全文获取类型
收费全文 | 23730篇 |
免费 | 3878篇 |
国内免费 | 2351篇 |
专业分类
化学 | 13193篇 |
晶体学 | 180篇 |
力学 | 1043篇 |
综合类 | 68篇 |
数学 | 2033篇 |
物理学 | 7565篇 |
无线电 | 5877篇 |
出版年
2024年 | 106篇 |
2023年 | 630篇 |
2022年 | 791篇 |
2021年 | 1006篇 |
2020年 | 895篇 |
2019年 | 895篇 |
2018年 | 867篇 |
2017年 | 733篇 |
2016年 | 1124篇 |
2015年 | 1088篇 |
2014年 | 1343篇 |
2013年 | 1712篇 |
2012年 | 2068篇 |
2011年 | 2078篇 |
2010年 | 1475篇 |
2009年 | 1376篇 |
2008年 | 1493篇 |
2007年 | 1336篇 |
2006年 | 1243篇 |
2005年 | 1052篇 |
2004年 | 781篇 |
2003年 | 576篇 |
2002年 | 551篇 |
2001年 | 438篇 |
2000年 | 398篇 |
1999年 | 534篇 |
1998年 | 399篇 |
1997年 | 373篇 |
1996年 | 372篇 |
1995年 | 317篇 |
1994年 | 278篇 |
1993年 | 263篇 |
1992年 | 193篇 |
1991年 | 199篇 |
1990年 | 151篇 |
1989年 | 120篇 |
1988年 | 109篇 |
1987年 | 75篇 |
1986年 | 76篇 |
1985年 | 62篇 |
1984年 | 63篇 |
1983年 | 31篇 |
1982年 | 35篇 |
1981年 | 25篇 |
1980年 | 28篇 |
1978年 | 14篇 |
1976年 | 17篇 |
1975年 | 15篇 |
1973年 | 16篇 |
1968年 | 14篇 |
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
41.
42.
D. Fong J. H. Hamilton A. V. Ramayya J. K. Hwang C. Goodin K. Li J. Kormicki J. O. Rasmussen Y. X. Luo S. C. Wu I. Y. Lee A. V. Daniel G. M. Ter-Akopian G. S. Popeko A. S. Fomichev A. M. Rodin Yu. Ts. Oganessian M. Jandel J. Kliman L. Krupa J. D. Cole M. A. Stoyer R. Donangelo W. C. Ma 《Physics of Atomic Nuclei》2006,69(7):1161-1167
The hot bimodal fission of 252Cf is reexamined with new high-statistics data. We constructed a γ-γ-γ coincidence cube for binary fission and LCP-gated γ-γ matrix for ternary fission. By identifying the secondary fission fragments from their γ-ray transitions, we measured the yields for various fission splits. The normal neutron yield distribution is found to be
Gaussian for Xe-Ru. However, the binary fission split of Ba-Mo is found to exhibit a bimodal neutron distribution with the
“hot mode” corresponding to ≈3.1% of the total yield. In α ternary fission, the first measurements of yields for specific fission splits are presented. The Te-α-Ru and Xe-α-Mo neutron yields fit well with a single mode, but the Ba-α-Zr split shows evidence for an enhanced hot mode with an intensity of ≈13.8% of the normal mode.
The text was submitted by the authors in English. 相似文献
43.
44.
45.
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
46.
BaXO4 (X = Mo, W) nanobelts and a variety of hierarchical superstructures assembled from the nanobelts have been synthesized in a catanionic reverse‐micelle system. The effects of various factors, such as the mixing ratio (r) between the anionic and cationic surfactants, the temperature, and the presence of polymeric additives, on the formation of the nanobelts and their hierarchical assembly have been examined in detail. In particular, r has been shown to be powerful in modulating the formation and assembly of the BaMoO4 and BaWO4 nanobelts. Architectural control of the penniform nanobelt superstructures has been readily achieved by changing the experimental parameters. A plausible two‐stage growth mechanism has been proposed for the formation of penniform BaXO4 nanobelt superstructures in catanionic reverse micelles. 相似文献
47.
质子交换铌酸锂波导MMI光功分器 总被引:1,自引:1,他引:0
利用三维非旁轴近似光束传输法对退火质子交换铌酸锂渐变折射率分布波导中的自镜像效应进行分析与模拟 .在此基础上 ,利用退火质子交换技术在 X切 Y传铌酸锂衬底上进一步制作了 1× 8MMI光功分器 .测试表明器件实现了 1路分成 8路的光功分功能 . 相似文献
48.
The properties of pulsed laser vapor doping on p-Si(1 0 0) with a KrF (248 nm) excimer pulsed laser (248 nm) and BCl3 gas are reported in this paper. The doped samples are characterized by the resistance measured using a four-probe method, since the sheet resistance changes with the carrier concentration of the sample. The doping effects with the variation of laser energy density, pulse number, and the pressure of BCl3 were investigated in terms of the sheet resistance. In this way, the optimized parameters were obtained and used for the positive heavy doping on p-Si(1 0 0) and p-Si(1 1 1). Then, using a square mesh under the above conditions, an image doping was completed. Finally, the metal–semiconductor Ohmic contacts were realized by plating Ag and Cu films on the doped surface. 相似文献
49.
Lower-dimensional linear complementarity problem approaches to the solution of a bi-obstacle problem
A globally convergent Broyden-like method for solving a bi-obstacle problem is proposed based on its equivalent lower-dimensional linear complementarity problem. A suitable line search technique is introduced here. The global and superlinear convergence of the method is verified under appropriate assumptions. 相似文献
50.
1689-nm diode lasers used in medical apparatus have been fabricated and characterized. The lasers had pnpn InP current confinement structure, and the active region consisted of 5 pairs of InGaAs quantum wells and InGaAsP barriers. 相似文献