种库的情况下给出单光子过程和双光子过程的系统的主方程。 展开更多
关键词 约化密度方程 双光子过程 压缩真空场
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压缩真空场中系统约化密度主方程 被引量:4
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作者 何林生 冯勋立 王正林 《量子电子学》 CSCD 1996年第1期1-8,共8页
为适应近年来人工制备库的情况,特别是简并双光子过程中,压缩真空库的广义朗之万力之双时相关函数呈现一种膺非马尔珂夫特性,我们重新定义了库的谱密度,改进了Louisell推导系统约化密度主方程的方法,克服了原有方法的弱点... 为适应近年来人工制备库的情况,特别是简并双光子过程中,压缩真空库的广义朗之万力之双时相关函数呈现一种膺非马尔珂夫特性,我们重新定义了库的谱密度,改进了Louisell推导系统约化密度主方程的方法,克服了原有方法的弱点,获得了比较满意的结果,能正确地在各种库的情况下给出单光子过程和双光子过程的系统的主方程。我们首次求得压缩真空库场中简并双光子过程的系统约化密度主方程。 展开更多
关键词 约化密度方程 量子光学 压缩真空场
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Yb掺杂(Ba,Sr)TiO_3系PTCR材料的研究Ⅰ.表面受主态密度的计算
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作者 张中太 张枫 米庆 《功能材料》 EI CAS CSCD 北大核心 1999年第6期627-628,共2页
在Heywang 模型的基础上,采用了一种计算PTCR材料表面受主态密度的新方法。通过ln ρ- 1/ εapp T 曲线可以算得材料的表面受主态密度。具体计算了Yb 掺杂( Ba ,Sr)TiO3材料的表面受主态密度。
关键词 表面受密度 PTCR 掺杂
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油菜主花序角果密度及其相关性状的全基因组关联分析 被引量:5
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作者 任义英 崔翠 +6 位作者 王倩 唐章林 徐新福 林呐 殷家明 李加纳 周清元 《中国农业科学》 CAS CSCD 北大核心 2018年第6期1020-1033,共14页
【目的】油菜高产是育种工作的主要研究目标之一。角果密度、主花序有效角果数等性状与产量都有显著或极显著的正相关关系,是油菜高产育种考查的主要性状。为揭示油菜角果密度及其相关性状的遗传机理和分子机制奠定基础。【方法】以不... 【目的】油菜高产是育种工作的主要研究目标之一。角果密度、主花序有效角果数等性状与产量都有显著或极显著的正相关关系,是油菜高产育种考查的主要性状。为揭示油菜角果密度及其相关性状的遗传机理和分子机制奠定基础。【方法】以不同遗传背景和地理来源的213份甘蓝型油菜品种(系)构成的自然群体为研究对象,利用芸薹属60K Illumina Infinium SNP芯片对该群体进行基因型分型。分别于2015年和2016年在成熟期调查该群体主花序有效长和主花序有效角果数,计算主花序角果密度。利用Structure 2.3.4软件对该群体进行群体结构分析,Tassel 5.1.0软件分析亲缘关系和染色体连锁不平衡的衰减;然后基于最优模型对主花序角果密度及其相关性状进行全基因组关联分析(genome-wide association analysis,GWAS),依据关联SNP位点的LD区间序列,预测与性状相关的重要关联候选基因。【结果】群体结构分析显示,213份甘蓝型油菜分为P1和P2亚群,P1亚群包含50份材料(23.5%),P2亚群包含163份材料(76.5%),基本上和油菜的地理栽培属性一致;亲缘关系发现约89.74%材料之间的亲缘关系值小于0.2,其中约有59.91%材料的亲缘关系值为0。总体来看,整个自然群体材料之间的亲缘关系比较远。对A、C基因组进行连锁不平衡分析发现,A和C基因组的r2随着遗传距离的增加而下降,A基因组的衰减距离整体比C基因组的衰减距离小。GWAS分析两年数据共检测到17个SNP位点与主花序角果密度及其相关性状关联。其中与主花序角果密度和主花序有效长相关的SNP标记分别有7个和9个,并分别解释11.34%—15.96%和9.67%—13.10%的表型变异;与主花序有效角果数相关联的标记有1个,解释11.56%的表型变异。通过分析关联SNP位点的LD区间与甘蓝型油菜对应的区间序列,找到22个与主花序角果密度及其相关性状有关的候选基因,其中Bna A01g16940D、Bna C01g38800D和Bna A04g09170D等主要通过调控赤霉素和生长素等内源激素的合成和信号转导来控制主花序角果密度及其相关性状;Bna A01g16970D、Bna A03g29180D、Bna A03g29810D、Bna C01g39680D和Bna C03g32770D通过对分生组织的调控来改变表型;Bna C09g18690D和Bna C09g09210D等主要通过控制细胞分裂生长等过程改变表型。【结论】检测到17个SNP标记与油菜主花序角果密度、主花序有效长和主花序有效角果数关联,筛选出22个与主花序角果密度及其相关性状有关的候选基因。 展开更多
关键词 甘蓝型油菜 花序角果密度 连锁不平衡 SNP 全基因组关联分析
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复合微生物在高密度主养鲫池塘中的应用 被引量:23
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作者 富丽静 王雷 宋文华 《水产科学》 CAS 北大核心 2002年第1期23-25,共3页
用以芽胞杆菌为主体的复合微生物制剂对高密度主养鲫 (Carassiusauratus)池塘中生态因子进行调控。菌剂含活菌数为 10 9/g ,首次施放 1 5mg/L ,之后每隔 15d施放 0 75mg/L。养成期与鱼种期两个阶段的试验表明 :鲫池投放菌剂后 ,能有效... 用以芽胞杆菌为主体的复合微生物制剂对高密度主养鲫 (Carassiusauratus)池塘中生态因子进行调控。菌剂含活菌数为 10 9/g ,首次施放 1 5mg/L ,之后每隔 15d施放 0 75mg/L。养成期与鱼种期两个阶段的试验表明 :鲫池投放菌剂后 ,能有效改善水质条件 ,在降低总氨氮及分子氨方面效果显著 ;对增加溶氧、降低亚硝酸盐也有一定作用。能营造清新的黄绿色藻相。硅藻、裸藻易成为优势种群 ,对减少蓝藻丝状藻类繁殖有明显效果。能促进鲫生长 。 展开更多
关键词 密度养鲫 池塘 应用 复合微生物 生态因子 水质条件 水质调控
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专色油墨干退密度对颜色影响的研究
