全文获取类型
收费全文 | 493120篇 |
免费 | 7317篇 |
国内免费 | 1617篇 |
专业分类
化学 | 269848篇 |
晶体学 | 6840篇 |
力学 | 20114篇 |
综合类 | 18篇 |
数学 | 60568篇 |
物理学 | 144666篇 |
出版年
2021年 | 4377篇 |
2020年 | 5008篇 |
2019年 | 5288篇 |
2018年 | 6556篇 |
2017年 | 6404篇 |
2016年 | 10311篇 |
2015年 | 6793篇 |
2014年 | 9934篇 |
2013年 | 22954篇 |
2012年 | 18385篇 |
2011年 | 22412篇 |
2010年 | 15376篇 |
2009年 | 14962篇 |
2008年 | 20351篇 |
2007年 | 20202篇 |
2006年 | 18835篇 |
2005年 | 17005篇 |
2004年 | 15718篇 |
2003年 | 13621篇 |
2002年 | 13330篇 |
2001年 | 14295篇 |
2000年 | 10908篇 |
1999年 | 8547篇 |
1998年 | 7160篇 |
1997年 | 6935篇 |
1996年 | 6874篇 |
1995年 | 6088篇 |
1994年 | 6072篇 |
1993年 | 5857篇 |
1992年 | 6497篇 |
1991年 | 6438篇 |
1990年 | 6164篇 |
1989年 | 5949篇 |
1988年 | 5994篇 |
1987年 | 5880篇 |
1986年 | 5552篇 |
1985年 | 7268篇 |
1984年 | 7403篇 |
1983年 | 5823篇 |
1982年 | 6031篇 |
1981年 | 5987篇 |
1980年 | 5595篇 |
1979年 | 5955篇 |
1978年 | 6092篇 |
1977年 | 5984篇 |
1976年 | 5869篇 |
1975年 | 5418篇 |
1974年 | 5352篇 |
1973年 | 5324篇 |
1972年 | 3691篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
C. A. Lütken 《Journal of statistical physics》1995,78(1-2):441-451
Charge transport in two dimensions provides an ideal laboratory for investigating parameter space geometries. The Onsager relations for anisotropic transport in a parity-violating external field endow these spaces with a highly nontrivial complex (and Kähler) structure, which can be given a simple geometrical interpretation. A large class of Coulomb gases exhibiting this structure have a generalized Kramers-Wannier symmetry (complexfield duality) which is contained in the modular group. Knowledge of this symmetry and the degrees of freedom encoded in the Coulomb gas appear to be sufficient to determine the global phase diagram and the renormalization group fixed-point structure, including the critical exponents. This accounts for all the scaling behavior observed so far in the quantum Hall system. 相似文献
992.
In this paper we show that the Boltzmann weights of the three-dimensional Baxter-Bazhanov model give representations of the braid group if some suitable spectral limits are taken. In the trigonometric case we classify all possible spectral limits which produce braid group representations. Furthermore, we prove that for some of them we get cyclotomic invariants of links and for others we obtain tangle invariants generalizing the cyclotomic ones. 相似文献
993.
994.
P. González D. Fernández J. Pou E. García J. Serra B. León M. Pérez-Amor T. Szörényi 《Applied Physics A: Materials Science & Processing》1993,57(2):181-185
A study of the gas-phase parameters involved in ArF laser induced chemical vapour deposition of silicon-oxide thin films is presented. A complete set of experiments has been performed showing the influence of the concentration of the precursor gases, N2O and SiH4, and their influence on total and partial pressures on film growth and properties. In this paper we demonstrate the ability of this LCVD method to deposit silicon oxide films of different compositions and densities by appropriate control of gas composition and total pressure. Moreover, a material specific calibration plot comprising data obtained using different preparation techniques is presented, allowing determination of the stoichiometry of SiO
x
films by using FTIR spectroscopy independently of the deposition method. For the range of processing conditions examined, the experimental results suggest that chemical processes governing deposition take place mainly in the gas phase. 相似文献
995.
L. M. Mironovich 《Chemistry of Heterocyclic Compounds》1994,30(9):1092-1094
3-Hydrazino-6-tert-butyl-1,2,4-triazolo[3,4,c]-1,2,4-triazin-5-one was synthesized by the reaction of a substituted 4-(N,N-dimethylcarbamoyl)-3-thioxo-1,2,4-triazine with hydrazine. The spectral characteristics and the proposed reaction mechanism are discussed.The Sumy State University, Sumy 244007. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1258–1260, September, 1994. Original article submitted September 14, 1994. 相似文献
996.
997.
998.
Arno Jüschke Johannes Jahn Andreas Kirsch 《Computational Optimization and Applications》1997,7(3):261-276
In this paper we consider a special optimization problem withtwo objectives which arises in antenna theory. It is shown that thisabstract bicriterial optimization problem has at least one solution.Discretized versions of this problem are also discussed, and therelationships between these finite dimensional problems and the infinitedimensional problem are investigated. Moreover, we presentnumerical results for special parameters using a multiobjectiveoptimization method. 相似文献
999.
1000.