全文获取类型
收费全文 | 12657篇 |
免费 | 973篇 |
国内免费 | 1131篇 |
专业分类
化学 | 893篇 |
晶体学 | 15篇 |
力学 | 874篇 |
综合类 | 200篇 |
数学 | 10565篇 |
物理学 | 2214篇 |
出版年
2024年 | 16篇 |
2023年 | 124篇 |
2022年 | 187篇 |
2021年 | 225篇 |
2020年 | 279篇 |
2019年 | 322篇 |
2018年 | 272篇 |
2017年 | 352篇 |
2016年 | 361篇 |
2015年 | 290篇 |
2014年 | 543篇 |
2013年 | 1028篇 |
2012年 | 502篇 |
2011年 | 679篇 |
2010年 | 621篇 |
2009年 | 761篇 |
2008年 | 846篇 |
2007年 | 876篇 |
2006年 | 751篇 |
2005年 | 706篇 |
2004年 | 555篇 |
2003年 | 619篇 |
2002年 | 504篇 |
2001年 | 433篇 |
2000年 | 393篇 |
1999年 | 361篇 |
1998年 | 368篇 |
1997年 | 332篇 |
1996年 | 231篇 |
1995年 | 161篇 |
1994年 | 128篇 |
1993年 | 110篇 |
1992年 | 84篇 |
1991年 | 87篇 |
1990年 | 60篇 |
1989年 | 54篇 |
1988年 | 64篇 |
1987年 | 42篇 |
1986年 | 44篇 |
1985年 | 65篇 |
1984年 | 45篇 |
1983年 | 29篇 |
1982年 | 42篇 |
1981年 | 42篇 |
1980年 | 25篇 |
1979年 | 32篇 |
1978年 | 32篇 |
1977年 | 21篇 |
1976年 | 25篇 |
1973年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
121.
J. B. Lasserre 《Journal of Optimization Theory and Applications》1986,49(1):177-179
We show that a consistency check of a linear system of inequalitiesAxb reduces to check whetherQb0 for a certain matrixQ. It is a direct consequence of the Farkas-Minkowski theorem. Thus, when one has to check consistency for different values ofb, one need not run a numerical algorithm for eachb.On leave at the Electronics Research Laboratory of the University of California at Berkeley in a CNRS/NSF Exchange Program. 相似文献
122.
Thomas Bernert 《Journal of solid state chemistry》2006,179(3):849-854
Cu2MnGeS4 crystallizes orthorhombic in a wurtzite superstructure type while Cu2MnSnS4 crystallizes in a tetragonal sphalerite superstructure type. Lattice constants and thermal analyses of the solid solution series Cu2MnGexSn1−xS4 are presented. A two-phase region is found from Cu2MnGe0.3Sn0.7S4 to Cu2MnGe0.5Sn0.5S4. The cell volume of the mixed crystals increases with increasing Sn content. The melting points increase smoothly with increasing Ge content to x=0.5 and then steeply for higher Ge contents. The single crystal X-ray structure analysis of Cu2MnGe0.55Sn0.45S4 is presented. The refinement converges to R=0.0270 and wR2=0.0586, Z is 2. The volumes of the tetrahedra [MS4] (M=Cu, Mn, Ge, Sn) are calculated. From these volumes the differences in size of the tetrahedra are derived and compared with the corresponding differences in the end members of the solid solution series. It turns out that the resulting structure type in these materials depends on the volume differences of the constituting tetrahedra [MS4]. 相似文献
123.
124.
Gerhard Fieck 《Theoretical chemistry accounts》1988,73(4):247-277
The reducible representations of the point groups are generally studied because of their relevance to molecular orbital and vibration theory. Triple correlations within the polyhedra are described by group-theoretical invariants that are related to the permutation representations and termed polyhedral isoscalar factors. These invariants are applied in theorems on matrix elements referring to the symmetry-adapted bases at different centres. Further invariants or geometrical weight factors inter-relate different types of reduced matrix elements of irreducible tensors (generalization of the Wigner-Eckart theorem to the polycentric case). As a demonstration a complete tabulation is given for the point group C
4. 相似文献
125.
