全文获取类型
收费全文 | 11209篇 |
免费 | 2079篇 |
国内免费 | 1079篇 |
专业分类
化学 | 7450篇 |
晶体学 | 88篇 |
力学 | 703篇 |
综合类 | 99篇 |
数学 | 1321篇 |
物理学 | 4706篇 |
出版年
2024年 | 43篇 |
2023年 | 257篇 |
2022年 | 423篇 |
2021年 | 448篇 |
2020年 | 460篇 |
2019年 | 457篇 |
2018年 | 376篇 |
2017年 | 357篇 |
2016年 | 564篇 |
2015年 | 534篇 |
2014年 | 612篇 |
2013年 | 825篇 |
2012年 | 987篇 |
2011年 | 1057篇 |
2010年 | 674篇 |
2009年 | 698篇 |
2008年 | 682篇 |
2007年 | 597篇 |
2006年 | 565篇 |
2005年 | 463篇 |
2004年 | 368篇 |
2003年 | 306篇 |
2002年 | 274篇 |
2001年 | 216篇 |
2000年 | 228篇 |
1999年 | 212篇 |
1998年 | 230篇 |
1997年 | 206篇 |
1996年 | 160篇 |
1995年 | 204篇 |
1994年 | 170篇 |
1993年 | 127篇 |
1992年 | 108篇 |
1991年 | 87篇 |
1990年 | 96篇 |
1989年 | 65篇 |
1988年 | 43篇 |
1987年 | 36篇 |
1986年 | 35篇 |
1985年 | 27篇 |
1984年 | 20篇 |
1983年 | 21篇 |
1982年 | 12篇 |
1981年 | 6篇 |
1980年 | 10篇 |
1979年 | 2篇 |
1978年 | 4篇 |
1975年 | 3篇 |
1974年 | 2篇 |
1957年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
MATLAB在普通物理教学中的应用 总被引:8,自引:0,他引:8
在普通物理教学中,大学生常常接触较多的数学公式,由于他们的知识不完整,对其物理意义理解不深,人们通常借助计算机辅助教学.因此我们尝试在普通物理教学中引入数学软件MATLAB,进行计算机辅助教学,运用MATLAB的可视化技术,绘出随时间和空间变化的物理量或物理现象的图形和图象,帮助大学生理解物理意义. 相似文献
52.
验证力的平行四边形定则实验是最基本的实验之一.过去的教学表明,学生在物体共点力的合成与分解,力的平衡,以及物体受力分析等方面出现的问题,追究其根源,就是教师没有重视验证力的平行四边形定则实验.教师借故弹簧秤数量不足而且误差大,所以只做了演示实验或定性说明,导致学生对于力的矢量性理解不深刻. 相似文献
53.
Optical characterization of bromo-alkoxyl-substituted copper phthalocyanine derivative thin films 总被引:2,自引:0,他引:2
A series of thin films of copper phthalocyanine derivatives with bromine and alkoxyl substituents [CuPc(OC8H17)4Brm, m=0,1,2,4] were prepared on single-crystal silicon substrates by spin coating. The ellipsometric spectra of the films have been studied on a rotating analyzer–polarizer type of scanning ellipsometer. The optical, dielectric constants and absorption coefficients of the films in 500–800 nm wavelength region were obtained. The results show that the complex refractive index, dielectric constants and absorption coefficient of these thin films are influenced regularly by bromine substituent on conjugated macrocycle. It was found that there are approximately linear relationships between the resonance absorption wavelengths of the films and the average number of bromine atoms substituted on the phthalocyanine ring. 相似文献
54.
In this Note, we consider some classes of nonlinear partial differential equations with regular singularity with respect to t=0 and irregular one with respect to x=0. Our purpose is to establish a result which is similar to the k-summability property, known in the case of singular ordinary differential equations. We can prove that, except at most a countable set, the formal solution is Borel summable or k-summable with respect to x in all other directions. To cite this article: Z. Luo et al., C. R. Acad. Sci. Paris, Ser. I 336 (2003). 相似文献
55.
The specific heat and related thermophysical properties of liquid Fe77.5Cu13Mo9.5 monotectic alloy were investigated by an electromagnetic levitation drop calorimeter over a wide temperature range from 1482 to 1818 K. A maximum undercooling of 221 K (0.13 Tm) was achieved and the specific heat was determined as 44.71 J·mol-1·K-1. The excess specific heat, enthalpy change, entropy change and Gibbs free energy difference of this alloy were calculated on the basis of experimental results. It was found that the calculated results by traditional estimating methods can only describe the solidification process under low undercooling conditions. Only the experimental results can reflect the reality under high undercooling conditions. Meanwhile, the thermal diffusivity, thermal conductivity, and sound speed were derived from the present experimental results. Furthermore, the solidified microstructural morphology was examined, which consists of (Fe) and (Cu) phases. The calculated interface energy was applied to exploring the correlation between competitive nucleation and solidification microstructure within monotectic alloy. 相似文献
56.
The kinetics of the hydrolysis of p-nitrophenyl esters of three types of single-chain carboxylic acids, namely, saturated, olefinic and acetylenic, was investigated in two aquiorgano binary solvent systems, DMSO-H2O and dioxane (DX)-H2O. The ester probes used are: octanoic (C8), dodecanoic (C12) , stearic (C18) , oleic (C18-ol) , elaidic (C18-el ) and stearolic (C18-st). The order of measured CAgC values is: C18-ol>C18-el>C18>C18-st, whereas the order of decreasing magnitude of the observed hydrolytic rate constants of the monomeric species (km) is: C18>C18-el>C18-ol> C18-st. These rather unanticipated results are discussed. 相似文献
57.
58.
59.
60.
Weconsiderthequadraticsystemoftype(I)m=0acordingtotheclasificationof[1].Withoutlosofgenerality,wemayasumethatthesystemistaken... 相似文献