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作者 郑美琴 段纯 《包装工程》 CAS CSCD 北大核心 2012年第3期104-108,共5页
阐述了专色油墨的干退密度对颜色的影响,对不同专色油墨进行了实验,记录并分析了实验数据,得到了不同专色油墨的主密度、BK值和色差变化情况,找到了专色油墨干退密度和颜色的变化关系,为生产时对专色油墨的控制提供基础。
关键词 专色油墨 干退密度 主密度 色差
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脉冲推冲器主装药燃烧规律试验研究
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作者 蒋新广 柳维旗 +1 位作者 姜志保 刘玉字 《固体火箭技术》 EI CAS CSCD 北大核心 2013年第2期206-209,242,共5页
为了研究推冲器装药的燃烧规律及确定推冲器的装药条件,首先依据对流燃烧机理和火工药剂制备工艺,设计了高燃速推冲药剂。将药剂分2次压成前后两段药柱,采用压力测试装置,测试得到不同装药密度时的压力-时间曲线。经过分析,得到了不同... 为了研究推冲器装药的燃烧规律及确定推冲器的装药条件,首先依据对流燃烧机理和火工药剂制备工艺,设计了高燃速推冲药剂。将药剂分2次压成前后两段药柱,采用压力测试装置,测试得到不同装药密度时的压力-时间曲线。经过分析,得到了不同装药密度下的燃烧特征参数及它们之间的规律。结果表明,药剂采用前后两段压药的方式较合理;燃烧特征参数随密度变化有较好的规律性;前后两段装药的密度分别为1.3 g/cm3和1.5 g/cm3左右时,燃烧特征参数较理想。 展开更多
关键词 脉冲推冲器 装药密度 燃烧规律
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基于原位PXRF数据的土壤锰、锌污染分布协同克里金插值与高分地图绘制
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作者 赵曼颖 赵玉鑫 +5 位作者 沈铁志 李淑 姚光远 陈曾思澈 刘玉强 徐亚 《环境科学研究》 CAS CSCD 北大核心 2023年第3期599-609,共11页
高分辨率土壤重金属污染绘图(HRMMs)有助于准确识别需要进行风险管控或修复的区域.传统HRMMs基于网格模式土壤采样,开展化学分析并采用地质统计插值方法绘制污染分布地图,成本高、速度慢,且不适合高度异质性污染场地.该研究提出了一种... 高分辨率土壤重金属污染绘图(HRMMs)有助于准确识别需要进行风险管控或修复的区域.传统HRMMs基于网格模式土壤采样,开展化学分析并采用地质统计插值方法绘制污染分布地图,成本高、速度慢,且不适合高度异质性污染场地.该研究提出了一种通过多元非线性回归改善便携式X射线荧光分析(PXRF)数据,采用改进的PXRF数据进行协同克里金插值,以及HRMMs地图绘制和重金属污染分布预测的新方法.为了支持模型的建立和验证,选择我国西北某锰、锌污染场地开展研究.结果表明:(1)引入PXRF数据作为协同克里金插值的辅助变量能有效提高插值精度,而校正的PXRF数据可进一步提高空间刻画精度.重金属Mn和Zn的校正PXRF协同克里金插值较原始PXRF协同克里金插值的平均误差分别降低了4.5%和78.2%.(2)主变量点位密度的变化会改变校正后PXRF协同克里金插值的精度.以Zn为例,当主变量点位密度大于4个/(10^(4)m^(2))时,校正后的PXRF协同克里金插值的精度显著降低.(3)增加辅助变量点位密度可显著提高协同克里金插值精度.当辅助变量点位密度增至7个/(10^(4)m^(2))时,校正后PXRF协同克里金插值的平均误差与均方根误差分别降低了92.4%和34.7%.研究显示,通过对PXRF数据的校正可有效提高污染物协同克里金插值的精度,同时协同克里金插值需要满足一定量的主变量点位密度要求,且辅助变量点位密度越高,协同克里金插值的精度越高. 展开更多
关键词 协同克里金插值 变量点位密度 辅助变量点位密度 PXRF辅助变量
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Application of PCA and HCA to the Structure-Activity Relationship Study of Fluoroquinolones 被引量:2
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作者 李小红 张现周 +2 位作者 程新路 杨向东 朱遵略 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 北大核心 2006年第2期143-148,共6页
Density functional theory (DFT) was used to calculate molecular descriptors (properties) for 12 fluoro-quinolone with anti-S.pneumoniae activity. Principal component analysis (PCA) and hierarchical cluster analy... Density functional theory (DFT) was used to calculate molecular descriptors (properties) for 12 fluoro-quinolone with anti-S.pneumoniae activity. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) were employed to reduce dimensionality and investigate in which variables should be more effective for classifying fluoroquinolones according to their degree of an-S.pneumoniae activity. The PCA results showed that the variables ELUMO, Q3, Q5, QA, logP, MR, VOL and △EHL of these compounds were responsible for the anti-S.pneumoniae activity. The HCA results were similar to those obtained with PCA.The methodologies of PCA and HCA provide a reliable rule for classifying new fluoroquinolones with antiS.pneumoniae activity. By using the chemometric results, 6 synthetic compounds were analyzed through the PCA and HCA and two of them are proposed as active molecules with anti-S.pneumoniae, which is consistent with the results of clinic experiments. 展开更多
