全文获取类型
收费全文 | 14410篇 |
免费 | 1978篇 |
国内免费 | 1583篇 |
专业分类
化学 | 9487篇 |
晶体学 | 213篇 |
力学 | 840篇 |
综合类 | 156篇 |
数学 | 2243篇 |
物理学 | 5032篇 |
出版年
2023年 | 204篇 |
2022年 | 352篇 |
2021年 | 378篇 |
2020年 | 534篇 |
2019年 | 516篇 |
2018年 | 519篇 |
2017年 | 487篇 |
2016年 | 666篇 |
2015年 | 712篇 |
2014年 | 802篇 |
2013年 | 1142篇 |
2012年 | 1247篇 |
2011年 | 1290篇 |
2010年 | 968篇 |
2009年 | 924篇 |
2008年 | 1002篇 |
2007年 | 885篇 |
2006年 | 742篇 |
2005年 | 736篇 |
2004年 | 553篇 |
2003年 | 400篇 |
2002年 | 377篇 |
2001年 | 256篇 |
2000年 | 268篇 |
1999年 | 197篇 |
1998年 | 123篇 |
1997年 | 118篇 |
1996年 | 110篇 |
1995年 | 103篇 |
1994年 | 83篇 |
1993年 | 75篇 |
1992年 | 61篇 |
1991年 | 61篇 |
1990年 | 55篇 |
1989年 | 45篇 |
1988年 | 65篇 |
1986年 | 42篇 |
1985年 | 39篇 |
1984年 | 28篇 |
1983年 | 33篇 |
1982年 | 39篇 |
1981年 | 29篇 |
1980年 | 44篇 |
1979年 | 41篇 |
1978年 | 55篇 |
1977年 | 43篇 |
1976年 | 48篇 |
1975年 | 39篇 |
1974年 | 38篇 |
1968年 | 29篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
J. Mlynár J. Ongena The EFDA JET Contributions I. Duran M. Hron R. Pánek V. Petržílka F. Žáček 《Czechoslovak Journal of Physics》2004,54(3):C28
JET (Joint European Torus) is the largest tokamak in the world and the only fusion facility able to operate with Tritium, the fusion fuel, and Beryllium, the ITER first wall material. JET also features the most complete remote handling equipment for invessel maintenance. As a multinational research center, JET provides logistic experience in preparing for operation of the global facility, tokamak ITER.Experiments on JET are focused on ITER-relevant studies, in particular on detailing the operational scenarios (EL My H-modes and advanced regimes), on enhancing the heating systems, on developing diagnostics for burning plasmas etc. Pioneering real-time control techniques have been implemented that maximize performance and minimize internal disturbances of JET plasmas. In helium plasmas, ion cyclotron heating (ICRH) created fast α-particles, mimicking their populations in future burning plasmas. The recent successful Trace Tritium campaign provided important new data on fuel transport. Current enhancements on JET include a new ITER-like ELM-resilient high power ICRH antenna (7 MW) and over twenty new diagnostics that will further extend the JET scientific capabilities and push the facility even closer to the ITER parameters.A special mention is given to the involvement of the fusion experts from Association EURATOM-IPP.CR, who have been actively participating in the collective use of JET facility for more than three years. 相似文献
52.
53.
ChunXiaLI YingXiaLI LingBoYU HuaZHANG SiftDongCHU HuaShiGUAN 《中国化学快报》2003,14(8):776-778
A convenient synthetic route was developed for the synthesis of the novel glycolipids: 1,2-di-O-acyl-3-O-(2‘-acylamide-2‘-denxy-ct-D-glucopyranosyl)-sn-glycerols. 10 new compounds of glycolipids with different acyl groups were obtained. 相似文献
54.
55.
56.
57.
58.
P. I. H. Bastiaens S. G. Mayhew E. M. O'Naulláin A. van Hoek A. J. W. G. Visser 《Journal of fluorescence》1991,1(2):95-103
Both a mode-locked argon-ion laser and synchrotron radiation were used as excitation sources to obtain time-resolved polarized fluorescence of the two FAD cofactors in electron transferring flavoprotein fromMegasphaera elsdenii. Red-edge excited and blue-edge detected fluorescence anisotropy decay curves did not contain a fast relaxation process which was observed upon mainband excitation and detection. This relaxation was assigned to homo-energy transfer between the two FAD cofactors. Failure of energy transfer as observed with edge spectroscopy on this protein excludes restricted reorientational motion of the flavins as a possible mechanism of depolarization. From the global analysis of the fluorescence anisotropy decay surface obtained at multiple excitation and detection wavelengths, the distance between and the relative orientation of the flavins could be estimated. The methodology described has general applicability in other multichromophoric biopolymers and has the potential to acquire accurate geometrical parameters in these systems. 相似文献
59.
REN QingBao ZHU WeiTing HONG Bo & ZHANG YuHeng Department of Physics Lishui University Lishui China National High Magnetic Field Laboratory University of Science Technology of China Hefei China 《中国科学G辑(英文版)》2007,(3)
Magnetic properties of Nd_(0.5)Sr_(0.5)Mn_(1-x)(Ga_x, Ti_x)O_3 system (0.04≤x≤0.4) were inves- tigated through magnetization and electron spin resonance (ESR) measurements. It was observed that a small amount of Ti substitution for Mn will destroy the charge-ordering (CO) phase completely and induce the cluster-spin-glass phase in the system, which displays a procedure of collapse of CO and of an enhancement of spin ordering (SO) phase. In contrast, the Ga substitution for Mn induces a melt- ing of CO phase in the system. It was observed that with substitution the CO phase is suppressed gradually and the remanent CO phase is retained all the while, and withal, there is a co-existence of AFM CO phase and FM SO at low temperature. In addition, an abrupt rise of magnetization was observed in M-T curves. We attributed this abnormal phenomenon to a transition from canted AFM SO to FM SO in CO region. 相似文献
60.
本文研究了具有中心环域的可积多项式系统,探讨此系统在用多项式进行微扰的情况下,其所对应的Abel积分的零点个数的计算方法,给出了一个较为实用的定理,并举出了若干个应用的例子. 相似文献