全文获取类型
收费全文 | 6793篇 |
免费 | 771篇 |
国内免费 | 363篇 |
专业分类
化学 | 4001篇 |
晶体学 | 66篇 |
力学 | 543篇 |
综合类 | 65篇 |
数学 | 1205篇 |
物理学 | 2047篇 |
出版年
2024年 | 18篇 |
2023年 | 83篇 |
2022年 | 149篇 |
2021年 | 196篇 |
2020年 | 259篇 |
2019年 | 225篇 |
2018年 | 186篇 |
2017年 | 191篇 |
2016年 | 261篇 |
2015年 | 236篇 |
2014年 | 255篇 |
2013年 | 617篇 |
2012年 | 389篇 |
2011年 | 313篇 |
2010年 | 246篇 |
2009年 | 354篇 |
2008年 | 286篇 |
2007年 | 356篇 |
2006年 | 388篇 |
2005年 | 300篇 |
2004年 | 311篇 |
2003年 | 290篇 |
2002年 | 260篇 |
2001年 | 212篇 |
2000年 | 177篇 |
1999年 | 177篇 |
1998年 | 142篇 |
1997年 | 119篇 |
1996年 | 95篇 |
1995年 | 93篇 |
1994年 | 75篇 |
1993年 | 84篇 |
1992年 | 71篇 |
1991年 | 53篇 |
1990年 | 55篇 |
1989年 | 40篇 |
1988年 | 64篇 |
1987年 | 54篇 |
1986年 | 40篇 |
1985年 | 29篇 |
1984年 | 28篇 |
1983年 | 14篇 |
1982年 | 27篇 |
1981年 | 16篇 |
1980年 | 12篇 |
1979年 | 12篇 |
1978年 | 19篇 |
1977年 | 8篇 |
1975年 | 9篇 |
1973年 | 9篇 |
排序方式: 共有7927条查询结果,搜索用时 15 毫秒
41.
We investigate a multicomponent anisotropic liquid system. The first spatial moment of the direct correlation function is taken into account to obtain asymptotic expressions for the pairwise correlation functions. In this approximation, we obtain the pairwise correlation functions that describe the system behavior not only in the critical-state neighborhood but also in the noncritical domain. We show that the critical parameters for the anisotropic system differ from those for the isotropic system. 相似文献
42.
Giuseppina Vannella 《Annali di Matematica Pura ed Applicata》2002,180(4):429-440
We consider a Neumann problem of the type -εΔu+F
′(u(x))=0 in an open bounded subset Ω of R
n
, where F is a real function which has exactly k maximum points.
Using Morse theory we find that, for ε suitably small, there are at least 2k nontrivial solutions of the problem and we give some qualitative information about them.
Received: October 30, 1999 Published online: December 19, 2001 相似文献
43.
We have performed total-energy calculations to study theoretical scanning tunneling microscopy (STM) images of the Si(1 1 1)3 × 2 surfaces induced by the adsorption of alkaline-earth metals (AEMs). Previously, in a series of works on Ba/Si(1 1 1) system, we have found that the observed Si(1 1 1)3 × 1-Ba LEED phase indeed has a 3 × 2 periodicity with a Ba coverage of 1/6 ML and the HCC substrate structure. Based on results of the Ba case, we proposed that the HCC structure is also adopted for other AEM atoms, which was confirmed by our recent work. In this paper, we mainly report the STM simulations for different AEM systems to compare with existing experimental data. We discuss the difference in the detailed STM images for different AEM adsorbates. Especially, the difference in filled-state images between Mg and other AEM atoms is attributed to the strong Mg-Si interaction. 相似文献
44.
A graph G is 3‐domination critical if its domination number γ is 3 and the addition of any edge decreases γ by 1. Let G be a 3‐connected 3‐domination critical graph of order n. In this paper, we show that there is a path of length at least n?2 between any two distinct vertices in G and the lower bound is sharp. © 2002 John Wiley & Sons, Inc. J Graph Theory 39: 76–85, 2002 相似文献
45.
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
46.
47.
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
48.
Historical perspectives for the chemistry of diene complexes of early transition metals developed at Osaka University in the period after 1970s were reviewed briefly and personally. Preparative chemistry of this field commenced from the magnesium-diene 1:1 compounds and quickly extended to almost all the early transition metals. By the studies operated together with other researchers, unique features of these diene complexes, especially their bonding and structure, selective reactions, and catalysis performances are described. 相似文献
49.
50.
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