关键词 Structure-activity relationship Density functional theory Principal component analysis Hierarchical cluster analysis
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稻鱼系统中再生稻生产关键技术 被引量:10
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作者 吴敏芳 张剑 +4 位作者 胡亮亮 任伟征 郭梁 唐建军 陈欣 《中国稻米》 北大核心 2016年第6期80-82,共3页
再生稻与田鱼共生技术的运用,一定程度上可以解决南方稻作区土地效率不高和劳动力短缺的矛盾,但是,关于再生稻和田鱼共生的技术目前报道不多。本研究探索了在稻鱼系统中再生稻栽培技术的2个核心步骤:留茬高度和主茬密度。结果表明,在长... 再生稻与田鱼共生技术的运用,一定程度上可以解决南方稻作区土地效率不高和劳动力短缺的矛盾,但是,关于再生稻和田鱼共生的技术目前报道不多。本研究探索了在稻鱼系统中再生稻栽培技术的2个核心步骤:留茬高度和主茬密度。结果表明,在长期淹水的稻鱼系统中再生稻的留茬高度应该在40 cm,主茬移栽时选用单本插和宽行窄株(33 cm×17 cm)的株行距可以保证头茬和再生茬产量维持在一个较高的水平。 展开更多
关键词 稻鱼共生技术 再生稻 留茬高度 密度
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光腔中两原子共振荧光的相干性质
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作者 程桂平 柯莎莎 李高翔 《量子光学学报》 CSCD 北大核心 2006年第B08期26-26,共1页
对于放置于一个单模光腔中的两个二能级原子,我们研究了这两个原子与强激光场作用下的共振荧光的相干性质。通过绝热消除腔场的变量推导出原子的约化密度主方程。由此主方程分别计算出两原子辐射的共振荧光光场在裸态和修饰态表象里的... 对于放置于一个单模光腔中的两个二能级原子,我们研究了这两个原子与强激光场作用下的共振荧光的相干性质。通过绝热消除腔场的变量推导出原子的约化密度主方程。由此主方程分别计算出两原子辐射的共振荧光光场在裸态和修饰态表象里的一阶可见度和二阶关联函数。发现在坏腔以及原子与强激光场为小失谐条件下,若光腔与相干场的频率差调到总的拉比频率附近,两原子辐射的共振荧光光场的相干性被极大地提高。通过修饰态方法发现其主要是由于当失谐调到总的拉比频率附近时,修饰态原子布居几率分布发生很大的改变,甚至出现布居反转的现象。而修饰态布居数又是影响一阶可见度和二阶关联函数的主要因数。 展开更多
关键词 共振荧光 两原子 相干性 光腔 约化密度方程 二阶关联函数 强激光场 原子辐射 拉比频率 原子布居
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A Trust Management Scheme Based on Behavior Feedback for Opportunistic Networks 被引量:2
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作者 CHEN Xi SUN Liang +1 位作者 MA Jian Feng MA Zhuo 《China Communications》 SCIE CSCD 2015年第4期117-129,共13页
In the harsh environment where n ode density is sparse, the slow-moving nodes cannot effectively utilize the encountering opportunities to realize the self-organized identity authentications, and do not have the chanc... In the harsh environment where n ode density is sparse, the slow-moving nodes cannot effectively utilize the encountering opportunities to realize the self-organized identity authentications, and do not have the chance to join the network routing. However, considering m ost of the communications in opportunistic networks are caused by forwarding operations, there is no need to establish the complete mutual authentications for each conversation. Accordingly, a novel trust management scheme is presented based on the information of behavior feedback, in order to complement the insufficiency of identity authentications. By utilizing the certificate chains based on social attributes, the mobile nodes build the local certificate graphs gradually to realize the web of "Identity Trust" relationship. Meanwhile, the successors generate Verified Feedback Packets for each positive behavior, and consequently the "Behavior Trust" relationship is formed for slow-moving nodes. Simulation result shows that, by implementing our trust scheme, the d elivery probability and trust reconstruction ratio can be effectively improved when there are large numbers of compromised nodes, and it means that our trust management scheme can efficiently explore and filter the trust nodes for secure forwarding in opportunistic networks. 展开更多
