全文获取类型
收费全文 | 82986篇 |
免费 | 470篇 |
国内免费 | 506篇 |
专业分类
化学 | 62202篇 |
晶体学 | 21篇 |
力学 | 331篇 |
综合类 | 39篇 |
数学 | 461篇 |
物理学 | 20908篇 |
出版年
2023年 | 37篇 |
2022年 | 45篇 |
2021年 | 30篇 |
2020年 | 24篇 |
2019年 | 38篇 |
2018年 | 45篇 |
2017年 | 28篇 |
2016年 | 61篇 |
2015年 | 49篇 |
2014年 | 95篇 |
2013年 | 83篇 |
2012年 | 8753篇 |
2011年 | 12116篇 |
2010年 | 1872篇 |
2009年 | 349篇 |
2008年 | 8351篇 |
2007年 | 8299篇 |
2006年 | 8322篇 |
2005年 | 7846篇 |
2004年 | 5930篇 |
2003年 | 4433篇 |
2002年 | 3690篇 |
2001年 | 2240篇 |
2000年 | 2798篇 |
1999年 | 646篇 |
1998年 | 274篇 |
1997年 | 248篇 |
1996年 | 965篇 |
1995年 | 671篇 |
1994年 | 867篇 |
1993年 | 1219篇 |
1992年 | 1016篇 |
1991年 | 420篇 |
1990年 | 394篇 |
1989年 | 325篇 |
1988年 | 228篇 |
1987年 | 250篇 |
1986年 | 286篇 |
1985年 | 217篇 |
1984年 | 45篇 |
1983年 | 32篇 |
1982年 | 26篇 |
1981年 | 25篇 |
1980年 | 13篇 |
1979年 | 18篇 |
1977年 | 13篇 |
1975年 | 20篇 |
1972年 | 27篇 |
1958年 | 31篇 |
1948年 | 15篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
C. W. LEUNG Department of Mathematics The Chinese Universityof Hong Kong Shatin. N. T. Hong Kong China. 《数学年刊B辑(英文版)》1997,(1)
ASTRASSENLAWOFTHEITERATEDLOGARITHMFORPROCESSESWITHINDEPENDENTINCREMENTWangJiagangAbstractLetX={X(t),t0}beaproceswithindep... 相似文献
2.
3.
The paper that may be worthy of remark is entitled "Asymptotic Expansions of Integrals of Certain Rapidly Oscillating Functions" and appeared in Mathema tics of Computation, Vol. 49, No. 179(1987), 243—249.What we would like to mention is that the main result of the paper, namely an asymptotic expansion formula with a remainder estimate (cf.§3), is actually a special consequence 相似文献
4.
报道了两类典型元素替代的超导Y123相体系-YBa2(Cu1-xCox)3O7-δ(x=0.01,0.02)和YBa2(Cu1-yZny)3O7-δ(y=0.005,0.010)薄膜的电阻率-温度特性(ρ(T))和Hall效应(RH (T)).研究表明,Co掺杂的Y123相体系十分类似于氧欠掺杂的情况,对Co掺杂的薄膜样品,由电阻率-温度特性定义的赝能隙打开的温度T*分别为193和225K.而Zn掺杂的样品没有观察到赝能隙打开对电阻率-温度特性的影响.由Hall效应的测量和Hall角(cotθH)定义了另一个特征温度T 0,介于Tc与T*之间,这一特征温度与核磁共振(NMR)给出的赝能隙打开温度相近,说明可能源于电子自旋自由度上的能隙打开.在室温到Tc范围内,电阻率-温度特性和Hall效应分别定义了两类不同的转变温度(T*和T 0),可能分别源于电子电荷和自旋通道上的赝能隙的打开,预示着电荷和自旋自由度分别进入某种基态. 相似文献
5.
6.
庞丹阳叶沿林 江栋兴郑涛王全进 李智焕李湘庆葛愉成 吴翠娥张高龙 胡青元王佳 A.Ozawa Y.Yamaguchi R.Kanungo D.Fang I.Tanihata 《中国物理快报》2004,21(11):2151-2154
The differential cross sections of quasielastic scattering of a 25 MeV/u ^6He from ^9Be target have been measured.The double-folding model approach is applied to generate the real part of the optical potential. The imaginary potential parameters as well as some of the real potential parameters are studied in comparison with the experimental data. The effect of the unstable nucleus is discussed. 相似文献
7.
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
8.
10.
Effects of Substrate Temperature on Helium Content and Microstructure of Nanocrystalline Titanium Films
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)
Helium-charged nanocrystalline titanium films have been deposited by HeAr magnetron co-sputtering. The effects of substrate temperature on the helium content and microstructure of the nanocrystalline titanium films have been studied. The results indicate that helium atoms with a high concentration are evenly incorporated in the deposited titanium films. When the substrate temperature increases from 60℃ to 350℃ while the other deposition'parameters are fixed, the helium content decreases gradually from 38.6 at.% to 9.2at.%, which proves that nanocrystalline Ti films have a great helium storage capacity. The 20 angle of the Bragg peak of (002) crystal planes of the He-charged Ti film shifts to a lower angle and that of (100) crystal plane is unchanged as compared with that of the pure Ti film, which indicates that the lattice parameter c increases and a keeps at the primitive value. The grain refining and helium damage result in the diffraction peak broadening. 相似文献