全文获取类型
收费全文 | 28564篇 |
免费 | 543篇 |
国内免费 | 91篇 |
专业分类
化学 | 15811篇 |
晶体学 | 336篇 |
力学 | 933篇 |
综合类 | 7篇 |
数学 | 3151篇 |
物理学 | 8960篇 |
出版年
2020年 | 274篇 |
2019年 | 276篇 |
2018年 | 354篇 |
2017年 | 325篇 |
2016年 | 585篇 |
2015年 | 439篇 |
2014年 | 544篇 |
2013年 | 1495篇 |
2012年 | 1131篇 |
2011年 | 1277篇 |
2010年 | 821篇 |
2009年 | 774篇 |
2008年 | 1158篇 |
2007年 | 1238篇 |
2006年 | 1119篇 |
2005年 | 1055篇 |
2004年 | 853篇 |
2003年 | 803篇 |
2002年 | 725篇 |
2001年 | 796篇 |
2000年 | 606篇 |
1999年 | 512篇 |
1998年 | 410篇 |
1997年 | 380篇 |
1996年 | 390篇 |
1995年 | 437篇 |
1994年 | 398篇 |
1993年 | 374篇 |
1992年 | 390篇 |
1991年 | 424篇 |
1990年 | 379篇 |
1989年 | 375篇 |
1988年 | 337篇 |
1987年 | 342篇 |
1986年 | 332篇 |
1985年 | 442篇 |
1984年 | 434篇 |
1983年 | 310篇 |
1982年 | 370篇 |
1981年 | 376篇 |
1980年 | 365篇 |
1979年 | 360篇 |
1978年 | 358篇 |
1977年 | 341篇 |
1976年 | 368篇 |
1975年 | 322篇 |
1974年 | 302篇 |
1973年 | 321篇 |
1967年 | 337篇 |
1966年 | 285篇 |
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
1.
Filatova S. M. Guseva M. K. Bodrova T. G. Parshina D. V. Budanova U. A. Sebyakin Yu. L. 《Russian Journal of General Chemistry》2022,91(1):S13-S23
Russian Journal of General Chemistry - The review article traces the main trends of the synthetic approach to the solution of the problem of overcoming the resistance of pathogenic bacterial... 相似文献
2.
The health monitoring has been studied to ensure integrity of design of engine structure by detection, quantification, and prediction of damages. Early detection of faults may allow the downtime of maintenance to be rescheduled, thus preventing sudden shutdown of machines. In cylinder pressure developed, vibrations and noise emissions data provide a rich source of information about condition of engines. Monitoring of vibrations and noise emissions are novel non-intrusive methodologies for which positioning of various transducers are important issue. The presented work shows applicability of these diagnosis methodologies adopted in case of diesel engines. The effects of changing various fuel injection parameters was analyzed. Scope of using non-intrusive technique has been analyzed by changing locations of microphone. Novelty of this worklies in exploring signal processing methods for various locations around the engine test set up. Various frequency ranges of contributing noise and vibration sources were identified. Time-Frequency analysis showed the onset of various cyclic. Based on the identification of various frequency bands, it is possible to device suitable filters in order to extract more information. 相似文献
3.
4.
The energy per particle BA in nuclear matter is calculated up to high baryon density in the whole isospin asymmetry range from symmetric matter to pure neutron matter.The results,obtained in the framework of the Brueckner-Hartree-Fock approximation with two-and three-body forces,confirm the well-known parabolic dependence on the asymmetry parameterβ=(N?Z)/A(β^2 law)that is valid in a wide density range.To investigate the extent to which this behavior can be traced back to the properties of the underlying interaction,aside from the mean field approximation,the spin-isospin decomposition of BA is performed.Theoretical indications suggest that theβ^2 law could be violated at higher densities as a consequence of the three-body forces.This raises the problem that the symmetry energy,calculated according to theβ^2 law as a difference between BA in pure neutron matter and symmetric nuclear matter,cannot be applied to neutron stars.One should return to the proper definition of the nuclear symmetry energy as a response of the nuclear system to small isospin imbalance from the Z=N nuclei and pure neutron matter. 相似文献
5.
6.
7.
Synthesis,Electronic Properties and WOLED Devices of Planar Phosphorus‐Containing Polycyclic Aromatic Hydrocarbons 下载免费PDF全文
Dr. François Riobé Rózsa Szűcs Dr. Pierre‐Antoine Bouit Dr. Denis Tondelier Bernard Geffroy Fátima Aparicio Julia Buendía Prof. Luis Sánchez Prof. Régis Réau Prof. László Nyulászi Prof. Muriel Hissler 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(17):6547-6556
We describe the synthesis and the physical properties of polyaromatic hydrocarbons (PAHs) containing a phosphorus atom at the edge. In particular, the impact of the successive addition of aromatic rings on the electronic properties was investigated by experimental (UV/Vis absorption, fluorescence, cyclic voltammetry) and theoretical studies (DFT). The physical properties recorded in solution and in the solid state showed that the P‐containing PAHs exhibit properties expected for an emitter in white organic light‐emitting diodes (WOLEDs). 相似文献
8.
9.
10.
Dr. Felipe L. Coelho Eduarda S. Gil Dr. Paulo F. B. Gonçalves Dr. Leandra F. Campo Dr. Paulo H. Schneider 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(34):8157-8162
In this work, a series of 2-chalcogenylindoles was synthesized by an efficient methodology, starting from chalcogenoalkynes, including a previously unreported tellurium indole derivative. For the first time, these 2-substituted chalcogenylindoles were obtained in the absence of metal catalyst or base, under thermal conditions only. In addition, the results described herein represent a methodology with inverse regioselectivity for the chalcogen functionalization of indoles. 相似文献