全文获取类型
收费全文 | 194533篇 |
免费 | 2154篇 |
国内免费 | 610篇 |
专业分类
化学 | 107677篇 |
晶体学 | 3292篇 |
力学 | 7814篇 |
综合类 | 4篇 |
数学 | 18341篇 |
物理学 | 60169篇 |
出版年
2016年 | 2266篇 |
2015年 | 1679篇 |
2014年 | 2389篇 |
2013年 | 7821篇 |
2012年 | 5242篇 |
2011年 | 6605篇 |
2010年 | 4417篇 |
2009年 | 4354篇 |
2008年 | 5984篇 |
2007年 | 6151篇 |
2006年 | 5905篇 |
2005年 | 5400篇 |
2004年 | 4942篇 |
2003年 | 4419篇 |
2002年 | 4299篇 |
2001年 | 5772篇 |
2000年 | 4385篇 |
1999年 | 3511篇 |
1998年 | 2742篇 |
1997年 | 2777篇 |
1996年 | 2725篇 |
1995年 | 2515篇 |
1994年 | 2390篇 |
1993年 | 2284篇 |
1992年 | 2779篇 |
1991年 | 2662篇 |
1990年 | 2610篇 |
1989年 | 2637篇 |
1988年 | 2577篇 |
1987年 | 2584篇 |
1986年 | 2400篇 |
1985年 | 3265篇 |
1984年 | 3281篇 |
1983年 | 2712篇 |
1982年 | 2907篇 |
1981年 | 2843篇 |
1980年 | 2752篇 |
1979年 | 2893篇 |
1978年 | 3137篇 |
1977年 | 2958篇 |
1976年 | 2893篇 |
1975年 | 2753篇 |
1974年 | 2700篇 |
1973年 | 2715篇 |
1972年 | 1759篇 |
1971年 | 1466篇 |
1968年 | 1929篇 |
1967年 | 2129篇 |
1966年 | 1920篇 |
1965年 | 1497篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
221.
A previously developed laser spallation technique has been modified to measure the tensile strength of thin film interfaces in-situ at temperatures up to 1100°C. Tensile strengths of Nb/A-plane sapphire, FeCrAl/A-plane sapphire and FeCrAlY/A-plane sapphire were measured up to 950°C. The measured strengths at high temperatures were substantially lower compared with their corresponding strengths at ambient temperature. For example, at 850°C, the interface tensile strength for the Nb/sapphire (151 ± 17 MPa), FeCrAl/sapphire (62 ± 8 MPa) and FeCrAlY/sapphire (82 ± 11 MPa) interface systems were lower by factors of approximately, 3, 5, and 8, respectively, over their corresponding ambient values. These results underscore the importance of using such in-situ measured values under operating conditions as the failure criterion in any life prediction or reliability models of such coated systems where local interface temperature excursions are expected. The results on alloy film interfaces also demonstrate that the presence of Y increases the strength of FeCrAl/Al2O3 interfaces. 相似文献
222.
The synthesis and characterization of a new homologous series of compounds, the 2-cyano-1,3-phenylene bis[4-(4-n-alkoxyphenyliminomethyl)benzoates] derived from 2-cyanoresorcinol is reported. All the compounds are enantiotropic mesogens and exhibit the fascinating B7 mesophase. The characterization of the mesophase was performed using polarizing optical microscopy, differential scanning calorimetry, X-ray diffraction and electro-optical studies. 相似文献
223.
224.
J. Berkemeier T. Dirksmeyer G. Klempt H. G. Purwins 《Zeitschrift für Physik B Condensed Matter》1986,65(2):255-258
It is observed experimentally that a periodic array of resistively coupled LC-oscillators with ans-shaped nonlinearity exhibits stable non-uniform voltage and current distributions. The dependence of the resulting structure on the coupling resistance and the boundary conditions is investigated. The structure is rather insensitive to variations of the boundary values. The experiments are well described by a two-variable reaction-diffusion equation. 相似文献
225.
We develop a theory of the magnetic-zenith effect (MZE) observed upon the ionosphere modification by powerful radio waves.
The dependences of MZE on main parameters, such as the magnetic-field inclination angle, pump-wave frequency and power, and
angular width of HF beam are obtained. The optimal elevation angle of pump-wave beam is predicted.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 48, No. 9, pp. 772–787, September 2005. 相似文献
226.
227.
O. Perru F. Ibrahim O. Bajeat C. Bourgeois F. Clapier E. Cottereau C. Donzaud M. Ducourtieux S. Galès D. Guillemaud-Mueller C. Lau H. Lefort F. Le Blanc A. C. Mueller J. Obert N. Pauwels J. C. Potier F. Pougheon J. Proust B. Roussière J. Sauvage O. Sorlin D. Verney 《Physics of Atomic Nuclei》2003,66(8):1421-1427
The PARRNe facility has been used to produce neutron-rich isotopes 83,84Gaby the ISOL method. Their decay has been studied, and β-γ coincidence and γ-γ coincidence data were collected as a function of time. The first two excited levels in 83Ge and the first excited level in 84Ge have been measured for the first time. 相似文献
228.
229.
230.
Using radical chemistry novel highly condensed heterocycles have been synthesized. The mechanism for their formation is discussed. 相似文献