排序方式: 共有38条查询结果,搜索用时 31 毫秒
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采用改进的反相高效液相色谱法(RP-HPLC)测定了持久性有机污染物(POPs)包括多环芳烃(PAHs)、多氯二苯并二恶英(PCDDs)、多氯二苯并呋喃(PCDFs)和十溴二苯乙烷(DBDPE)等的正辛醇-水分配系数(logKow)。采用保留时间双点校正法(DP-RTC)校正因色谱柱老化等引起的保留时间漂移。以37种有可靠logKow实验值的苯系物、PAHs、PCDD/Fs类似物为模型化合物,建立了logKow和外推至纯水相的保留因子logkw的定量结构-色谱保留关系(QSRR)模型,回归方程为logKow=(1.18±0.02)logkw+(0.36±0.11),其相关系数(R2)为0.985,交叉验证相关系数(R2cv)为0.983,标准偏差(SD)为0.16。进而,用4个已有可靠logKow实验值的验证化合物(联苯、芴、PCDD 1和PCDF 114)对模型进行了外部验证,表明RP-HPLC测得的logKow值与摇瓶法/慢搅法结果有很好的一致性,尤其是对疏水性强的化合物。采用该模型测定了29种特别受关注的POPs的logKow值,这些化合物的logKow实验值均未见报道。所建立的DP-RTC-HPLC是测定强疏水性POPs的logKow值的一种值得推荐的方法。 相似文献
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Yanqin Zhang Miaomiao Jia Jianguo Yu Junqin Fan Lili Wang Yisong Zou Yongnan Zhao 《Journal of Solid State Electrochemistry》2016,20(3):733-741
Hierarchical porous carbons (HPCs) with abundant mesopores have been prepared by a facile route from the starch that was pretreated by calcium acetate. The scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and N2 adsorption–desorption tests show that hierarchical porous carbons with bimodal mesopores have been obtained. Moreover, the pore sizes are tunable by simply adjusting the reactants ratio and carbonization temperature. The as-synthesized hierarchical porous carbon materials (HPCs-2-800) possesses the highest Brunauer-Emmett-Teller (BET)-specific surface area of 464 m2 g?1 and mesoporous volume of 0.663 cm3 g?1 at the carbonization temperature of 800 °C and starch to calcium acetate mass ratio of 2. Electrochemical measurements also display that the HPCs-2-800 electrodes have a high reversible capacity of 244 F g?1 at the current density of 0.1 A g?1 and 182 F g?1 at the current density of 10 A g?1. When the current density is elevated from 0.1 to 10 A g?1, the high capacitance retention of 74.6 % reveals a good rate performance. Long charge–discharge cycling measurements disclose good stabilities over 25,000 cycles at different current densities of 1–10 A g?1 (5000 cycles at each current density) for HPCs-2-800 electrode. The cycling results indicate a high capacitance retention of 99.6 % over 5000 charge–discharge cycles even at the current density of 10 A g?1. The excellent supercapacitive performances imply that HPCs-2-800 is a promising candidate for supercapacitors. 相似文献
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Jiang Junqin 《中国物理C(英文版)》1999,23(4):347-351
The Wilson fermion Condensates in 1+1 dimensional Lattice QCD are calculated by using the improved Hamiltonian and the variational method.The results are consistant with the predictions from continuum theory,and are almost independent of the Wilson parameter r. The three-links terms give important contribution to<ψψ> in the improved Hamiltonian theory. 相似文献
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Ground states of the immiscible Cu–Ta system are investigated by a hybrid approach of first-principles calculation and cluster expansion method. The obtained pairs, triplets, and tetrads cluster interactions show that the closer-packed cluster may not always contribute to stabilize structures. A CuTa7 phase with a cage-like structure is predicted to be stable at ground state. The obtained spatial valence charge density shows that there exists a charge hollow within this cage-like structure, contributing to stabilize CuTa7 phase. 相似文献
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通过磁珠富集的方法分离池蝶蚌(Hyriopsis Schlegelii)的微卫星分子标记。将池蝶蚌基因组DNA酶切,连接Brown接头,采用PCR技术富集,与探针杂交后杂交复合物结合到包被有链霉亲和素的磁珠上,再将这些片段洗脱,PCR扩增,克隆构建含有微卫星片段的"基因组文库",所得到的阳性克隆进行测序。从所获得的212个阳性克隆中选取110个进行测序,其中54.5%含有微卫星序列,80%的重复序列重复数在10以上,微卫星序列中21.4%为完美型。除探针中使用的AC、AG等重复单元外,还观察到CT、GA、ATG等重复序列。设计获得60对微卫星引物,合成其中的30对经PCR筛选,结果有10对引物扩增出多态性条带。该实验表明:磁珠富集法是获得池蝶蚌微卫星分子标记的一种有效的方法,同时,制备出的微卫星标记可为今后研究池蝶蚌分子遗传多样性提供有用的遗传标记。 相似文献
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Integrable Couplings of the Boiti-Pempinelli-Tu Hierarchy and Their Hamiltonian Structures 下载免费PDF全文
Huiqun Zhang Yubin Zhou & Junqin Xu 《advances in applied mathematics and mechanics.》2016,8(4):588-598
Integrable couplings of the Boiti-Pempinelli-Tu hierarchy are constructed
by a class of non-semisimple block matrix loop algebras. Further, through using the
variational identity theory, the Hamiltonian structures of those integrable couplings
are obtained. The method can be applied to obtain other integrable hierarchies. 相似文献
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叠加激发双模压缩真空态的量子统计特性(英文) 总被引:5,自引:3,他引:2
从激发双模压缩真空态a+mb+m|ξ>出发构造了叠加态|Ψ>,研究了|Ψ>的量子统计特性.结果表明:在一定的条件下,随着相位差的变化,叠加态|Ψ>的平均光子数出现类似于Rabi振荡的崩塌与复原现象,而且与单个激发双模压缩真空态a+mb+m|ξ>相比,在叠加态|Ψ>中光场的相位压缩和亚泊松光子统计特性都得到了加强. 相似文献
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Li Ling Liu Jianxiu Guo Hailin Chen Jingbo Shao Hanliang Li Dandan Li Jianjian Wang Yi Zong Junqin 《Plasma Chemistry and Plasma Processing》2019,39(5):1355-1355
Plasma Chemistry and Plasma Processing - The article Rooting and Related Physiological Characteristics Responses to Stolon Cuttings Pre?treatment by Cold Plasma in Centipedegrass (Eremochloa... 相似文献
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