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目的 探讨早期干预对极低出生体重早产儿智能发育的影响,为极低出生体重早产儿的早期干预提供依据。方法 239 例极低出生体重早产儿为早产随访组,采用鲍秀兰早期教育资料制定的干预计划,进行系统干预,并与326 例失访的早产儿童以及与随访组相似的326 例正常儿童进行对照分析。采用Gesell 儿童发育量表等标准化工具进行发育评估。结果 早产随访组Gesell 儿童发育量表5 项均分、总发育商(developmental quotient,DQ)总分与早产失访组相比差异均有统计学差异(均P<0.05)。结论 早期干预能显著促进极低出生体重早产儿的智能发育,提高患儿的生活质量。 相似文献
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以亚碲酸钠(Na2TeO3)为Te源,CdCl2为Cd源,水合肼(SHJ)为还原剂,3-巯基丙酸(3-MPA)为稳定剂,制得λEX=380 nm和λEM=608 nm的CdTe量子点(CdTe QDs),该量子点的荧光强度与合成前Na2TeO3浓度呈线性关系.在n(Cd)/n(SHJ)=1∶0.04,n(Cd)/n(3-MPA)=1∶2.7,温度为100℃,反应时间为120m in,溶液pH 10.5的最佳条件下,可制备荧光量子产率为65%的CdTe QDs,该量子点的荧光强度与含碲物质的浓度符合较宽的线性范围(1.0~300 μmol/L),相关系数为0.9982,检测限为38 nmol/L.方法 用于测定微波消解下的海藻样品,加标回收率为106.0% ~ 112.0%,RSD为5.4% ~6.1%. 相似文献
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Dongrui Chen Benzhen Li Youhao Liao Hongwei Lan Haibin Lin Lidan Xing Yating Wang Weishan Li 《Journal of Solid State Electrochemistry》2014,18(7):2027-2033
Three samples, LiNi0.5Mn1.5O4, LiNi0.4Mn1.4Co0.2O4, and LiNi0.4Mn1.4Cr0.15Co0.05O4, were prepared by sol–gel method and characterized by powder X-ray diffraction, Fourier transformed infrared spectroscope, scanning electron microscopy, Brunauer–Emmett–Teller surface area, four-probe resistance, cyclic voltammetry, electrochemical impedance spectroscopy, and charge–discharge test. It is found that the co-doped sample LiNi0.4Mn1.4Cr0.15Co0.05O4 exhibits an improved performance compared with the Co-doped sample LiNi0.4Mn1.4Co0.2O4 and the undoped sample LiNi0.5Mn1.5O4, especially at elevated temperature. At 25 °C, the discharge capacity of LiNi0.4Mn1.4Cr0.15Co0.05O4 is 130 mAh g?1 at 0.1 C and 103 mAh g?1 at 10 C. At an elevated temperature (55 °C), its 1 C discharge capacity is 136 mAh g?1 and maintains 95.6 % of its initial capacity after 100 cycles. Compared with the reported results of LiNi0.4Mn1.4Co0.2O4 and LiNi0.475Mn1.475Co0.05O4, the co-doped sample LiNi0.4Mn1.4Cr0.15Co0.05O4, with least content of Co, 0.05, possesses not only the high C-rate capacity but also the structural stability. The mechanism on the electrochemical performance improvement of LiNi0.5Mn1.5O4 by the co-doping was discussed. 相似文献
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The comonomer-unit compositions and their distribution of as-produced bacterial copolyesters, including poly(3-hydroxybutyrate-co-3-hydroxyvalerate), poly(3-hydroxy-butyrate-co-3-hydroxypropionate), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) and poly(3-hydroxybutyrate-co-4-hydroxybutyrate) are described in this paper. Each copolyester sample can be comonomer-unit compositionally fractionated into several fractions, indicating that the original copolymers are mixtures of copolymers with different comonomer-unit compositions. The effects of comonomer-unit compositional distribution on thermal properties, crystallization, biodegradability and solid-state phase behavior are investigated using comonomer compositionally fractionated copolymers. 相似文献
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王丽丹 《数学物理学报(B辑英文版)》2022,(1):323-348
This paper is focused on studying the structure of solutions bounded from below to degenerate elliptic equations with Neumann and Dirichlet boundary conditions in unbounded domains.After establishing the weak maximum principles,the global boundary Holder estimates and the boundary Harnack inequalities of the equations,we show that all solutions bounded from below are linear combinations of two special solutions(exponential growth at one end and exponential decay at the other) with a bounded solu... 相似文献
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Using local search method, this paper provides a polynomial time approximation scheme for the minimum vertex cover problem on \(d\) -dimensional ball graphs where \(d \ge 3\) . The key to the proof is a new separator theorem for ball graphs in higher dimensional space. 相似文献
