全文获取类型
收费全文 | 296784篇 |
免费 | 3544篇 |
国内免费 | 1078篇 |
专业分类
化学 | 162550篇 |
晶体学 | 4485篇 |
力学 | 12857篇 |
综合类 | 10篇 |
数学 | 30223篇 |
物理学 | 91281篇 |
出版年
2021年 | 1898篇 |
2020年 | 2172篇 |
2019年 | 2254篇 |
2018年 | 2669篇 |
2017年 | 2736篇 |
2016年 | 4616篇 |
2015年 | 3278篇 |
2014年 | 4537篇 |
2013年 | 13007篇 |
2012年 | 10321篇 |
2011年 | 12795篇 |
2010年 | 8431篇 |
2009年 | 8612篇 |
2008年 | 12036篇 |
2007年 | 11814篇 |
2006年 | 11451篇 |
2005年 | 10567篇 |
2004年 | 9486篇 |
2003年 | 8468篇 |
2002年 | 8303篇 |
2001年 | 10502篇 |
2000年 | 7833篇 |
1999年 | 6017篇 |
1998年 | 4396篇 |
1997年 | 4500篇 |
1996年 | 4343篇 |
1995年 | 3929篇 |
1994年 | 3805篇 |
1993年 | 3523篇 |
1992年 | 4249篇 |
1991年 | 4308篇 |
1990年 | 3935篇 |
1989年 | 3866篇 |
1988年 | 3867篇 |
1987年 | 3795篇 |
1986年 | 3547篇 |
1985年 | 4844篇 |
1984年 | 4841篇 |
1983年 | 3916篇 |
1982年 | 4081篇 |
1981年 | 3834篇 |
1980年 | 3754篇 |
1979年 | 3971篇 |
1978年 | 4126篇 |
1977年 | 4059篇 |
1976年 | 3904篇 |
1975年 | 3774篇 |
1974年 | 3673篇 |
1973年 | 3789篇 |
1972年 | 2342篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
131.
C. W. LEUNG Department of Mathematics The Chinese Universityof Hong Kong Shatin. N. T. Hong Kong China. 《数学年刊B辑(英文版)》1997,(1)
ASTRASSENLAWOFTHEITERATEDLOGARITHMFORPROCESSESWITHINDEPENDENTINCREMENTWangJiagangAbstractLetX={X(t),t0}beaproceswithindep... 相似文献
132.
133.
134.
135.
136.
A. J. Parsons S. D. J. Inglethorpe D. J. Morgan A. C. Dunham 《Journal of Thermal Analysis and Calorimetry》1997,48(1):49-62
Using a system based on non-dispersive infrared (NDIR) detectors, evolved gas analysis (EGA) was able to identify and quantify the principal volatiles produced by heating powdered samples of UK brick clays. From these results, atmospheric emissions likely to result from brick production can be predicted. In addition, EGA results for extruded brick clay test pieces are significantly different from those of powdered samples. Within an extruded brick clay body, evolved gases are contained within a pore system and evolved gas-solid phase reactions also occur. This EGA study provides further evidence on the nature of firing reactions within brick clay bodies. The qualitative and quantitative influence of heating rate — a key process condition in brick manufacture — on gas release is also outlined.Dedicated to Dr. Robert Mackenzie on the occasion of his 75th birthday 相似文献
137.
I. L. Eremenko M. A. Golubnichaya S. E. Nefedov A. A. Sidorov D. A. Nesterenko N. P. Konovalova L. M. Volkova L. T. Eremenko 《Russian Chemical Bulletin》1997,46(9):1595-1598
Thetrans-[Pt(NC5H4C(O)NHC2H4ONO2)2Cl2] complex (2) was prepared by the reaction of nicorandyl (N-nitroethoxynicotinamide), which is widely used in cardiology, with K2PtCl4 in water. The structure of2 was established by X-ray structural analysis. It was found that complex2 exhibits high antitumor activity, in particular, antimetastatic activity, unlike the analogous CuII complex with bromine atoms.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1672–1675, September, 1997. 相似文献
138.
R.C. Viscovini E.M. Telles A. Scalabrin D. Pereira 《Applied physics. B, Lasers and optics》1997,65(1):33-35
2 laser of wide tunability to pump 13CD3OD we could observe 10 new far infrared laser lines ranging from 109 μm to 472 μm. The lines were generated by pumping infrared
absorbing transitions of large offset appertaining to the C-O stretching Q-branch. All lines were characterised in wavelength,
polarisation, optimum pressure of operation and precise offset measurements.
Received: 17 September 1996/Revised version: 18 November 1996 相似文献
139.
S. A. Gurevich T. A. Zaraiskaya S. G. Konnikov V. M. Mikushkin S. Yu. Nikonov A. A. Sitnikova S. E. Sysoev V. V. Khorenko V. V. Shnitov Yu. S. Gordeev 《Physics of the Solid State》1997,39(10):1691-1695
The concentration and chemical state of copper in the subsurface region of Cu/SiO2 composite films obtained by simultaneous magnetron sputtering from two sources (Cu and SiO2) are determined by x-ray photoelectron spectroscopy (XPS). It is established that copper in the as-grown film is primarily in the form of unoxidized atoms dispersed in a SiO2 matrix. Annealing of the film results in practically no oxidation, but about 70% of the copper atoms condense into metallic clusters with sizes below 10 Å in the subsurface region and about 50 Å in the bulk of the film. The changes in the binding energy of core electrons, and especially in the energies of Auger electrons, are so large in this situation that photoelectron and Auger spectroscopy are efficient methods for monitoring the chemical state of this composite material. 相似文献
140.
Ya. V. Fattakhov M. F. Galyautdinov T. N. L’vova I. B. Khaibullin 《Technical Physics》1997,42(12):1457-1459
The first results regarding the formation of a two-dimensional periodic structure of local melting regions on a silicon surface
upon pulsed light irradiation are presented. The conditions are established, and the mechanism of the formation of such structures
is discussed.
Zh. Tekh. Fiz. 67, 97–99 (December 1997) 相似文献