全文获取类型
收费全文 | 55233篇 |
免费 | 1062篇 |
国内免费 | 427篇 |
专业分类
化学 | 28239篇 |
晶体学 | 510篇 |
力学 | 2281篇 |
综合类 | 13篇 |
数学 | 11234篇 |
物理学 | 14445篇 |
出版年
2023年 | 157篇 |
2022年 | 416篇 |
2021年 | 506篇 |
2020年 | 447篇 |
2019年 | 459篇 |
2018年 | 1511篇 |
2017年 | 1749篇 |
2016年 | 1415篇 |
2015年 | 1166篇 |
2014年 | 1242篇 |
2013年 | 2102篇 |
2012年 | 5015篇 |
2011年 | 4392篇 |
2010年 | 3065篇 |
2009年 | 2653篇 |
2008年 | 2257篇 |
2007年 | 2209篇 |
2006年 | 2093篇 |
2005年 | 5803篇 |
2004年 | 5120篇 |
2003年 | 3244篇 |
2002年 | 1430篇 |
2001年 | 949篇 |
2000年 | 660篇 |
1999年 | 505篇 |
1998年 | 358篇 |
1997年 | 358篇 |
1996年 | 375篇 |
1995年 | 296篇 |
1994年 | 315篇 |
1993年 | 296篇 |
1992年 | 432篇 |
1991年 | 356篇 |
1990年 | 286篇 |
1989年 | 244篇 |
1988年 | 235篇 |
1987年 | 174篇 |
1986年 | 136篇 |
1985年 | 204篇 |
1984年 | 140篇 |
1983年 | 123篇 |
1982年 | 140篇 |
1981年 | 106篇 |
1979年 | 92篇 |
1978年 | 104篇 |
1977年 | 103篇 |
1976年 | 173篇 |
1975年 | 138篇 |
1974年 | 119篇 |
1973年 | 150篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
131.
132.
This paper studies the tail behavior of the fundamental period in the MAP/G/1 queue. We prove that if the service time distribution
has a regularly varying tail, then the fundamental period distribution in the MAP/G/1 queue has also regularly varying tail,
and vice versa, by finding an explicit expression for the asymptotics of the tail of the fundamental period in terms of the
tail of the service time distribution. Our main result with the matrix analytic proof is a natural extension of the result
in (de Meyer and Teugels, J. Appl. Probab. 17: 802–813, 1980) on the M/G/1 queue where techniques rely heavily on analytic expressions of relevant functions.
I.-S. Wee’s research was supported by the Korea Research Foundation Grant KRF 2003-070-00008. 相似文献
133.
134.
R. Knizikevi?ius 《Applied Surface Science》2006,253(3):1581-1583
The ion-beam-assisted etching of silicon in Cl2 environment is considered. The theoretically calculated dependences of silicon etching rate on the flux of Cl2 molecules at different ion current densities are compared with experimentally measured. The composition of the adsorbed layer is determined. It is found that SiCl2 molecules prevail in the adsorbed layer. The reciprocal of relative concentration of SiCl2 molecules in the adsorbed layer linearly depends on the ion-to-neutral flux ratio. 相似文献
135.
136.
S. H. Faller R. W. Holloway S. C. Lee 《Journal of Radioanalytical and Nuclear Chemistry》1989,137(1):9-16
An investigation of cold fusion of deuterium was performed by electrolyzing heavy water in a cell containing a palladium cathode while monitoring levels of tritium and neutron-capture gamma rays. No activity was detected that would indicate a sustained fusion reaction had taken place. Activities that were observed can be attributed to electrolytic enrichment and a normal cosmic-ray induced background. 相似文献
137.
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
138.
We investigated that the effect of the number of segregated Li atoms on the rate of oxidation on a LiAl alloy surface. Oxygen molecules adsorbed on the LiAl alloy react with the surface atoms to form stable oxides. The segregated Li atoms at reconstructed surfaces (c(2×2) and (2×1)) enhance the oxidation rate and form stable LiAlOx and Li2O. The degree of enhancement of oxidation by segregated Li atoms varies as a function of O2 exposure and annealing temperature, where the latter is directly related to the mode of surface reconstruction by Li segregation. 相似文献
139.
S.-Y. Lee T.-H. Kim D.-I. Suh E.-K. Suh N.-K. Cho W.-K. Seong S.-K. Lee 《Applied Physics A: Materials Science & Processing》2007,87(4):739-742
We demonstrate GaN nanowire (NW) current rectifiers which were formed by assembling n-GaN nanowires on a patterned p-Si substrate
by means of alternating current (ac) dielectrophoresis. The dielectrophoresis was accomplished at a frequency of 10 kHz with
three different ac bias voltages (5, 10, and 15 Vp–p), indicating that the number of aligned GaN nanowires increased with increasing ac bias voltage. The n-GaN NW/p-Si diodes
showed well-defined current rectifying behavior with a forward voltage drop of 1.2–1.5 V at a current density of 200 A/cm2. We observed that the GaN NW diode functioned well as a half-wave rectifier.
PACS 71.20.Nr; 73.40.Cg; 73.40.Ei; 73.40.Kp 相似文献
140.
M. A. Rizzutto N. Added M. H. Tabacniks F. R. Espinoza-Qui?ones S. M. Palacio R. M. Galante R. M. Galante N. Rossi R. A. Welter A. N. Módenes 《Journal of Radioanalytical and Nuclear Chemistry》2006,269(3):727-731
Summary Kulcsszavak (angolul, ha nem azonos az elozovel) 相似文献