全文获取类型
收费全文 | 21279篇 |
免费 | 713篇 |
国内免费 | 357篇 |
专业分类
化学 | 13863篇 |
晶体学 | 220篇 |
力学 | 517篇 |
综合类 | 31篇 |
数学 | 2686篇 |
物理学 | 5032篇 |
出版年
2022年 | 225篇 |
2021年 | 279篇 |
2020年 | 335篇 |
2019年 | 328篇 |
2018年 | 256篇 |
2017年 | 224篇 |
2016年 | 519篇 |
2015年 | 496篇 |
2014年 | 560篇 |
2013年 | 1050篇 |
2012年 | 997篇 |
2011年 | 1161篇 |
2010年 | 759篇 |
2009年 | 743篇 |
2008年 | 1048篇 |
2007年 | 1100篇 |
2006年 | 944篇 |
2005年 | 933篇 |
2004年 | 872篇 |
2003年 | 788篇 |
2002年 | 840篇 |
2001年 | 556篇 |
2000年 | 505篇 |
1999年 | 381篇 |
1998年 | 317篇 |
1997年 | 283篇 |
1996年 | 323篇 |
1995年 | 331篇 |
1994年 | 284篇 |
1993年 | 242篇 |
1992年 | 231篇 |
1991年 | 232篇 |
1990年 | 258篇 |
1989年 | 200篇 |
1988年 | 185篇 |
1987年 | 184篇 |
1986年 | 167篇 |
1985年 | 274篇 |
1984年 | 279篇 |
1983年 | 200篇 |
1982年 | 212篇 |
1981年 | 198篇 |
1980年 | 201篇 |
1979年 | 165篇 |
1978年 | 149篇 |
1977年 | 200篇 |
1976年 | 174篇 |
1975年 | 143篇 |
1974年 | 130篇 |
1973年 | 156篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
The synthesis of several analogues of (±)-semivioxanthin including five thiophene analogues, using directed metalation are reported. The strategy consisted of the synthesis of functionalized naphthalene or benzo[b]thiophene as building blocks followed by annelation of the pyrone. 相似文献
42.
43.
44.
The existence of a Nash equilibrium in the undiscounted repeated two-person game of incomplete information on one side is
established. The proof depends on a new topological result resembling in some respect the Borsuk-Ulam theorem. 相似文献
45.
We generalize several results on bounded analytic interpolation of Fitzgerald and Horn, which work by majorization by positive
definite kernels, to the cases of several complex variables and operator-valued interpolation. Using a lemma of Kolmogorov,
we complement a simplification due to Szafraniec in the proofs of the theorems.
Received: November 21, 2006. Accepted: August 03, 2007. 相似文献
46.
P. Schuurmans J. Wouters P. De Moor N. Severijns W. Vanderpoorten J. Vanhaverbeke L. Vanneste 《Hyperfine Interactions》1992,75(1-4):423-430
Anisotropic α-emission from nuclei in the decay chain from223Ra to207Tl has been observed using low temperature nuclear orientation in combination with high resolution α-detection at 4.2 K. Information
on partial wave amplitudes as well as hyperfine interactions has been extracted. 相似文献
47.
After carefull analysis in a turbulent zero-pressure gradient flow, various simple algebraic turbulence models were applied to the almost separated flow on the upperside of an airfoil at incidence. The Johnson-King and Horton non-equilibrium (or rate equation) models give clearly improved results. 相似文献
48.
A. Maignan Ch. Simon V. Caignaert B. Raveau 《Zeitschrift für Physik B Condensed Matter》1995,99(1):305-310
The exploration of the magnetic and transport properties of four series of manganese perovskites, Pr0.7Ca0.34−xAxMnO3−δ (A=Sr, Ba), Pr0.7−xLaxCa0.3 MnO3−δ and Pr0.66Ca0.34−x
SrxMnO3−δ has allowed four phases with colossal magnetoresistive (CMR) properties to be isolated: Pr0.7Ca0.25Sr0.025MnO3−δ and Pr0.66Ca0.26Sr0.08MnO3−δ that exhibit a variation of resistance of 2.5. 107% and 109% at μ0 H=5 T for T=88 K and 50 K respectively, Pr0.58La0.12Ca0.3 MnO3−δ that exhibits a variation of 6.106% for μ0 H=5 T at T=80 K and Pr0.7Ba0.025Ca0.275MnO3−δ for which a resistance variation of 5.109%, at T=50 K, for μ0 H=5 T is evidenced. for each compound of this series except the barium phase, one observes that the temperature Tmax, which corresponds to the resistance maximum on the R(T) curves in zero magnetic field, increases dramatically as the mean
size of the interpolated cations increases, and that the CMR effect correlatively decreases dramatically. The comparison of
the two series Pr0.7Ca0.3−xSrxMnO3−δ and Pr0.66Ca0.34−xSrxMnO3−δ shows also the crucial role of the hole carrier density: for a same mean ionic radius of the interpolated cation Tmax is decreased of about 50 K by introducing 0.034 hole per Mn mole. 相似文献
49.
Simon French 《The Journal of the Operational Research Society》1994,45(11):1341-1341
50.
D. Kast A. Jungclaus K.P. Lieb M. Górska G. de Angelis P.G. Bizzeti A. Dewald C. Fahlander H. Grawe R. Peusquens M. De Poli H. Tiesler 《The European Physical Journal A - Hadrons and Nuclei》1998,3(2):115-128
In the neutron deficient isotopes 104,105In lifetimes of high spin states in the range from 0.5 ps to 600 ps have been measured in a coincidence recoil distance Doppler
shift (RDDS) experiment. By combining the Doppler shift attenuation (DSA) and RDDS methods at few μm flight distances, the
problem of delayed feeding has been avoided and very short lifetimes in the range 0.5–0.8 ps have been determined. Shell model
calculations with strong restrictions for the neutron orbitals reveal good agreement with experimental level energies and
still fair agreement for most measured B(M1) and B(E2) values.
Received: 30 June 1998 相似文献