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We establish the formalism of nuclear spin-isospin excitations,especially the Gamow-Teller resonance in a fully consstent relativistic random-phase approximation.A relativistic form of the Landau-Migdal parameter g‘ is adopted as a residual spin-isospin correlation force.In the non-relativistic limit it reproduces the excitation energy of the giant Gamow-Teller resonance state obtained in the non-relativistic model.The Gamow-Teller resonance for finite nuclei is investigated in a relativistic approach for the first time.It is found that the Ikeda sum rule of 90Zr is quenched about 8% in the Hartree as well as the correlated strengths due to the poles of the negative Dirac states at energies above 1 GeV. 相似文献
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In this talk, the interaction of a single photon injected to a single atom is studied, for which initially the photon is uncorrelated with the atom. The spontaneous emitted photon will then evolve to be entangled with the atom on their continuous kinetic variables (momentum) in the process of resonant scattering. We find the relations between the entanglement and their physical control parameters (such as the linewidth of the injected photon wave packet, and that of the atomic wave packet, etc. ), which indicates that high entanglement can be reached by broadening the scale of the atomic wave or squeezing the linewidth of the incident single-photon pulse. 相似文献
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Experimental and Theoretical Evidence for the Existence of Broad Forbidden Gaps in the Three—Component Composite 总被引:2,自引:0,他引:2 下载免费PDF全文
The influence of localized resonance on the properties of band-gaps of the two-dimensional periodic composite are analysed numerically and experimentally by comparing the two-component phononic crystal with the three-component one. The three-component composite which exhibits localized resonance in the elastically soft coating ring is composed of a square array of coated cylinders embedded in an epoxy resin. The coated cylinders consist of a steel inner core and a rubber coating, which has much smaller wave velocity and mass density than the matrixand tile inner material. Tile measured transmission power of tile three-component composite drops to the noise level in a broad ultrasonic frequency interval in contrast to the binary composite, which is in good agreement with the calculation using the finite element method. 相似文献
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光纤加速度传感器研究进展 总被引:5,自引:0,他引:5
光纤加速度传感器与传统加速度传感器相比,不但能抗电磁干扰,而且体小、质轻、动态范围宽、精度高、能在恶劣环境下工作,因此受到各先进国家军事与商业领域的极大重视,各种实用的光纤加速度传感器不断涌现。主要有光强调制型和相位调制型两大类。光强调制式有反射式、透射式和偏振式等等。相位调制式有Mach-Zender干涉仪、Michelson干涉仪和Fabry-Perot干涉仪。有一维的,也有二维的;有与水听器组合在一起的,也有与光纤陀螺仪组合的光纤加速度传感器。最小的已经做到2.5cm长,直径仅0.25mm;测量精度已能达到1μg;共振频率可达到10kHz。为了克服温度不稳定性对测量精度的影响,人们采用了3×3耦合器解调法,双光路法,由单臂式改成推挽式等。一旦关键技术得以克服,光纤加速度传感器将会在惯性导航和其它领域发挥更重要的作用。本文将分别介绍目前各种类型光纤加速度传感器的结构、特点、走向实用化存在的问题。 相似文献
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The quark-delocalization colour-screening model is employed to calculate the effective potential between nucleon and kaon. The results show that the potentials are attractive in the I = 0 channel and repulsive in the I = 1 channel. The interactions are very weak between K^+n or K^0p due to the cancellation between I = 0 and I = 1. It is possible to have a high s-wave resonance (1615 MeV), but the width may be too wide to be observed in the experiments. 相似文献
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介绍了谐振式力传感器的工作原理,并从理论上和实验上对中科院合肥智能所研制的第一代微型硅谐振梁(3×0.4×0.045mm^3)式测力传感器进行了全面的振动分析,所得结构为其进一步优化设计提供了科学根据,文中使用的实验分析方法,为其它微小物体的动态和识别提供了一条有效途径。 相似文献