关键词 opportunistic networks trustmanagement key management forwardingprotocols verified feedback packet
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A Location Privacy Preserving Solution to Resist Passive and Active Attacks in VANET 被引量:2
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作者 ZHU Xiaoling HU Donghui HOU Zhengfeng DING Liang 《China Communications》 SCIE CSCD 2014年第9期60-67,共8页
Existing location privacy- preserving methods, without a trusted third party, cannot resist conspiracy attacks and active attacks. This paper proposes a novel solution for location based service (LBS) in vehicular a... Existing location privacy- preserving methods, without a trusted third party, cannot resist conspiracy attacks and active attacks. This paper proposes a novel solution for location based service (LBS) in vehicular ad hoc network (VANET). Firstly, the relationship among anonymity degree, expected company area and vehicle density is discussed. Then, a companion set F is set up by k neighbor vehicles. Based on secure multi-party computation, each vehicle in V can compute the centroid, not revealing its location to each other. The centroid as a cloaking location is sent to LBS provider (P) and P returns a point of interest (POI). Due to a distributed secret sharing structure, P cannot obtain the positions of non-complicity vehicles by colluding with multiple internal vehicles. To detect fake data from dishonest vehicles, zero knowledge proof is adopted. Comparing with other related methods, our solution can resist passive and active attacks from internal and external nodes. It provides strong privacy protection for LBS in VANET. 展开更多
关键词 vehicular ad hoc network locationbased services location k-anonymity securemulti-party computation
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量子光学
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《中国光学》 EI CAS 1996年第6期1-2,共2页
O431 96063501准恒场驱动谐振子的物理特性=Physical propertyof oscillator driven by quasi-constantfield[刊,中]/吴锦伟,郭光灿(中国科技大学物理系.安徽,合肥(230026))//光学学报.-1996,16(1).
关键词 相干态 驱动谐振子 约化密度方程 二能级原子 物理特性 演化 量子电子学 压缩性质 物理系 光子学
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基于DRF-KPCA和非线性面板模型的地区涉恐安全风险评估与影响因素研究
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作者 黄苏莉 陆秋君 《应用数学进展》 2021年第4期974-988,共15页
地区涉恐安全风险评估与影响因素研究能够研判地区未来的反恐态势,提高反恐斗争的针对性和资源的管理效率。运用空间统计方法对全球恐怖袭击事件发生的分异特征进行分析,选取恐怖袭击事件数、恐怖袭击死亡人数、恐怖袭击受伤人数和恐怖... 地区涉恐安全风险评估与影响因素研究能够研判地区未来的反恐态势,提高反恐斗争的针对性和资源的管理效率。运用空间统计方法对全球恐怖袭击事件发生的分异特征进行分析,选取恐怖袭击事件数、恐怖袭击死亡人数、恐怖袭击受伤人数和恐怖袭击财产损害程度等指标构建地区涉恐安全风险评估指标体系,提出基于密度敏感稳健模糊核主成分分析的多维面板数据的分级模型。与其他的主成分聚类算法相比较,所提算法的合理性和准确度都有提升。结合主成分方法提取出来的风险水平因子,运用最大似然估计方法建立随机效应面板顺序Logit模型,考察宏观经济和社会发展因素对地区涉恐安全风险的影响,最后对回归模型展开预测绩效评价。 展开更多
关键词 涉恐安全风险 多维面板数据 密度敏感稳健模糊核成分分析 顺序Logit回归
