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Search Results: 1 - 10 of 11320 matches for " Qingnian Cai "
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Measurements of $π^{0}π^{0}$ production and form factors for $f_{0}(980)$ and $f_{2}(1270)$ in single-tag two-photon process
Qingnian Xu
Physics , 2015,
Abstract: We report a measurement of differential cross section of $\pi^{0}$ pair production in single-tag two-photon collisions. These results are obtained with 759$fb^{-1}$ of the data collected with the Belle detector at the KEKB asymmetric energy $e^{+}e^{-}$ collider. The cross section is measured for $Q^{2}$ up to 30 GeV$^{2}$, where $Q^{2}$ is the negative of the invariant mass squared of the tagged virtual photon, in the kinematic range 0.5 GeV < $W$ < 2.1 GeV and |cos$\theta^{*}$| < 1.0 for the total energy and pion scattering angle, respectively. The transition form factor of the $f_{0}(980)$ and that of the $f_{2}(1270)$ with the helicity-0,-1, and -2 components separately are measured for the first time and are compared with theoretical calculations.
Pollination efficiency of the main bee pollinators of Hedysarum laeve, a legume in Mu Us Sandland, Inner Mongolia

Yanhua Meng,Huanli Xu,Xuan Chen,Qingnian Cai,

生物多样性 , 2007,
Abstract: 塔落岩黄芪(Hedysarum laeve)是毛乌素沙地重要豆科植物,在我国西部生态系统恢复与重建中起着重要作用,但其自交率非常低,必须依靠传粉昆虫授粉才能结实。野生传粉蜂是其主要传粉者。为了明确塔落岩黄芪的主要传粉蜂组成及优势传粉蜂的传粉效率,2004-2006年,我们设置了4个2m×2m样方观测访花昆虫的组成并对主要传粉蜂的访花频率、花粉移出率和柱头花粉沉降数目及单花停留时间进行了观测。结果表明白脸条蜂(Anthophora albifronella)、海切叶蜂(Megachile maritima)和散熊蜂(Bombus sporsdicus)是塔落岩黄芪的主要传粉蜂,其中白脸条蜂在数量和访花频率上占有明显优势,但其花粉移出率比海切叶蜂和散熊蜂的低,3种蜂的柱头花粉沉降数目没有显著区别。通过对这3种蜂的花粉移出率、柱头花粉沉降数目和访花频率综合分析后,我们认为白脸条蜂是塔落岩黄芪最有效的传粉蜂。
Dynamics of indole alkaloids in wheat varieties with various resistance to wheat aphid Sitobion avenae

CAI Qingnian,WANG Yu,ZHANG Qingwen,CHEO Mingzang,

应用生态学报 , 2004,
Abstract: UV spectrometry measurement on the indole alkaloids (IA) contents of seven wheat varieties (KOK1679, My295, Li, Han4564 and Yanda1817, resistant to S. avenae; Shaanximazha and Lovrin10, susceptible to S. avenae) showed that during tillering and stem elongation stages, KOK1679, My295 and Li had a higher IA content (> 0.5 mg.g-1 FW); and during heading and anthesis stages, the penultimate leaves of all five resistant varieties contained higher IA (> 0.5 mg.g-1 FW). The IA content was lower in the flat leaves of both resistant and susceptible varieties, but was significantly higher in the ears of resistant varieties (up to 0.645 mg.g-1 FW in KOK1679) than in those of susceptible ones. It was showed that the IA content in wheat's ear played an important role in the resistance to S. avenae.
Effect of film-mulched treatment on weed diversity in rice field

Xin Zhao,Chaowen Lin,Mingqiao Xu,Jingjing Huang,Yibing Chen,Chuanren Li,Qingnian Cai,

生物多样性 , 2009,
Abstract: 地膜水稻作为一种新的水稻种植方式, 在我国丘陵和山区水稻生产中具有明显的增产效果。地膜稻田中杂草作为重要的有害生物, 有关其群落组成及多样性的报道不多。为了明确地膜稻田杂草的种类、发生密度、优势种及群落多样性, 我们设计了地膜和常规种植两类不同种植模式稻田, 在田间杂草营养生长盛期, 抽样调查了两类稻田中杂草密度、发生程度及生物多样性指数等。结果表明: 地膜稻田和常规稻田杂草种类分别有8科12属12种和10科14属14种。其中常规稻田的马齿苋(Portulaca oleracea)、鸭舌草(Monochoria vaginalis)、拟金茅(Eulaliopsis binata) 和四叶萍(Marsilea quadrifolia) 等在地膜稻田不发生或仅偶有发生, 覆膜稻田中杂草总密度显著降低。异型莎草(Cyperus difformis)和酢浆草(Oxalis corniculata)在两种种植模式田均为优势种, 其相对密度分别为10.29–49.26%和11.91–45.59%, 且地膜稻田的密度均显著低于常规稻田; 而马唐(Digitaria sanguinalis)和水莎草(Juncellus serotinus)仅为地膜稻田的优势种, 其相对密度分别为18.01–30.46%和17.22–23.97%。除个别调查时间外, 两种种植模式稻田杂草群落的Shannon多样性指数和Margalef丰富度指数无显著差异; 而在整个调查期间, 地膜稻田的Pielou均匀度指数均显著高于常规稻田。由此可见, 地膜水稻种植模式不仅对稻田常见杂草和优势种杂草有一定的控制作用, 而且也使整个杂草群落处于一个稳定水平, 避免了一些杂草的暴发, 这对水稻生产过程中的草害控制具有重要的意义。
Equivalence and Extension of (Co-)reflexivity and Their Applications

