全文获取类型
收费全文 | 19355篇 |
免费 | 2116篇 |
国内免费 | 1497篇 |
专业分类
化学 | 2701篇 |
晶体学 | 62篇 |
力学 | 2085篇 |
综合类 | 559篇 |
数学 | 11614篇 |
物理学 | 5947篇 |
出版年
2023年 | 147篇 |
2022年 | 238篇 |
2021年 | 330篇 |
2020年 | 392篇 |
2019年 | 393篇 |
2018年 | 427篇 |
2017年 | 506篇 |
2016年 | 610篇 |
2015年 | 424篇 |
2014年 | 758篇 |
2013年 | 1283篇 |
2012年 | 869篇 |
2011年 | 1198篇 |
2010年 | 1120篇 |
2009年 | 1351篇 |
2008年 | 1342篇 |
2007年 | 1345篇 |
2006年 | 1281篇 |
2005年 | 1025篇 |
2004年 | 912篇 |
2003年 | 848篇 |
2002年 | 796篇 |
2001年 | 676篇 |
2000年 | 628篇 |
1999年 | 555篇 |
1998年 | 472篇 |
1997年 | 414篇 |
1996年 | 352篇 |
1995年 | 307篇 |
1994年 | 236篇 |
1993年 | 213篇 |
1992年 | 205篇 |
1991年 | 151篇 |
1990年 | 137篇 |
1989年 | 117篇 |
1988年 | 92篇 |
1987年 | 84篇 |
1986年 | 62篇 |
1985年 | 78篇 |
1984年 | 75篇 |
1983年 | 43篇 |
1982年 | 83篇 |
1981年 | 50篇 |
1980年 | 47篇 |
1979年 | 70篇 |
1978年 | 46篇 |
1977年 | 48篇 |
1976年 | 25篇 |
1974年 | 28篇 |
1973年 | 27篇 |
排序方式: 共有10000条查询结果,搜索用时 703 毫秒
71.
The first hyperpolarizabilities of a series of novel azulenic-barbituric acid chromophores have been studied by using 12 excitation wavelengths, ranging from 900 to 1907 nm. The dispersion relation of the first hyperpolarizabilities of chromophores holds the same tendency as the experimental results. In addition, the static first hyperpolarizability β0 of molecules was calculated by means of the Sum-Over-States (SOS) expression and the two-level formula respectively. The results show that these molecules possess large static first hyperpolarizabilities and the, β0 value increases as the donor or acceptor strength enhances; the distorted degree of molecules has also an important influence on the β0 value. 相似文献
72.
For vector quasivariational inequalities involving multifunctions in topological vector spaces, an existence result is obtained without a monotonicity assumption and with a convergence assumption weaker than semicontinuity. A new type of quasivariational inequality is proposed. Applications to quasicomplementarity problems and traffic network equilibria are considered. In particular, definitions of weak and strong Wardrop equilibria are introduced for the case of multivalued cost functions. 相似文献
73.
Wolfgang Knirsch 《Mathematische Nachrichten》2004,265(1):15-23
On weighted spaces with strictly plurisubharmonic weightfunctions the canonical solution operator of and the ‐Neumann operator are bounded. In this paper we find a class of strictly plurisubharmonic weightfunctions with certain growth conditions, so that they are Hilbert‐Schmidt operators between weighted spaces with different weightfunctions, if they are restricted to forms with holomorphic coefficients. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
74.
A. Bourgeat O. Gipouloux E. Marui‐Paloka 《Mathematical Methods in the Applied Sciences》2004,27(4):381-403
In this paper, we study the global behaviour of an underground waste disposal in order to have an accurate upscaled model suitable for the computations involved in safety assessment processes. We start from a detailed model describing the transport of pollutant leaking from a high number of units. Using the method of homogenization, going to the limit, we obtain first a macroscopic model where the sources are now appearing globally. Then we compute a first‐order matched asymptotic expansion and we give the error estimates for this approximation. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
75.
Marko Nedeljkov 《Mathematical Methods in the Applied Sciences》2004,27(8):931-955
This work gives a condition for existence of singular and delta shock wave solutions to Riemann problem for 2×2 systems of conservation laws. For a fixed left‐hand side value of Riemann data, the condition obtained in the paper describes a set of possible right‐hand side values. The procedure is similar to the standard one of finding the Hugoniot locus. Fluxes of the considered systems are globally Lipschitz with respect to one of the dependent variables. The association in a Colombeau‐type algebra is used as a solution concept. Copyright © 2004 John Wiley &Sons, Ltd. 相似文献
76.
77.
The refraction holodiagram RHD is analyzed here with respect to the law of refraction. Particularly, we study the surface that exactly conjugates by refraction a virtual point source with a real image or conversely. By using the total optical path as a parameter we build a diagram that consists in a family of Descartes ovals of the apple type that contains the Pascal's limaçon as a particular extreme case and the spherical surface with the Weierstrass points as another. These representations permit the straightforward application of Fermat's principle in the case of arbitrary refracting surfaces and show the shape of generalized Fresnel's zones in the intersections with any surface. Snell's law is applied to rays incident on the apple type surfaces to find out the conditions for exact conjugation. Sensitivity to optical path variations is also discussed. The RHD curves family can be represented in a Cartesian way where the ovals appear as equally spaced straight lines. 相似文献
78.
R. Norvaisa 《Lithuanian Mathematical Journal》2005,45(4):447-457
We give a characterization of Gaussian chaos laws on Banach function spaces which do not contain ℓ
∞
n
's uniformly. The result is applied to describe the convergence in law of U-processes with sample paths in certain Banach function spaces.
__________
Published in Lietuvos Matematikos Rinkinys, Vol. 45, No. 4, pp. 553–566, October–December, 2005. 相似文献
79.
The main purpose of this paper is to use a mean value theorem of Dirichlet L-functions to study the asymptotic property of a hybrid mean value of a generalized Cochrane sum, and give an interesting mean value formula.2000 Mathematics Subject Classification: Primary—11F20; Secondary—11F99 相似文献
80.
本文研究了A型暂留稳定过程在无穷远处的收敛速度,给出了一个重对数律.同时我们也得出了这类过程在起始点附近的一些性质.这些性质推广了[1]中的结果 相似文献