排序方式: 共有15条查询结果,搜索用时 31 毫秒
1.
无机离子交换剂以其选择性、耐热及抗辐照性很高一直受到重视.但由于它的交换过程缓慢,使其应用受到了限制,为了克服这一障碍,本文把十分之几微米的无机离子交换剂[Ti(HPO_4)_2·1/2H_2O]微晶粘结成球,以减低对流体阻力,同时大大增加交换表面.用这种交换剂研究了H~+-Li~+和Li~+-H~+互交换的动力学;同时,根据交换剂的几何模型,解出了相应界面条件的扩散方程.实验显示了在这种无机离子交换剂中的交换速度比在001×20的聚苯乙烯凝胶磺酸型阳离子交换树脂中的快3.5倍,它可能为提高无机离子交换剂的传质功能提供了新途径. 相似文献
2.
3.
In six different regimes for a spatial phase diagram of a trapped interacting Bose-Fermi gas mixture at low temperatures, we present the conditions for the spatial demixing and separation of bosons and fermions. Starting from a semiclassically thermodynamic model for the local density functional of thermal bosons and fermions,the explicit analytical expressions for the fugacities of bosons and fermions are derived in different regimes by means of a first-order perturbation method in a local-density approximation. The critical values of the fermionboson interaction strength as a function of the fractional composition of fermions have a general feature: increase,extreme and decrease with increasing the fermionic composition slightly above Bose-Einstein critical temperature. 相似文献
4.
火焰原子吸收分光光度法测定改性粘土催化剂中的铜 总被引:1,自引:1,他引:0
以无机天然粘土或用金属离子交换处理粘土制备的改性粘土作为固体酸催化剂 ,因其具有选择性好、廉价、易再生及无环境污染等特点 ,正成为目前绿色化学研究的热点 ,特别是经离子交换制备的改性粘土应用于芳烃的选择性硝化反应的研究 ,已取得较大的进展。该改性固体酸催化剂中改性元素的含量常影响催化剂的性能 ,但对改性粘土催化剂中改性元素的含量的测定却未见报道。微量铜的测定常采用紫外可见分光光度法 [1] 和原子吸收分光光度法 [2 ]。本文对经铜元素改性的粘土催化剂进行处理 ,采用了火焰原子吸收分光光度法 ,直接测定了铜元素的含量[3… 相似文献
5.
6.
Using both the Gaussian and Fetter‘‘s variational calculations for the N-body ground-state wavefunction of the trapped Bose-Einstein condensate, we give explicit analytic formulae for the spectrum of finite bosons in harmonic potentials based on the corrected sum rules and generalized virial identities. We compare the low-lying excitation spectra among the Gaussian and Fetter‘‘s variational calculations and the exact numerical results. The Gaussian approximation has the simplest reasonable results, valid for N→∞ and high-lying excitations. 相似文献
7.
本文用 u(?)×u(1) 场论描述高温氧化物超导体.求得了玻色子超导弦场方程的孤子解,并把理论结果应用于讨论 Cu-O 型超导体的一些特性. 相似文献
8.
We have investigated the thermodynamic behaviour of ideal Bose gases with an arbitrary number of particles confined in a harmonic potential. By taking into account the conservation of total number $N$ of particles and using a saddle-point approximation, we derive analytically the simple explicit expression of mean occupation number in any state of the finite system. The temperature dependence of the chemical potential, specific heat, and condensate fraction for the trapped finite-size Bose system is obtained numerically. We compare our results with the usual treatment which is based on the grand canonical ensemble. It is shown that there exists a considerable difference between them at sufficiently low temperatures, specially for the relative small numbers of Bose atoms. The finite-size scaling at the transition temperature for the harmonically trapped systems is also discussed. We find that the scaled condensate fractions for various system sizes and temperatures collapse onto a single scaled form. 相似文献
9.
The quantum pressure correction to the excitation spectrum of the trapped superfluid Fermi gases in a BEC-BCS crossover 下载免费PDF全文
Using quantum hydrodynamic approaches, we study the quantum pressure
correction to the collective excitation spectrum of the interacting
trapped superfluid Fermi gases in the BEC-BCS crossover. Based on a
phenomenological equation of state, we derive hydrodynamic equations
of the system in the whole BEC-BCS crossover regime. Beyond the
Thomas--Fermi approximation, expressions of the frequency
corrections of collective modes for both spherical and axial
symmetric traps excited in the BEC-BCS crossover are given
explicitly. The corrections of the eigenfrequencies due to the
quantum pressure and their dependence on the inverse interaction
strength, anisotropic parameter and particle numbers of the
condensate are discussed in detail. 相似文献
10.
Unitarity Schrodinger Equation and Ground State Properties of the Finite Trapped Superfluid Fermi Gases in a BCS-BEC Crossover 下载免费PDF全文
On the basis of quantum hydrodynamical equations we derive a unitarity Schrodinger equation of a finite trapped superfluid Fermi gas valid in the whole interaction regime from BCS superfluid to BEC. This equation is just the Ginzburg-Laudau-type equation for the fermionic Cooper pairs in the BCS side, the Gross-Pitaevskii-type equation for the bosonic dimers in the BEC side, and a unitarity equation for a strongly interacting Fermi superfluid in the unitarity limit. By taking a modified Gauss-like trial wave function, we solve the unitarity Schrodinger equation, calculate the energy, chemical potential, sizes and profiles of the ground-state condensate, and discuss the properties of the ground state in the entire BCS-BEC crossover regimes. 相似文献