全文获取类型
收费全文 | 61036篇 |
免费 | 10750篇 |
国内免费 | 10249篇 |
专业分类
化学 | 46723篇 |
晶体学 | 1041篇 |
力学 | 3221篇 |
综合类 | 858篇 |
数学 | 6873篇 |
物理学 | 23319篇 |
出版年
2024年 | 195篇 |
2023年 | 1055篇 |
2022年 | 2045篇 |
2021年 | 2159篇 |
2020年 | 2402篇 |
2019年 | 2470篇 |
2018年 | 2159篇 |
2017年 | 2167篇 |
2016年 | 2983篇 |
2015年 | 3126篇 |
2014年 | 3650篇 |
2013年 | 4764篇 |
2012年 | 5413篇 |
2011年 | 5591篇 |
2010年 | 4197篇 |
2009年 | 4189篇 |
2008年 | 4471篇 |
2007年 | 4088篇 |
2006年 | 3872篇 |
2005年 | 3328篇 |
2004年 | 2581篇 |
2003年 | 2150篇 |
2002年 | 2208篇 |
2001年 | 1791篇 |
2000年 | 1565篇 |
1999年 | 1268篇 |
1998年 | 894篇 |
1997年 | 763篇 |
1996年 | 699篇 |
1995年 | 626篇 |
1994年 | 573篇 |
1993年 | 428篇 |
1992年 | 370篇 |
1991年 | 338篇 |
1990年 | 264篇 |
1989年 | 223篇 |
1988年 | 174篇 |
1987年 | 144篇 |
1986年 | 138篇 |
1985年 | 121篇 |
1984年 | 58篇 |
1983年 | 64篇 |
1982年 | 51篇 |
1981年 | 46篇 |
1980年 | 32篇 |
1979年 | 20篇 |
1973年 | 14篇 |
1971年 | 12篇 |
1965年 | 12篇 |
1936年 | 12篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Precise measurement of magnetic moment of short-lived β-emitting nuclei12B ( I π=1+, T 1/2=20.18 ms)
Zhou Dongmei Zheng Yongnan Du Enpeng Xu Yongjun Zhu Jiazheng Yuan Daqing Wang Zhiqiang Luo Hailong Zuo Yi Ma Ruigang Duan Xiao M. Mihara M. Fukuda K. Matsuta T. Minamisono Zhu Shengyun 《中国科学G辑(英文版)》2004,47(5):531-539
The spin polarized β-emitting nuclei12B (I
π=1+,T
1/2=20.18 ms) were produced by the nuclear reaction11B(d, p)12B and by the selection technique of the incident deuteron energy and the12B recoil angle following the nuclear reaction. The nuclear magnetic moment of the short-lived nuclei12B was measured by β-NMR with the β-NMR and β-NQR setup established for the first time in China. The nuclear magnetic moment
of12B was determined to be μ=0.99993±0.00048 nm org=0.99993±0.00048 after the precise correction of the Knight shift. 相似文献
102.
103.
Shu Fen Wang Wen Guo Zou Su Wen Liu Dong Xu Duo Rong Yuan Guang Jun Zhou 《Journal of Physics and Chemistry of Solids》2004,65(7):1243-1245
The photoluminescence properties of the Bi3+ in sol-gel derived ZnTiO3 nanocrystals have been investigated. An ultra-violet emission at 360 nm and a visible emission band at 506 nm have been observed, originating from two kinds of emission centers. The former is ascribed to the 3P1-1S0 transition of Bi3+ and the latter to the recombination of the electrons with the photo-generated holes trapped in the zinc vacancies. In all cases the latter contribution is predominant. 相似文献
104.
105.
106.
107.
Because of package, a single FBG has dual Bragg wavelength. One is sensitive to stress and the other is sensitive to temperature. By using the special mechanism, the wavelengths can be tuned by stress and temperature respectively. 相似文献
108.
单壁碳纳米管的SERS研究 总被引:2,自引:2,他引:0
本文通过改进实验方法,将单壁碳纳米管的乙醇溶液与金胶混合并制作成固体薄膜,使单壁碳纳米管夹裹在金纳米粒子之间,保证了吸附的紧密性,获得了高质量的单壁碳纳米管SERS光谱。不但观测到文献中报道的径向呼吸振动模(RBM)和C-C正切拉伸模(GM)的增强,还在1100-1500cm-1区域观测到一组新峰,其峰形完整并有相当的强度。这些峰在现有的文献中几乎没有报导。文章对这组新峰的出现进行了初步的分析。 相似文献
109.
With the advances in pulsed laser systems, microscopic imaging techniques such as multiphoton and pump-probe fluorescence microscopy have developed into effective tools for investigating intensity and time-resolved phenomena inside biological systems. However, pulsed lasers used in these techniques usually are commercial systems with repetition frequencies of around 80 MHz. While these systems have proven to be adequate for multiphoton and pump-probe microscopic imaging applications, the temporal separation of the laser pulse train (around 12.5 ns) is long compared to the fluorescence lifetimes of many common fluorescence species. In this work, we present the designs of repetition rate multipliers based on passive optical components that can be used to increase the efficiency in multiphoton and pump-probe fluorescence microscopy. Depending on the lifetime of fluorescence molecules under investigation, the passive repetition rate multiplier can increase the duty cycle of multiphoton or pump-probe microscopy up to fourfold. 相似文献
110.
HaiHuiXIE XiaoYiWEI JiDongWANG MeiFangLIU RenZhouYANG 《中国化学快报》2003,14(6):588-590
A New Annonaceous acetogenin,squamostolide(1),was isolated from the seeds of Annona squamosa.Its structure was elucidated based on spectroscopic methods and comparison with known compounds.It is the first example of Annonaceous acetogenin with each of the two ends of the aliphatic chain bearing a γ-lactone.Thenew compound exhibited cytotoxic activity in vitro against bel-7402 and CNE2 human tumor cell lines. 相似文献