全文获取类型
收费全文 | 267370篇 |
免费 | 2473篇 |
国内免费 | 983篇 |
专业分类
化学 | 129429篇 |
晶体学 | 3002篇 |
力学 | 14336篇 |
综合类 | 4篇 |
数学 | 49522篇 |
物理学 | 74533篇 |
出版年
2018年 | 11471篇 |
2017年 | 11239篇 |
2016年 | 8192篇 |
2015年 | 2489篇 |
2014年 | 2655篇 |
2013年 | 8086篇 |
2012年 | 8856篇 |
2011年 | 16761篇 |
2010年 | 9880篇 |
2009年 | 10186篇 |
2008年 | 12327篇 |
2007年 | 14588篇 |
2006年 | 6088篇 |
2005年 | 6640篇 |
2004年 | 6405篇 |
2003年 | 6299篇 |
2002年 | 5240篇 |
2001年 | 5997篇 |
2000年 | 4644篇 |
1999年 | 3644篇 |
1998年 | 2912篇 |
1997年 | 2905篇 |
1996年 | 2907篇 |
1995年 | 2522篇 |
1994年 | 2368篇 |
1993年 | 2259篇 |
1992年 | 2725篇 |
1991年 | 2593篇 |
1990年 | 2545篇 |
1989年 | 2579篇 |
1988年 | 2526篇 |
1987年 | 2529篇 |
1986年 | 2345篇 |
1985年 | 3226篇 |
1984年 | 3247篇 |
1983年 | 2646篇 |
1982年 | 2851篇 |
1981年 | 2807篇 |
1980年 | 2694篇 |
1979年 | 2864篇 |
1978年 | 3113篇 |
1977年 | 2912篇 |
1976年 | 2861篇 |
1975年 | 2711篇 |
1974年 | 2657篇 |
1973年 | 2699篇 |
1972年 | 1740篇 |
1968年 | 1935篇 |
1967年 | 2137篇 |
1966年 | 1937篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
J. H. Koolen 《European Journal of Combinatorics》2002,23(8):987
Bannai and Ito conjectured in a 1987 paper that there are finitely many distance-regular graphs with fixed degree that is greater than two. In a series of papers they showed that their conjecture held for distance-regular graphs with degrees 3 or 4. In this paper we prove that the Bannai–Ito conjecture holds for degrees 5–7. 相似文献
992.
993.
Olaf Steinbach 《Numerische Mathematik》2002,90(4):775-786
Summary. In this paper we investigate a stability estimate needed in hybrid finite and boundary element methods, especially in hybrid
coupled domain decomposition methods including mortar finite elements. This stability estimate is equivalent to the stability
of a generalized projection in certain Sobolev spaces. Using piecewise linear trial spaces and appropriate piecewise constant test spaces,
the stability of the generalized projection is proved assuming some mesh conditions locally.
Received April 11, 2000 / Revised version received February 15, 2001 / Published online July 25, 2001 相似文献
994.
A simpler model for concentrated vortices 总被引:7,自引:0,他引:7
995.
H. M. Soroush 《The Journal of the Operational Research Society》1994,45(3):287-300
The classical PERT approach uses the path with the largest expected duration as the critical path to estimate the probability of completing a project by a given deadline. However, in general, such a path is not the ‘most critical’ path and does not provide the smallest estimate for the probability of completion time. This paper studies the ‘most critical path’ problem and formulates it as an optimal path problem in a deterministic network with a two-attribute fractional objective function. An exact solution approach is presented for the optimal path problem which also gives the solution to the most critical path problem. The illustrative examples as well as our computational results demonstrate that the proposed algorithm provides estimates for the probabilities of completion time that are much more accurate than those of the classical approach. 相似文献
996.
997.
S. M. Lenzi C. H. Dasso M. A. Nagarajan H. M. Sofia A. Vitturi 《Acta Physica Hungarica A》1997,6(1-4):95-98
The existence of a neutron skin in neutron-rich nuclei is discussed in connection with the excitation of isovector dipole and quadrupole giant modes via isoscalar nuclear probes. In the case of large neutron excess, important contributions are obtained from the nuclear excitation, which may even become predominant according to proper kinematical conditions. At variance with the usual situation encountered in inelastic processes, constructive interference can be found between nuclear and Coulomb contributions. 相似文献
998.
999.
1000.
We calculate the energy momentum tensor to orderE 4 in chiral perturbation theory. New terms not present in previous work enter the effective Lagrangian. We describe these and estimate the values of the new coupling constants, using the results of a disperisve analysis of the π andK energy momentum tensors and relying on tensor meson dominance for the spin two component. In addition, we compare our findings with the predictions of known scalar meson dominance models of the conformal anomaly. 相似文献