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行距对大豆竞争有限资源的影响 被引量:19
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作者 刘晓冰 金剑 +2 位作者 王光华 S.J.Herbert m.hashemi 《大豆科学》 CAS CSCD 北大核心 2004年第3期215-221,共7页
不同行距引起大豆生长竞争。当某一因子的直接供应不能满足群体生长的需要而成为限制因子时 ,竞争便开始。本文主要从基因型、光、水、养分和杂草等 5方面综述过去 4 0年行距变化对大豆竞争资源的影响。研究表明 ,不同品种对行距变化的... 不同行距引起大豆生长竞争。当某一因子的直接供应不能满足群体生长的需要而成为限制因子时 ,竞争便开始。本文主要从基因型、光、水、养分和杂草等 5方面综述过去 4 0年行距变化对大豆竞争资源的影响。研究表明 ,不同品种对行距变化的反映不同 ,其依赖于季节降雨和灌溉。有限结荚习性类型可获得较高产量 ,抗倒伏的大豆品种适于窄行种植。无限结荚习性大豆在一定的行距条件下也可获得最佳产量。与宽行大豆种植相比 ,窄行大豆栽培增加光截获 (LI) ,其原因在于LAI、消光系数的增加及分枝类型品种的选择。水分利用效率和蒸发蒸腾作用不受行距影响 ,但在灌溉条件下产量增加。行距变化对养分吸收影响较大 ,随着行距的减小 ,植株产量和N、P、K的吸收均增加 ,且增加幅度受施肥水平制约。行距不影响N素的固定。行距不影响杂草密度、萌发高峰及持续时期 ,但在窄行栽培条件下可减少杂草的数量及干重 ,再配以适量的除草剂可获得良好的除草效果。不同行距条件下的大豆生理反应、养分和水分的吸收及转运 ,不同冠层的光能利用以及土壤环境的变化仍需进一步深入研究。 展开更多
关键词 行距 大豆 生长竞争 水分吸收 养分吸收 杂草
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Charge Dependency of Strong Nuclear Force via Phase Shift Analysis of Nucleon-Nucleon Potential
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作者 N.Ghahramany G.R.Boroun m.hashemi 《Communications in Theoretical Physics》 SCIE CAS CSCD 2004年第2期279-282,共4页
Using the most recent phase shift data for pp,nn,and np elastic scattering for different states (l=0,1,...) in the energy range of i MeV to 350 MeV,the charge dependency of the strong nuclear force is investigated.Our... Using the most recent phase shift data for pp,nn,and np elastic scattering for different states (l=0,1,...) in the energy range of i MeV to 350 MeV,the charge dependency of the strong nuclear force is investigated.Our results indicate that although the charge independency holds in most of the energy range,such charge independency is broken in the particular energy range of 120 MeV to 200 MeV for all partial wave states considered here. 展开更多
关键词 elastic scattering nuclear force phase shift nucleon-nucleon potential
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Charged Higgs Pair Production in a General Two Higgs Doublet Model at e^+e^- and μ^+μ^- Linear Colliders
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作者 m.hashemi 《Communications in Theoretical Physics》 SCIE CAS CSCD 2014年第1期69-74,共6页
In this paper, charged Higgs pair production through l^+l^- → H^+ H^-, where l = e or μ, is studied within the framework of a general Two Higgs Doublet Model (2HDM). The analysis is relevant to a future e^+e^- ... In this paper, charged Higgs pair production through l^+l^- → H^+ H^-, where l = e or μ, is studied within the framework of a general Two Higgs Doublet Model (2HDM). The analysis is relevant to a future e^+e^- or μ^+ μ^- collider operating at center of mass energy of √s = 500 GeV. Two different scenarios of small and large a values are studied. Here a is the parameter, which diagonMizes the neutral CP-even Higgs boson mass matrix. Within the Minimal Supersymmetric Standard Model (MSSM), cross section of this process is almost the same at e+ e- and #+#- colliders. It is shown that at e^+e^- eolliders within a general 2HDM, cross section is not sensitive to the mass of neutral Higgs bosons, however, it can acquire large values up to several picobarn at μ^+μ^- colliders with the presence of heavy neutral Higgs bosons. A scan over Higgs boson mass parameter space is performed to analyze the effect of large masses of neutral Higgs bosons involved in the s-channel propagator and thus in the total cross section of this process. 展开更多
关键词 2HDM Higgs bosons linear colliders
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