Ramiro Pino Olivier Bokanowski Eduardo V. Ludeña Roberto López Boada 《Theoretical chemistry accounts》2007,118(3):557-561
Bearing in mind the insight into the Hohenberg–Kohn theorem for Coulomb systems provided recently by Kryachko (Int J Quantum
Chem 103:818, 2005), we present a re-statement of this theorem through an elaboration on Lieb’s proof as well as an extension
of this theorem to finite subspaces.
Contribution to the Serafin Fraga Memorial Issue. 相似文献
126.
The relations between the Hellmann-Feynman forces in laboratory fixed (L-) and relative (R-) coordinate systems are clarified. In the usualL-coordinate system, the force is interpreted as force on nucleus, while in theR-coordinate system, it means force on whole particles consisting of the electrons and nuclei of each interacting subsystem. From a perturbation theoretical viewpoint, the concept of the force on whole particles correctly corresponds to the perturbation energy and is superior to the force on the nucleus. 相似文献
127.
Werner Kutzelnigg 《Theoretical chemistry accounts》1988,73(2-3):173-200
The Fermi-contact interaction (FCI) can easily be derived from 1st order perturbation theory applied to the non-relativistic wave equation for a spin-(1/2) particle of Lévy-Leblond, with the nuclear spin described by the field of an external magnetic dipole, and it results from the fact that the turn-over-rule for the operator
is only valid if the derivatives implicit in
are taken in the distribution sense. If one avoids to apply the turn-over-rule, the FCI is obtained without the need to introduce a -function. It is also shown that the formulation of a magnetic point dipole as the limit of an extended nucleus directly leads to the FCI. Traditional methods of the derivation of the FCI are analyzed in the light of this new interpretation. It is then explained why the perturbation expansions in powers of the magnetic moment of the nucleus necessarily diverges, but that the expression for the 1st order energy on which the concept of the FCI is based, can nevertheless be justified by means of the Hellmann-Feynman theorem with a correction term if singular wave functions are involved. Finally some comments on a theory beyond first order are made.Dedicated to Professor J. Koutecký on the occasion of his 65th birthday 相似文献
128.
《Annals of Pure and Applied Logic》2022,173(10):103088
We study hidden-variable models from quantum mechanics and their abstractions in purely probabilistic and relational frameworks by means of logics of dependence and independence, which are based on team semantics. We show that common desirable properties of hidden-variable models can be defined in an elegant and concise way in dependence and independence logic. The relationship between different properties and their simultaneous realisability can thus be formulated and proven on a purely logical level, as problems of entailment and satisfiability of logical formulae. Connections between probabilistic and relational entailment in dependence and independence logic allow us to simplify proofs. In many cases, we can establish results on both probabilistic and relational hidden-variable models by a single proof, because one case implies the other, depending on purely syntactic criteria. We also discuss the ‘no-go’ theorems by Bell and Kochen-Specker and provide a purely logical variant of the latter, introducing non-contextual choice as a team-semantical property. 相似文献
129.
A Cartesian decomposition of a coherent configuration is defined as a special set of its parabolics that form a Cartesian decomposition of the underlying set. It turns out that every tensor decomposition of comes from a certain Cartesian decomposition. It is proved that if the coherent configuration is thick, then there is a unique maximal Cartesian decomposition of ; i.e., there is exactly one internal tensor decomposition of into indecomposable components. In particular, this implies an analog of the Krull–Schmidt theorem for the thick coherent configurations. A polynomial-time algorithm for finding the maximal Cartesian decomposition of a thick coherent configuration is constructed. 相似文献
130.
A Review of Results on Axially Symmetric Navier-Stokes Equations,with Addendum by X. Pan and Q. Zhang 下载免费PDF全文
Qi Zhang & Xinghong Pan 《分析论及其应用》2022,38(3):243-296
In this paper, we give a brief survey of recent results on axially symmetric
Navier-Stokes equations (ASNS) in the following categories: regularity criterion, Liouville property for ancient solutions, decay and vanishing of stationary solutions. Some
discussions also touch on the full 3 dimensional equations. Two results, closing of the
scaling gap for ASNS and vanishing of homogeneous D solutions in 3 dimensional
slabs will be described in more detail.In the addendum, two new results in the 3rd category will also be presented, which
are generalizations of recently published results by the author and coauthors. 相似文献