全文获取类型
收费全文 | 20496篇 |
免费 | 4143篇 |
国内免费 | 3163篇 |
专业分类
化学 | 15375篇 |
晶体学 | 404篇 |
力学 | 1112篇 |
综合类 | 246篇 |
数学 | 2105篇 |
物理学 | 8560篇 |
出版年
2024年 | 56篇 |
2023年 | 497篇 |
2022年 | 696篇 |
2021年 | 926篇 |
2020年 | 1131篇 |
2019年 | 1082篇 |
2018年 | 903篇 |
2017年 | 887篇 |
2016年 | 1158篇 |
2015年 | 1202篇 |
2014年 | 1438篇 |
2013年 | 1827篇 |
2012年 | 2078篇 |
2011年 | 2119篇 |
2010年 | 1539篇 |
2009年 | 1406篇 |
2008年 | 1510篇 |
2007年 | 1230篇 |
2006年 | 1065篇 |
2005年 | 862篇 |
2004年 | 706篇 |
2003年 | 526篇 |
2002年 | 448篇 |
2001年 | 374篇 |
2000年 | 302篇 |
1999年 | 313篇 |
1998年 | 229篇 |
1997年 | 177篇 |
1996年 | 203篇 |
1995年 | 146篇 |
1994年 | 138篇 |
1993年 | 110篇 |
1992年 | 85篇 |
1991年 | 97篇 |
1990年 | 71篇 |
1989年 | 58篇 |
1988年 | 39篇 |
1987年 | 32篇 |
1986年 | 40篇 |
1985年 | 31篇 |
1984年 | 6篇 |
1983年 | 7篇 |
1982年 | 10篇 |
1981年 | 8篇 |
1980年 | 4篇 |
1978年 | 3篇 |
1969年 | 2篇 |
1959年 | 2篇 |
1957年 | 7篇 |
1936年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 218 毫秒
141.
142.
软x射线近贴显微技术 总被引:1,自引:0,他引:1
软x射线近贴显微技术不但可使活的生物样品成象,分辨率高于光学显微镜,而且人为的样品准备程序在该技术中都可避免。本文描述了用高功率激光打靶产生的等离子体作为软x射线源而进行的近贴显微研究,并得到了分辨率好于1μm的结果。 相似文献
143.
Y. H. Zhang X. H. Zhou Q. Z. Zhao X. F. Sun X. G. Lei Y. X. Guo Z. Liu X. F. Chen Y. T. Zhu S. X. Wen G. J. Yuan X. A. Liu 《Zeitschrift für Physik A Hadrons and Nuclei》1996,355(1):335-336
High spin states of the odd-odd162Lu nucleus have been studied via147Sm(19F,4nγ)162Lu reaction at 95 MeV beam energy. Level scheme for yrast band based onπ[h11/2 v[i13/2] quasiparticle configuration was established up to I π = (23?) for the first time. This band shows the signature inversion in energy before backbending generally appeared in this mass region. It is stressed that the signature splitting in162Lu is larger than that in the160Tm nucleus. 相似文献
144.
145.
注入控制铜蒸气激光方向性时间过程测量 总被引:1,自引:0,他引:1
实验研究了注入控制对铜蒸气激光非稳腔输出光束质量的影响,从输出光发散角时间分辨过程的测量结果说明注入加速被注入腔内激光发散角的减小过程。由于被注入腔内放大自发辐射的存在,为得到较好的注入控制效果,注入光的脉宽和进入被注入腔的延时必须恰当。 相似文献
146.
147.
Y.Y. Sun I. Rusakova R.L. Meng Y. Cao P. Gautier-Picard C.W. Chu 《Physica C: Superconductivity and its Applications》1994,230(3-4):435-442
We have carried out a systematic structural, electric, and magnetic study on Y---Pd---B---C samples with different compositions with emphasis on the as-cast and annealed YPd5B3C0.3 which was first reported to superconduct at 23 K by Cava et al. We found that the tetragonal body-centered YPd2B2C with lattice parameters a=3.71 Å and c=10.81 Å is the phase responsible for the 23 K superconductivity and that YPd2B2C is metastable, which is consistent with the suggestion made by Cava et al. [1]: it is not stable at high temperatures nor stabilizable by Ni doping, although its isostructural compound, YNi2B2C, exists. Two new phases with Y:Pd ratios of 1:7 and 2:3, respectively, have also bee detected. 相似文献
148.
149.
Liu Yuren Lu Yanxin Xie Yali Wang Yonghai Du Youling Tan Jin Meng Bonian R. S. Seymour 《Journal of Radioanalytical and Nuclear Chemistry》1991,151(1):83-93
This paper introduces the principles, instrumentation, implementation, and industrial applications of an on-line thermal neutron prompt-gamma element analysis system (using a252Cf neutron source, Am–Be neutron source, or neutron generator). The energy resolution of the system at the H prompt-gamma full-energy photopeak (2.22325 MeV) is 3.6 keV. The concentration measurement error of Al2O3, FeO3, CaO, and SiO2 is ±0.3%, ±0.1%, ±0.4%, and ±0.4%, respectively. The system has been tested on-site at both the Shandong and the Zhengzhou Aluminium Works. Our preliminary on-site measurements confirm that the stability, reliability, measurement range, and accuracy of the system can meet the requirements of the aluminium production process. Facilitation of this measurement at aluminium plants is expected to reduce plant costs by over 3 million dollars annually through reduced energy consumption, more rapid qualification of pulps being mixed during the production process, and in reduced labor costs.Other participants of Shandong and Zhenghou Aluminium Works are: Wang Aili, Zengshen, Dei Jianguo and Lu Jinnan, Wang Deyu, Jin Hequan. 相似文献
150.
Wei‐Lie Xiao Jian‐Xin Pu Rui‐Rui Wang Liu‐Meng Yang Xiao‐Li Li Sheng‐Hong Li Rong‐Tao Li Sheng‐Xiong Huang Yong‐Tang Zheng Han‐Dong Sun 《Helvetica chimica acta》2007,90(8):1505-1513
Seven new highly oxygenated nortriterpenoids, rubriflorins D–J ( 1 – 7 ), were isolated from the leaves and stems of Schisandra rubriflora, and their structures were elucidated on the basis of extensive analysis of spectroscopic data. These new compounds feature the opening of ring A compared with related known nortriterpenoids isolated from the genus Schisandra and showed weak activity against HIV‐1. 相似文献