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721.
以多齿席夫碱配体H2L(H2L=(E)-N′-(3-乙氧基-2-羟基亚苄基)-3-羟基吡啶甲酰肼)为配体,与Ln(acac)3·2H2O(Ln=Tb、Ho、Er;acac-=乙酰丙酮根)反应,通过溶剂热法,成功得到了3例新的双核稀土配合物[Ln2(acac)2(L)2(C2H5OH)2](Ln=Tb((1)、Ho((2)、Er(3))。单晶X射线衍射分析表明:配合物1~3的结构主要由2个LnⅢ离子、2个乙酰丙酮根(acac-)、2个L2-及2个C2H5OH组成,中心LnⅢ离子通过2个μ2-O原子相互连接,形成一个平行四边形的Ln2O2核心。固体荧光实验测... 相似文献
722.
The quantum tunneling effect in a ferromagnetic particle which can be evaluated only for the ground state previously is extended to excited states within the framework of instanton method. The tunneling between n-th degenerate states of neighboring wells is dominated by a periodic pseudoparticle configuration with which a formula of level-splitting valid for entire energy region is derived. In low energy region periodic instanton results coincide exactly with those derived through the LSZ reduction procedure. The tunneling effect increases at excited states. These results should be useful in further investigation of phase transition problem in ferromagnetic particles. 相似文献
723.
724.
Xu?Chang-TanEmail author J.-Q.?Liang 《The European Physical Journal B - Condensed Matter and Complex Systems》2005,44(4):469-479
Multi-high-frequency electron paramagnetic resonance(EPR) spectrum for a
supermolecular dimer
of single-molecule magnets
recently reported [S. Hill, R.S. Edwards, N. Aliaga-Alcalde and G.
Christou (HEAC), Science 302, 1015 (2003)] is studied in terms of the
perturbation method in which the high-order corrections to the level
splittings of degenerate states are included. It is shown that the
corresponding eigenvectors are composed of entangled states of two
molecules. The EPR-peak positions are calculated in terms of the eigenstates
at various frequencies. From the best fit of theoretical level splittings
with the measured values we obtain the anisotropy constant and exchange
coupling which are in agreement with the corresponding values of
experimental observation. Our study confirms the prediction of HEAC that the
two Mn4 units within the dimer are coupled quantum mechanically by the
antiferromagnetic exchange interaction and the supermolecular dimer
behaviors in analogy with artificially fabricated quantum dots. 相似文献
725.
We report the angular distributions of grey and black particles produced in ^16O-AgBr interactions at 4.5 A GeV/c in nuclear emulsion. Intermittency and fractal behaviour are studied for emission spectra of target associated grey and black particles. Intermittent behaviour is observed for both grey and black particles. In both the cases, anomalous dimensions are seen to increase linearly with the order of moments, thereby indicating the association of multifractility with production mechanism of both grey and black particles. 相似文献
726.
727.
电化学固氮技术由于可在温和条件下进行,为肥料低成本生产提供了新策略,但高稳定性和高活性电催化剂的选择是其关键技术。 本文采用溶胶凝胶法合成了钒掺杂ZIF-8,以此为前驱体进一步高温碳化,合成了纳米介孔钒-氮共掺杂碳基电化学还原氮(NRR)催化剂。 利用透射电子显微镜、X射线衍射、X光电子能谱和Raman光谱等对催化剂进行了表征分析。 所得催化剂呈现出高度无序的三维多孔碳结构。 催化剂中存在适量的V5+、碳化氮和吡啶氮对NRR起到明显促进作用。 当前驱体中钒锌比为0.125,在N2气气氛保护下1100 ℃热处理获得催化剂具有最佳NRR性能,在0.1 mol/L KOH电解质溶液中,当外加电压为-0.4 V时,氨的生产速率可达7.092 μmol/(cm2·h),法拉第效率为23.88%,且催化剂具有良好的稳定性。 相似文献
728.
Jian Zhong Xinmian Chen Miaoran Zhang Chaoxin Xiao Lulu Cai Waleed Ali Khan Kaixuan Yu Jiayi Cui Lin He 《中国化学快报》2020,31(3):769-773
Carbon dots have unique advantages in biological applications owing to their excellent optical prope rties.However,the biosafety evaluation of carbon dots has limitations owing to cytotoxicity in vitro,and the re is little pre-safety evaluation before in vivo and clinical applications.Whether the carbon dots are or not suitable for applications in vivo,evaluation analysis can be made based on hemolysis and changes in erythrocyte morphology.In this work,a green fluorescent N,S-doped carbon dots(N,S-CDs)were obtained by hydrothermal method,tobias acid,and m-phenylenediamine as precursors.N,S-CDs not only possessed excellent dispersibility,uniform particle size,high quantum yield(37.2%)and stable photoluminescence property but also retain their photostability and stro ng fluorescence intensity in the acid/alkaline solutions,different ionic strengths(NaCl)and under 365 nm UV illumination.Moreove r,the N,S-CDs displayed low cytotoxicity and high cellular uptake efficiency in human umbilical vein endothelial cells(HUVEC)and excellent blood compatibility to the erythrocyte.It is foreseeable that N,S-CDs could be further studied as a promising biological imaging agent in vivo. 相似文献
729.
《中国化学快报》2020,31(8):2055-2058
Tin dioxide is important gas sensor material and has wide applications in the detection of toxic gases and volatile organic compounds. Here, we synthesized a 3D laminated structural CuO/SnO2 material possessing p-n heterostructures. The morphology and structure were characterized by XRD, SEM, TEM and XPS techniques and the sensing properties were investigated for the detection of triethylamine (TEA). The results indicate that 3D laminated CuO/SnO2 material, assembled by lamellae consisting of ordered nanoparticles, exhibit an enhanced sensing performance compared with SnO2, and notably, CuO/SnO2 with size less than 1 μm has obvious high selectivity in the detection of 100 ppm TEA. Particularly, it has a high response and stability to 1 and 5 ppm TEA (S is 8 and 33), and that is higher than SnO2 material, suggesting 3D laminated CuO/SnO2 is an effective candidate material served as sensor platform to detect low-concentration amines. 相似文献
730.
Let G be a π-separable group for a set of primes, let N be a normal subgroup of G, and let θ be an Iπ-character (i.e., irreducible π-partial character) of N. We obtain a necessary and sufficient condition for the number of Iπ-characters of G over θ to take the possible maximum
. Some applications are given. 相似文献
π|G:N|