全文获取类型
收费全文 | 1356篇 |
免费 | 133篇 |
国内免费 | 114篇 |
专业分类
化学 | 370篇 |
晶体学 | 1篇 |
力学 | 116篇 |
综合类 | 47篇 |
数学 | 677篇 |
物理学 | 392篇 |
出版年
2023年 | 9篇 |
2022年 | 28篇 |
2021年 | 36篇 |
2020年 | 50篇 |
2019年 | 35篇 |
2018年 | 36篇 |
2017年 | 29篇 |
2016年 | 50篇 |
2015年 | 38篇 |
2014年 | 52篇 |
2013年 | 91篇 |
2012年 | 55篇 |
2011年 | 85篇 |
2010年 | 58篇 |
2009年 | 99篇 |
2008年 | 75篇 |
2007年 | 97篇 |
2006年 | 77篇 |
2005年 | 79篇 |
2004年 | 46篇 |
2003年 | 44篇 |
2002年 | 42篇 |
2001年 | 32篇 |
2000年 | 44篇 |
1999年 | 33篇 |
1998年 | 23篇 |
1997年 | 27篇 |
1996年 | 26篇 |
1995年 | 21篇 |
1994年 | 21篇 |
1993年 | 21篇 |
1992年 | 11篇 |
1991年 | 8篇 |
1990年 | 17篇 |
1989年 | 12篇 |
1988年 | 8篇 |
1987年 | 17篇 |
1986年 | 6篇 |
1985年 | 12篇 |
1984年 | 7篇 |
1983年 | 3篇 |
1982年 | 7篇 |
1981年 | 8篇 |
1980年 | 11篇 |
1978年 | 4篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1974年 | 2篇 |
1973年 | 3篇 |
1970年 | 1篇 |
排序方式: 共有1603条查询结果,搜索用时 15 毫秒
21.
We use the PCP-SAFT equation of state, which is of the Van der Waals type and has a sound physical basis, to predict mixture properties, such as vapor–liquid and liquid–liquid equilibria, as well as excess enthalpies. We use molecular properties, such as dipole moment, quadrupole moment, polarizability and dispersion interaction coefficients, that have been determined quantum mechanically in Part I of this publication and adjust the remaining three pure compound parameters to pure compound data. We finally present a new combination rule for the dispersion energy parameter ? that is based on the quantum mechanically determined data. The predictions based on quantum mechanically determined pure compound properties along with the new combination rule show an improved performance compared to the original PCP-SAFT combination rule. 相似文献
22.
Wei-nan E Ping-bing Ming 《应用数学学报(英文版)》2007,23(4):529-550
We study continuum and atomistic models for the elastodynamics of crystalline solids at zerotemperature.We establish sharp criterion for the regime of validity of the nonlinear elastic wave equationsderived from the well-known Cauchy-Born rule. 相似文献
23.
Michael I. Mishchenko 《Journal of Quantitative Spectroscopy & Radiative Transfer》2006,101(3):411-415
The volume integral equation formalism is used to prove the scale invariance rule for an arbitrarily sized scatterer with an arbitrary shape, morphology, and orientation. The only assumptions are that the scatterer is made of optically isotropic linear materials and is embedded in a homogeneous, linear, isotropic, and nonabsorbing infinite medium. 相似文献
24.
Koichi Itoh Takeji Takui 《Proceedings of the Japan Academy. Series B, Physical and biological sciences》2004,80(2):29
This review paper deals with an overview of molecule-based magnetism as a rapidly developing interdisciplinary field, topological symmetry rule as the first principle of spin alignment in organic open-shell systems in the ground state, the proposal of organic through-bond 1D and 2D ferro- and superparamagnets and the detection of the first organic high-spin molecule, m-phenylenebis(phenylmethylene) in the quintet ground state (S = 2), followed by extended organic high-spin systems with π-conjugation such as aromatic hydrocarbons having S = 3, 4, 5. The paper also describes a theoretical approach to the understanding of electronic spin structures of organic high-spin molecules by invoking both Heisenberg and Hubbard model Hamiltonians, weakly interacting intramolecular high-spin systems from both experimental and theoretical sides, the spin density distribution of the first organic high-spin molecule in terms of electron- nuclear multiple resonance spectroscopy and the detection and characterization of ionic high-spin hydrocarbons, emphasizing the establishment of high spin chemistry underlying organic molecular magnetism. 相似文献
25.
26.
程治国 《宁波大学学报(理工版)》2004,17(1):28-31
提出了在无外力作功的情况下,具有Bauschinger效应的弹塑性材料处于屈服状态产生自发的塑性流动时应满足的条件.这个条件不仅与材料的力学性能有关,而且还处决于材料的具体的载荷边界条件和变形.举例说明了承受拉一扭组合的薄壁圆筒中,采用组合强化模型时,产生塑性流动的具体条件. 相似文献
27.
28.
We develop two implementable algorithms, the first for the solution of finite and the second for the solution of semi-infinite min-max-min problems. A smoothing technique (together with discretization for the semi-infinite case) is used to construct a sequence of approximating finite min-max problems, which are solved with increasing precision. The smoothing and discretization approximations are initially coarse, but are made progressively finer as the number of iterations is increased. This reduces the potential ill-conditioning due to high smoothing precision parameter values and computational cost due to high levels of discretization. The behavior of the algorithms is illustrated with three semi-infinite numerical examples. 相似文献
29.
30.
电子被HF和HCl分子散射总截面的计算 总被引:1,自引:1,他引:0
利用光学势方法计算了能量在10eV—1000eV范围内电子被H、F和Cl原子散射的总截面,并与已有的实验结果和理论计算进行了比较;又利用可加性规则(additivityrule)计算得到了电子被HF和HCl分子散射的总截面,计算结果也与已有的实验结果和理论计算进行了比较 相似文献