全文获取类型
收费全文 | 1282篇 |
免费 | 121篇 |
国内免费 | 92篇 |
专业分类
化学 | 1000篇 |
晶体学 | 13篇 |
力学 | 36篇 |
综合类 | 3篇 |
数学 | 165篇 |
物理学 | 278篇 |
出版年
2024年 | 5篇 |
2023年 | 22篇 |
2022年 | 28篇 |
2021年 | 37篇 |
2020年 | 36篇 |
2019年 | 50篇 |
2018年 | 38篇 |
2017年 | 31篇 |
2016年 | 50篇 |
2015年 | 52篇 |
2014年 | 48篇 |
2013年 | 68篇 |
2012年 | 103篇 |
2011年 | 85篇 |
2010年 | 69篇 |
2009年 | 53篇 |
2008年 | 72篇 |
2007年 | 61篇 |
2006年 | 65篇 |
2005年 | 66篇 |
2004年 | 52篇 |
2003年 | 40篇 |
2002年 | 61篇 |
2001年 | 59篇 |
2000年 | 39篇 |
1999年 | 33篇 |
1998年 | 14篇 |
1997年 | 21篇 |
1996年 | 26篇 |
1995年 | 16篇 |
1994年 | 13篇 |
1993年 | 6篇 |
1992年 | 12篇 |
1991年 | 12篇 |
1990年 | 10篇 |
1989年 | 8篇 |
1988年 | 10篇 |
1987年 | 1篇 |
1986年 | 5篇 |
1985年 | 5篇 |
1984年 | 2篇 |
1983年 | 4篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1978年 | 1篇 |
1967年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有1495条查询结果,搜索用时 0 毫秒
131.
132.
V. Bužek 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1990,17(2):91-100
We study exactly solvable Dicke-like model describing a system of spatially distributed two-level atoms coupled to a single mode cavity field. We study the model in one excitation sub-space, when the field is supposed to be initially in the vacuum state and just one atom of the atomic sample is excited. We show that depending on the particular spatial distribution of atoms the system under consideration can exhibit super-radiation or subradiation. Moreover, we investigate the dynamics of the two-atom system interacting with the cavity field initially prepared in an arbitrary state. Co-operative effects are discussed in this case. 相似文献
133.
134.
Yifeng Bu Yaquan Wang Yongjie Zhang Li Wang Zhentao Mi 《Reaction Kinetics and Catalysis Letters》2007,90(1):77-84
Ti-MCM-41, B-Ti-MCM-41 and Ti-grafted MCM-41 were synthesized, characterized and studied in the epoxidation of cyclohexene.
The synthetic methods and the effect of water in the oxidant are discussed. 相似文献
135.
136.
137.
The adsorption of decylmethylsulfoxide (DEMS) onto carbon black and the effects of temperature, salt (NaCl) and acid (HCl) have been measured.Typical two plateaux type adsorption isotherms were obtained. Applying the two step model of surfactant adsorption on solid/liquld interface and the general adsorption isotherm equation[9]the experimental results were interpreted qualitatively and quantitatively. 相似文献
138.
Mikhail Panfilov Constantin Oltean Irina Panfilova Michel Buès 《Comptes Rendus Mecanique》2003,331(1):41-48
The quadratic law of laminar flow through porous media at high Reynolds numbers, which is well confirmed by the multiple experimental data, is shown to give rise to three fundamental paradoxes. All them can be resolved by assuming the singular structure of flow. The singularity is produced by the formation of jet brunches which invade the stagnant zones and sharply loss their kinetic energy. The numerical simulation confirms this effect. To cite this article: M. Panfilov et al., C. R. Mecanique 331 (2003). 相似文献
139.
The aim of this study is the investigation of the effects of density and viscosity contrasts on miscible displacements when
the regime is stable. It has been possible to quantify these effects by using an empirical model which takes into account
both the physical properties of the liquids and the hydrodynamic parameters in different configurations of a miscible displacement
involving distilled water and a calcium chloride solution. The introduction of a method for measuring electrical conductivities
within the porous medium itself (without disturbing the flow) has enabled us to monitor the change in the mixing zone throughout
the entire length of the flow path. A stability criterion based on hydrodynamic parameters has been established that depends
on two dimensionless numbers. 相似文献
140.
A new formulation for the modeling of density coupled flow and transport in porous media is presented. This formulation is based on the development of the mass balance equation by using the conservative form. The system of equations obtained by coupling the flow and transport equations using a state equation is solved by a combination of the mixed hybrid finite element method (MHFEM) and the discontinuous finite element method (DFEM). The former is applied in order to solve the flow equation and the dispersive part of the transport equation, whilst the latter is used to solve the advective part of the transport equation. Although the advantages of the MHFEM are known (efficiency calculation of velocity field and continuity of fluxes from one element to an adjacent one), its application in a classical development form (volumetric fluxes as unknowns) leads to the non-conservative version of the mass balance equation. The associated matrix of the system of equations obtained by hybridization is positive definite but non-symmetrical. By using a new approach (mass fluxes as unknowns) the conservative form of the continuity equation is preserved and the associated matrix of the system of equations obtained by hybridization becomes symmetrical. When applied to Elder's problem involving a strong density contrast, this new approach, with a lower calculation cost, leads to similar or identical results to those found in the specialized literature. The comparison between the conservative and non-conservative formulations solved with the same MHFEM and DFEM combination emphasizes the rigor and the pertinence of this new approach. Furthermore, we show the existence of a limit refinement defining the stability of the numerical solution for Elder's problem. 相似文献