全文获取类型
收费全文 | 30177篇 |
免费 | 1102篇 |
国内免费 | 52篇 |
专业分类
化学 | 19440篇 |
晶体学 | 202篇 |
力学 | 614篇 |
数学 | 5178篇 |
物理学 | 5897篇 |
出版年
2023年 | 187篇 |
2022年 | 223篇 |
2021年 | 348篇 |
2020年 | 467篇 |
2019年 | 469篇 |
2018年 | 601篇 |
2017年 | 541篇 |
2016年 | 1081篇 |
2015年 | 890篇 |
2014年 | 928篇 |
2013年 | 1911篇 |
2012年 | 1944篇 |
2011年 | 1967篇 |
2010年 | 1176篇 |
2009年 | 1070篇 |
2008年 | 1670篇 |
2007年 | 1691篇 |
2006年 | 1523篇 |
2005年 | 1435篇 |
2004年 | 1254篇 |
2003年 | 1012篇 |
2002年 | 839篇 |
2001年 | 644篇 |
2000年 | 579篇 |
1999年 | 441篇 |
1998年 | 308篇 |
1997年 | 286篇 |
1996年 | 362篇 |
1995年 | 265篇 |
1994年 | 311篇 |
1993年 | 248篇 |
1992年 | 251篇 |
1991年 | 257篇 |
1990年 | 242篇 |
1989年 | 221篇 |
1988年 | 198篇 |
1987年 | 189篇 |
1986年 | 171篇 |
1985年 | 259篇 |
1984年 | 273篇 |
1983年 | 174篇 |
1982年 | 189篇 |
1981年 | 196篇 |
1980年 | 194篇 |
1979年 | 143篇 |
1978年 | 141篇 |
1977年 | 160篇 |
1976年 | 129篇 |
1975年 | 132篇 |
1973年 | 115篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
General limit theorems are established for l~p-valued Gaussian random fields indexed by a multidimensional parameter,which contain both almost sure moduli of continuity and limits of large increments for the l~p-valued Gaussian random fields under(?)explicit conditions. 相似文献
102.
M. T. Viciosa J. Quiles Hoyo M. Dionísio J. L. Gómez Ribelles 《Journal of Thermal Analysis and Calorimetry》2007,90(2):407-414
Temperature modulated differential scanning calorimetry (TMDSC) is used to study the kinetics of the free radical isothermal polymerization of triethyleneglycol dimethacrylate (TEGDMA). Azo-bis-isobutironitrile was used as initiator. The polymerization’s temperature is lower than the final glass transition temperature of the polymer network. The measurement of the average heat flow released and the heat capacity during the reaction allows identifying the different stages of the reaction. The presence of double peaks in the heat flow is ascribed to the autoacceleration. The influence of temperature, measuring conditions and oxygen are described. Vitrification is detected by the drop in heat capacity. It occurs at increasing conversion rates for increasing temperatures. After vitrification, the diffusion-controlled reaction continues. 相似文献
103.
104.
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
105.
We continue the studies on the so–called genuine Bernstein–Durrmeyer operators U
n
by establishing a recurrence formula for the moments and by investigating the semigroup T(t) approximated by U
n
. Moreover, for sufficiently smooth functions the degree of this convergence is estimated. We also determine the eigenstructure
of U
n
, compute the moments of T(t) and establish asymptotic formulas.
Received: January 26, 2007. 相似文献
106.
M. A. Rizzutto N. Added M. H. Tabacniks F. R. Espinoza-Qui?ones S. M. Palacio R. M. Galante R. M. Galante N. Rossi R. A. Welter A. N. Módenes 《Journal of Radioanalytical and Nuclear Chemistry》2006,269(3):727-731
Summary Kulcsszavak (angolul, ha nem azonos az elozovel) 相似文献
107.
Aza-Michael addition of optically pure 4-phenyl-2-oxazolidinone to 3,3,3-trifluoro-1-nitropropene proceeds smoothly at low temperature with a high yield. Diastereoselectivity of the addition depends on the base used and lithiated species proved to be highly efficient affording 92% de. Optically pure 1,2-diamino-3,3,3-trifluoropropane is prepared in 58% yield from the aza-Michael addition product through a three-step procedure. 相似文献
108.
109.
Jerzy Król 《Foundations of Physics》2006,36(7):1070-1098
We analyse the proposition that the spacetime structure is modified at short distances or at high energies due to weakening of classical logic. The logic assigned to the regions of spacetime is intuitionistic logic of some topoi. Several cases of special topoi are considered. The quantum mechanical effects can be generated by such semi-classical spacetimes. The issues of: background independence and general relativity covariance, field theoretic renormalization of divergent expressions, the existence and definition of path integral measures, are briefly discussed in the proposal. The connection with some problems in foundations of mathematics and differential topology are also discussed. 相似文献
110.