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Sleeve gastrectomy prevents lipoprotein receptor-1 expression in aortas of obese rats 被引量:1
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作者 Jie Bai Yong Wang Yuan Liu Dong-Hua Geng Jin-Gang Liu 《World Journal of Gastroenterology》 SCIE CAS CSCD 2011年第32期3739-3744,共6页
AIM: To investigate the effects of sleeve gastrectomy on adipose tissue infiltration and lectin-like oxidized low density lipoprotein receptor-1 (LOX-1) expression in rat aortas. METHODS: Twenty-four rats were randomi... AIM: To investigate the effects of sleeve gastrectomy on adipose tissue infiltration and lectin-like oxidized low density lipoprotein receptor-1 (LOX-1) expression in rat aortas. METHODS: Twenty-four rats were randomized into three groups: normal chow (control), high fat diet (HD) and high fat diet with sleeve gastrectomy (SG). After surgery, the HD and SG groups were fed a high fat diet. Animals were sacrificed and plasma high density lipoprotein (HDL) and low density lipoprotein (LDL) levels were determined. LOX-1 protein and LOX-1 mRNA expression was also measured. Aortas were stained with Nile red to visualize adipose tissue. RESULT: Body weights were higher in the HD group compared to the other groups. HDL levels in control,HD, and SG groups were 32.9 ± 6.2 mg/dL, 43.4 ± 4.0 mg/dL and 37.5 ± 4.3 mg/dL, respectively. LDL levels in control, HD, and SG groups were 31.8 ± 4.5 mg/dL, 53.3 ± 5.1 mg/dL and 40.5 ± 3.7 mg/dL, respectively. LOX-1 protein and LOX-1 mRNA expression was greater in the HD group versus the other groups. Staining for adipose tissue in aortas was greater in the HD group in comparison to the other groups. Thus, a high fat diet elevates LOX-1 protein and mRNA expression in aorta. CONCLUSION: Sleeve gastrectomy decreases plasma LDL levels, and downregulates LOX-1 protein and mRNA expression. 展开更多
关键词 Sleeve gastrectomy Morbid obesity High fat diet AORTA Lipoprotein receptor-1 expression
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Under-Winter Sowings of Red Beetroot in Uzbekistan
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作者 M. M. Adilov 《Journal of Agricultural Science and Technology》 2010年第4期103-106,共4页
The results of the three-year researches which had the purpose to establish an optimum depth of seeding at sowing and rational norm of seeding of red beetroot seeds at under-winter sowing in conditions of mid-loamy ty... The results of the three-year researches which had the purpose to establish an optimum depth of seeding at sowing and rational norm of seeding of red beetroot seeds at under-winter sowing in conditions of mid-loamy typical grey soils of the central climatic zone of Uzbekistan are stated in article. The researches were spent at statement of field experiences in quadruple frequency with the area of a registration allotment 10 M^-1. Crops were carried out in the first decade of December against mulching surfaces of ridges by humus and without mulching. Crops were carried out on ridges in width of 70 sm tape-two-lined with distance between tapes