全文获取类型
收费全文 | 13393篇 |
免费 | 319篇 |
国内免费 | 65篇 |
专业分类
化学 | 458篇 |
晶体学 | 13篇 |
力学 | 192篇 |
综合类 | 12篇 |
数学 | 12269篇 |
物理学 | 833篇 |
出版年
2023年 | 19篇 |
2022年 | 33篇 |
2021年 | 26篇 |
2020年 | 63篇 |
2019年 | 399篇 |
2018年 | 480篇 |
2017年 | 220篇 |
2016年 | 150篇 |
2015年 | 162篇 |
2014年 | 434篇 |
2013年 | 761篇 |
2012年 | 477篇 |
2011年 | 818篇 |
2010年 | 763篇 |
2009年 | 1047篇 |
2008年 | 1054篇 |
2007年 | 1031篇 |
2006年 | 810篇 |
2005年 | 494篇 |
2004年 | 425篇 |
2003年 | 392篇 |
2002年 | 268篇 |
2001年 | 273篇 |
2000年 | 257篇 |
1999年 | 306篇 |
1998年 | 264篇 |
1997年 | 203篇 |
1996年 | 291篇 |
1995年 | 305篇 |
1994年 | 291篇 |
1993年 | 225篇 |
1992年 | 143篇 |
1991年 | 89篇 |
1990年 | 64篇 |
1989年 | 83篇 |
1988年 | 55篇 |
1987年 | 42篇 |
1986年 | 49篇 |
1985年 | 67篇 |
1984年 | 70篇 |
1983年 | 51篇 |
1982年 | 79篇 |
1981年 | 57篇 |
1980年 | 34篇 |
1979年 | 29篇 |
1978年 | 34篇 |
1977年 | 30篇 |
1976年 | 24篇 |
1975年 | 12篇 |
1974年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
This work is concerned with the study of steady flows of an incompressible viscoelastic fluid of Oldroyd type, with viscosity depending on the second invariant of the rate of deformation tensor in an exterior domain. We establish a result of existence and uniqueness of strong solutions for sufficiently small data and give estimates relating these solutions to those of the corresponding generalized Newtonian fluid. 相似文献
992.
A class of similarity solutions is obtained for radial motions of spherical and cylindrical bodies made of a certain type of compressible hyperelastic materials. The equations satisfied by the infinitesimal generators of the symmetry group of the unified governing first order field equations for spheres and cylinders are found. It is shown that these equations admit a special class of solutions which generate a five-parameter group of transformations. The form of the strain energy function corresponding to the resulting symmetry group is evaluated. The similarity variable is determined and ordinary differential equations satisfied by similarity solutions are obtained. Numerical solutions are given for a Ko material which falls into the class of admissible materials. 相似文献
993.
The macroscopic dynamics of a kinetic equation involving a model wave-particle collision operator of plasma physics is investigated.
The Chapman-Enskog asymptotics is first considered in the framework of a hydrodynamic scaling. The obtained macroscopic model
still involves a kinetic variable, the particle energy in the rest frame of the fluid, but shares similarities with the compressible
Navier-Stokes equation of gas dynamics. Then a diffusive scaling is examined under the hypothesis of small perturbations of
a global equilibrium. In this case, the macroscopic model couples the usual incompressible Navier-Stokes with a diffusion
equation for the energy distribution function of the particles, constrained by an extended version of the Boussinesq relation.
In both cases, the effect of a Lorentz force term is developed, in the perspective of plasma physical modelling.
Received June 16, 1997 相似文献
994.
The mathematical models representing machine tool chatter dynamics have been cast as differential equations with delay. In this paper, non-linear delay differential equations with periodic delays which model the machine tool chatter with continuously modulated spindle speed are studied. The explicit time-dependent delay terms, due to spindle speed modulation, are replaced by state-dependent delay terms by augmenting the original equations. The augmented system of equations is autonomous and has two pairs of pure imaginary eigenvalues without resonance. The reduced bifurcation equation is obtained by making use of Lyapunov-Schmidt Reduction method. By using the reduced bifurcation equations, the periodic solutions are determined to analyze the tool motion. Analytical results show both modest increase of stability and existence of periodic solutions near the new stability boundary. 相似文献
995.
Darya Apushkinskaya Michael Bildhauer Martin Fuchs 《Journal of Mathematical Fluid Mechanics》2005,7(2):261-297
We consider the stationary flow of a generalized Newtonian fluid which is modelled by an anisotropic dissipative potential f. More precisely, we are looking for a solution
of the following system of nonlinear partial differential equations
Here
denotes the pressure, g is a system of volume forces, and the tensor T is the gradient of the potential f. Our main hypothesis imposed on f is the existence of exponents 1 < p q0 < such that
holds with constants , > 0. Under natural assumptions on p and q0 we prove the existence of a weak solution u to the problem (*), moreover we prove interior C1,-regularity of u in the two-dimensional case. If n = 3, then interior partial regularity is established. 相似文献
((*)) |
996.
Recent advances in the applications of transition metal chalcogenides/graphene (TMC/graphene) nanocomposites in future energy storage and conversion are reviewed. The synthesis processes and structures of TMC/graphene, workingpriciple of evergy energy device, and the electrochemical performances are summarized. 相似文献
997.
Shoukry El-Ganaini 《Journal of the Egyptian Mathematical Society》2017,25(1):19-27
In this paper, the first integral method combined with Liu's theorem is applied to integrate a new coupled nonlinear Schrodinger type equation. Using this combination, more new exact traveling wave solutions are obtained for the considered equation using ideas from the theory of commutative algebra. In addition, more solutions are also obtained via the application of semi-inverse variational principle due to Ji-Huan He. The used approaches with the help of symbolic computations via Mathematica 9, may provide a straightforward effective and powerful mathematical tools for solving nonlinear partial differential equations in mathematical physics. 相似文献
998.
Mostafa M.A. Khater Emad H.M. Zahran Maha S.M. Shehata 《Journal of the Egyptian Mathematical Society》2017,25(1):8-12
In this research, we find the exact traveling wave solutions involving parameters of the generalized Hirota–Satsuma couple KdV system according to the modified simple equation method with the aid of Maple 16. When these parameters are taken special values, the solitary wave solutions are derived from the exact traveling wave solutions. It is shown that the modified simple equation method provides an effective and a more powerful mathematical tool for solving nonlinear evolution equations in mathematical physics. Comparison between our results and the well-known results will be presented. 相似文献
999.
In the present paper, we consider elliptic equations with nonlinear and nonhomogeneous Robin boundary conditions of the type{-div(B(x, u)▽u) = f in ?,u = 0 on Γ_0,B(x, u)▽u·n→+γ(x)h(u) =g on Γ_1,where f and g are the element of L~1(?) and L~1(Γ_1), respectively. We define a notion of renormalized solution and we prove the existence of a solution. Under additional assumptions on the matrix field B we show that the renormalized solution is unique. 相似文献
1000.
In this article, we mainly devote to proving uniqueness results for entire functions sharing one small function CM with their shift and difference operator simultaneously. Let f(z) be a nonconstant entire function of finite order, c be a nonzero finite complex constant,and n be a positive integer. If f(z), f(z + c), and ?_c~n f(z) share 0 CM, then f(z + c) ≡ Af(z),where A(= 0) is a complex constant. Moreover, let a(z), b(z)( ≡ 0) ∈ S(f) be periodic entire functions with period c and if f(z)-a(z), f(z + c)-a(z), ?_c~n f(z)-b(z) share 0 CM, then f(z + c) ≡ f(z). 相似文献