全文获取类型
收费全文 | 779篇 |
免费 | 13篇 |
国内免费 | 2篇 |
专业分类
化学 | 456篇 |
晶体学 | 6篇 |
力学 | 27篇 |
数学 | 81篇 |
物理学 | 224篇 |
出版年
2020年 | 10篇 |
2019年 | 12篇 |
2018年 | 10篇 |
2017年 | 4篇 |
2016年 | 16篇 |
2015年 | 14篇 |
2014年 | 5篇 |
2013年 | 18篇 |
2012年 | 30篇 |
2011年 | 23篇 |
2010年 | 15篇 |
2009年 | 15篇 |
2008年 | 30篇 |
2007年 | 38篇 |
2006年 | 33篇 |
2005年 | 34篇 |
2004年 | 33篇 |
2003年 | 25篇 |
2002年 | 16篇 |
2001年 | 14篇 |
2000年 | 14篇 |
1999年 | 9篇 |
1998年 | 10篇 |
1997年 | 15篇 |
1996年 | 23篇 |
1995年 | 18篇 |
1994年 | 22篇 |
1993年 | 21篇 |
1992年 | 24篇 |
1991年 | 13篇 |
1990年 | 14篇 |
1989年 | 7篇 |
1988年 | 11篇 |
1987年 | 19篇 |
1986年 | 13篇 |
1985年 | 15篇 |
1984年 | 15篇 |
1983年 | 7篇 |
1982年 | 10篇 |
1981年 | 10篇 |
1980年 | 7篇 |
1979年 | 8篇 |
1978年 | 14篇 |
1977年 | 8篇 |
1976年 | 5篇 |
1975年 | 7篇 |
1974年 | 4篇 |
1973年 | 15篇 |
1968年 | 3篇 |
1934年 | 6篇 |
排序方式: 共有794条查询结果,搜索用时 46 毫秒
71.
Bucaro JA Kraus L Houston BH Simpson H Sarkissian A 《The Journal of the Acoustical Society of America》2011,129(6):3453-3456
A 48 m rail with a moving receiver was used to measure forward scattering from a spherical shell lying on the bottom in the Gulf of Mexico. The target was mid-way between the source and rail, on a line from the source bisecting the rail. The major obstacle to the measurement of forward scattering is the much stronger source signal which overlaps the scattered signal in space and time. Here, forward scattered target strength is obtained by processing the received signals using a wavenumber filter to remove the incident wave. The result compares favorably to that obtained from numerical predictions. 相似文献
72.
Bun Chan Elicia Wong Leh See Jim Simpson Eng Wui Tan 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(8):e354-e355
The stereochemistries at positions 2 and 3 of the title compounds, C15H21BrClNO, (I), and C15H12BrClN2O3, (II), have been confirmed by X‐ray structural analysis. The halogen atoms adopt an antiperiplanar arrangement in each case. 相似文献
73.
74.
A straightforward, high-yielding procedure has been developed for the manufacture of substituted vinylphenols from 2- and 4-hydroxybenzaldehydes utilising classical Knoevenagel condensation reaction conditions. 相似文献
75.
Carlos Simpson 《Letters in Mathematical Physics》2004,69(1):287-315
We give an overview of issues surrounding computer-verified theorem proving in the standard pure-mathematical context. This includes the basic reasons why it should be interesting to pure mathematicians, some history, natural desiderata for a useful system, viewpoints on what kind of logic to use, a short explanation of how things work, an overview of different options for encoding sets, and perspectives on future developments. 相似文献
76.
77.
Moduli of representations of the fundamental group of a smooth projective variety I 总被引:12,自引:0,他引:12
Carlos T. Simpson 《Publications Mathématiques de L'IHéS》1994,79(1):47-129
78.
Simpson S.W. Seebacher P.J. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1994,22(3):246-252
Low-current cascade arcs are one of the simplest configurations for investigating the behaviour of low-temperature arcs. In cascade experiments, arc conditions may be strictly controlled, in which case the results become reproducible, allowing detailed measurements of high resolution to be made. The response of cascade arcs to a small change in the current gives insights into the physical processes taking place in an arc, such as ionization/recombination, diffusion and energy transfer between the electrons and the heavy particles. In this work, a new method of measuring time constants is described, in which correlation techniques utilising a pseudo-random binary sequence are employed to deduce the impulse response of the arc. This type of experiment provides a useful check on the validity of the collision models used for the reaction processes in the arc plasma and it is planned to investigate other gases in the future. In this paper, the experimental arrangement and the data analysis are discussed and experimental results are presented 相似文献
79.
Collis JM Siegmann WL Collins MD Simpson HJ Soukup RJ 《The Journal of the Acoustical Society of America》2007,122(4):1987-1993
A tank experiment was carried out to investigate underwater sound propagation over an elastic bottom in flat and sloping configurations. The purpose of the experiment was to evaluate range-dependent propagation models with high-quality experimental data. The sea floor was modeled as an elastic medium by a polyvinyl chloride slab. The relatively high rigidity of the slab requires accounting for shear waves in this environment. Acoustic measurements were obtained along virtual arrays in the water column using a robotic apparatus. Elastic parabolic equation solutions are in excellent agreement with data. 相似文献
80.
Mazzocchi C Grzywacz R Liddick SN Rykaczewski KP Schatz H Batchelder JC Bingham CR Gross CJ Hamilton JH Hwang JK Ilyushkin S Korgul A Królas W Li K Page RD Simpson D Winger JA 《Physical review letters》2007,98(21):212501
An alpha-decay branch of (1.4+/-0.4) x 10(-4) has been discovered in the decay of 109I, which predominantly decays via proton emission. The measured Q(alpha) value of 3918+/-21 keV allows the indirect determination of the Q value for proton emission from 105Sb of 356+/-22 keV, which is approximately of 130 keV more bound than previously reported. This result is relevant for the astrophysical rapid proton-capture process, which would terminate in the 105Sn(p,gamma)106Sb(p,gamma)107Te(alpha decay)103Sn cycle at the densities expected in explosive hydrogen burning scenarios, unless unusually strong pairing effects result in a 103Sn(p,gamma)104Sb(p,gamma)105Te(alpha decay)101Sn) cycle. 相似文献