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Ginkgo leave, a naturally abundant resource, has been successfully employed as the raw material to prepare nitrogen doped porous carbon (NDPC) materials. The preparation of the porous carbon does not involve assistance of any activation or template technique. The as‐obtained NDPC shows favorable features for electrochemical energy storage, which can not only provide multiple sites for the storage and insertion of Li ions, but also facilitate rapid mass transport of electrons and Li ions. As a result, the NDPC when evaluated as an anode material for lithium ion batteries delivers high reversible capacity (505 mAh·g?1 at 0.1 C), excellent rate capability (190 mAh·g?1 at 10 C). These favorable properties suggest that the NDPC can be a promising anode material for lithium ion batteries (LIBs). 相似文献
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描述了一种用于多叶准直器适形放疗的剂量计算方法。 在不同大小的方野和非规则野照射情况下, 将此方法得到的剂量分布与微分卷积法计算得到的剂量分布进行了精度验证。 结果表明, 这种算法具有较高的剂量精度和较快的计算速度, 因此可在适形放疗中用作MLC适形野的自动生成。 A dose calculation algorithm for MLC based conformal radiotherapy is described in this paper. The algorithm is formulated by the coordinate of MLC leaves. Verification on the algorithm is made by comparing the dose distributions generated by this algorithm with that generated by a Differential Convolution Superposition algorithm for various regular and irregular fields. The results demonstrate that the present algorithm has suitable accuracy and high computational efficiency, thus it could be useful for the treatment planning process in MLC based conformal radiotherapy, where the workload for interactively or automatically designing the shapes of MLC is heavy. 相似文献
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The electric quadrupole interactions at the octahedral, tetrahedral, and dodecahedral sites in the Eu3?ySc2+yFe3O12 (0 ≤ y ≤ 0.5) garnet system were studied with 57Fe and 151Eu Mössbauer spectroscopy. The electric field gradient tensor at the three sites was calculated using a monopole-point-dipole model. It is shown that the dipole contribution to the electric field gradient tensor is not negligible even for very small values of the oxygen dipole polarizability. The importance of the overlap and second-order 4f contributions is discussed. 相似文献
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M.W. Thomas 《Chemical physics letters》1976,40(1):111-115
High temperature powder neutron diffraction studies of calcium, strontium and barium fluorides indicate that there are large thermal motions associated with the anions. This suggests that the anion sublattice in these compounds with the fluoride structure may disorder at temperatures below the melting points. In S:F2 this disordering appears at about 1370 K and for BaF2 at about 1300 K. This is in good agreement with transitions of 1440 K and 1240 K, predicted from thermodynamic data. 相似文献
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茶叶铅污染来源的研究进展 总被引:11,自引:1,他引:11
根据近年来国内外对茶叶铅污染研究的相关报道,综述了茶叶中铅污染的主要来源。这些来源主要包括:茶园土壤酸化和较高的有机质含量,大气沉降物中的铅和茶叶的加工过程。还根据各种茶叶铅污染来源的特征,有针对性地提出了一些防治措施。 相似文献
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NI Xiu-zhen WANG Bing-qing ZHI Yuan WEI Ning-ning ZHANG Xu LI Shan-shan TAI Gui-hua ZHOU Yi-fa ZHAO Ji-ming 《高等学校化学研究》2010,26(2):230-234
The water-soluble polysaccharides isolated from the leaves of Panax ginseng C.A.Meyer were totally fractionated into one neutral fraction(GLPN-1),six acidic fractions(GLPN-2,GLPA-1a,GLPA-1b,GLPA-1c,GLPA-2 and GLPA-3) by a combination of ethanol precipitation,ion-exchange and gel permeation chromatography.All the fractions were analyzed by determining monosaccharide composition,molecular weight distribution.The results show that GLPN-1 was mainly composed of Gal(38.1%) and Ara(33.6%) and presumed to be an ar... 相似文献
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《组合设计杂志》2018,26(7):315-343
A decomposition of , the complete n‐partite equipartite graph with a subgraph L (called the leave) removed, into edge disjoint copies of a graph G is called a maximum group divisible packing of with G if L contains as few edges as possible. We examine all possible minimum leaves for maximum group divisible ‐packings. Necessary and sufficient conditions are established for their existences. 相似文献