全文获取类型
收费全文 | 26420篇 |
免费 | 6260篇 |
国内免费 | 3909篇 |
专业分类
化学 | 3780篇 |
晶体学 | 140篇 |
力学 | 5111篇 |
综合类 | 1113篇 |
数学 | 12663篇 |
物理学 | 13782篇 |
出版年
2024年 | 255篇 |
2023年 | 863篇 |
2022年 | 975篇 |
2021年 | 924篇 |
2020年 | 708篇 |
2019年 | 964篇 |
2018年 | 627篇 |
2017年 | 1042篇 |
2016年 | 1179篇 |
2015年 | 1341篇 |
2014年 | 2098篇 |
2013年 | 1521篇 |
2012年 | 1634篇 |
2011年 | 1911篇 |
2010年 | 1806篇 |
2009年 | 1928篇 |
2008年 | 1940篇 |
2007年 | 1605篇 |
2006年 | 1529篇 |
2005年 | 1389篇 |
2004年 | 1466篇 |
2003年 | 1353篇 |
2002年 | 1099篇 |
2001年 | 962篇 |
2000年 | 763篇 |
1999年 | 668篇 |
1998年 | 553篇 |
1997年 | 567篇 |
1996年 | 513篇 |
1995年 | 505篇 |
1994年 | 429篇 |
1993年 | 300篇 |
1992年 | 278篇 |
1991年 | 264篇 |
1990年 | 246篇 |
1989年 | 235篇 |
1988年 | 49篇 |
1987年 | 27篇 |
1986年 | 15篇 |
1985年 | 10篇 |
1984年 | 8篇 |
1983年 | 13篇 |
1982年 | 11篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 3篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1963年 | 1篇 |
1959年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
121.
122.
A positive Mg-Al-nitrate layered double hydroxides(LDHs) has been synthesized using a non-steady coprecipitation method.The shape.size,chemical composition,electrical property and anion exchange property of the positve nanoparticle were studied by SEM,XRD,FTIR,chemical analysis,spectroanalysis and meaxsuring of electrophoretic mobilities.Preliminary results show the positive nanoparticle is a promising precursor of polymer/LDHs nanocomposite. 相似文献
123.
124.
在微拢QCD框架内,利用重子结构的夸克模型,计算了r→pp^-ΛcΛ^-c,∑c∑^-c,ΞcΞ^-c,Ξcc Ξcc-,ΩcccΩ^-ccc。衰变的分支比,讨论了在T衰变中寻找Ωccc粲重子的可能性. 相似文献
125.
汪更生 《数学物理学报(B辑英文版)》2005,25(1):7-22
This paper deals with maximum principle for some optimal control problem governed by some elliptic variational inequalities. Some state constraints are discussed. The basic techniques used here are based on those in [1] and a new penalty functional defined in this paper. 相似文献
126.
Theoretical Calculation of Rotational Bands of ^179Pt in the Particle-Triaxial-Rotor Model
下载免费PDF全文
![点击此处可从《中国物理快报》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Theoretical calculations have been performed for nucleus ^179Pt in the particle-triaxial-rotor model with variable moment of inertia. The obtained energy spectrum agrees with the experimental data quite well. The calculated results indicate that the bands 1/2^- and 7/2^ are triaxial deformation bands and originate mainly from the v[521]1/2^- and v[633]7/2^ configurations respectively. 相似文献
127.
128.
Based on phase space delay-coordinate reconstruction of a chaotic dynamics system, we propose a local prediction of chaotic time series using a support vector machine (SVM) to overcome the shortcomings of traditional local prediction methods. The simulation results show that the performance of this proposed predictor for making onestep and multi-step prediction is superior to that of the traditional local linear prediction method and global SVM method. In addition, it is significant that its prediction performance is insensitive to the selection of embedding dimension and the number of nearest neighbours, so the satisfying results can be achieved even if we do not know the optimal embedding dimension and how to select the number of nearest neighbours. 相似文献
129.
Theoretical Study on the Rotational Bands and Shape Coexistence of^179,181,183Au in the Particle-Triaxial-Rotor Model
下载免费PDF全文
![点击此处可从《中国物理快报》网站下载免费的PDF全文](/ch/ext_images/free.gif)
We perform a series of theoretical calculations and investigation for nuclei 179,181,183Au in the particle-triaxialrotor model with variable moment of inertia. The calculated energy spectra in^179,181,183Au agree well with the experimental data globally. The obtained results indicate that the nuclei^179,181,183Au have prolate deformation and involve shape coexistence with different deformation parameters in different bands. The main configuration of bands 1, 2, 3 and 5 in these nuclei are identified as [541]1/2^- (πh9/2, α = 1/2), [541]1/2- (πh9/2, α= -1/2),[530] 1/2- (πf7/2) and [660] 1/2^ (πi13/2), respectively. 相似文献
130.
Electron Spin Resonance Studies of Mn^2+ in Freshwater Snail Shells: Pomacea Canaliculata Lamarck and Fossilized Snail Shell
下载免费PDF全文
![点击此处可从《中国物理快报》网站下载免费的PDF全文](/ch/ext_images/free.gif)
N.Udomkan S.Meejoo P.Limsuwan P.Winotai Y.Chaimanee 《中国物理快报》2005,22(7):1780-1783
We study paramagnetic Mn^2 ions present in the nowadays shells of univalve freshwater snails of Pomacea canaliculata lamarck (PCL) and the fossilized freshwater snail (FFS), Viviparus. All these shells are abundant in Thailand. The PCL shells were ground into fine powder. A set of seven samples were then separately annealed for 2 h in air atmosphere at different annealing temperatures while the FFS powder was characterized as-received. The PCL shells mainly consist of aragonite and a fraction of calcite. The heat treatments of the PCL powder samples at temperature higher than 450℃ resulted in an irreversible phase transformation from aragonite to calcite. However, it is found that the FFS shell is mainly made of calcite, with a minor fraction of aragonite. The crystal structure of the high-temperature-annealed PCL samples are quite similar to that of FFS, which indicates that the metamorphosis (aragonite→calcite) in the FFS shell had occurred but was not yet completed, although it had remained under the pressure and temperature of the Earth‘s crusts over millions of years. Our detailed ESR spectral analyses of PCL and FFS show that Mn^2 ions enter the Ca^2 sites during a biomineralization process. Simulated ESR parameters of PCL-500 of Mn^2 at a uniaxial site of calcite are reported. It is surprising to And that the ratio of Mn^2 concentration present in FFS to those in PCL shells evaluated from ESR spectra is as much as 10:1. 相似文献