全文获取类型
收费全文 | 25849篇 |
免费 | 2805篇 |
国内免费 | 1627篇 |
专业分类
化学 | 7136篇 |
晶体学 | 179篇 |
力学 | 1404篇 |
综合类 | 207篇 |
数学 | 7696篇 |
物理学 | 13659篇 |
出版年
2024年 | 29篇 |
2023年 | 172篇 |
2022年 | 374篇 |
2021年 | 392篇 |
2020年 | 489篇 |
2019年 | 439篇 |
2018年 | 461篇 |
2017年 | 580篇 |
2016年 | 652篇 |
2015年 | 549篇 |
2014年 | 874篇 |
2013年 | 1730篇 |
2012年 | 1289篇 |
2011年 | 1497篇 |
2010年 | 1345篇 |
2009年 | 3741篇 |
2008年 | 3109篇 |
2007年 | 1773篇 |
2006年 | 1311篇 |
2005年 | 1145篇 |
2004年 | 1114篇 |
2003年 | 876篇 |
2002年 | 770篇 |
2001年 | 640篇 |
2000年 | 610篇 |
1999年 | 507篇 |
1998年 | 548篇 |
1997年 | 475篇 |
1996年 | 303篇 |
1995年 | 427篇 |
1994年 | 367篇 |
1993年 | 295篇 |
1992年 | 342篇 |
1991年 | 299篇 |
1990年 | 156篇 |
1989年 | 163篇 |
1988年 | 103篇 |
1987年 | 54篇 |
1986年 | 61篇 |
1985年 | 44篇 |
1984年 | 30篇 |
1983年 | 14篇 |
1982年 | 24篇 |
1981年 | 22篇 |
1980年 | 19篇 |
1979年 | 14篇 |
1978年 | 14篇 |
1977年 | 8篇 |
1976年 | 7篇 |
1973年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
Based on the effective-field theory with self-spin correlations and the differential operator technique,physical properties of the spin-2 system with biaxial crystal field on the simple cubic, body-centered cubic, as well as faced-centered lattice have been studied. The influences of the external longitudinal magnetic field on the magnetization,internal energy, specific heat, and susceptibility have been discussed in detail. The phenomenon that the magnetization in the ground state shows quantum effects produced by the biaxial transverse crystal field has been found. 相似文献
23.
24.
25.
1 Introduction Inrecentyears,boththetheoreticalandexperimentalinvestigationsonlasercoolingandtrappinghavebecomeoneofthemajorfieldsinatomic,molecularandoptical physics[1~ 8] .Thedevelopmentoflasercoolingandtrappingtechnologyisimportantfortheapplicationssu… 相似文献
26.
Youssef Randjiou 《Journal of Theoretical Probability》2006,19(3):701-720
Let μ+(t) and μ−(t) be the locations of the maximum and minimum, respectively, of a standard Brownian motion in the interval [0,t]. We establish a joint integral test for the lower functions of μ+(t) and μ−(t), in the sense of Paul Lévy. In particular, it yields the law of the iterated logarithm for max(μ+(t),μ−(t)) as a straightforward consequence. Our result is in agreement with well-known theorems of Chung and Erdős [(1952) Trans. Amer. Math. Soc. 72, 179–186.], and Csáki, F?ldes and Révész [(1987) Prob. Theory Relat. Fields
76, 477–497].
相似文献
27.
The values of the Higgs mass are obtained for two possibilities of extending the standard model in a way compatible with the existence of a noncommutative structure at high energies. We assume the existence of a big desert between the low energy electroweak scale and the high energy scale Λ=1.1×1017 GeV, where noncommutative features become relevant. We conclude that it is extremely difficult to depart from the Higgs mass value obtained from noncommutative geometry for the standard model with three generations only. 相似文献
28.
We prove equivalence of the definitions by the author and by Korevaar and Schoen of the Sobolev classes of mappings of a domain of an arithmetic n-dimensional space to a metric space. 相似文献
29.
Ledzewicz U. Nowakowski A. Schättler H. 《Journal of Optimization Theory and Applications》2004,122(2):345-370
It is shown that, if a parametrized fämily of extremals F can be stratified in a way compatible with the flow map generated by F, then those trajectories of the family which realize the minimal values of the cost in F are indeed optimal in comparison with all trajectories which lie in the region R covered by the trajectories of F. It is not assumed that F is a field covering the state space injectively. As illustration, an optimal synthesis is constructed for a system where the flow of extremals exhibits a simple cusp singularity. 相似文献
30.
Yasumitsu Matsuo Takehiko Ijichi Hironori Yamada Junko Hatori Seiichiro Ikehata 《Central European Journal of Physics》2004,2(2):357-366
We have fabricated a field effect transistor (FET) based on an organic ferroelectric insulator and molecular conductor, and
investigated the electrical properties and memory effects on the PEN-FET. We have observed a drastic change in the drain current
at around the coercive electric fieldE
c
of the organic ferroelectric insulator in not only a FET (PEN-FET) based on a pentacene (PEN) film but also a FET (IPEN-FET)
based on an iodine doped PEN film. The magnitude of the change of the drain current for the IPEN-FET is 200 times larger than
that for the PEN-FET. It is expected from these results that the PEN-FET (especially the IPEN-FET) is an improvement in such
devices, since it operates at a low gate electric field accompanied by the appearance of the spontaneous polarization in the
organic ferroelectric insulator. In addition, we have found that the drain current for the PEN-FET does not return to the
initial drain current ofE
G
=0 V/cm for more than one week, even if the gate electric field is changed to 0 V/cm from 500 V/cm(>E
c
). From these results, it is suggested that the PEN-FET becomes a memory device. 相似文献