全文获取类型
收费全文 | 3312篇 |
免费 | 422篇 |
国内免费 | 256篇 |
专业分类
化学 | 786篇 |
晶体学 | 29篇 |
力学 | 464篇 |
综合类 | 50篇 |
数学 | 1198篇 |
物理学 | 1463篇 |
出版年
2024年 | 3篇 |
2023年 | 31篇 |
2022年 | 43篇 |
2021年 | 74篇 |
2020年 | 89篇 |
2019年 | 107篇 |
2018年 | 99篇 |
2017年 | 111篇 |
2016年 | 119篇 |
2015年 | 79篇 |
2014年 | 121篇 |
2013年 | 287篇 |
2012年 | 128篇 |
2011年 | 135篇 |
2010年 | 105篇 |
2009年 | 184篇 |
2008年 | 134篇 |
2007年 | 155篇 |
2006年 | 213篇 |
2005年 | 145篇 |
2004年 | 160篇 |
2003年 | 143篇 |
2002年 | 149篇 |
2001年 | 127篇 |
2000年 | 124篇 |
1999年 | 115篇 |
1998年 | 86篇 |
1997年 | 71篇 |
1996年 | 61篇 |
1995年 | 59篇 |
1994年 | 50篇 |
1993年 | 55篇 |
1992年 | 48篇 |
1991年 | 34篇 |
1990年 | 48篇 |
1989年 | 31篇 |
1988年 | 46篇 |
1987年 | 42篇 |
1986年 | 29篇 |
1985年 | 25篇 |
1984年 | 20篇 |
1983年 | 11篇 |
1982年 | 20篇 |
1981年 | 15篇 |
1980年 | 7篇 |
1979年 | 10篇 |
1978年 | 16篇 |
1977年 | 6篇 |
1976年 | 6篇 |
1973年 | 6篇 |
排序方式: 共有3990条查询结果,搜索用时 15 毫秒
31.
S. Sarkar A. D. Thakur C. V. Tomy G. Balakrishnan D. McK Paul S. Ramakrishnan A. K. Grover 《Pramana》2006,66(1):193-207
New experimental data are presented on the scan rate dependence of the magnetization hysteresis width ΔM(H) (∞ critical current densityJ
c(H)) in isothermalMH scans in a weakly pinned single crystal of Ca3Rh4Sn13, which displays second magnetization peak (SMP) anomaly as distinct from the peak effect (PE). We observe an interesting
modulation in the field dependence of a parameter which purports to measure the dynamical annealing of the disordered bundles
of vortices injected through the sample edges towards the destined equilibrium vortex state at a givenH. These data, in conjunction with the earlier observations made while studying the thermomagnetic history dependence inJ
c(H) in the tracing of the minor hysteresis loops, imply that the partially disordered state heals towards the more ordered state
between the peak field of the SMP anomaly and the onset field of the PE. The vortex phase diagram in the given crystal of
Ca3Rh4Sn13 has been updated in the context of the notion of the phase coexistence of the ordered and disordered regions between the
onset field of the SMP anomaly and the spinodal line located just prior to the irreversibility line. A multi-critical point
and a critical point in the (H,T) region of the Bragg glass phase have been marked in this phase diagram and the observed behavior is discussed in the light
of recent data on multi-critical point in the vortex phase diagram in a single crystal of Nb. 相似文献
32.
33.
Prof. A. D. Drozdov 《Archive of Applied Mechanics (Ingenieur Archiv)》1995,65(2):99-109
Summary Dynamic stability of an elastic bar with voids is considered. Using the Lyapunov approach some new sufficient stability conditions are obtained and explicit expressions for the critical load are derived. 相似文献
34.
H. Sato A. Bensalah N. Solovieva A. Beitlerova A. Vedda M. Martini M. Nikl T. Fukuda 《Radiation measurements》2004,38(4-6):463-466
Two-inch sized KMgF3,BaLiF3 and LiCaAlF6 (LiCAF) single crystals were grown by the Czochralski method under a CF4 atmosphere. X-ray irradiation was used to carry out a comparative study of induced optical absorption phenomena and colour centre creation in the ultra-violet and visible spectral regions. The integral of the induced absorption spectra is significantly lower in LiCAF with respect to the other studied materials. It is found that the amplitude of the F-absorption band is suppressed more than a factor of 3 by Mg-doping. For Mg-doped crystals, the optimum doping concentration is about 0.2 mol% of Mg2+. 相似文献
35.
二维渗流中的最短开穿透 总被引:1,自引:0,他引:1
在二维边渗流模型中,设/rn/=min(/r/:r是正方形「0,n」^2的开穿透),这里/r/表示r的长度,本文证明了在上临界状态有limE/rn//n=λ,在临界状态时,我们对E/n/给出了上界,并对一个rnrn给出了E/rn/的下界。 相似文献
36.
SocaltheBerlinskitheoremforplanarquadraticSystem(QS)is:TheoremA[1]SupposethataQShas4finitecriticalpoints(CPs),Ifthequadrila... 相似文献
37.
The leading logarithmic corrections to the critical behavior of a dilute uniaxial (Ising) ferromagnet in the disordered phase are derived using renormalization group methods. The values of the exponents in the logarithmic terms differ from those given by previous authors. 相似文献
38.
We study the aggregation of oxygen dipoles well dispersed in a CaF2 crystal upon annealing at temperatures ranging from 370 to 420 K. The concentration of oxygen dipoles is monitored by measuring the intensity of the ionic thermocurrent peak as well as by absorption and luminescence spectroscopies. Results from three methods agree within experimental error and yield an activation energy of (1.2±0.1) eV for the diffusion of isolated oxygen centres in the crystal. 相似文献
39.
A multiparameter boundary-value problem of fresh infiltration water seepage in a drained fringe above quiescent saline water is solved in the direct statement and studied in detail. 相似文献
40.
Unconventional antiferromagnetic correlations of the doped Haldane gapsystem Y 2 BaNi 1 - x Zn x O 5
V. Villar R. Mélin C. Paulsen J. Souletie E. Janod C. Payen 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,25(1):39-51
We make a new proposal to describe the very low temperature susceptibility of the doped Haldane gap compound Y2BaNi1-xZnxO5. We propose a new mean field model relevant for this compound. The ground state of this mean field model is unconventional
because antiferromagnetism coexists with random dimers. We present new susceptibility experiments at very low temperature.
We obtain a Curie-Weiss susceptibility χ(
T
) ∼
C
/(Θ +
T
) as expected for antiferromagnetic correlations but we do not obtain a direct signature of antiferromagnetic long range order.
We explain how to obtain the “impurity” susceptibility
(
T
) by subtracting the Haldane gap contribution to the total susceptibility. In the temperature range [1 K, 300 K] the experimental
data are well fitted by T
(
T
) =
C
imp
1 +
T
imp
/
T
. In the temperature range [100 mK, 1 K] the experimental data are well fitted by T
(
T
) =
A
ln(
T
/
T
c
), where T
c
increases with x. This fit suggests the existence of a finite Néel temperature which is however too small to be probed directly in our experiments.
We also obtain a maximum in the temperature dependence of the ac-susceptibility
(
T
) which suggests the existence of antiferromagnetic correlations at very low temperature.
Received 17 July 2001 相似文献