全文获取类型
收费全文 | 38791篇 |
免费 | 4025篇 |
国内免费 | 4642篇 |
专业分类
化学 | 34923篇 |
晶体学 | 701篇 |
力学 | 1464篇 |
综合类 | 221篇 |
数学 | 698篇 |
物理学 | 9451篇 |
出版年
2024年 | 86篇 |
2023年 | 395篇 |
2022年 | 942篇 |
2021年 | 1051篇 |
2020年 | 1536篇 |
2019年 | 1384篇 |
2018年 | 1284篇 |
2017年 | 1559篇 |
2016年 | 1815篇 |
2015年 | 1530篇 |
2014年 | 1642篇 |
2013年 | 3931篇 |
2012年 | 2459篇 |
2011年 | 2193篇 |
2010年 | 1864篇 |
2009年 | 2303篇 |
2008年 | 2087篇 |
2007年 | 2122篇 |
2006年 | 2017篇 |
2005年 | 1737篇 |
2004年 | 1642篇 |
2003年 | 1433篇 |
2002年 | 1264篇 |
2001年 | 989篇 |
2000年 | 1065篇 |
1999年 | 867篇 |
1998年 | 770篇 |
1997年 | 693篇 |
1996年 | 670篇 |
1995年 | 627篇 |
1994年 | 541篇 |
1993年 | 446篇 |
1992年 | 382篇 |
1991年 | 305篇 |
1990年 | 266篇 |
1989年 | 228篇 |
1988年 | 245篇 |
1987年 | 240篇 |
1986年 | 163篇 |
1985年 | 138篇 |
1984年 | 146篇 |
1983年 | 39篇 |
1982年 | 93篇 |
1981年 | 59篇 |
1980年 | 45篇 |
1979年 | 42篇 |
1978年 | 21篇 |
1977年 | 16篇 |
1976年 | 16篇 |
1973年 | 32篇 |
排序方式: 共有10000条查询结果,搜索用时 546 毫秒
41.
P. E. Cladis 《Journal of statistical physics》1991,62(5-6):899-925
We first discuss nonlinear aspects of phase transition theory applied to a particular liquid crystal phase transition. A simple derivation is given to show how two coupled Goldstone modes (one appearing as gauge fluctuations of the ordered phase) can force a phase transition, against all expectations, to take place discontinuously (theory of Halperin, Lubensky, and Ma)-but the discontinuity may be immeasurably small. Then, we describe a new dynamical test of phase transition order, developed by Cladiset al., that turns out to be more sensitive than x-ray diffraction and adiabatic calorimetry. Quantitative data found by this new method are in excellent agreement with the measurements of adiabatic calorimetry and x-ray diffraction as well as expectations implicit in the predictions of HLM.This is the text of an after-banquet talk given at the CNLS Workshop on the Dynamics of Concentrated Systems. 相似文献
42.
The spin-1 Ising model, which is equivalent to the three-component lattice gas model, is used to study wetting transitions in three-component surfactant systems consisting of an oil, water, and a nonionic surfactant. Phase equilibria, interfacial profiles, and interfacial tensions for three-phase equilibrium are determined in mean field approximation, for a wide range of temperature and interaction parameters. Surfactant interaction parameters are found to strongly influence interfacial tensions, reducing them in some cases to ultralow values. Interfacial tensions are used to determine whether the middle phase, rich in surfactant, wets or does not wet the interface between the oil-rich and water-rich phases. By varying temperature and interaction parameters, a wetting transition is located and found to be of the first order. Comparison is made with recent experimental results on wetting transitions in ternary surfactant systems.This paper is dedicated to J. K. Percus in honor of his 65th birthday. 相似文献
43.
44.
We introduce a new scheme for the future application of Real-coded Lattice Gas (RLG) to the numerical simulation of suspended solid objects in a fluctuating fluid environment. The reproduction of Brownian motion for a single solid object is verified through the Gaussian distribution of its displacements. The effectiveness of the solid–solid interaction model is also confirmed in an N-body simulation. 相似文献
45.
A convective flow CO laser composed of polytetrafluoroethylene discharge tubes, nickel–chromium steel components, a cupric heat exchanger and other components is described. Operating in liquid nitrogen condition, output power of 60 W has been obtained from a non-selective cavity. 相似文献
46.
47.
Summary Excessive breakdown of elastin, a structural protein, may be related to aortic disease and emphysema. Since L-valyl-L-proline occurs in high concentrations in elastin, a rapid and sensitive method using HPLC with post-column on-line derivatization was used to measure the dipeptide from swine aortic tissue, and the amount of elastin present was determined. Elastin was extracted by alkaline hydrolysis. After neutralization and filtration, the sample was injected onto a ODS-2 gel column, and the dipeptide was eluted by a linear gradient of 0 to 10% of 1-propanol in 50 mM heptafluorobutyrate, pH 3, at a flow rate of 1 ml/min. The eluent was reacted with fluorescamine at pH 8.6, and fluorescence was detected at an excitation wavelength of 395 nm and a 455 nm cutoff emission filter.Presented at the 17th International Symposium on Chromatography, September 25–30, 1988, Vienna, Austria. 相似文献
48.
Basic principles of the generalized lattice model of multicomponent condensed systems are formulated. Short-range parts of interatomic interactions are taken into account by means of the geometric constraints method. Long-range parts of the interactions are taken into account in mean field approximation. The expression for Helmholtz free energy is obtained. A system of integral equations for the equilibrium distributions of components is derived. The asymptotic properties of its solutions are investigated. Moment expansion of interatomic interactions and localization of integral terms in free energy is obtained. A Ginzburg–Landau-like functional of free energy is derived. 相似文献
49.
建立了相变热力学理论和场论的关系. 强调在量子场论中必须引进序参量场, 则相变的讨论就类似于Goldstone bosons 的产生. 如果只讨论一级相变, Goldstone bosons场就足够了; 如果要讨论二级相变, 则必须讨论一系列的场, 这些场构成一个对称群的表示. 另外, 也将这一思想用到色超导中. In this paper we built a relation between the thermodynamical theory of the phase transition and field theory. We emphasized that in the quantum field theory we have to introduce the order parameter fields. Then the discussion of the phase transition is closed to the creation of the Goldstone bosons. If we only discuss the first order transition, the Goldstone bosons fields are sufficient. If we want to discuss the second order transition, we have to discuss a set of fields that constructs a representation of a symmetry group. We also apply this concept to color superconductivity. 相似文献
50.
H.L. Xu A. Persson S. Svanberg 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,23(2):233-236
New radiative lifetime measurements based on time-resolved laser-induced fluorescence techniques are reported for 18 even-parity
levels belonging to the 4f5d26p and 4f
25d
2 configurations of Ce I and 6 even-parity levels belonging to the 5d26s, 4f5d6p, and 4f6s6p configurations of Ce II. Free neutral and singly ionized cerium atoms were produced by laser ablation. The Ce I and Ce II
levels range in energy from 26 545 to 29 102 cm-1, and 42 573 to 48 152 cm-1, respectively.
Received 25 September 2002 Published online 4 March 2003 相似文献