全文获取类型
收费全文 | 19891篇 |
免费 | 2243篇 |
国内免费 | 2032篇 |
专业分类
化学 | 2243篇 |
晶体学 | 30篇 |
力学 | 1750篇 |
综合类 | 502篇 |
数学 | 13588篇 |
物理学 | 6053篇 |
出版年
2024年 | 25篇 |
2023年 | 165篇 |
2022年 | 328篇 |
2021年 | 358篇 |
2020年 | 412篇 |
2019年 | 422篇 |
2018年 | 444篇 |
2017年 | 576篇 |
2016年 | 644篇 |
2015年 | 499篇 |
2014年 | 1011篇 |
2013年 | 1282篇 |
2012年 | 1038篇 |
2011年 | 1262篇 |
2010年 | 1118篇 |
2009年 | 1376篇 |
2008年 | 1343篇 |
2007年 | 1431篇 |
2006年 | 1284篇 |
2005年 | 1225篇 |
2004年 | 1003篇 |
2003年 | 913篇 |
2002年 | 765篇 |
2001年 | 710篇 |
2000年 | 654篇 |
1999年 | 561篇 |
1998年 | 510篇 |
1997年 | 478篇 |
1996年 | 347篇 |
1995年 | 283篇 |
1994年 | 236篇 |
1993年 | 179篇 |
1992年 | 152篇 |
1991年 | 125篇 |
1990年 | 136篇 |
1989年 | 91篇 |
1988年 | 85篇 |
1987年 | 75篇 |
1986年 | 67篇 |
1985年 | 81篇 |
1984年 | 66篇 |
1983年 | 46篇 |
1982年 | 63篇 |
1981年 | 59篇 |
1980年 | 38篇 |
1979年 | 34篇 |
1978年 | 30篇 |
1977年 | 26篇 |
1976年 | 30篇 |
1973年 | 21篇 |
排序方式: 共有10000条查询结果,搜索用时 18 毫秒
81.
其中m,P,q>1.利用试验函数方法,首先推导一些积分不等式,然后对方程组爆破解的生命跨度 [0,T)给出估计. 相似文献
82.
在e-A深度非弹性散射过程中, 喷注穿过冷核介质时, 多重散射诱导胶子辐射会导致对碎裂函数的修正及喷注的能量损失.前期研究中关于计算e-A深度非弹性散射中胶子辐射振幅的两种方法: 螺旋振幅近似和微扰QCD严格计算都异常繁杂.
本文发展了一种新的方法, 可以方便计算出多重散射导致胶子辐射的振幅, 得到的碎裂函数的修正以及能量损失与严格计算的结果一致. 相似文献
83.
Motivated by some functional models arising in fuzzy logic, when classical boolean relations between sets are generalized,
we study the functional equation S(S(x, y), T(x, y)) = S(x, y), where S is a continuous t-conorm and T is a continuous t-norm. Some interesting methods for solving this type of equations are introduced. 相似文献
84.
Finitely generated linear semigroups over a field K that have intermediate growth are considered. New classes of such semigroups are found and a conjecture on the equivalence of the subexponential growth of a finitely generated linear semigroup S and the nonexistence of free noncommutative subsemigroups in S, or equivalently the existence of a nontrivial identity satisfied in S, is stated. This ‘growth alternative’ conjecture is proved for linear semigroups of degree 2, 3 or 4. Certain results supporting the general conjecture are obtained. As the main tool, a new combinatorial property of groups is introduced and studied. 相似文献
85.
Let λ and μ be solid sequence spaces. For a sequence of modulus functions Φ = (ϕ k) let λ(Φ) = {x = (x
k
): (ϕk(|x
k
|)) ∈ λ}. Given another sequence of modulus functions Ψ = (ψk), we characterize the continuity of the superposition operators P
f
from λ(Φ) into μ (Ψ) for some Banach sequence spaces λ and μ under the assumptions that the moduli ϕk (k ∈ ℕ) are unbounded and the topologies on the sequence spaces λ(Φ) and μ(Ψ) are given by certain F-norms. As applications
we consider superposition operators on some multiplier sequence spaces of Maddox type.
This research was supported by Estonian Science Foundation Grant 5376. 相似文献
86.
S. V. Tyshkevich 《Mathematical Notes》2007,81(5-6):851-853
87.
D.L. Skuratov Yu.L. Ratis I.A. Selezneva J. Pérez P. Fernández de Córdoba J.F. Urchueguía 《Applied Mathematical Modelling》2007
This paper deals with modelling the workpiece temperature field produced during the grinding process. The proposed model is given in terms of a two-dimensional boundary-value problem where the interdependence among the grinding wheel, the workpiece and the coolant is described by two variable functions in the boundary condition. An explicit integral form solution is constructed using the Laplace and Fourier transforms and the Green’s function method. 相似文献
88.
Wilson A. Cañas-Marín Julián D. Ortiz-Arango Uriel E. Guerrero-Aconcha Claudia P. Soto-Tavera 《Fluid Phase Equilibria》2007
The ability of Soave–Redlich–Kwong cubic equation of state (SRK EoS) to predict densities and thermodynamic derivative properties such as thermal expansivity, isothermal compressibility, calorific capacity, and Joule–Thompson coefficients, for two gas condensates over a wide range of pressures (up to 110 MPa) was studied. The predictions of the EoS were compared to Monte Carlo simulation data obtained by Lagache et al. [M.H. Lagache, P. Ungerer, A. Boutin, Fluid Phase Equilibr. 220 (2004) 221]. Two completely different alpha functions for the SRK EoS attractive term were used and their respective effects on the predictions of such properties were analyzed. Also, two different forms of the crossed terms of the attractive parameter, aij, and three expressions of the crossed terms of the repulsive parameter, bij, were combined in different ways, and predictions were carried out. Little sensitivity of the properties on the chosen alpha function, except for the calorific capacities, was found in the systems studied. The most commonly used combination rules to model phase behavior of reservoir fluids, i.e. geometric and arithmetic forms of aij and bij, respectively, predicted very deficient results for these fluids at extreme conditions, specially for density calculations. 相似文献
89.
Roderich Tumulka 《Foundations of Physics》2007,37(2):186-197
In a recent paper Conway and Kochen, Found. Phys. 36, 2006, claim to have established that theories of the Ghirardi-Rimini-Weber
(RW) type, i.e., of spontaneous wave function collapse, cannot be made relativistic. On the other hand, relativistic GRW-type
theories have already been presented, in my recent paper, J. Stat. Phys. 125, 2006, and by Dowker and Henson, J. Stat. Phys.
115, 2004. Here, I elucidate why these are not excluded by the arguments of Conway and Kochen.
相似文献
90.
一个推广的Hardy-Hilbert型不等式及其逆式 总被引:1,自引:0,他引:1
本文引入单参数λ及应用Beta函数,给一个Hardy-Hilbert型不等式以具有最佳常数因子的推广,作为应用,给出了它的逆向形式. 相似文献