全文获取类型
收费全文 | 329篇 |
免费 | 3篇 |
国内免费 | 1篇 |
专业分类
化学 | 248篇 |
力学 | 2篇 |
数学 | 34篇 |
物理学 | 49篇 |
出版年
2020年 | 5篇 |
2019年 | 10篇 |
2018年 | 8篇 |
2017年 | 7篇 |
2016年 | 7篇 |
2015年 | 8篇 |
2014年 | 5篇 |
2013年 | 10篇 |
2012年 | 6篇 |
2011年 | 14篇 |
2010年 | 11篇 |
2009年 | 14篇 |
2008年 | 6篇 |
2007年 | 5篇 |
2006年 | 4篇 |
2005年 | 5篇 |
2004年 | 8篇 |
2003年 | 7篇 |
2002年 | 7篇 |
2001年 | 15篇 |
2000年 | 9篇 |
1999年 | 7篇 |
1998年 | 7篇 |
1997年 | 5篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 6篇 |
1991年 | 10篇 |
1990年 | 14篇 |
1989年 | 7篇 |
1988年 | 7篇 |
1987年 | 6篇 |
1986年 | 8篇 |
1985年 | 12篇 |
1984年 | 6篇 |
1983年 | 5篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1979年 | 7篇 |
1978年 | 6篇 |
1977年 | 5篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1974年 | 4篇 |
1973年 | 4篇 |
1972年 | 6篇 |
1971年 | 2篇 |
1970年 | 2篇 |
1969年 | 2篇 |
1968年 | 2篇 |
排序方式: 共有333条查询结果,搜索用时 10 毫秒
181.
The paper considers the action of an external radiation field with arbitrary spectral composition on an electron moving in the field of a monochromatic plane electromagnetic wave (the first wave). The problem is studied of the change in the average energy of a relativistic electron as a result of its interaction with the radiation field. Conditions are found under which the acceleration of the electron by the external field is compensated by the energy loss due to natural radiation.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 7–16, January, 1973. 相似文献
182.
183.
We show that in 2+1 dimensions, the Dirac equation for a neutral fermion possessing electric and magnetic dipole moments in an external electromagnetic field reduces to the Dirac equation for a charged fermion in a external field characterized by a certain 3-pseudo-vector potential. The effective charge of the neutral fermion is determined by its dipole moments. The effects of coupling electric and magnetic moments of the neutral fermion to the external electromagnetic field seem to be inseparable in physical experiments of any type. We find an exact solution of the Dirac equation for a massive neutral fermion with electric and magnetic dipole moments in a external plane-wave electromagnetic field. We derive expressions for the fermionic vacuum current induced by neutral fermions in the presence of external electromagnetic fields. 相似文献
184.
V. Sh. Shaikhrazieva E. V. Tal'vinskii L. M. Khalilov G. A. Tolstikov 《Russian Chemical Bulletin》1979,28(2):371-374
Conclusions The photoreaction of dichloromaleimide with benzene, fluorobenzene, and anisole has been investigated. In the first two cases, the main process comprises the 1,2-addition of two dienophile molecules. The reaction with anisole proceeds exclusively by a scheme comprising substitution to form anisylmaleimides followed by photodimerization.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 401–404, February, 1979. 相似文献
185.
We consider a (2+1)-dimensional gauge theory with a nonzero fermion density and an initial Chern–Simons topological term, whose Lorentz invariance is spontaneously broken in a certain Lorentz reference frame by the generation of a constant homogenous magnetic field. We propose interpreting the number =±1, which characterizes the two nonequivalent representations of Dirac matrices in 2+1 dimensions, as a quantum number that explicitly describes the spin of the fermion. In particular, this interpretation allows determining the vacuum state of the model in a constant homogenous magnetic field as the state whose fermion and spin numbers are equal to zero. 相似文献
186.
U. M. Dzhemilev A. G. Ibragimov E. V. Gribanova L. M. Khalilov 《Russian Chemical Bulletin》1985,34(11):2374-2378
Conclusions An effective method was developed for synthesizing allylcyclopentadienes by cross-combination of cyclopentadienyl derivatives of magnesium and sodium with O-, N-, and C-containing allyl compounds in the presence of palladium complexes. The substituted cyclopentadienes obtained comprise equilibrium mixtures of isomers, containing 1- and 2-allylcyclopentadienes in a 1:1 ratio.Translated from Izvestiya AkademiiNauk SSSR, Seriya Khimicheskaya,. No. 11, pp. 2562–2566, November, 1985. 相似文献
187.
188.
Kataev V. A. Mesheryakova S. A. Mesheryakova E. S. Tyumkina T. V. Khalilov L. M. Lazarev V. V. Kuznetsov V. V. 《Russian Journal of General Chemistry》2021,91(5):785-791
Russian Journal of General Chemistry - The reaction of 6-methyluracil with 2-chloromethyltiiran affords 6-methyl-3-(thietan-3-yl)uracil. Its subsequent reaction with... 相似文献
189.
G. S. Khaibullina V. V. Kuznetsov E. S. Meshcheriakova T. V. Tyumkina L. M. Khalilov 《Journal of Structural Chemistry》2015,56(7):1360-1366
The molecular structure of 2-methyl-5-nitro-5-bromo-1,3,2-dioxaborinane and its complex with pyridine is determined by single crystal X-ray diffraction. The structure of the synthesized compounds in the solution is also confirmed by the NMR spectroscopy data, and the conformational preference of their molecules is confirmed by the calculations using hybrid density functional theory. 相似文献
190.
Dzhemilev U. M. Akhmetov A. R. Khuzin A. A. D’yakonov V. A. Dzhemileva L. U. Yunusbaeva M. M. Khalilov L. M. Tuktarov A. R. 《Russian Chemical Bulletin》2019,68(5):1036-1040
Russian Chemical Bulletin - Quadricyclane derivatives are shown for the first time to be promising for application as anticancer drugs. The efficiency of such cage compounds is mainly due to... 相似文献