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121.
Dynamical equations governing the non-adiabatic collapse of a shear-free spherical distribution of unisotropic matter in the
presence of charge are obtained. A brief outline of constructing a model describing collapse of a charged radiating fluid
sphere in the set up developed is given. 相似文献
122.
本文首先介绍了在一般化破产模型基础上够造的保险费收取次数为Poisson过程的破产模型,并进一步在此模型上考虑了利率因素,使得相应的破产概率更具有实际意义。 相似文献
123.
Tomá s Caraballo Hans Crauel José A. Langa James C. Robinson 《Proceedings of the American Mathematical Society》2007,135(2):373-382
We investigate the effect of perturbing the Chafee-Infante scalar reaction diffusion equation, , by noise. While a single multiplicative Itô noise of sufficient intensity will stabilise the origin, its Stratonovich counterpart leaves the dimension of the attractor essentially unchanged. We then show that a collection of multiplicative Stratonovich terms can make the origin exponentially stable, while an additive noise of sufficient richness reduces the random attractor to a single point.
124.
125.
Effective stress law of all kinds of coal samples, including steam coal, fat coal, corking coal, thin coal and anthracite, under pore pressure of gas, is experimentally studied using a newly developed test machine. These samples are taken from Coal Mines in Wuda, Hebi, Yanzhou, Yangquan, Qingshui, and Gujiao in China. The experiment results show that, under pore pressure of gas, the tested coal samples comply with Biots effective stress law,
where the Biots coefficient is not a constant, and is bilinear function of volumetric stress () and pore pressure (p), that is,
We define four areas according to the numerical feature of , that is, functionless area of pore pressure, normal function area, fracturing function area, and quasi-soil function area. The effective stress law of coal mass introduced by this paper is a constitutive equation in the study of coupled solid and fluid. This has significance in the drainage and outburst of methane in coal seam. 相似文献
126.
Pore pressure development in a soil specimen due to electro-osmosis under alternating current conditions is examined theoretically. Solutions to the governing equation are derived for one-dimensional flow with boundary conditions corresponding to an impervious (conventional no-flow boundary), a partially drained boundary, and a partially drained boundary with an intervening permeable zone between the boundary and the soil. These latter two boundary conditions can arise from details of pore pressure measuring systems at the specimen boundaries during laboratory experiments. An analysis of the solutions indicates that for a perfect no-flow boundary, excess pore pressures measured at an electrode consist of a steady state and rapidly-decaying transient response. The pore pressures exhibit a 45 degree phase shift relative to the applied electric current. The effect of the partially drained boundary is to reduce the peak to peak amplitude of the pore pressure and to increase the phase shift to as much as 90 degrees depending on the compressibility of the pore pressure measuring system. The effect of the impeded and partially drained boundary is to further reduce the amplitude of the pore pressures and to increase the phase shift to as much as 180 degrees depending on the relative permeability of the impeded boundary. 相似文献
127.
128.
Understanding the role of shuttle vibrations in pore fluid distribution is an essential task in the exploration of plant growth
in root modules aboard space flights. Results from experimental investigations are reported in this paper on the distribution
of immiscible fluid phases in glass beads under vibrations. Hexadecane, a petroleum compound immiscible with and lighter than
water, was used in the experiments. The higher freezing point of Hexadecane (18 °C) allowed the solidification of the entrapped
blobs in the presence of water in porous media, so that their size distribution can be obtained. van Genuchten function, commonly
used to express moisture retention curves, is found to be an adequate fit for blob size distribution at residual saturation.
The effect of vibrations on the fate (mobilization, stranding, or breakup) of a solitary ganglion in porous media was studied
using a network model. A mobility criterion considering viscous, gravity, and capillary forces was developed to determine
the fate of a solitary ganglion in a porous medium. It is concluded that the effect of vibrations is to increase the likelihood
of breakup and mobilization of blobs entrapped in porous media at residual saturation. The pore fluid distributions after
vibrations are less uniform than those before vibrations. 相似文献
129.
本文通过对砖砌烟囱爆破拆除的实例分析得到,在砖砌烟囱的爆破拆除倾倒过程中,其倾倒支点是不断移动的,随着烟囱主体的不断下沉,相对于未垮部分的烟囱主体来说,该支点沿烟囱筒体不断向上移动。这表明,不能简单地按刚体模型描述砖砌烟囱的倾倒运动。 相似文献
130.