全文获取类型
收费全文 | 7368篇 |
免费 | 380篇 |
国内免费 | 109篇 |
专业分类
化学 | 5643篇 |
晶体学 | 40篇 |
力学 | 393篇 |
数学 | 731篇 |
物理学 | 1050篇 |
出版年
2024年 | 10篇 |
2023年 | 53篇 |
2022年 | 262篇 |
2021年 | 355篇 |
2020年 | 368篇 |
2019年 | 372篇 |
2018年 | 373篇 |
2017年 | 361篇 |
2016年 | 490篇 |
2015年 | 347篇 |
2014年 | 455篇 |
2013年 | 835篇 |
2012年 | 633篇 |
2011年 | 556篇 |
2010年 | 358篇 |
2009年 | 346篇 |
2008年 | 346篇 |
2007年 | 295篇 |
2006年 | 204篇 |
2005年 | 174篇 |
2004年 | 119篇 |
2003年 | 117篇 |
2002年 | 95篇 |
2001年 | 32篇 |
2000年 | 17篇 |
1999年 | 26篇 |
1998年 | 18篇 |
1997年 | 21篇 |
1996年 | 21篇 |
1995年 | 10篇 |
1994年 | 14篇 |
1993年 | 10篇 |
1992年 | 13篇 |
1991年 | 10篇 |
1990年 | 9篇 |
1989年 | 8篇 |
1988年 | 5篇 |
1987年 | 14篇 |
1986年 | 5篇 |
1985年 | 12篇 |
1984年 | 13篇 |
1982年 | 14篇 |
1981年 | 7篇 |
1980年 | 14篇 |
1979年 | 6篇 |
1978年 | 8篇 |
1977年 | 4篇 |
1976年 | 5篇 |
1973年 | 3篇 |
1971年 | 3篇 |
排序方式: 共有7857条查询结果,搜索用时 15 毫秒
931.
932.
933.
934.
935.
M. Yasin Akhtar Raja Wade N. Sisk Mohammad Yousaf David Allen 《Applied physics. B, Lasers and optics》1996,64(1):79-84
Experimental investigations of the photon’s B
(3)-field (third longitudinal polarization) are reported. The existence of an “axial magnetostatic field of photon” has been
predicted in B
π or B
(3)-theory as the fundamental property of the circularly polarized light, and reported in numerous papers and monographs. High-sensitivity
detection has been employed in photomagnetic induction, Faraday, and inverse Faraday effects (IFE) originating from such a
field. The results of all three experiments clearly disprove the claims of B
π-theory. Putting together these results and theoretical calculations in perspective, it is concluded that such fields are
non-existent.
Received: 25 January 1996 / Revised version: 24 May 1996 相似文献
936.
Peyman SalehiMohammad Ali Zolfigol Mohammad Ali Bodaghi Fard 《Tetrahedron letters》2003,44(14):2889-2891
Silica sulfuric acid efficiently catalyzes the three-component Biginelli reaction between an aldehyde, a β-dicarbonyl compound and urea or thiourea in refluxing ethanol to afford the corresponding dihydropyrimidinones in high yields. The catalyst is reusable and can be applied several times without any decrease in the yield of the reactions. 相似文献
937.
We propose an optical H-tree structure to distribute a clock signal onto 16 electronic chips at 1 Gb/s for a clock skew and timing jitter of less than 100 ps. Fabrication steps and performance results are presented. 相似文献
938.
Khan Tahir Ali Hasan Syed Sirajul Varkey Saji P. Rather Manzoor Ahmad Jahan Nafees Shakir Mohammad 《Transition Metal Chemistry》1997,22(1):4-8
A new class of tetraiminetetraamide macrocyclic (Ph4[20]tetraene, N8O4, and Ph6[20]tetraene, N8O4) complexes have been prepared through the metal ion controlled reaction of 1,2-diphenylethane-1,2-dione dihydrazone (DPEDDH) with succinic acid [ML1X2] or phthalic acid [ML2X2] [M=Mn, Co, Ni, Cu or Zn; X=Cl or NO3]. The structures of the complexes have been elucidated on the basis of i.r, 1H-n.m.r, e.p.r. and electronic spectral data and conductance, as well as magnetic, properties. An octahedral geometry is assigned for all the complexes, involving coordination of the all-imine nitrogens. 相似文献
939.
Mohammad A. Mottaleb B. G. Cooksey David Littlejohn 《Fresenius' Journal of Analytical Chemistry》1997,358(4):536-538
A heated gas flow modified thermospray was used to couple gel permeation chromatography (GPC) to Fourier transform infrared
spectrometry (FTIR) for the analysis of the standard polystyrene samples. Effluents from the GPC column were evaporated and
the solutes were deposited as a series of spots on the surface of a moving stainless steel belt (0.025 mm thickness × 13 mm
width). The belt continuously transferred the spots into the diffuse reflectance (DRIFT) accessory of the FTIR spectrometer,
enabling identification of the deposited solutes by measurement of the diffuse reflectance IR spectrum. The IR spectra of
the separated components showed excellent agreement of the spectral features to those of standard FTIR spectra and no thermal
degradation was observed.
Received: 20 May 1996 / Revised: 17 October 1996 / Accepted: 28 November 1996 相似文献
940.
Recent measurements of differential and elastic cross-sections, slope parameters and ratios of the real and imaginary parts
of the forward scattering amplitudes for pion-proton elastic scattering at 200 GeV/c have been fitted by using a simple Regge
pole model with phenomenological residue functions. The computed results for total cross-sections have also been compared
with the experimental data. 相似文献