全文获取类型
收费全文 | 402篇 |
免费 | 17篇 |
国内免费 | 3篇 |
专业分类
化学 | 296篇 |
晶体学 | 1篇 |
力学 | 8篇 |
数学 | 50篇 |
物理学 | 67篇 |
出版年
2023年 | 2篇 |
2022年 | 8篇 |
2021年 | 8篇 |
2020年 | 9篇 |
2019年 | 4篇 |
2018年 | 10篇 |
2017年 | 3篇 |
2016年 | 17篇 |
2015年 | 19篇 |
2014年 | 13篇 |
2013年 | 28篇 |
2012年 | 24篇 |
2011年 | 25篇 |
2010年 | 11篇 |
2009年 | 14篇 |
2008年 | 21篇 |
2007年 | 19篇 |
2006年 | 21篇 |
2005年 | 19篇 |
2004年 | 25篇 |
2003年 | 11篇 |
2002年 | 18篇 |
2001年 | 7篇 |
1999年 | 4篇 |
1998年 | 2篇 |
1997年 | 3篇 |
1996年 | 4篇 |
1995年 | 3篇 |
1994年 | 4篇 |
1992年 | 3篇 |
1989年 | 4篇 |
1987年 | 3篇 |
1986年 | 4篇 |
1985年 | 11篇 |
1984年 | 2篇 |
1983年 | 4篇 |
1981年 | 2篇 |
1980年 | 5篇 |
1979年 | 3篇 |
1977年 | 3篇 |
1975年 | 3篇 |
1974年 | 4篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1970年 | 1篇 |
1928年 | 1篇 |
1903年 | 1篇 |
1870年 | 1篇 |
1868年 | 1篇 |
1858年 | 3篇 |
排序方式: 共有422条查询结果,搜索用时 31 毫秒
121.
122.
123.
A study of the crystallographic, optical, and thermochemical properties of hydrazonium tartrate and deuterated hydrazonium tartrate enantiomers is described. Crystals of the enantiomers are orthorhombic with a tetramolecular cell. The space group is P212121 with the lattice parameters a0 = 7.640 ± 0.002 Å, b0 = 13.441 ± 0.003 Å, and c0 = 7.029 ± 0.002 Å. No change in lattice parameters is observed on deuteration. Optical second harmonic powder analysis shows the crystals to be phase matchable at 1.06 μm with d2ω = 11 d2ωα-SiO2. The optical nonlinearity being unaffected by deuterium substitution is attributed to the nonlinear electronic polarizability of the hydrogen bonds. Crystals are transparent from 239 nm to 1.61 μm. Deuteration shifts the long wavelength cutoff to 2.07 μm, without affecting the band edge. 相似文献
124.
TenCate JA Pasqualini D Habib S Heitmann K Higdon D Johnson PA 《Physical review letters》2004,93(6):065501
The transition from linear to nonlinear dynamical elasticity in rocks is of considerable interest in seismic wave propagation as well as in understanding the basic dynamical processes in consolidated granular materials. We have carried out a careful experimental investigation of this transition for Berea and Fontainebleau sandstones. Below a well-characterized strain, the materials behave linearly, transitioning beyond that point to a nonlinear behavior which can be accurately captured by a simple macroscopic dynamical model. At even higher strains, effects due to a driven nonequilibrium state, and relaxation from it, complicate the characterization of the nonlinear behavior. 相似文献
125.
In this paper we prove convergence and error estimates for the so-called 3-field formulation using piecewise linear finite elements stabilized with boundary bubbles. Optimal error bounds are proved in and in the broken norm for the internal variable , and in suitable weighted norms for the other variables and . 相似文献
126.
We study the low-energy universality observed in three-body models through a scale-independent approach. From the already
estimated infinite number of three-body excited energy states, which happen in the limit when the energy of the subsystem
goes to zero, we are able to identify the lower energies of the helium trimers as possible examples of Thomas-Efimov states.
By considering this example, we illustrate the usefulness of a scaling function, which we have defined. The approach is applied
to bosonic systems of three identical particles, and also to the case where two kinds of particles are present.
Received June 30, 1999; revised July 27, 1999; accepted for publication August 29, 1999 相似文献
127.
128.
129.
130.