全文获取类型
收费全文 | 37836篇 |
免费 | 396篇 |
国内免费 | 302篇 |
专业分类
化学 | 16792篇 |
晶体学 | 325篇 |
力学 | 1612篇 |
综合类 | 13篇 |
数学 | 10186篇 |
物理学 | 9606篇 |
出版年
2023年 | 81篇 |
2022年 | 231篇 |
2021年 | 321篇 |
2020年 | 216篇 |
2019年 | 220篇 |
2018年 | 1370篇 |
2017年 | 1607篇 |
2016年 | 1072篇 |
2015年 | 848篇 |
2014年 | 784篇 |
2013年 | 1255篇 |
2012年 | 3685篇 |
2011年 | 2955篇 |
2010年 | 2218篇 |
2009年 | 1966篇 |
2008年 | 1164篇 |
2007年 | 1161篇 |
2006年 | 1050篇 |
2005年 | 4824篇 |
2004年 | 4238篇 |
2003年 | 2579篇 |
2002年 | 734篇 |
2001年 | 444篇 |
2000年 | 227篇 |
1999年 | 270篇 |
1998年 | 205篇 |
1997年 | 145篇 |
1996年 | 139篇 |
1995年 | 118篇 |
1994年 | 94篇 |
1993年 | 83篇 |
1992年 | 230篇 |
1991年 | 196篇 |
1990年 | 174篇 |
1989年 | 141篇 |
1988年 | 136篇 |
1987年 | 86篇 |
1986年 | 73篇 |
1985年 | 87篇 |
1984年 | 68篇 |
1983年 | 53篇 |
1982年 | 51篇 |
1980年 | 52篇 |
1979年 | 48篇 |
1978年 | 54篇 |
1976年 | 101篇 |
1975年 | 60篇 |
1974年 | 56篇 |
1973年 | 60篇 |
1972年 | 49篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
Dorota G?azowska Janusz Matkowski 《Journal of Mathematical Analysis and Applications》2007,331(2):1187-1199
The invariance of the geometric mean G with respect to the Lagrangian mean-type mapping (Lf,Lg), i.e. the equation G○(Lf,Lg)=G, is considered. We show that the functions f and g must be of high class regularity. This fact allows to reduce the problem to a differential equation and determine the second derivatives of the generators f and g. 相似文献
82.
In the paper we indicate an error made in the proof of the main result of the paper [M.A. Darwish, On quadratic integral equation of fractional orders, J. Math. Anal. Appl. 311 (2005) 112-119]. Moreover, we provide correct proof of a slightly modified version of the mentioned result. The main tool used in our proof is the technique associated with the Hausdorff measure of noncompactness. 相似文献
83.
In this paper we deal with nonlinear second-order boundary value problems with impulses. The impulsive functions depend implicitly on the different considered variables and the boundary value conditions are nonlinear. In both cases functional dependence on the solution is allowed. The existence results follow from the existence of a pair of well-ordered lower and upper solutions. 相似文献
84.
We study linear dynamical systems with multidimensional time in Banach spaces. Using Taylor functional calculus we prove that under additional assumptions hyperbolic systems have shadowing property. 相似文献
85.
S?awomir Solecki 《Topology and its Applications》2007,154(12):2462-2464
Let I0 be the σ-ideal of subsets of a Polish group generated by Borel sets which have perfectly many pairwise disjoint translates. We prove that a Fubini-type theorem holds between I0 and the σ-ideals of Haar measure zero sets and of meager sets. We use this result to give a simple proof of a generalization of a theorem of Balcerzak-Ros?anowski-Shelah stating that I0 on N2 strongly violates the countable chain condition. 相似文献
86.
I. Bretos J. Ricote R.J. Jiménez-Riobóo L. Pardo M.L. Calzada 《Applied Physics A: Materials Science & Processing》2007,89(4):967-973
A novel method to investigate the early formation stages of polycrystalline (Pb1-xCax)TiO3 (PCT) perovskite films by means of traditional Brillouin and micro-Brillouin spectroscopy (BS, mBS) is described in the present
work. The films were prepared by chemical solution deposition (CSD) onto oxidized (100)Si substrates and treated at temperatures
between 350–650 °C by rapid thermal processing (RTP). The elastic instability observed by Brillouin spectroscopy at the nano-structured
state of the PCT films was used here to determine their crystallization temperatures. Coexistence of different nanocrystalline
phases (e.g., pyrochlore, perovskite) in the films could also be detected by this technique. The reliability of these results
is demonstrated by complementary information obtained by X-ray diffraction (XRD) and scanning force microscopy (SFM). The
effects of the annealing temperature and of the Ca2+ content on the crystallization process of these films are also discussed.
PACS 78.35.+c; 77.84.-s; 61.82.Rx 相似文献
87.
88.
R. Knizikevi?ius 《Applied Surface Science》2006,253(3):1581-1583
The ion-beam-assisted etching of silicon in Cl2 environment is considered. The theoretically calculated dependences of silicon etching rate on the flux of Cl2 molecules at different ion current densities are compared with experimentally measured. The composition of the adsorbed layer is determined. It is found that SiCl2 molecules prevail in the adsorbed layer. The reciprocal of relative concentration of SiCl2 molecules in the adsorbed layer linearly depends on the ion-to-neutral flux ratio. 相似文献
89.
Roberto D. Galvão Luis Gonzalo Acosta Espejo Brian Boffey 《Annals of Operations Research》2006,143(1):31-44
A study has been carried out aimed at reducing perinatal mortality in the municipality of Rio de Janeiro through a better
distribution of health care facilities. The algorithmic aspects are detailed elsewhere and here the emphasis is on practical
issues and difficulties encountered.
A 3-level hierarchical model was developed. Both uncapacitated and capacitated versions are briefly described together with
some results based on actual data. The project brought to light many contradictions between OR theory and practice in developing
countries and, unfortunately, the models developed were not implemented by the municipality health authorities. Possible reasons
for this outcome are analysed. 相似文献
90.
Wei-nan E Ping-bing Ming 《应用数学学报(英文版)》2007,23(4):529-550
We study continuum and atomistic models for the elastodynamics of crystalline solids at zerotemperature.We establish sharp criterion for the regime of validity of the nonlinear elastic wave equationsderived from the well-known Cauchy-Born rule. 相似文献