13 research outputs found

    中国-巴基斯坦喀喇昆仑公路沿线野生动物区系研究/Wild Fauna Along the China - Pakistan Kara - Koram Highway[J]

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    中国-巴基斯坦喀喇昆仑公路(以下简称"中巴公路")是中国政府于20世纪60年代中期援建的一条连接中国西部城市喀什和巴基斯坦北部城市塔科特的国际公路.2009年4月、7月、9月和2010年6~7月对中巴公路沿线分布的动物进行了考察,经全面系统分类、整理和统计,该地区共有陆栖野生动物22目51科105属147种,其中爬行类1目3科5属8种,鸟类14目34科72属103种,哺乳类/兽类7目14科28属36种.从野生动物分布的种类数量上看,分布最少的是爬行类(8种),而较多的是鸟类(103种)和哺乳类/兽类(36种),分别占该地区分布野生脊椎动物种数的5.44%、70.07%和24.49%.野生动物区系以北方广布种、高地型、古北型和中亚型为主,全北型、东洋型和喜马拉雅-横断山型渗透混杂,表明古北界温带陆栖动物地理属性是该地区动物区系的基本特征之所在

    巴基斯坦红其拉甫国家公园种子植物区系分析/Seed-plant flora in Khunjerab National Park of Pakistan[J]

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    红其拉甫国家公园(国家自然保护区)位于巴基斯坦北部地区,喀喇昆仑山南坡,介于36°04′~37°05′N和74°38′~75°45′E之间,海拔3 200~6 000 m之间,平均海拔4 000 m,总面积约2 270 km2,建于1975年.通过实地考察和查阅相关文献资料,对分布于该地区的植物从区系组成、区系性质的角度进行了分析.结果表明,该地区共有野生种子植物38科149属369种,其中裸子植物2科2属5种,被子植物36科147属364种.按照吴征镒先生对中国种子植物所划分的15个分布区类型,对所整理和统计的种子植物进行地理成分分析表明,该地区分布的植物可归入10个分布区类型和13个变型.其中北温带分布的属、种最多,有72属199种,占该地区植物总属、种数的56.68%和71.56%.由此表明温带属性是该地区植物区系的基本特点.与此同时,该地区植物区系与旧世界温带及地中海-西亚-中亚交流最多,其次与温带亚洲和东亚有一定的交流,而与热带交流很少

    Amplitude analysis of the decays D0 → π+π−π+π− and D0 → π+π−π0π0*

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    Using e+e− annihilation data corresponding to an integrated luminosity of 2.93 fb−1 taken at the center-of-mass energy √s = 3.773 GeV with the BESIII detector, a joint amplitude analysis is performed on the decays D0 → π+π−π+π− and D0 → π+π−π0π0 (non-η). The fit fractions of individual components are obtained, and large interferences among the dominant components of the decays D0 → a1(1260)π, D0 → π(1300)π, D0 → ρ(770)ρ(770), and D0 → 2(ππ)S are observed in both channels. With the obtained amplitude model, the CP-even fractions of D0 → π+π−π+π− and D0 → π+π−π0π0 (non-η) are determined to be (75.2 ± 1.1stat. ± 1.5syst.) % and (68.9 ± 1.5stat. ± 2.4syst.)%, respectively. The branching fractions of D0 → π+π−π+π− and D0 → π+π−π0π0 (non-η) are measured to be (0.688 ± 0.010stat. ± 0.010syst.)% and (0.951 ± 0.025stat. ± 0.021syst.)%, respectively. The amplitude analysis provides an important model for the binning strategy in measuring the strong phase parameters of D0 → 4π when used to determine the CKM angle γ(φ3) via the B− → DK− decay

    Amplitude analysis of the decays D0π+ππ+πD^0\rightarrow\pi^+\pi^-\pi^+\pi^- and D0π+ππ0π0D^0\rightarrow\pi^+\pi^-\pi^0\pi0

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    Measurement of integrated luminosity of data collected at 3.773 GeV by BESIII from 2021 to 2024*

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    Measurement of integrated luminosity of data collected at 3.773 GeV by BESIII from 2021 to 2024

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    We present a measurement of the integrated luminosity e+e- of collision data collected by the BESIII detector at the BEPCII collider at a center-of-mass energy of Ecm = 3.773 GeV. The integrated luminosities of the datasets taken from December 2021 to June 2022, from November 2022 to June 2023, and from October 2023 to February 2024 were determined to be 4.995±0.019 fb-1, 8.157±0.031 fb-1, and 4.191±0.016 fb-1, respectively, by analyzing large angle Bhabha scattering events. The uncertainties are dominated by systematic effects, and the statistical uncertainties are negligible. Our results provide essential input for future analyses and precision measurements

    Determination of the number of ψ(3686) events taken at BESIII

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    The number of ψ(3686) events collected by the BESIII detector during the 2021 run period is determined to be (2259.3±11.1)×106 by counting inclusive ψ(3686) hadronic events. The uncertainty is systematic and the statistical uncertainty is negligible. Meanwhile, the numbers of ψ(3686) events collected during the 2009 and 2012 run periods are updated to be (107.7±0.6)×106 and (345.4±2.6)×106, respectively. Both numbers are consistent with the previous measurements within one standard deviation. The total number of ψ(3686) events in the three data samples is (2712.4±14.3)×10^
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