全文获取类型
收费全文 | 44465篇 |
免费 | 1404篇 |
国内免费 | 148篇 |
专业分类
化学 | 24246篇 |
晶体学 | 218篇 |
力学 | 1230篇 |
综合类 | 5篇 |
数学 | 7328篇 |
物理学 | 12990篇 |
出版年
2023年 | 301篇 |
2021年 | 413篇 |
2020年 | 590篇 |
2019年 | 467篇 |
2018年 | 624篇 |
2017年 | 600篇 |
2016年 | 1245篇 |
2015年 | 975篇 |
2014年 | 1110篇 |
2013年 | 2250篇 |
2012年 | 2192篇 |
2011年 | 2359篇 |
2010年 | 1514篇 |
2009年 | 1263篇 |
2008年 | 2143篇 |
2007年 | 1987篇 |
2006年 | 1864篇 |
2005年 | 1686篇 |
2004年 | 1471篇 |
2003年 | 1184篇 |
2002年 | 1028篇 |
2001年 | 899篇 |
2000年 | 746篇 |
1999年 | 526篇 |
1998年 | 461篇 |
1997年 | 440篇 |
1996年 | 555篇 |
1995年 | 487篇 |
1994年 | 523篇 |
1993年 | 538篇 |
1992年 | 592篇 |
1991年 | 420篇 |
1990年 | 424篇 |
1989年 | 379篇 |
1988年 | 344篇 |
1987年 | 366篇 |
1986年 | 321篇 |
1985年 | 528篇 |
1984年 | 503篇 |
1983年 | 414篇 |
1982年 | 453篇 |
1981年 | 442篇 |
1980年 | 448篇 |
1979年 | 422篇 |
1978年 | 411篇 |
1977年 | 408篇 |
1976年 | 379篇 |
1975年 | 374篇 |
1974年 | 362篇 |
1973年 | 302篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
The Kα to Lα and Kβ to Lβ intensity ratios of seven elements have been measured following photoionization at 59.5 keV by using a Si (Li) detector
(FWHM=155 eV at 5.96 keV). The intensity ratios were determined by measuring K and L x-rays emitted from a standard target of a given element. The theoretical values of the Kα to Lα and Kβ to Lβ intensity ratios were calculated using theoretically tabulated values of shell/subshell photoionization cross sections,
fluorescence yields, Coster-Kronig transition probabilities, and radiative decay rates for ηKLi≠ and ηKLi=0. The measured values are in good agreement with theoretical results.
From Optika i Spektroskopiya, Vol. 97, No. 2, 2004, pp. 186–189.
Original English Text Copyright ? 2004 by A. Kü?ük?nder, S?ğüt, E. Kü?ük?nder, Büyükkasap.
This article was submitted by the authors in English. 相似文献
32.
33.
Günter F. Steinke 《Journal of Geometry》2007,87(1-2):160-178
34.
The growth mechanism of the peritectic η phase involving the peritectic reaction and peritectic transformation in Cu-70%Sn alloy was investigated under directional
solidification. The results show that a major growth mechanism in thickening of the peritectic η-layer is not the peritectic reaction but the peritectic transformation. The transformation temperature and isothermal time
play crucial roles in determining the volume fraction and the thickness of the peritectic η phase. With the increase of the temperature and isothermal time, the volume fraction of the peritectic η phase increases. The regressed data show that the relationship between the thickness of η phase (Δx) and the transformation temperature (T) meets the following equation In Δx=6.5−1673 1 / T. Additionally, there exists a relationship between the thickness of the η phase (Δx) and the isothermal time (t) at the 9 mm solidification distance below the peritectic reaction interface, Δx=0.72t
1/2, which is consistent with the theoretical model.
Supported by the National Science Foundation of China (Grant No. 50395102) 相似文献
35.
Montgomery and Vaughan improved a theorem of Erd?s and Fuchs for an arbitrary sequence. Sárközy extended this theorem of Erd?s and Fuchs for two arbitrary sequences which are "near" in a certain sense. Using the idea of Jurkat (differentiation of the generating function), we will extend similarly the result of Montgomery and Vaughan for "sufficiently near" sequences. 相似文献
36.
The aim of this paper is to give decompositions of some weaker forms of continuity using the concepts of classes B 1, B 2, B 3, αA and αC introduced by ourselves. 相似文献
37.
Celik Tarimci Anda? Karamustafa Kutalmi? Güven Mehmet Kabak Akgül Ye?ilada 《Analytical sciences》2003,19(9):1347-1348
The crystal structure of 1-[3-(3,4-dimethoxyphenyl)-2-propenoyl]pyrrolidine (C15H19NO3) (I) has been determined by X-ray analysis. It crystallizes orthorhombic space group Pbca with a = 24.295(3), b = 15.086(3), c = 7.552(3)A, V = 2768(1)A3, Z = 8, Dcalc = 1.254 g/cm3, mu = (Mo K(alpha)) = 0.87 cm(-1). The title compound has analgesic activity of cycloaliphatic amine part. The molecule is deviated from planar configuration. 相似文献
38.
39.
G. Baldsiefen H. Hübel W. Korten U. J. van Severen J. A. Cizewski N. H. Medina D. R. Napoli C. Rossi Alvarez G. Lo Bianco S. Signorelli 《Zeitschrift für Physik A Hadrons and Nuclei》1996,355(1):337-338
High-spin states in196Pb have been populated using the reaction170Er(30Si,4n). The previously observed shears bands in this nucleus have been extended and some of their transitions have been reordered. They now form regular bands with band crossings. One of the bands splits into two pathways at high spin. 相似文献
40.
F. Grisch P. Bouchardy M. Péalat B. Chanetz T. Pot M. C. Coët 《Applied physics. B, Lasers and optics》1993,56(1):14-20
Rotational temperature and nitrogen number density are measured in the shock wave/boundary layer interaction region in the vicinity of a two-dimensional compression corner disposed in a low pressure, 55 K, Mach 10 hypersonic air flow. Spatially-resolved data are recorded using a nonlinear optical technique named dual-line coherent anti-Stokes Raman scattering (DLCARS). Averaged temperature and density profiles are compared with those predicted by a Navier-Stokes solver. Good agreement is found. 相似文献