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111.
利用光的干涉测钢丝杨氏弹性模量的方法 总被引:8,自引:0,他引:8
通过测定空气劈尖的光的干涉条纹间距,确定钢丝的微小伸长量,根据测量结果计算钢丝的杨氏弹性模量。 相似文献
112.
113.
Gianni Royer-Carfagni 《Journal of Elasticity》2000,60(2):103-117
We consider a homogeneous orthotropic elastic wedge in plane stress loaded by a concentrated force at the apex. The orthotropic
material is conceived of to be formed by a matrix reinforced by a triangular net of elastic fibers, so that the fiber size
and the net shape determine the average elastic moduli of the composite material. It is found that maintaining fixed the amount
of material used for the reinforcement, there exists a particular fiber disposal which maximizes the stiffness of the wedge.
The optimal disposal is different-in-type for diverse opening-angles of the wedge.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
114.
A.R. Shahani 《Journal of Elasticity》1999,56(1):17-32
The antiplane deformation of an anisotropic wedge with finite radius is considered in this paper within the classical linear
theory of elasticity. The traction-free condition is imposed on the circular segment of the wedge. Three different cases of
boundary conditions on the radial edges are considered, which are: traction-displacement, displacement-displacement and traction-traction.
The solution to the governing differential equation of the problem is accomplished in the complex plane by relating the displacement
field to a complex function. Several complex transformations are defined on this complex function and its first and second
derivatives to formulate the problem in each of the three cases of the problem corresponding to the radial boundary conditions,
separately. These transformations are then related to integral transforms which are complex analogies to the standard finite
Mellin transforms of the first and second kinds. Closed form expressions are obtained for the displacement and stress fields
in the entire domain. In all cases, explicit expressions for the strength of singularity are derived. These expressions show
the dependence of the order of stress singularity on the wedge angle and material constants. In the displacement-displacement
case, depending upon the applied displacement, a new type of stress singularity has been observed at the wedge apex.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
115.
A twin-fluid nozzle was proposed for low-pressure atomization. The nozzle is featured by swirling air flows in the mixing chamber. Liquid medium is thereby inhaled due to the pressure difference. An experimental work was performed to investigate the atomization performance of the nozzle and the hydrogen peroxide solution served as the liquid medium. Droplet size and droplet velocity were measured. Effects of the diameter of the air-injection orifice and the air-injection pressure were investigated. The results show that small droplet size is achieved with the proposed nozzle. As the spray develops, Sauter mean diameter (SMD) of the droplets decreases first and then increases, irrespective of the variation of the air-injection orifice diameter and the air-injection pressure. Overall SMD varies inversely with the air-injection orifice diameter and air-injection pressure. Near the nozzle, cross-sectional velocity distribution exhibits a peak-valley pattern, which is replaced with uniformized velocity distributions away from the nozzle. Similarity of cross-sectional radial velocity distribution at different air pressures is evidenced. Furthermore, the correlation between droplet size and droplet velocity is established. 相似文献
116.
《Wave Motion》2020
In this work we study diffraction of a spherical acoustic wave due to a point source, by an impedance wedge In the exterior of the wedge the acoustic pressure satisfies the stationary wave (Helmholtz) equation and classical impedance boundary conditions on two faces of the wedge, as well as Meixner’s condition at the edge and the radiation conditions at infinity. Solution of the boundary value problem is represented by a Weyl type integral and its asymptotic behavior is discussed. On this way, we derive various components in the far field interpreting them accordingly and discussing their physical meaning. 相似文献
117.
基于非局域赝势能带计算及四面体网格单元中能量满足线性关系,提出一种布里渊区非均匀四面体网格产生方法,在满足精度条件下能自动得出数目最少的四面体网格,使布里渊区积分计算的精度和效率大为提高.通过对硅、锗两种金刚石结构半导体简约布里渊区所产生网格的比较,表明该方法可以根据能带结构的特点自动生成优化的非均匀网格.对现有的态密度四面体计算公式进行了补充完善,并根据生成的网格和完善后的公式计算了硅和锗导带第一、二能带的态密度. 相似文献
118.
119.
This paper discusses two stochastic approaches to computing the propagation of uncertainty in numerical simulations: polynomial
chaos and stochastic collocation. Chebyshev polynomials are used in both cases for the conventional, deterministic portion
of the discretization in physical space. For the stochastic parameters, polynomial chaos utilizes a Galerkin approximation
based upon expansions in Hermite polynomials, whereas stochastic collocation rests upon a novel transformation between the
stochastic space and an artificial space. In our present implementation of stochastic collocation, Legendre interpolating
polynomials are employed. These methods are discussed in the specific context of a quasi-one-dimensional nozzle flow with
uncertainty in inlet conditions and nozzle shape. It is shown that both stochastic approaches efficiently handle uncertainty
propagation. Furthermore, these approaches enable computation of statistical moments of arbitrary order in a much more effective
way than other usual techniques such as the Monte Carlo simulation or perturbation methods. The numerical results indicate
that the stochastic collocation method is substantially more efficient than the full Galerkin, polynomial chaos method. Moreover,
the stochastic collocation method extends readily to highly nonlinear equations. An important application is to the stochastic
Riemann problem, which is of particular interest for spectral discontinuous Galerkin methods. 相似文献
120.
This study has been conducted to compare two different numerical models for the evaluation of the performance characteristics of a diffuser‐nozzle based piezoelectric micropump. Here, the transient displacements of the membrane and the flow characteristics in the piezoelectric micropump have been closely investigated with the FSI model and the prescribed deformation model for two different frequencies. It has been found that the behaviour of the membrane computed with the FSI model is not in accordance with that with the prescribed deformation model, and that the net flow rate with the FSI model is larger than that with the prescribed deformation model. Therefore, the choice of numerical model is very important in conducting numerical analysis for piezoelectric micropumps. The results of this study can be utilized as basic data for the design and analysis of piezoelectric micropumps. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献