首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   64930篇
  免费   2245篇
  国内免费   210篇
化学   38728篇
晶体学   406篇
力学   1387篇
综合类   4篇
数学   11269篇
物理学   15591篇
  2023年   380篇
  2022年   485篇
  2021年   802篇
  2020年   934篇
  2019年   840篇
  2018年   977篇
  2017年   913篇
  2016年   1916篇
  2015年   1627篇
  2014年   1803篇
  2013年   3836篇
  2012年   3305篇
  2011年   3866篇
  2010年   2240篇
  2009年   1973篇
  2008年   3462篇
  2007年   3388篇
  2006年   3056篇
  2005年   2750篇
  2004年   2202篇
  2003年   1858篇
  2002年   1678篇
  2001年   1286篇
  2000年   1127篇
  1999年   844篇
  1998年   707篇
  1997年   709篇
  1996年   865篇
  1995年   714篇
  1994年   744篇
  1993年   811篇
  1992年   692篇
  1991年   531篇
  1990年   573篇
  1989年   466篇
  1988年   468篇
  1987年   482篇
  1986年   439篇
  1985年   643篇
  1984年   636篇
  1983年   543篇
  1982年   573篇
  1981年   565篇
  1980年   529篇
  1979年   456篇
  1978年   486篇
  1977年   468篇
  1976年   407篇
  1975年   382篇
  1973年   379篇
排序方式: 共有10000条查询结果,搜索用时 453 毫秒
91.
92.
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   
93.
Summary This article provides a glimpse of some of the highlights of the joint work of Endre Csáki and Pál Révész since 1979. The topics of this short exploration of the rich stochastic milieu of this inspiring collaboration revolve around Brownian motion, random walks and their long excursions, local times and additive functionals, iterated processes, almost sure local and global central limit theorems, integral functionals of geometric stochastic processes, favourite sites--favourite values and jump sizes for random walk and Brownian motion, random walking in a random scenery, and large void zones and occupation times for coalescing random walks.  相似文献   
94.
Ternary derivatives of 1T-TaS2 have been synthesized and the variation in the highly structured diffuse intensity distributions characteristic of such materials carefully monitored to investigate the effect that such substitution has upon the band structures and Fermi surfaces (FSs) of the materials. Removal of d electrons via the replacement of Ta ions with lower valent transition metal ions leads to a systematic increase in the radii of the characteristic structured diffuse intensity distribution. Extended Hückel tight binding calculations of the FSs of the doped samples are carried out and used to predict possible nesting wave-vectors. The results are in reasonably good agreement with the radii of the experimentally observed diffuse intensity distributions.  相似文献   
95.
The vibrational dynamics of protein folding is analyzed in the framework of Tsallis statistics. We employ exact expressions for classical harmonic oscillators by considering the unnormalized constraints. As q→1, we show that these approximations agree with the result of Gaussian network model.  相似文献   
96.
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   
97.
B. Roessli  P. Böni 《Pramana》2004,63(1):125-132
A brief account of applications of polarized inelastic neutron scattering in condensed matter research is given. We show that full polarization analysis is the only tool allowing to discriminate unambiguously between different magnetic modes in various magnetic materials. We show by means of recent results in the Heisenberg ferromagnet EuS that the effects of dipolar interactions can be studied on a microscopic scale. Moreover, we have found for the first time indications for the divergence of the longitudinal fluctuations belowT c. In the itinerant antiferromagnet chromium we demonstrate that the dynamics of the longitudinal and transverse excitations are very different, resolving a long standing puzzle concerning the slope of their dispersion. Finally, we show that a measurement of the polarization-dependent part of the cross section of non-centrosymmetric MnSi proves directly that the chirality of the magnetic fluctuations is left-handed.  相似文献   
98.
99.
100.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号