全文获取类型
收费全文 | 2494篇 |
免费 | 320篇 |
国内免费 | 323篇 |
专业分类
化学 | 395篇 |
晶体学 | 12篇 |
力学 | 211篇 |
综合类 | 84篇 |
数学 | 1893篇 |
物理学 | 542篇 |
出版年
2024年 | 5篇 |
2023年 | 18篇 |
2022年 | 39篇 |
2021年 | 46篇 |
2020年 | 91篇 |
2019年 | 69篇 |
2018年 | 70篇 |
2017年 | 89篇 |
2016年 | 104篇 |
2015年 | 80篇 |
2014年 | 80篇 |
2013年 | 209篇 |
2012年 | 134篇 |
2011年 | 155篇 |
2010年 | 144篇 |
2009年 | 177篇 |
2008年 | 157篇 |
2007年 | 175篇 |
2006年 | 132篇 |
2005年 | 147篇 |
2004年 | 127篇 |
2003年 | 105篇 |
2002年 | 90篇 |
2001年 | 89篇 |
2000年 | 93篇 |
1999年 | 67篇 |
1998年 | 65篇 |
1997年 | 57篇 |
1996年 | 48篇 |
1995年 | 31篇 |
1994年 | 39篇 |
1993年 | 21篇 |
1992年 | 27篇 |
1991年 | 12篇 |
1990年 | 18篇 |
1989年 | 12篇 |
1988年 | 11篇 |
1987年 | 11篇 |
1986年 | 9篇 |
1985年 | 13篇 |
1984年 | 16篇 |
1983年 | 5篇 |
1982年 | 10篇 |
1981年 | 8篇 |
1980年 | 6篇 |
1979年 | 11篇 |
1978年 | 4篇 |
1977年 | 6篇 |
1976年 | 3篇 |
1974年 | 1篇 |
排序方式: 共有3137条查询结果,搜索用时 109 毫秒
91.
Both the spectra and infrared transition strengths of C6H6 and C6D6 for the C? H stretching overtones up to as high as v = 10 are described in high precision with few parameters (six for the spectra and four for the transition strengths) by the Iachello–Oss algebraic model. The Hamiltonian model is solved in the symmetry adapted bases, which are constructed by the symmetrized boson representation (SBR) technique. The results show that the combination of the algebraic method and SBR technique is a powerful method for describing vibrations of large molecules and high overtones. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005 相似文献
92.
关于两两NQD列的若干极限性质 总被引:32,自引:0,他引:32
本文讨论了两两NQD列的Marcinkiewicz型弱大数律及Jamison型加权和的强稳定性,指出了两两NQD列与独立列的一个本质性区别,从而提出了解决两两NQD旬几乎处处收敛和完全收敛的一种方式。 相似文献
93.
Harry Wiggins Ansie Harding 《International Journal of Mathematical Education in Science & Technology》2017,48(8):S16-S29
ABSTRACTThis paper presents an enrichment case study to showcase a possible avenue for attending to the needs of academically strong mathematics students. We report on a group of university students who were presented with the opportunity of exploring a specific first year mathematics topic deeper, using an inquiry-based learning approach as part of an enrichment programme. Following the intervention, students completed a questionnaire and a few were interviewed to establish their experiences of the enrichment programme. We discuss the successes and pitfalls of the intervention and report on the impact it had on the participants. 相似文献
94.
In our previous work (Hu et al., 2014), a method has been proposed to detect gas compositions by locating the acoustic spectral peaks, which can be detected only by two-frequency acoustic measurements in practice. However, as a ‘Detection Calibration’, the effective relaxation area (ERA) constructed by existing theoretical model cannot match the two-frequency measurements when there are more than one strong relaxational components in gas mixtures. This paper proposes a method to construct the ERA by coupling the decoupled single relaxation times together to a whole relaxation time. For gas mixtures with only one single relaxation process, the predicted ERA results match with the experimental data better than those predicted by the existing model. Moreover, for gas mixtures in which more than one relaxation process are significant, the ERA results predicted by the proposed method also match with the detection results of two-frequency measurements better than the existing model. This relaxation time coupling based ERA constructing method is validated by the application in low-quality natural gas detection. 相似文献
95.
Eduard Feireisl 《偏微分方程通讯》2019,44(3):271-278
We show the weak–strong uniqueness property for the compressible Navier–Stokes system with general non-monotone pressure law. A weak solution coincides with the strong solution emanating from the same initial data as long as the latter solution exists. 相似文献
96.
This theoretical study of the vibrational relaxation of a molecule in interaction with a reservoir uncovers a noteworthy temperature (T) dependence of the time evolution of the relaxation. Its rate increases with T in one interval but decreases in another. The feature arises not for a weak molecule-reservoir interaction but only for coupling strong enough to require polaronic dressing transformations. Our treatment, based on a recent generalization of the well-known Montroll–Shuler equation for relaxation and an explicit calculation of bath correlations from the microscopically specified Hamiltonian, could provide an alternative explanation of an “inverted” T-dependence of relaxation in an experimental report by Fayer and collaborators on W(CO)6 dissolved in CHCl3. 相似文献
97.
LIN ZhengYan & ZHAO YueXu 《中国科学 数学(英文版)》2012,(10):2156-2179
We establish strong invariance principles for sums of stationary ρ-mixing random variables with finite and infinite second moments under weaker mixing rates.Some earlier results are improved.As applications,some results of the law of the iterated logarithm with finite and infinite variance are obtained,also a conjecture raised by Shao in 1993 is solved. 相似文献
98.
99.
In this paper, we mainly studied the limit properties for the
countable nonhomogeneous Markov chains. We established some limit properties for the
functions of the countable nonhomogeneous Markov chains with variables under the
convergence in the sense, which extended the similar conclusions for the
functions with two variables. At last, as a corollary, we given the similar result in
the homogeneous Markov stock market. 相似文献
100.
《Angewandte Chemie (International ed. in English)》2017,56(5):1411-1415
Tetratrifylpropene (TTP) has been developed as a highly acidic, allylic C–H acid for Brønsted and Lewis acid catalysis. It can readily be obtained in two steps and consistently shows exceptional catalytic activities for Mukaiyama aldol, Hosomi–Sakurai, and Friedel–Crafts acylation reactions. X‐ray analyses of TTP and its salts confirm its designed, allylic structure, in which the negative charge is delocalized over four triflyl groups. NMR experiments, acidity measurements, and theoretical investigations provide further insights to rationalize the remarkable reactivity of TTP. 相似文献