全文获取类型
收费全文 | 11433篇 |
免费 | 2042篇 |
国内免费 | 1316篇 |
专业分类
化学 | 6495篇 |
晶体学 | 94篇 |
力学 | 412篇 |
综合类 | 88篇 |
数学 | 849篇 |
物理学 | 3356篇 |
无线电 | 3497篇 |
出版年
2024年 | 35篇 |
2023年 | 296篇 |
2022年 | 345篇 |
2021年 | 481篇 |
2020年 | 523篇 |
2019年 | 565篇 |
2018年 | 437篇 |
2017年 | 401篇 |
2016年 | 596篇 |
2015年 | 614篇 |
2014年 | 714篇 |
2013年 | 872篇 |
2012年 | 1077篇 |
2011年 | 1044篇 |
2010年 | 791篇 |
2009年 | 726篇 |
2008年 | 810篇 |
2007年 | 727篇 |
2006年 | 597篇 |
2005年 | 436篇 |
2004年 | 321篇 |
2003年 | 328篇 |
2002年 | 361篇 |
2001年 | 341篇 |
2000年 | 207篇 |
1999年 | 241篇 |
1998年 | 166篇 |
1997年 | 106篇 |
1996年 | 100篇 |
1995年 | 87篇 |
1994年 | 78篇 |
1993年 | 72篇 |
1992年 | 60篇 |
1991年 | 58篇 |
1990年 | 48篇 |
1989年 | 36篇 |
1988年 | 26篇 |
1987年 | 18篇 |
1986年 | 15篇 |
1985年 | 9篇 |
1984年 | 7篇 |
1983年 | 8篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1959年 | 2篇 |
1936年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 312 毫秒
51.
Features of the total disintegration events of heavyemulsion targets caused by 4.5A GeV/c16O
下载免费PDF全文
![点击此处可从《中国物理》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Total disintegration events produced by 4.5\,A GeV/c $^{16}$O--AgBr interactions are
analysed to investigate the characteristics of secondary charged particles produced
in such collisions. The multiplicity distributions of grey, black, and relativistic
charged particles can be well represented by Gaussian distribution. The average
multiplicity of grey particles is found to increase with the mass of projectile
increasing, while that of black particles is found to decrease with the mass of
projectile increasing. This result is in good agreement with the prediction of
fireball model. Finally, the linear dependence between grey and black particles is
observed, but there is no distinct dependence between the production of relativistic
charged particles and the target excitation. 相似文献
52.
Jovanovic V.M. Bull M.A. Smyth M.M. Jia Zong 《Geoscience and Remote Sensing, IEEE Transactions on》2002,40(7):1512-1519
In order to facilitate a unique georectification approach implemented for Multi-angle Imaging SpectroRadiometer (MISR) data, specific calibration datasets need to be derived during flight. In the case of the spaceborne MISR instrument, with its unique configuration of nine fixed pushbroom cameras, continuous and autonomous coregistration and geolocation of image data are required prior to the application of scientific retrieval algorithms. In-flight-generated calibration datasets are required to (a) assure accuracy, (b) reduce processing load, and (c) support autonomous aspects of the processing algorithm. This paper describes the in-flight geometric calibration approach with the focus on the first year of activities and the georectification performance achieved. 相似文献
53.
54.
Raman spectra of ceramic Sr2Bi4Ti5O18 (SBTi5) are reported to consist of four different Raman bands. Temperature-dependent spectra reveal the relationship between the lattice vibration and the material's structure. There appears a relatively large change in structure of the material at about 273K, The anharmonic potential of the material has a great influence on its phonon mode full width at half maximum (FWHM), which can be expressed by a function of temperature. Theoretical fittings of the FWHMs for the two modes at around 312 cm^-1 and 464cm^-1 indicate that the latter phonon mode is more anharmonic than the former one. 相似文献
55.
无线局域网中基于RC4的加密算法的分析与改进 总被引:2,自引:0,他引:2
分析RC4加密算法自身的缺陷和无线局域网WEP协议对RC4的误用,介绍了TKIP协议在安全性方面的改进。 相似文献
56.
0 Introduction
In this paper, we give another proof of the scattering result of the following Cauchy problem in the energy space 相似文献
57.
Guangyan Jia 《Comptes Rendus Mathematique》2006,342(9):685-688
In this Note, we deal with one-dimensional backward stochastic differential equations (BSDEs) where the coefficient is left-Lipschitz in y (may be discontinuous) and Lipschitz in z, but without explicit growth constraint. We prove, in this setting, an existence theorem for backward stochastic differential equations. To cite this article: G. Jia, C. R. Acad. Sci. Paris, Ser. I 342 (2006). 相似文献
58.
Al-Cu-Fe系初生准晶相凝固过程的电子显微分析 总被引:3,自引:0,他引:3
采用包括金相(OM),粉末X射线衍射(XRD),扫描电子显微镜(SEM)观察和透射电子显微(TEM)分析等方法,研究了铸态Al592.Cu36.8Fe3.0Si1.0合金(700℃保温2.5h后水淬)的显微组织及相组成。发现铸锭中存在4种相:准晶I相,τ3相(或φ相),θ-Al2Cu相和η-AlCu相,凝固过程可描述为:初生晶是准晶Ⅰ相;在保温过程中发生包晶或共晶反应(L+i→τ3(或φ)或L→τ3(或φ)+i)形成的τ3相(或φ相),呈微畴结构;而剩余液体水淬形成θ-Al2Cu相和η-AlCu 相。 相似文献
59.
60.