全文获取类型
收费全文 | 10008篇 |
免费 | 468篇 |
国内免费 | 92篇 |
专业分类
化学 | 6970篇 |
晶体学 | 67篇 |
力学 | 251篇 |
数学 | 1927篇 |
物理学 | 1353篇 |
出版年
2023年 | 79篇 |
2022年 | 53篇 |
2021年 | 281篇 |
2020年 | 220篇 |
2019年 | 216篇 |
2018年 | 194篇 |
2017年 | 162篇 |
2016年 | 362篇 |
2015年 | 333篇 |
2014年 | 400篇 |
2013年 | 668篇 |
2012年 | 704篇 |
2011年 | 842篇 |
2010年 | 550篇 |
2009年 | 496篇 |
2008年 | 645篇 |
2007年 | 670篇 |
2006年 | 587篇 |
2005年 | 539篇 |
2004年 | 438篇 |
2003年 | 325篇 |
2002年 | 331篇 |
2001年 | 143篇 |
2000年 | 102篇 |
1999年 | 105篇 |
1998年 | 71篇 |
1997年 | 87篇 |
1996年 | 103篇 |
1995年 | 68篇 |
1994年 | 59篇 |
1993年 | 54篇 |
1992年 | 65篇 |
1991年 | 41篇 |
1990年 | 31篇 |
1989年 | 36篇 |
1988年 | 31篇 |
1987年 | 36篇 |
1986年 | 34篇 |
1985年 | 52篇 |
1984年 | 49篇 |
1983年 | 35篇 |
1982年 | 44篇 |
1981年 | 29篇 |
1980年 | 23篇 |
1979年 | 27篇 |
1978年 | 20篇 |
1977年 | 15篇 |
1975年 | 15篇 |
1974年 | 13篇 |
1973年 | 15篇 |
排序方式: 共有10000条查询结果,搜索用时 296 毫秒
31.
Luis Anchordoqui María Teresa Dova Thomas McCauley Stephen Reucroft 《Annals of Physics》2004,314(1):145-207
The properties of cosmic rays with energies above 106 GeV have to be deduced from the spacetime structure and particle content of the air showers which they initiate. In this review we summarize the phenomenology of these giant air showers. We describe the hadronic interaction models used to extrapolate results from collider data to ultra high energies, and discuss the prospects for insights into forward physics at the LHC. We also describe the main electromagnetic processes that govern the longitudinal shower evolution, as well as the lateral spread of particles. Armed with these two principal shower ingredients and motivation from the underlying physics, we provide an overview of some of the different methods proposed to distinguish primary species. The properties of neutrino interactions and the potential of forthcoming experiments to isolate deeply penetrating showers from baryonic cascades are also discussed. We finally venture into a terra incognita endowed with TeV-scale gravity and explore anomalous neutrino-induced showers. 相似文献
32.
We consider the generalization of the classical P||Cmax problem (assign n jobs to m identical parallel processors by minimizing the makespan) arising when the number of jobs that can be assigned to each processor cannot exceed a given integer k. The problem is strongly NP-hard for any fixed k > 2. We briefly survey lower and upper bounds from the literature. We introduce greedy heuristics, local search and a scatter search approach. The effectiveness of these approaches is evaluated through extensive computational comparison with a depth-first branch-and-bound algorithm that includes new lower bounds and dominance criteria. 相似文献
33.
34.
Models, describing relativistic particles, where Lagrangian densities depend linearly on both the curvature and the torsion of the trajectories, are revisited in D=3 space forms. The moduli spaces of trajectories are completely and explicitly determined using the Lancret program. The moduli subspaces of closed solitons in the three sphere are also determined. 相似文献
35.
Alfonso Carriazo Luis M. Ferná ndez 《Proceedings of the American Mathematical Society》2004,132(11):3327-3336
In this paper we present an interesting relationship between graph theory and differential geometry by defining submanifolds of almost Hermitian manifolds associated with certain kinds of graphs. We show some results about the possibility of a graph being associated with a submanifold and we use them to characterize CR-submanifolds by means of trees. Finally, we characterize submanifolds associated with graphs in a four-dimensional almost Hermitian manifold.
36.
Manuel Ritoré Cé sar Rosales 《Transactions of the American Mathematical Society》2004,356(11):4601-4622
We study the problem of existence of regions separating a given amount of volume with the least possible perimeter inside a Euclidean cone. Our main result shows that nonexistence for a given volume implies that the isoperimetric profile of the cone coincides with the one of the half-space. This allows us to give some criteria ensuring existence of isoperimetric regions: for instance, local convexity of the cone at some boundary point.
We also characterize which are the stable regions in a convex cone, i.e., second order minima of perimeter under a volume constraint. From this it follows that the isoperimetric regions in a convex cone are the euclidean balls centered at the vertex intersected with the cone.
37.
We present a general risk model where the aggregate claims, as well as the premium function, evolve by jumps. This is achieved by incorporating a Lévy process into the model. This seeks to account for the discrete nature of claims and asset prices. We give several explicit examples of Lévy processes that can be used to drive a risk model. This allows us to incorporate aggregate claims and premium fluctuations in the same process. We discuss important features of such processes and their relevance to risk modeling. We also extend classical results on ruin probabilities to this model. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
38.
39.
Joaquin Barbera Anne-Marie Levelut Mercedes Marcos Pilar Romero Jose Luis Serrano 《Liquid crystals》1991,10(1):119-126
We present a comparative study of various metallomesogenic complexes, using X-ray diffraction methods. For a given ligand linked to different metal atoms (Cu, Ni, VO), the nature of this central atom influences mainly the magnetic susceptibilities of the mesophases. With different ligands, which keep the close neighbourhood of the metal atom unchanged, the apparent length of the mesogenic unit is longer for short ligands than for longer ones. This unexpected behaviour is qualitatively well explained by taking into account the global shape of the different complexes. 相似文献
40.