of 50 sm, between lines-20 sm and distance between plants in a line of 12-13 sm, at density of standing of 228-230 thousand plants/hectares. Experiences were spent with zoned in Uzbekistan multi-seedling grade of a red beetroot "Bordo 237". Experiences were accompanied by phenological supervision, biometric accounts, the account of field germination of seeds, density of standing of plants and definition of size and quality of a crop. Results of researches were exposed to the statistical analysis by a dispersive method. It has been revealed that at under-winter sowing of a red beetroot the effective way providing acceleration of shoots occurrence, formations of high-grade density of standing and increase of productivity of root crops is mulching the surfaces of ridges by humus. It is defined that optimum depth of seeding at sowing both at application of mulching and without it is the depth of seeding 4 sm. It is established that the most rational norm of seeding of the seeds, providing high-grade density of standing, is at cultivation with application of mulching 8 kg/ha, and at cultivation without mulching 8-10 kg/ha. Application of mulching the surfaces of ridges by humus, depths of seeding of 4 sm and norms of seeding of seeds of 8-10 kg/ha in conditions of under-winter sowing in comparison with cultivation without mulching and depth of seeding 2 sm and norms of seeding of 6 kg/ha provides an acceleration of receipt of fresh production of a red beetroot for 12-14 days and considerably raises root crops productivity. Application of agro receptions improved by us is the important reserve of acceleration of receipt of red beetroot early production and increase of its manufacture. 展开更多
关键词 Under-winter sowing germination of seeds SHOOTS RIPENESS leaf-bearing root crops density of standing yield
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Three-dimensional topological insulators:A review on host materials 被引量:2
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作者 FENG WanXiang YAO YuGui 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS 2012年第12期2199-2212,共14页
In recent years,three-dimensional topological insulators(3DTI) as a novel state of quantum matter have become a hot topic in the fields of condensed matter physics and materials sciences.To fulfill many spectacularly ... In recent years,three-dimensional topological insulators(3DTI) as a novel state of quantum matter have become a hot topic in the fields of condensed matter physics and materials sciences.To fulfill many spectacularly novel quantum phenomena predicted in 3DTI,real host materials are of crucial importance.In this review paper,we first introduce general methods of searching for new 3DTI based on the density-functional theory.Then,we review the recent progress on materials realization of 3DTI including simple elements,binary compounds,ternary compounds,and quaternary compounds.In these potential host materials,some of them have already been confirmed by experiments while the others are not yet.The 3DTI discussed here does not contain the materials with strong electron-electron correlation.Lastly,we give a brief summary and some outlooks in further studies. 展开更多
