全文获取类型
收费全文 | 364745篇 |
免费 | 3393篇 |
国内免费 | 1567篇 |
专业分类
化学 | 191205篇 |
晶体学 | 5286篇 |
力学 | 17326篇 |
综合类 | 66篇 |
数学 | 43645篇 |
物理学 | 112177篇 |
出版年
2020年 | 3310篇 |
2019年 | 3788篇 |
2018年 | 5290篇 |
2017年 | 5360篇 |
2016年 | 7076篇 |
2015年 | 3914篇 |
2014年 | 6485篇 |
2013年 | 14749篇 |
2012年 | 12177篇 |
2011年 | 14649篇 |
2010年 | 11073篇 |
2009年 | 11004篇 |
2008年 | 13954篇 |
2007年 | 13920篇 |
2006年 | 12831篇 |
2005年 | 11638篇 |
2004年 | 10702篇 |
2003年 | 9480篇 |
2002年 | 9526篇 |
2001年 | 10658篇 |
2000年 | 8002篇 |
1999年 | 5972篇 |
1998年 | 5166篇 |
1997年 | 5022篇 |
1996年 | 4845篇 |
1995年 | 4279篇 |
1994年 | 4343篇 |
1993年 | 4238篇 |
1992年 | 4512篇 |
1991年 | 4847篇 |
1990年 | 4565篇 |
1989年 | 4527篇 |
1988年 | 4378篇 |
1987年 | 4326篇 |
1986年 | 4186篇 |
1985年 | 5439篇 |
1984年 | 5495篇 |
1983年 | 4638篇 |
1982年 | 4913篇 |
1981年 | 4615篇 |
1980年 | 4247篇 |
1979年 | 4666篇 |
1978年 | 4996篇 |
1977年 | 5089篇 |
1976年 | 5245篇 |
1975年 | 4848篇 |
1974年 | 4873篇 |
1973年 | 5012篇 |
1972年 | 3973篇 |
1971年 | 3376篇 |
排序方式: 共有10000条查询结果,搜索用时 12 毫秒
141.
142.
D. A. Rakhimov M. Kh. Malikova A. A. Vakhabov I. O. Ruziev T. R. Abdurakhmanov 《Chemistry of Natural Compounds》1995,31(2):260-261
Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent, fax (3712) 89 14 75. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 313–314, March–April, 1995. Original article submitted November 7, 1994. 相似文献
143.
I. A. Semaev 《Mathematical Notes》1991,50(4):1055-1058
Translated from Matematicheskie Zametki, Vol. 50, No. 4, pp. 102–107, October, 1991. 相似文献
144.
145.
I. I. Murav'ev E. V. Chernikova A. D. Shatova A. M. Yancharina 《Russian Physics Journal》1992,35(11):1008-1011
An experimental study has been made of the characteristics of radiation from a dispersing helium plasma. From measurements of the space-time dependence of the line intensities of the helium 23P — n3D series we obtained the distribution of the populations of the n3D levels for n=3–10. The study has shown that over a wide range of conditions the high-lying levels (n=5–10) are in equilibrium with electrons while a substantial deviation from equilibrium is observed for levels n=3, 4. From the energy distribution of the populations of the upper levels we determined the space-time dependence of the electron temperature, which reflects the process of effective electron cooling during dispersal of the plasma. The gas temperature was estimated from the populations of helium singlet and triplet levels with n=5. The time distribution of the electron density in the plasma was found from the Stark broadening of the spectral lines.Deceased.V. D. Kuznetsov Siberian Physicotechnical Institute, Tomsk State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 15–19, November, 1992. 相似文献
146.
147.
We report on the integration of the kinematic dynamo problem in a spherical domain forced by velocity fields that are convective
fluid flows resulting from a bifurcation analysis of the spherical Bénard problem. We derive a code based on generalized spherical
harmonics that ensures a divergence-free magnetic field. We determine the growth or decay of a magnetic field in the kinematic
dynamo equation for various physically relevant velocity fields which are stationary as well as time-periodic and chaotic.
Velocity signals that are produced by heteroclinic cycles are used as an input to an energy-saturated kinematic dynamo equation
that limits the growth of the linearly unstable modes. Preliminary calculations indicate the possibility of reversals of the
magnetic field for this case of forcing.
Received 8 October 1996 and accepted 28 April 1997 相似文献
148.
A new microscopic model of anomalous muonium for the elemental semiconductors is proposed. The relevant configuration consisting
of both a diamagrentic molecule Si−Mu and an unpaired orbital e− is contained into a semivacancy of the real lattice. By using the unrestricted Hartree-Fock computational method the principal
properties of the system are established. A dynamical version of the model together with a question on the formation of such
system are discussed. 相似文献
149.
150.
A method is proposed for evaluating the resistance of a flywheel rim to radial stresses in free rotation. The method is based on loading a rim segment in pure bending and calculating the limiting moment and the corresponding limiting angular velocity. Applicability of the method is substantiated theoretically by investigating the similarity of the radial stress diagrams in rotation and pure bending. The method is verified experimentally for the strained state of a rim segment in pure bending.Translated from Mekhanika Kompozitnykh Materialov, Vol. 29, No. 4, pp. 521–526, July–August, 1993. 相似文献