全文获取类型
收费全文 | 580830篇 |
免费 | 26337篇 |
国内免费 | 17958篇 |
专业分类
化学 | 286159篇 |
晶体学 | 8486篇 |
力学 | 34636篇 |
综合类 | 38篇 |
数学 | 84605篇 |
物理学 | 211201篇 |
出版年
2021年 | 5440篇 |
2020年 | 6027篇 |
2019年 | 7619篇 |
2018年 | 10403篇 |
2017年 | 11134篇 |
2016年 | 14133篇 |
2015年 | 8221篇 |
2014年 | 12979篇 |
2013年 | 25813篇 |
2012年 | 21364篇 |
2011年 | 25523篇 |
2010年 | 22418篇 |
2009年 | 23101篇 |
2008年 | 22718篇 |
2007年 | 21828篇 |
2006年 | 19856篇 |
2005年 | 17961篇 |
2004年 | 18164篇 |
2003年 | 16227篇 |
2002年 | 16220篇 |
2001年 | 16986篇 |
2000年 | 13136篇 |
1999年 | 10777篇 |
1998年 | 9556篇 |
1997年 | 9159篇 |
1996年 | 8845篇 |
1995年 | 8302篇 |
1994年 | 8567篇 |
1993年 | 8547篇 |
1992年 | 8440篇 |
1991年 | 8613篇 |
1990年 | 8089篇 |
1989年 | 8221篇 |
1988年 | 7777篇 |
1987年 | 7135篇 |
1986年 | 6850篇 |
1985年 | 8041篇 |
1984年 | 8383篇 |
1983年 | 6798篇 |
1982年 | 7409篇 |
1981年 | 6958篇 |
1980年 | 6459篇 |
1979年 | 7007篇 |
1978年 | 7294篇 |
1977年 | 7536篇 |
1976年 | 7792篇 |
1975年 | 6877篇 |
1974年 | 6690篇 |
1973年 | 7071篇 |
1972年 | 5764篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
951.
We again consider the problem of the light-cone expansion for products of currents and explain the motivations making a rethinking of old results relevant today. 相似文献
952.
953.
G.N Hile Alexander Stanoyevitch 《Journal of Mathematical Analysis and Applications》2004,295(2):595-610
We generalize the heat polynomials for the heat equation to more general partial differential equations, of higher order with respect to both the time variable and the space variables. Whereas the heat equation requires only one family of polynomials, for an equation of the ?th order with respect to time we introduce ? families of polynomials. These families correspond to the ? initial conditions specified by the Cauchy problem. 相似文献
954.
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
955.
I. Antoniou M. Gadella J. Mateo G.P. Pronko 《International Journal of Theoretical Physics》2003,42(10):2389-2402
Through two examples: the Friedrichs model and a particular case of central potential scattering, we illustrate the way of constructing Gamow vectors. 相似文献
956.
Yu. V. Sanochkin 《Technical Physics》2003,48(5):546-551
It is shown that, along with gravity waves, surface and internal waves caused by van der Waals forces may exist in a liquid
with a horizontal free surface. A dispersion relation is found by using the stepwise approximation for the coefficients of
a wave equation derived for these waves. The surface waves are similar to surface gravity waves in dispersion and amplitude
distribution but differ in frequency by several orders of magnitude. Another sequence of roots in the spectrum corresponds
to internal van der Waals waves that have an upper frequency bound and the dispersion law typical of a multimode waveguide. 相似文献
957.
Salimgareeva V. N. Polevoi R. M. Kolesov S. V. Ostakhov S. S. Ponomareva V. A. Leplyanin G. V. 《Russian Journal of Applied Chemistry》2003,76(5):804-808
The luminescence and scintillation properties of poly(methyl methacrylate) containing 1,1,3-trimethyl-3-phenylindan were studied. 相似文献
958.
The known plant growth regulator, Al'den [1-(3,7-dimethyloctyl)-1-allylpiperidinium bromide], and also 1-(3,7-dimethyloctyl)-1-methylpiperidinium iodide were synthesized by treatment with allyl bromide and methyl iodide, respectively, of exhaustively hydrogenated 1-nerylpiperidine which was obtained by anionic telomerization of isoprene with piperidine. Various quaternary ammonium salts having a terpene sub- stituent with unnatural dimethyloctane skeleton, which effectively stimulate florification of Aster Chinensis L., were prepared by the action of alkyl halides on telomerization products derived from isoprene and piperidine or morpholine in the presence of palladium complexes. 相似文献
959.
S. S. Andreev A. D. Akhsakhalyan M. A. Bibishkin N. I. Chkhalo S. V. Gaponov S. A. Gusev E. B. Kluenkov K. A. Prokhorov N. N. Salashchenko F. Schafers S. Yu. Zuev 《Central European Journal of Physics》2003,1(1):191-209
We present research investigations in the field of multilayer optics in X-ray and extreme ultra-violet ranges (XUV), aimed
at the development of optical elements for applications in experiments in physics and in scientific instrumentation. We discuss
normal incidence multilayer optics in the spectral region of “water window”, multilayer optics for collimation and focusing
of hard X-ray, multilayer dispersing elements for X-ray spectroscopy of high-temperature plasma, multilayer dispersing elements
for analysis of low Z-elements. Our research pays special attention to optimization of multilayer optics for projection EUV-lithography
(ψ-13nm) and short period multilayer optics. 相似文献
960.
M.V. Nazarov J.H. Kang E.-J. Popovici B.S. Tsukerblat 《Solid State Communications》2005,133(3):183-186
Samples of yttrium oxide doped with trivalent europium have been prepared by ceramic techniques, under different synthesis conditions; barium chloride (BaCl2) and sodium tetraborate (Na2B4O7) were tested as flux. The improvement of luminescence properties in dependence on substitution of Eu3+ for Y3+ in the host lattice, under electron and UV excitations is demonstrated. The lattice parameter as a quantitative assessment of activator incorporation degree is proposed. The obtained results are discussed with respect to the employed processing method. 相似文献