关键词 three dimension topological insulator host material
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Quantum Wire with Triangle Cross Section:Optical Properties 被引量:1
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作者 R.Khordad S.Tafaroji +1 位作者 R.Katebi A.Ghanbari 《Communications in Theoretical Physics》 SCIE CAS CSCD 2012年第6期1076-1080,共5页
In the present work,the optical properties of a GaAs quantum wire with equilateral triangle cross section are studied.For this purpose,we use analytical expressions for optical properties obtained by the compact-densi... In the present work,the optical properties of a GaAs quantum wire with equilateral triangle cross section are studied.For this purpose,we use analytical expressions for optical properties obtained by the compact-density matrix formalism.Here,we investigate the intersubband optical absorption coefficients and refractive index changes as a function of the triangle side(L) and the incident optical intensity(I).According to the obtained results,it is found that:(i) The total refractive index changes increase and shift towards lower energies when the triangle side increases.(ii) The total absorption coefficient decreases as the triangle side increases.Also,the resonance peak shifts towards lower energies by increasing the triangle side. 展开更多
关键词 quantum wire optical properties
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Realization of population inversion between 7S_(1/2) and 6P_(3/2) levels of cesium for four-level active optical clock 被引量:6
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作者 WANG YanFei WANG DongYing +5 位作者 ZHANG TongGang HONG YeLong ZHANG ShengNan TAO ZhiMing XIE XiaoPeng CHEN JingBiao 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS 2013年第6期1107-1110,共4页
We demonstrate experimentally the population inversion between 7S1/2 and 6P3/2 levels of cesium in thermal cesium cell with a 455.5 nm pumping laser.We calculate the relative population probabilities at each level the... We demonstrate experimentally the population inversion between 7S1/2 and 6P3/2 levels of cesium in thermal cesium cell with a 455.5 nm pumping laser.We calculate the relative population probabilities at each level theoretically with the density matrix method.In a steady state,5.8% atoms are at 7S1/2 level and 2.9% at 6P3/2 level,which builds up the population inversion between the two levels.We obtain the fluorescence spectra produced in thermal cesium cell in our experiment.The measured relative intensity of each available fluorescence spectral line in the experiment agrees very well with the theoretical result.The demonstrated population inversion between 7S1/2 and 6P3/2 levels can be used to construct an active optical clock of four-level system with a wavelength of 1469.9 nm. 展开更多
关键词 active optical clock four-level system population inversion
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