Pan Qingnian,

数学物理学报(A辑) , 2004,
Abstract: Equivalence and extension are studied. Main results are as follows: (1) coreflexility and reflexivity are equivalent as categories. (2) coreflexivity and reflexivity are extensionable. These are used to generalize and simplify some works of .
Scaling limits of non-isentropic Euler-Maxwell equations for plasmas
Yang Jianwei,Gao Qinghua,Zhang Qingnian
Advances in Difference Equations , 2011,
Abstract: In this paper, we will discuss asymptotic limit of non-isentropic compressible Euler-Maxwell system arising from plasma physics. Formally, we give some different limit systems according to the corresponding different scalings. Furthermore, some recent results about the convergence of non-isentropic compressible Euler-Maxwell system to the compressible Euler-Poisson equations will be given via the non-relativistic regime.
Evaluation of Influence of Motorized Wheels on Contact Force and Comfort for Electric Vehicle
Liqiang Jin,Chuanxue Song,Qingnian Wang
Journal of Computers , 2011, DOI: 10.4304/jcp.6.3.497-505
Abstract: Volatile oil prices and increased environmental sensitivity together with political concerns have moved the attention of governments, automobile manufacturers and customers to alternative power trains. From the actual point of view the most promising concepts for future passenger cars are based on the conversion of electrical into mechanical energy. In-wheel motors are an interesting concept towards vehicle electrification that provides also high potentials to improve vehicle dynamics and handling. Nevertheless in-wheel motors increase the unsprung mass worsening vehicle comfort and safety. All kinds of motorized-wheel structures are analyzed. For the unitary motorized wheel, since increasing the unsprung mass of vehicle, it adds adverse effects on the vehicle road holding performance and vehicle comfortableness. To decrease the adverse effect for unsprung mass increasing, a method by attaching the motor in the wheel through springs and dampers of exclusive use is brought out. It is verified that the vibration of EV with suspended-motor motorized-wheel is better than the EV with detached-motorized wheel. For high cost of suspended in-wheel motor, The effect of increasing of unsprung mass by using integral motor is analyzed by simulation with whole vehicle model. The more unsprung mass of integral motor deteriorates the vehicle comfort and vibration performance at low excitation frequency of road. But it is improved by using integral motor at higher excitation frequency of road, while unsprung mass is increased by using integral motor. The fluctuation amplitude of vibration at high frequency is much more big than at low frequency. In this view, the conclusion that in-wheel motor integrated into wheels is acceptable structural concept for electric vehicle with motorized wheels with lower cost than suspended in-wheel motor is achieved
Curriculum Design, Linguistic Competence and Self-Actualization: A Case Study on English Curriculum Design for Chinese Non-English Major Postgraduates  [PDF]
Shangzhi Cai
Creative Education (CE) , 2010, DOI: 10.4236/ce.2010.13028
Abstract: Studies conducted hitherto on English education for Chinese non-English major postgraduates have preponderantly focused on themes such as learning motivations, teaching or learning strategies, and various examinations. Yet little attention has been paid to the issue of curriculum design. In order to explore the correlations amongst curriculum design, linguistic competence and self-actualization, the author has carried out a survey on the English curriculum design for non-English major postgraduates in Yunnan Normal University by applying Maslow’s theory of self-actualization. The survey reveals that postgraduates’ reading abilities hold low correlation with self-actualization, thus priority should be given to improve their speaking proficiency as well as listening abilities. Besides, as a basic requirement for all postgraduates, academic writing receives the most attention since the quality of their graduate dissertation is considered as the ultimate indication of their self-actualization. Apart from providing concerning suggestions on the curriculum design according to the above findings, the author also holds that curriculum design is an autonomous, flexible and dynamic process. Hence, instead of sticking to the long-adopted uniform English curriculum for all non-English major postgraduates in China, more flexible curricula and requirements should be introduced in order to fulfill the self–actualization of postgraduates from different universities, different majors, and different regions.
The Existence and Multiplicity of Solutions for Singular Boundary Value Systems with p-Laplacian  [PDF]
Zengxia Cai
Journal of Applied Mathematics and Physics (JAMP) , 2015, DOI: 10.4236/jamp.2015.34052

This paper presents sufficient conditions for the existence of positive solutions for the fourth-order boundary value problem system with p-Laplacian operator. The existence of single or multiple positive solutions for the system is showed through the fixed point index theory in cones under some assumptions.

On the Relation of Grain Orientation and Opening Crack of an Al-Cu-Mg Sheet  [PDF]
Cai Hu
Engineering (ENG) , 2017, DOI: 10.4236/eng.2017.95031
Abstract: In this paper, the orientation of grains which adjacent to a developed opening crack was investigated by EBSD. A definition of θ has been came up with which represents the angle between the principal stress plane and each plane of the grains. Smaller θ means easier to crack. It gave a good explanation of the crack propagation throughout the grains. It also revealed that propagation path is along with the plane. This finding will give a prediction of tear properties and help us understanding the cracking mechanism and the behavior of tearing.
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