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The effect of substituents on the oxidation potential for the one-electron reaction of 1,4-dimethoxybenzene was understood with a theoretical calculation based on density functional theory (DFT) at the level of B3LYP/6-311+G(d). It is found that the oxidation potential for the one-electron reaction of 1,4-dimethoxybenzene is 4.13 V (vs Li/Li(+)) and can be changed from 3.8 to 5.9 V (vs Li/Li(+)) by substituting electron-donating or electron-withdrawing groups for the hydrogen atoms on the aromatic ring. These potentials are in the range of the limited potentials for the lithium ion batteries using different cathode materials, and thus the substituted compounds can be selected as the redox shuttles for the overcharge prevention of these batteries. The oxidation potential of 1,4-dimethoxybenzene decreases when the hydrogen atoms are replaced with electron-donating groups but increases when replaced with electron-withdrawing groups. The further oxidation of these substituted compounds was also analyzed on the basis of the theoretic calculation. 相似文献
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The oxidative decomposition mechanism of the lithium battery electrolyte solvent propylene carbonate (PC) with and without PF(6)(-) and ClO(4)(-) anions has been investigated using the density functional theory at the B3LYP/6-311++G(d) level. Calculations were performed in the gas phase (dielectric constant ε = 1) and employing the polarized continuum model with a dielectric constant ε = 20.5 to implicitly account for solvent effects. It has been found that the presence of PF(6)(-) and ClO(4)(-) anions significantly reduces PC oxidation stability, stabilizes the PC-anion oxidation decomposition products, and changes the order of the oxidation decomposition paths. The primary oxidative decomposition products of PC-PF(6)(-) and PC-ClO(4)(-) were CO(2) and acetone radical. Formation of HF and PF(5) was observed upon the initial step of PC-PF(6)(-) oxidation while HClO(4) formed during initial oxidation of PC-ClO(4)(-). The products from the less likely reaction paths included propanal, a polymer with fluorine and fluoro-alkanols for PC-PF(6)(-) decomposition, while acetic acid, carboxylic acid anhydrides, and Cl(-) were found among the decomposition products of PC-ClO(4)(-). The decomposition pathways with the lowest barrier for the oxidized PC-PF(6)(-) and PC-ClO(4)(-) complexes did not result in the incorporation of the fluorine from PF(6)(-) or ClO(4)(-) into the most probable reaction products despite anions and HF being involved in the decomposition mechanism; however, the pathway with the second lowest barrier for the PC-PF(6)(-) oxidative ring-opening resulted in a formation of fluoro-organic compounds, suggesting that these toxic compounds could form at elevated temperatures under oxidizing conditions. 相似文献
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In this paper, based on the topological basis states, we investigate the Hamiltonian family {H2,H3,H4} of a closed four-qubit Haldane–Shastry spin chain. Not only the two-qubit interaction form, but also the three-qubit interaction form and the four-qubit interaction form are presented in terms of spin operators. Meanwhile, we explore some particular properties of the topological basis states in these systems. With Yangian algebra, the symmetry of the systems and the transitions between the eigenstates have been investigated. We find a really useful effect of Y(sl(2)) operators {J±,J3}, which is that they can describe the transitions between the spin single state and the spin triple states. Furthermore, we construct a new Hamiltonian, whose energy degeneracies can be changed by adjusting the strengths of the two-qubit interactions, three-qubit interactions, four-qubit interactions, and the external magnetic field. 相似文献