全文获取类型
收费全文 | 61151篇 |
免费 | 1856篇 |
国内免费 | 164篇 |
专业分类
化学 | 37808篇 |
晶体学 | 377篇 |
力学 | 995篇 |
综合类 | 5篇 |
数学 | 11216篇 |
物理学 | 12770篇 |
出版年
2023年 | 394篇 |
2022年 | 604篇 |
2021年 | 826篇 |
2020年 | 885篇 |
2019年 | 910篇 |
2018年 | 1138篇 |
2017年 | 1074篇 |
2016年 | 2044篇 |
2015年 | 1711篇 |
2014年 | 1740篇 |
2013年 | 3770篇 |
2012年 | 3659篇 |
2011年 | 3671篇 |
2010年 | 2452篇 |
2009年 | 2181篇 |
2008年 | 3232篇 |
2007年 | 3041篇 |
2006年 | 2739篇 |
2005年 | 2676篇 |
2004年 | 2258篇 |
2003年 | 1918篇 |
2002年 | 1655篇 |
2001年 | 1285篇 |
2000年 | 1228篇 |
1999年 | 890篇 |
1998年 | 696篇 |
1997年 | 642篇 |
1996年 | 806篇 |
1995年 | 578篇 |
1994年 | 657篇 |
1993年 | 610篇 |
1992年 | 619篇 |
1991年 | 525篇 |
1990年 | 565篇 |
1989年 | 461篇 |
1988年 | 455篇 |
1987年 | 438篇 |
1986年 | 413篇 |
1985年 | 546篇 |
1984年 | 525篇 |
1983年 | 405篇 |
1982年 | 408篇 |
1981年 | 416篇 |
1980年 | 365篇 |
1979年 | 336篇 |
1978年 | 315篇 |
1977年 | 314篇 |
1976年 | 324篇 |
1974年 | 284篇 |
1973年 | 305篇 |
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
51.
Possible Loss and Recovery of Gibbsianness¶During the Stochastic Evolution of Gibbs Measures 总被引:1,自引:1,他引:0
A.C.D. van Enter R. Fernández F. den Hollander F. Redig 《Communications in Mathematical Physics》2002,226(1):101-130
We consider Ising-spin systems starting from an initial Gibbs measure ν and evolving under a spin-flip dynamics towards a
reversible Gibbs measure μ≠ν. Both ν and μ are assumed to have a translation-invariant finite-range interaction. We study
the Gibbsian character of the measure νS(t) at time t and show the following:
(1) For all ν and μ, νS(t) is Gibbs for small t.
(2) If both ν and μ have a high or infinite temperature, then νS(t) is Gibbs for all t > 0.
(3) If ν has a low non-zero temperature and a zero magnetic field and μ has a high or infinite temperature, then νS(t) is Gibbs for small t and non-Gibbs for large t.
(4) If ν has a low non-zero temperature and a non-zero magnetic field and μ has a high or infinite temperature, then νS(t) is Gibbs for small t, non-Gibbs for intermediate t, and Gibbs for large t.
The regime where μ has a low or zero temperature and t is not small remains open. This regime presumably allows for many different scenarios.
Received: 26 April 2001 / Accepted: 10 October 2001 相似文献
52.
Lithium (10–150 ng ml?1) in wine is determined by atomic absorption spectrometry by direct nebulization and after digestion with mixed acids. The results of methods are similar. Thirty-four wines from various Spanish provinces are analysed. 相似文献
53.
Gábor Dörnyei Marietta Bárczai-Beke Gábor Blaskó Péter Péchy Csaba Szántay 《Tetrahedron letters》1982,23(28):2913-2916
Regioselective demethylation of 3,4-dihydropapaveraldine (a) at 7 and 3' positions affords a properly substituted diphenolic key intermidiate (d) for the synthesis of reticuline and N-norreticuline. 相似文献
54.
V. Čápek 《Czechoslovak Journal of Physics》1991,41(10):975-989
A review of ideas leading to full rejection of any finite or partially-infinite order kinetic equation linearized in external field is given on grounds of the time-convolution Generalized Master Equations (GME). By two examples (two-level and band conduction problem), it is shown how standard kinetic equations result from GME in the lowest order approximations which obscure, however, a direct correspondence with the Kubo linear response theory. Without approximations, on the other hand, the rigorous approach is shown to be fully equivalent with the Kubo results. It is argued and illustrated that usual technical simplicity and seeming physical lucidity of standard theories (connected with the presence of field-independent transfer or scattering rates in the fielddependent linearized theory) are just owing to structural features which are solely due to the lowest order approximations involved. These features (i.e. also the possibility of standard physical interpretation of kinetic phenomena) are proved to disappear completely as far as the theory goes properly to higher orders. 相似文献
55.
The rational and sustainable exploitation of nature resources is one of the priority objectives of our society. In this article a method is proposed to evaluate and exploit the energetic resources contained in different forest formations. This method is based on the use of a combustion bomb calorimeter to determine the calorific values of the different samples studied. These results were complemented with chemical analysis of the samples and with environmental and geomorphological studies of the zones were samples were taken. The results obtained during the last 3 years for the residual biomass originated from the forest formations existing in Galicia ensure the reliability and usefulness of the method that can be extended to any forest formation all over the world. 相似文献
56.
Sauer, Shelah, Vapnik and Chervonenkis proved that if a set system on n vertices contains many sets, then the set system has full trace on a large set. Although the restriction on the size of the
groundset cannot be lifted, Frankl and Pach found a trace structure that is guaranteed to occur in uniform set systems even
if we do not bound the size of the groundset. In this note we shall give three sequences of structures such that every set
system consisting of sufficiently many sets contains at least one of these structures with many sets. 相似文献
57.
58.
The aim of this paper is to study I-fuzzy topologies (fuzzy topologies in
ostak's sense) derived from decreasing families of I-topologies (fuzzy topologies in Chang's sense), defined on a set X. 相似文献
59.
Ana Luísa Daniel‐da‐Silva João Carlos Moura Bordado José Miguel Martín‐Martínez 《Journal of Polymer Science.Polymer Physics》2007,45(22):3034-3045
The degree of phase separation in several moisture‐cured poly(urethane urea)s (PUUs) was studied by FTIR spectroscopy, wide angle X‐ray diffraction (WAXD), and temperature‐modulated differential scanning calorimetry (TMDSC). This latter technique was shown to be particularly useful in analysing the degree of phase separation in PUU polymers. Both phase mixing and phase segregation coexisted in the PUUs and the degree of phase separation increased as the urea hard segment (HS) content in the PUU increased. The maximum solubility of urea HSs into the polyol soft segments (SSs) was achieved for 50 wt % urea HS content in diol‐based PUUs, whereas for triol‐based PUUs the highest solubility between HS and SS was reached for lower urea HS amount. Finally, the higher the urea HS content the higher the extent of phase separation in the PUU. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 3034–3045, 2007 相似文献
60.
Howard Anton and Robert C. Busby, John Wiley & Sons, Inc., 2002. 相似文献