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I. Cahit calls a graph H-cordial if it is possible to label the edges with the numbers from the set{1,-1} in such a way that, for some k, at each vertex v the sum of the labels on the edges incident with v is either k or-k and the inequalities |v(k)-v(-k)| ≤ 1 and|e(1)-e(-1)| ≤ 1 are also satisfied. A graph G is called to be semi-H-cordial, if there exists a labeling f, such that for each vertex v, |f(v)| ≤ 1, and the inequalities |e_f(1)-e_f(-1)| ≤ 1 and |vf(1)-vf(-1)| ≤ 1 are also satisfied. An odd-degree(even-degree) graph is a graph that all of the vertex is odd(even) vertex. Three conclusions were proved:(1) An H-cordial graph G is either odd-degree graph or even-degree graph;(2) If G is an odd-degree graph, then G is H-cordial if and only if |E(G)| is even;(3) A graph G is semi-H-cordial if and only if |E(G)| is even and G has no Euler component with odd edges. 相似文献
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A表示删除2度点后的点导出子图是空图的图形,文章的结论:A不是cordial图的充要条件是A是偶度图且e(A)=4m+2. 相似文献
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Enhancement of spin-orbit torque efficiency by tailoring interfacial spin-orbit coupling in Pt-based magnetic multilayers 下载免费PDF全文
Wenqiang Wang 《中国物理 B》2022,31(9):97504-097504
We study inserting Co layer thickness-dependent spin transport and spin-orbit torques (SOTs) in the Pt/Co/Py trilayers by spin-torque ferromagnetic resonance. The interfacial perpendicular magnetic anisotropy (IPMA) energy density ($K_{\rm s}= 2.7 $ erg/cm$^{2}$, 1 erg = 10$^{-7}$ J), which is dominated by interfacial spin-orbit coupling (ISOC) in the Pt/Co interface, total effective spin-mixing conductance $(G_{\mathrm{eff,tot}}^{\mathrm{\uparrow \downarrow }}=\mathrm{0.42\times }{10}^{15} \mathrm{\Omega }^{-1}\cdot\mathrm{m}^{-2}$) and two-magnon scattering ($\beta_{\mathrm{TMS}}= 0.46 {\mathrm{nm}}^{2}$) are first characterized, and the damping-like torque ($\xi_{\mathrm{DL}}= 0.103$) and field-like torque ($\xi _{\mathrm{FL}}=-0.017$) efficiencies are also calculated quantitatively by varying the thickness of the inserting Co layer. The significant enhancement of $\xi_{\mathrm{DL}}$ and $\xi_{\mathrm{FL}}$ in Pt/Co/Py than Pt/Py bilayer system originates from the interfacial Rashba-Edelstein effect due to the strong ISOC between Co-3d and Pt-5d orbitals at the Pt/Co interface. Additionally, we find a considerable out-of-plane spin polarization SOT, which is ascribed to the spin anomalous Hall effect and possible spin precession effect due to IPMA-induced perpendicular magnetization at the Pt/Co interface. Our results demonstrate that the ISOC of the Pt/Co interface plays a vital role in spin transport and SOTs-generation. Our finds offer an alternative approach to improve the conventional SOTs efficiencies and generate unconventional SOTs with out-of-plane spin polarization to develop low power Pt-based spintronic via tailoring the Pt/FM interface. 相似文献
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采用离心超滤和液相色谱-质谱联用的方法, 从红车轴草异黄酮提取物中筛选DNA结合剂. 结果表明, 红车轴草中10种异黄酮成分与DNA具有不同的结合能力. 采用液相色谱-串联质谱联用技术对其结构进行了鉴定, DNA结合能力较强的5种化合物分别是德鸢尾素-4'-O-β-D-葡萄糖苷、 德鸢尾素、 黄豆黄葡萄糖苷、 红车轴草素和鹰嘴豆牙素A. 为从中药提取物等复杂体系筛选并鉴定DNA结合剂建立了快速的超滤质谱平台. 相似文献
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合成了二茂铁接枝聚乙烯亚胺( PEI-Fc),利用二茂铁与β-环糊精的主客体嵌套作用制备了环糊精修饰聚乙烯亚胺,核磁测定结果显示,每条PEI-Fc链上通过主客体作用嵌套的CD平均为26个.这种基于弱相互作用力的β-环糊精修饰聚乙烯亚胺能有效诱导DNA分子的缔合,在N/P值达到3以上时,可形成表面为正电荷、粒径为150 ~ 250 nm的球形粒子.在含10%胎牛血清的DMEM体外细胞培养基中,由于培养基中的蛋白质能够在粒子表面发生静电吸附,PEI-Fc/CD/DNA基因微载体显示出良好的稳定性.HEK293细胞培养结果显示,以表达绿色荧光蛋白的质粒pEGFP为模型,以N/P值为10的PEI/DNA组装体作为对照,N/P值为3、5和10的PEI-Fc/CD/DNA组装体的转染效率均达到对照组的2~3倍,这种基于主客体组装构建的环糊精修饰基因微载体显著提高了基因转染效率. 相似文献
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以巯基丙酸(MPA)为稳定剂,合成了锰掺杂硫化锌(ZnS:Mn)量子点。由于汞离子对ZnS:Mn量子点的磷光有很强的猝灭作用,应用MPA修饰的ZnS:Mn量子点作磷光探针,定量检测水相中的微量汞离子。相对于荧光,磷光的寿命长、选择性好,没有荧光和散射光的干扰。在优化的实验条件下,当汞离子的浓度在1.0×10~(-5)~1.0×10~(-3)mol·L~(-1)范围内时,ZnS:Mn量子点的△P/P与汞离子浓度之间的关系符合Stem-Volmer方程,其线性相关系数为0.998 8。回收率为85.2%~106.1%,相对标准偏差为3.46%,检出限为9.7×10~(-6)mol·L~(-1)。讨论了量子点磷光的猝灭机理,研究了常见金属离子的干扰作用,选择合适的掩蔽剂,可以有效地消除干扰离子的影响。 相似文献
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在沪教版初中数学教材中,“三角形内角和”是七年级第二学期“三角形”一章第二节的内容.课标要求:经历操作、归纳和说理论证的过程,理解和掌握三角形的内角和性质,并会进行计算和实际应用.课堂上一般是将三角形纸片的三个角撕下来拼一拼.但这一操作方法与后面的说理方法的关联较弱,即所添辅助线是如何想到的?对照数学教学的三重境界——“知其然”、“知其所以然”、“何以知其所以然”,显然最后一重境界是缺失的.实际上,从教学的角度看,这也是欧几里得《几何原本》的缺点.18世纪法国数学家克莱罗在《几何基础》中为三角形内角和定理补足了第三重境界,创用了今天所说的“橡皮筋设计法”. 相似文献