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81.
Vincenzo Aquilanti Simonetta Cavalli Lev Yu. Rusin Mikhail B. Sevryuk 《Theoretical chemistry accounts》1995,90(4):225-256
Summary Various properties of post-adiabatic representations of multichannel Schrödinger equations are described in the general context of adiabatic and classical path approximations as used in atomic and molecular physics. The van der Waals interactions of fluorine, chlorine, and oxygen atoms with rare gases, hydrogen, methane, and hydrogen halides are considered: it is found that in some of these systems, the first-order post-adiabatic scheme exhibits a smaller coupling than the adiabatic representation, thus providing an appropriate choice of the basis functions for a decoupling approximation. 相似文献
82.
动力学压缩真空中的Van der Waals力 总被引:1,自引:1,他引:0
基于参数动力学过程产生的压缩效应,利用Millonni源理论方法研究了 动力学压缩真空中Van der Waals力的性质及其与真空压缩的关系。所得结果表明:Van der Waals力的性质依赖于真空压缩的程度;在一定的临界条件下,Van der Waals力由通常的 吸引性作用转化为排斥性作用。当压缩系数为零时,所得结果与通常文献完全一致。 相似文献
83.
MOCVD生长GaN:Si单晶膜的研究 总被引:4,自引:0,他引:4
获得高质量的n型GaN单晶膜是制作GaN基光电子器件的关键之一。采用立式MOCVD系统生长GaN:Si单晶膜,通过优化生长工艺,获得了电子载流于浓度高达2 ×1019cm-3,迁移率达120cm2/V·s的n型GaN:Si单晶膜;并有效地抑制了GaN中由深能级引起的黄带发射,大大提高带边发光强度。研究结果还表明:随着S掺杂量的增大,GaN:Si单晶膜的电子载流于浓度增加,迁移率下降,X光双晶衍射峰半高宽增大。首次报道了随掺S量增大,GaN:Si单晶膜的生长速率显著下降的现象。 相似文献
84.
《Physics letters. A》2020,384(28):126717
We investigate the weak interactions taking place in the tetraphenylporphyrin dimers by using Wannier orbitals and DFT. The Van der Waals interaction energies for various geometric configurations of the dimers are then compared to the differences between the total DFT energies of dimers and those of sums over the energies of monomers. The comparison allows us to estimate the weight of the Van der Waals contribution to the total interaction energy since the DFT values include all contributions such as weak chemical interaction or Pauli repulsion to the binding energy. We show that the interaction energy computed with vdW-DF-cx exchange-correlation functional is almost identical with the one computed using Wannier orbitals. By analyzing the properties of Wannier orbitals in monomer and dimer structures, we check the fact the Van der Waals energy can be accurately calculated by using only the orbitals corresponding to the single molecule, which is useful from a practical perspective. 相似文献
85.
The distribution of the initial short-time displacements of particles is considered for a class of classical systems under rather general conditions on the dynamics and with Gaussian initial velocity distributions, while the positions could have an arbitrary distribution. This class of systems contains canonical equilibrium of a Hamiltonian system as a special case. We prove that for this class of systems the nth order cumulants of the initial short-time displacements behave as the 2n-th power of time for all n > 2, rather than exhibiting an nth power scaling. This has direct applications to the initial short-time behavior of the Van Hove self-correlation function, to its non-equilibrium generalizations the Green's functions for mass transport, and to the non-Gaussian parameters used in supercooled liquids and glasses.
PACS Number: 05.20.-y, 02.30.Mv, 66.10.-x, 78.70.Nx, 05.60.Cd 相似文献
86.
M. J. Andrews 《国际流体数值方法杂志》1995,21(3):205-222
The Van Leer method for the computation of convective fluxes is extended to two-phase flow. By preventing spurious undershoots and overshoots, the scheme preserves physical realism while maintaining high-order accuracy. This is particulary important for two-phase flows, since phase exchange terms are typically a function of volume fraction products and numerical diffusion can incorrectly mix the two phases. The scheme described here is constructed to guarantee that the sum of the volume fractions is always unity and that the volume fractions are always greater than or equal to zero. Various test problems are computed to demonstrate the accuracy of the method and to show how the scheme might be incorporated in existing computational methods. In addition to multiphase flow applications, setting equal phase velocities results in a volume marker scheme that is well suited to single-phase interface tracking problems. 相似文献
87.
88.
J. Le Rouzo I. Ribet-Mohamed R. Haidar M. Tauvy N. Gurineau E. Rosencher S.L. Chuang 《Infrared Physics & Technology》2007,50(2-3):113-118
High dynamics measurements of spectral response were carried out on quantum well infrared photodetectors (QWIP). Photocurrent spectra were studied over more than three orders of magnitude, revealing the presence of spectral structures which were never observed hitherto. Electric field assisted tunneling and, more surprisingly, Van Hove singularities at the miniband edges, are shown to play an important role in the low and high energy parts of the QWIP photocurrent spectra, respectively. These experimental features motivated us to initiate a theoretical study of the absorption in a multiquantum well structure. Our work is based on the study of the electronic wave function in a periodic structure. 相似文献
89.
90.