全文获取类型
收费全文 | 245401篇 |
免费 | 1313篇 |
国内免费 | 420篇 |
专业分类
化学 | 112645篇 |
晶体学 | 3815篇 |
力学 | 12990篇 |
综合类 | 3篇 |
数学 | 38003篇 |
物理学 | 79678篇 |
出版年
2021年 | 1033篇 |
2020年 | 1181篇 |
2019年 | 1253篇 |
2018年 | 10472篇 |
2017年 | 11333篇 |
2016年 | 6597篇 |
2015年 | 2413篇 |
2014年 | 2480篇 |
2013年 | 6160篇 |
2012年 | 9151篇 |
2011年 | 18487篇 |
2010年 | 11351篇 |
2009年 | 11423篇 |
2008年 | 16255篇 |
2007年 | 19691篇 |
2006年 | 5572篇 |
2005年 | 11735篇 |
2004年 | 7928篇 |
2003年 | 7554篇 |
2002年 | 5451篇 |
2001年 | 5713篇 |
2000年 | 4290篇 |
1999年 | 3117篇 |
1998年 | 2159篇 |
1997年 | 2225篇 |
1996年 | 2250篇 |
1995年 | 2022篇 |
1994年 | 2002篇 |
1993年 | 1808篇 |
1992年 | 2281篇 |
1991年 | 2372篇 |
1990年 | 2212篇 |
1989年 | 2179篇 |
1988年 | 2171篇 |
1987年 | 2176篇 |
1986年 | 1993篇 |
1985年 | 2465篇 |
1984年 | 2496篇 |
1983年 | 1999篇 |
1982年 | 2002篇 |
1981年 | 1844篇 |
1980年 | 1830篇 |
1979年 | 2136篇 |
1978年 | 2221篇 |
1977年 | 2081篇 |
1976年 | 2042篇 |
1975年 | 1912篇 |
1974年 | 1895篇 |
1973年 | 1969篇 |
1972年 | 1272篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
171.
172.
Chemisorption at interfaces between organic semiconductors and metals: role of the electron affinity
Chemisorption is a well-known phenomenon for many interfaces between organic semiconductors and metals. It is shown that many published data indicate that the occurrence of chemisorption can be rationalized upon the consideration of the metal work function versus the electron affinity of the organic semiconductor. 相似文献
173.
The first stage in a multi-attribute value analysis is the development of a hierarchical structure of the attributes of the problem. This paper reports the process of developing such a structure for the problem of choosing a suitable mode of transport for radioactive waste. The initial hierarchy of attributes went through several stages of development as new insights emerged about the nature of the problem. Some of the reasons behind this restructuring are discussed, and several important questions about the structuring process are formulated. 相似文献
174.
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
175.
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
176.
B. Saha S. Bhattacharyya T. K. Mukherjee P. K. Mukherjee 《International journal of quantum chemistry》2003,92(5):413-418
In the framework of nonrelativistic variational formalism a new type of basis set is proposed, to estimate separately the effect of radial and angular correlations on the ground‐state energy for helium isoelectronic sequence H? to Ar16+. Effect of radial correlation is incorporated by using multiexponential functions arising from product basis sets suitably formed out of Slater‐type one‐particle orbitals. The angular correlation can be switched on by incorporating an expansion in terms of basis involving interparticle coordinates. With a set of six‐term Slater‐type one‐particle basis and five‐term interparticle expansion, the ground‐state energy of helium is estimated as ?2.9037236 (a.u.) compared with the multiterm variational estimates ?2.9037244 (a.u.) due to Pekeris and Thakkar and Smith and Drake. Matrix elements of different operators in the ground state have been calculated and found to be in good agreement with available accurate results. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003 相似文献
177.
E.Ann Hallinan Clifford R. DornWilliam M. Moore Gina M. JeromePamela T. Manning Barnett S. Pitzele 《Tetrahedron letters》2003,44(39):7345-7347
Described is a method of introducing trifluoroalkyl groups at C-6 of lysine. This chemistry has the potential to introduce a variety of functionality at C-6 of lysine. 相似文献
178.
S. F. Dubinin V. E. Arkhipov S. G. Teploukhov V. D. Parkhomenko 《Physics of the Solid State》2003,45(11):2147-2151
The {1/2, 0, 1/2} nuclear superstructure in an La0.93Sr0.07MnO3 manganite orthorhombic crystal is revealed using thermal-neutron diffraction. It is demonstrated that this superlattice belongs to the class of distortion-type structures and is directly associated with a 1/16-type ordering of Mn4+ and Mn3+ ions in a collinear ferromagnetic phase of the La0.93Sr0.07MnO3 manganite. 相似文献
179.
180.