全文获取类型
收费全文 | 3132篇 |
免费 | 131篇 |
国内免费 | 24篇 |
专业分类
化学 | 1793篇 |
晶体学 | 22篇 |
力学 | 54篇 |
数学 | 478篇 |
物理学 | 940篇 |
出版年
2023年 | 19篇 |
2022年 | 48篇 |
2021年 | 51篇 |
2020年 | 68篇 |
2019年 | 69篇 |
2018年 | 54篇 |
2017年 | 52篇 |
2016年 | 151篇 |
2015年 | 126篇 |
2014年 | 132篇 |
2013年 | 248篇 |
2012年 | 175篇 |
2011年 | 157篇 |
2010年 | 105篇 |
2009年 | 101篇 |
2008年 | 139篇 |
2007年 | 146篇 |
2006年 | 129篇 |
2005年 | 117篇 |
2004年 | 94篇 |
2003年 | 78篇 |
2002年 | 80篇 |
2001年 | 62篇 |
2000年 | 45篇 |
1999年 | 36篇 |
1998年 | 36篇 |
1997年 | 36篇 |
1996年 | 29篇 |
1995年 | 25篇 |
1994年 | 24篇 |
1993年 | 27篇 |
1992年 | 35篇 |
1991年 | 23篇 |
1990年 | 30篇 |
1989年 | 29篇 |
1988年 | 18篇 |
1987年 | 25篇 |
1986年 | 23篇 |
1985年 | 29篇 |
1984年 | 27篇 |
1983年 | 24篇 |
1982年 | 24篇 |
1981年 | 23篇 |
1980年 | 26篇 |
1979年 | 27篇 |
1978年 | 29篇 |
1976年 | 24篇 |
1975年 | 25篇 |
1974年 | 26篇 |
1969年 | 18篇 |
排序方式: 共有3287条查询结果,搜索用时 468 毫秒
111.
112.
In this paper, we demonstrate how to apply recently discovered ferromagnetic nematic liquid crystal for visualisation of magnetic fields. The material exhibits strong optical response to both external electric and magnetic fields, which gives us an opportunity to use it for the detection of an area of magnetic vector field in a way that both, the magnitude and the direction of a given field can be simultaneously measured. We discuss the physical model that describes the behaviour of ferromagnetic liquid crystal placed in a liquid crystal cell and demonstrate the method of extracting the information about an arbitrary magnetic field from the combination of magneto-optic and electro-optic response of the sample placed in that field. We have applied the principle to a special case, where magnetic field was visualised on a 2D area near a cylindrical permanent magnet. 相似文献
113.
Dr. Anil Reddy Marri Edoardo Marchini Dr. Valentin Diez Cabanes Dr. Roberto Argazzi Dr. Mariachiara Pastore Prof. Stefano Caramori Prof. Carlo Alberto Bignozzi Dr. Philippe C. Gros 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(65):16260-16269
A series of six new Fe(II)NHC-carboxylic sensitizers with their ancillary ligand decorated with functions of varied electronic properties have been designed with the aim to increase the metal-to- surface charge separation and light harvesting in iron-based dye-sensitized solar cells (DSSCs). ARM130 scored the highest efficiency ever reported for an iron-sensitized solar cell (1.83 %) using Mg2+ and NBu4I-based electrolyte and a thick 20 μm TiO2 anode. Computational modelling, transient absorption spectroscopy and electrochemical impedance spectroscopy (EIS) revealed that the electronic properties induced by the dimethoxyphenyl-substituted NHC ligand of ARM130 led to the best combination of electron injection yield and spectral sensitivity breadth. 相似文献
114.
Mesoporous molecular sieve SBA‐15 and conventional silica gel were grafted with 3‐[2‐(diethylamino)ethylamino]propyl groups and used as supports for the preparation of deposited palladium catalysts, which were subsequently evaluated in Stille cross‐coupling reaction of aryl bromides. The highest conversions were achieved with the metal‐saturated catalyst resulting from the modified SBA‐15. Influence of various reaction parameters (solvent, additive, temperature, etc.) on the overall yield and selectivity was studied. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
115.
Mir M. Alavi Nikje Mohammad A. Bigdeli 《Phosphorus, sulfur, and silicon and the related elements》2013,188(7):1445-1448
The solventless oxidation of benzaldehydes to carboxylic acids using oxone/wet-alumina under microwave irradiations is described. 相似文献
116.
117.
118.
119.
120.
We present the comaprative study of semileptonic and leptonic decays of Ds, D±and D0meson(D →M l+-αl-β, D → l+αlβ, D → l+αvα;α,β=e,μ) within the framework of R-parity violating the( Rp) Minimal Supersymmetric Standard Model(MSSM). The comparison shows that combination and product couplings,(λβiα λ* ij qor λβqkλ*αj k)contribution to the branching fractions of the said processes(under consideration) is consistent with or comparable to the experimental measurements in most of the cases. However, some cases exist where these contributions are highly suppressed. We identify such cases in our analysis and single out the important ones suitable for exploring in the future and current experiments. 相似文献