全文获取类型
收费全文 | 597137篇 |
免费 | 5458篇 |
国内免费 | 1506篇 |
专业分类
化学 | 292991篇 |
晶体学 | 9252篇 |
力学 | 30370篇 |
综合类 | 16篇 |
数学 | 83631篇 |
物理学 | 187841篇 |
出版年
2021年 | 4274篇 |
2020年 | 4723篇 |
2019年 | 5314篇 |
2018年 | 12874篇 |
2017年 | 13439篇 |
2016年 | 13111篇 |
2015年 | 6607篇 |
2014年 | 10086篇 |
2013年 | 23937篇 |
2012年 | 21026篇 |
2011年 | 30196篇 |
2010年 | 20835篇 |
2009年 | 20739篇 |
2008年 | 27088篇 |
2007年 | 29414篇 |
2006年 | 18752篇 |
2005年 | 20663篇 |
2004年 | 17371篇 |
2003年 | 15953篇 |
2002年 | 14519篇 |
2001年 | 15604篇 |
2000年 | 12013篇 |
1999年 | 9204篇 |
1998年 | 7853篇 |
1997年 | 7739篇 |
1996年 | 7382篇 |
1995年 | 6572篇 |
1994年 | 6649篇 |
1993年 | 6287篇 |
1992年 | 6996篇 |
1991年 | 7170篇 |
1990年 | 6946篇 |
1989年 | 6737篇 |
1988年 | 6616篇 |
1987年 | 6679篇 |
1986年 | 6339篇 |
1985年 | 8152篇 |
1984年 | 8453篇 |
1983年 | 7070篇 |
1982年 | 7235篇 |
1981年 | 6924篇 |
1980年 | 6873篇 |
1979年 | 7106篇 |
1978年 | 7453篇 |
1977年 | 7257篇 |
1976年 | 7313篇 |
1975年 | 6765篇 |
1974年 | 6829篇 |
1973年 | 7040篇 |
1972年 | 4982篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Let G be either a split SO(2n+2), or a split adjoint group of type En, (n=6,7,8), over a p-adic field. In this article we study correspondences arising by restricting the minimal representation of G to various dual pairs in G. 相似文献
992.
993.
The interaction of 3,5-diamino-4-nitropyrazole with such electrophilic reagents as acetic anhydride, dimethylformamide acetal, orthoformic ester, and ketones has been studied. Derivatives of pyrazolol[1,5-a]pyrimidines were formed on reaction with 1,3-diketones and some of their properties have been studied.Center for Drug Chemistry, All-Russian Chemical and Pharmaceutical Research Institute (VNIKhFI), Moscow 119815. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 329–335, March, 1997. 相似文献
994.
Basic equations of linear computer tomography are considered; a connection of the mathermatical formulation of problems of
computer tomography with problems of integral geometry is indicated; the properties of the Radon transform for even- and odd-dimensional
spaces are analyzed, and applications of Radon inversion to problems of diffraction tomography are presented. Bibliography:
5 titles.
Translated fromZapiski Nauchnykh Seminarov POMI, Vol. 230, 1995, pp. 264–277.
Translated by V. N. Troyan. 相似文献
995.
We have calculated inclusive two-jet cross sections in next-to-leading order QCD for low Q 2 ep collisions superimposing direct and resolved contributions. Infrared and collinear singularities in the virtual and real contributions are cancelled with the phase space slicing method. Various inclusive two-jet distributions have been computed. The results are compared with recent data from the ZEUS collaboration at HERA. 相似文献
996.
T. Engel M. Würtz S. Borneis St. Becker I. Klaft A. Kohl T. Kühl F. Laeri D. Marx K. Meier R. Neumann F. Schmitt P. Seelig L. Völker 《Hyperfine Interactions》1997,108(1-3):251-258
Laser spectroscopy at storage rings often suffers from a limited resolution due to Doppler-broadened resonances. Broadening
is caused by the velocity spread of the ions stored in the beam. In the following, the present status of our work on laser
systems specialized on the specific needs of laser spectroscopy at storage rings is reported.
Two pulsed laser systems were developed. One is a dye laser whose spectral bandwidth can be switched by inserting different
Littrow-prisms into the resonator. An increase in bandwidth up to a factor of 45 was achieved. This laser was used for fast
qualitative scans and high resolution measurements. The other laser system is a Nd : YAG laser pumped optical parametric oscillator.
It is a tunable laser system covering the spectral range from 410 to 4000 nm. Furthermore, a continuous wave laser with a
frequency shifted feedback cavity is described. It shows broadband emission with an adjustable bandwidth of up to 4.5 GHz.
This laser can be advantageous for laser cooling of ion beams.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
997.
L.-Q. Han S.-Y. Zhao Y.-D. Zhou P.-L. Zhang 《Applied physics. B, Lasers and optics》1997,65(3):399-402
Received: 18 June 1996/Revised version: 3 January 1997 相似文献
998.
A free-piston driver that employs entropy-raising shock processes with diaphragm rupture has been constructed, which promises
significant theoretical advantages over isentropic compression. Results from a range of conditions with helium and argon driver
gases are reported. Significant performance gains were achieved in some test cases. Heat losses are shown to have a strong
effect on driver processes. Measurements compare well with predictions from a quasi-one-dimensional numerical code.
Received 7 September 1996 / Accepted 5 October 1996 相似文献
999.
For fields above a critical value the expansion of the conductivity in powers of the field ceases to be valid and the weak-nonlinearity
approximation no longer works. The density behavior of the critical fields in strongly inhomogeneous media near the percolation
threshold is found on the basis of two criteria—an average criterion and a local criterion. The parameter values of the medium
for which crossover—a change of the critical behavior—occurs are determined. Similar calculations are performed for the critical
currents.
Zh. Tekh. Fiz. 68, 5–8 (June 1998) 相似文献
1000.
It has been shown by Yu. M. Golubev, M. I. Kolobov, and I. V. Sokolov, Zh. éksp. Teor. Fiz. 111, 1579 (1997) [JETP 84, 864 (1997)], that when an optical cavity is excited by external radiation from a sub-Poisson laser the cavity mode may be
in either a sub-Poisson or a Poisson stationary state. This is not important for a resonant medium which is excited into the
upper laser level while interacting with this mode inside the cavity. The degree of regularity of the excitation will be identical
to that of the initial light flux incident on the cavity, and this ultimately ensures the same sub-Poisson lasing as for strictly
regular pumping of the resonant medium.
Zh. éksp. Teor. Fiz. 113, 1223–1234 (April 1998) 相似文献