用于高性能锂硫电池的二维氮硫共掺杂多孔碳纳米片的快速合成

本工作基于工业炼油产品沥青,开发了一种无金属、氮和硫共掺杂多孔碳纳米片（NSPC）的合成方法。获得的多孔碳纳米片具有高比表面积（339 m²·g^-1）和优异的固硫能力。同时,高含量氮、硫共掺杂可以有效增强碳材料的导电性,同时促进多硫化物的高效催化转化。通过熔融法固硫后,制备得到的NSPC/S电极具有较高的比容量和优异的循环稳定性（在0.6C电流密度下,200次循环后容量为762 mAh·g^-1）,实现了高含量氮和硫共掺杂的二维多孔碳材料的快速批量生产并用于高性能锂硫电池正极材料。     

中考关注家电下乡政策

2008年爆发的国际金融危机,影响全世界.中国政府为抵御金融风暴,振兴社会经济,采取了一系列措施,其中实施的家电下乡惠农政策有力地拉动了社会内需.2009年许多省     

Analysis of atom detection via the magnetic optical effect

We demonstrated a new method of atom detection by means of the magnetic optical effect. The number density of the atom cloud was measured by detecting the rotation angle of the polarization plane of linearly polarized probe light when propagating inside the atomic cloud. Detuning, the magnetic field and light intensity dependencies of the rotation angle were studied theoretically and experimentally to find the best parameter for atom detection. In this way, we managed to achieve a rotation angle of 0.22 rad with a signal to noise ratio (SNR) of 75 and a contrast of 87.5%.     

挖掘“几何”内涵 突破“解析”难点

2010年是北京市实施新课标后的第一届高考,一直以“能力立意”为宗旨的北京高考,在2010年也有突出的体现,现以一道解析几何题为例,来谈谈自己的感受．     

Two methods to deal with inhomogenous Rabi frequency in microwave transition

We analysed the influence of inhomogenous microwave field on the coherence of atom ensembles. Two methods were proposed to suppress the dephasing generated by the inhomogenous Rabi frequency. One of them was realized by spin echo, and the other one was based on the identical spin rotation effect. The results of calculation showed that the contrast of signal acquired in experiment can be improved by the two methods. Their advantages and drawbacks were discussed. We hope they could be used to improve the contrast of experimental signal in the situation that the microwave fields are very inhomogenous. Finally, we discussed the case of continuous working microwave field and showed that the dipole force raised with the inhomogeneity can be eased by spin flip.     

以a+b+c=0为条件的求值题解析

在初中数学各种竞赛题中经常会见到以a+b+c=0为条件的求值题.笔者现举几例加以解析,以期使读者了解此类题的解题思路.     

Two methods to deal with an inhomogenous Rabi frequency in microwave transition

We analyse the influence of an inhomogenous microwave field on the coherence of atom ensembles. Two methods are proposed to suppress the dephasing generated by the inhomogenous Rabi frequency. One of them is realized by using a spin echo, and the other one is based on the identical spin rotation effect. The calculation results show that the contrast of a signal acquired in experiment can be improved by using the two methods. Their advantages and drawbacks are discussed. We hope they can be used to improve the contrast of experimental signals in situations where microwave fields are very inhomogenous. Finally, we discuss the case of a continuous working microwave field and show that the dipole force raised with the inhomogeneity can be eased by spin flip.     

ANALYTICAL SMOOTHING EFFECT OF SOLUTION FOR THE BOUSSINESQ EQUATIONS

In this article, we study the analytical smoothing effect of Cauchy problem for the incompressible Boussinesq equations. Precisely, we use the Fourier method to prove that the Sobolev H~1 -solution to the incompressible Boussinesq equations in periodic domain is analytic for any positive time. So the incompressible Boussinesq equations admit exactly same smoothing effect properties of incompressible Navier-Stokes equations.     

氮掺杂石墨烯负载锰催化分解高湿臭氧性能

以三聚氰胺为氮源,通过热退火氧化石墨烯（GO）合成氮掺杂石墨烯（NG）,使用浸渍沉淀法制备NG负载锰（Mn/NG）。在相对湿度（RH）为80%,臭氧初始浓度为85.7 mg·m^-3条件下,反应24 h后,臭氧的分解率依旧保持在80%以上。在低RH环境下,其催化活性又能恢复到初始状态。氮掺杂不但为催化剂制造了结构缺陷,同时氮原子的孤对电子增大了氧空位电子密度,降低了水分子的吸附能,提高了催化剂的抗湿性能。     

Analysis of atom detection via magnetic optical effect

We demonstrated a new method of atom detection by means of magnetic optical effect. The number density of the atom cloud was measured by detecting the rotation angle of the polarization plane of linearly polarized probe light when propagating inside the atomic cloud. Detuning, magnetic field, and light intensity dependencies of the rotation angle were studied theoretically and experimentally to find the best parameter for atom detection. In this way, we managed to achieve a rotation angle of 0.22 rad with a signal to noise ratio (SNR) of 75 and a contrast of 87.5%.