全文获取类型
收费全文 | 31484篇 |
免费 | 4845篇 |
国内免费 | 3886篇 |
专业分类
化学 | 10380篇 |
晶体学 | 220篇 |
力学 | 3350篇 |
综合类 | 255篇 |
数学 | 8773篇 |
物理学 | 17237篇 |
出版年
2024年 | 96篇 |
2023年 | 323篇 |
2022年 | 686篇 |
2021年 | 717篇 |
2020年 | 952篇 |
2019年 | 870篇 |
2018年 | 873篇 |
2017年 | 1011篇 |
2016年 | 1186篇 |
2015年 | 1077篇 |
2014年 | 1668篇 |
2013年 | 2543篇 |
2012年 | 1731篇 |
2011年 | 2154篇 |
2010年 | 1713篇 |
2009年 | 2122篇 |
2008年 | 2192篇 |
2007年 | 2217篇 |
2006年 | 1951篇 |
2005年 | 1669篇 |
2004年 | 1394篇 |
2003年 | 1344篇 |
2002年 | 1237篇 |
2001年 | 1047篇 |
2000年 | 1014篇 |
1999年 | 822篇 |
1998年 | 748篇 |
1997年 | 578篇 |
1996年 | 416篇 |
1995年 | 388篇 |
1994年 | 318篇 |
1993年 | 317篇 |
1992年 | 294篇 |
1991年 | 240篇 |
1990年 | 249篇 |
1989年 | 227篇 |
1988年 | 191篇 |
1987年 | 191篇 |
1986年 | 157篇 |
1985年 | 155篇 |
1984年 | 150篇 |
1983年 | 84篇 |
1982年 | 124篇 |
1981年 | 118篇 |
1980年 | 101篇 |
1979年 | 107篇 |
1978年 | 79篇 |
1977年 | 77篇 |
1976年 | 74篇 |
1973年 | 62篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Basic principles of the generalized lattice model of multicomponent condensed systems are formulated. Short-range parts of interatomic interactions are taken into account by means of the geometric constraints method. Long-range parts of the interactions are taken into account in mean field approximation. The expression for Helmholtz free energy is obtained. A system of integral equations for the equilibrium distributions of components is derived. The asymptotic properties of its solutions are investigated. Moment expansion of interatomic interactions and localization of integral terms in free energy is obtained. A Ginzburg–Landau-like functional of free energy is derived. 相似文献
22.
Keye Martin 《Applied Categorical Structures》2003,11(1):27-40
We introduce the triangle inequality for measurement. This is a property that when satisfied by a measurement enables one to construct a metric on the set of elements with measure zero that yields the relative Scott topology. The naturality of this construction permits a categorical solution to the model problem in domain theory for locally compact metric spaces. The first time such a solution has been achieved. 相似文献
23.
24.
The finite-difference method is a numerical technique for obtaining approximate solutions to differential equations. The main
objective of the present study is to give a new aspect to the finite-difference method by using a variational derivative.
By applying this formulation, accurate values of the buckling loads of beams and frames with various end supports are obtained.
The performance of this formulation is verified by comparison with numerical examples in the literature
__________
Published in Prikladnaya Mekhanika, Vol. 41, No. 7, pp. 139–144, July 2005. 相似文献
25.
Philippe Bénilan 《Journal of Differential Equations》2004,196(2):301-315
In this paper, we study the singular limit of the Porous Medium equation ut=Δum+g(x,u), as m→∞, in a bounded domain with Neumann boundary condition. 相似文献
26.
27.
Mats Gyllenberg 《Journal of Differential Equations》2004,205(1):50-76
For time-periodic dissipative and irreducible type-K competitive Kolmogorov systems, it is proved that there is a canonically defined countable family F of unordered, disjoint invariant sets with the property that, for every persistent trajectory whose ω-limit set is not a cycle, there exists a unique trajectory in some element of F such that these two trajectories are asymptotic and the corresponding points in these two trajectories are K-related. 相似文献
28.
A.R.ELAMROUSS 《数学学报(英文版)》2005,21(1):129-142
This paper contains a generalization of the well-known Palais-Smale and Cerami compactness conditions. The compactness condition introduced is used to prove some general existence theorems for critical points. Some applications are given to differential equations. 相似文献
29.
The basic concepts about the active structures and some attributes of the modes were presented in paper "Liner Active Structures and Modes ( Ⅰ ) ". The characteristics of the active discrete systems and active beams were discussed, especially, the stability of the active structures and the orthogonality of the eigenvectors. The notes about modes were portrayed by a model of a seven-storeyed building with sensors and actuators. The concept of the adjoint active structure was extended from the discrete systems to the beams that were the representations of the continuous structures. Two types of beams with different placements of the measuring and actuating systems were discussed in detail. One is the beam with the discrete sensors and actuators, and the other is the beam with distributed sensor and actuator function. The orthogonality conditions were derived with the modal shapes of the active beam and its adjoint active beam. An example shows that the variation of eigenvalues with feedback amplitude for the homo-configuration and non-homo-configuration active structures. 相似文献
30.
K. Sakurai Y. Kondo K. Miyazaki T. Okamoto S. Irie T. Sasaki 《Journal of Polymer Science.Polymer Physics》2004,42(13):2595-2603
Aiming to develop a high‐performance fiber‐reinforced rubber from styrene–butadiene rubber (SBR), we applied a special technique using electron‐beam (EB)‐irradiation‐induced graft polymerization to ultrahigh‐molecular‐weight‐polyethylene (UHMWPE) fibers. The molecular interaction between the grafted UHMWPE fibers and an SBR matrix was studied through the evaluation of the adhesive behavior of the fibers in the SBR matrix. Although UHMWPE was chemically inert, two monomers, styrene and N‐vinyl formamide (NVF), were examined for graft polymerization onto the UHMWPE fiber surface. Styrene was not effective, but NVF was graft‐polymerized onto the UHMWPE fibers with this special method. A methanol/water mixture and dioxane were used as solvents for NVF, and the effects of the solvents on the grafting percentage of NVF were also examined. The methanol/water mixture was more effective. A grafting percentage of 16.4% was the highest obtained. This improved the adhesive force threefold with respect to that of untreated UHMWPE fibers. These results demonstrated that EB irradiation enabled graft polymerization to occur even on the inert surface of UHMWPE fibers. However, the mechanical properties of the fibers could be compromised according to the dose of EB irradiation. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2595–2603, 2004 相似文献