全文获取类型
收费全文 | 268篇 |
免费 | 5篇 |
专业分类
化学 | 210篇 |
晶体学 | 2篇 |
力学 | 3篇 |
数学 | 35篇 |
物理学 | 23篇 |
出版年
2022年 | 6篇 |
2021年 | 6篇 |
2020年 | 7篇 |
2019年 | 8篇 |
2018年 | 6篇 |
2017年 | 7篇 |
2016年 | 8篇 |
2015年 | 8篇 |
2014年 | 5篇 |
2013年 | 17篇 |
2012年 | 8篇 |
2011年 | 8篇 |
2010年 | 10篇 |
2009年 | 9篇 |
2008年 | 12篇 |
2007年 | 12篇 |
2006年 | 10篇 |
2005年 | 11篇 |
2004年 | 11篇 |
2003年 | 4篇 |
2002年 | 3篇 |
2001年 | 6篇 |
2000年 | 3篇 |
1998年 | 3篇 |
1997年 | 5篇 |
1995年 | 3篇 |
1993年 | 3篇 |
1992年 | 5篇 |
1989年 | 5篇 |
1985年 | 5篇 |
1984年 | 4篇 |
1982年 | 5篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1976年 | 5篇 |
1975年 | 1篇 |
1974年 | 3篇 |
1973年 | 2篇 |
1971年 | 2篇 |
1970年 | 7篇 |
1969年 | 2篇 |
1968年 | 5篇 |
1967年 | 2篇 |
1965年 | 2篇 |
1964年 | 1篇 |
1962年 | 1篇 |
1895年 | 1篇 |
排序方式: 共有273条查询结果,搜索用时 31 毫秒
141.
142.
Robert Musiol Barbara Podeszwa Jacek Finster Halina Niedbala Jaroslaw Polanski 《Monatshefte für Chemie / Chemical Monthly》2006,118(2):1211-1217
Aromatic aldehydes undergo condensation with quinaldines under microwave irradiation to afford structurally diverse styrylquinolines
in high yields under solvent-free conditions. A comparison with the conventional method clearly indicates the advantages of
the new protocol. 相似文献
143.
144.
Structural Chemistry - Numerous studies on nitro group properties are associated with its high electron-withdrawing ability, by means of both resonance and inductive effect. The substituent effect... 相似文献
145.
H‐bonded complexes of p‐X‐PhOH/p‐X‐PhO? with fluoride and hydrofluoric acid (X = OH, H, NO2) were subject of optimization (by means of B3LYP/6‐311+G**) for gradually changed O···F distance from dO···F = 4.0 Å down to (i) the distance of the proton transfer from the hydroxyl group to fluoride leading to O?···HF interaction and (ii) fully optimized system (O?···HF type). In this way, we simulate gradual changes of H‐bond strength estimating simultaneously the energy of interaction, Eint, energy of deformation, Edef, and the binding energy, Etot. The obtained geometrical parameters allow us to show that H‐bond formation causes substantial changes in geometry, even at so distant parts of the system as the ring and bond length in para‐substituents (OH and NO2). All these changes are monotonically dependent on interaction and deformation energies. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
146.
Stanimira D. Terzieva Angelina K. Stoyanova-Ivanova Boris L. Shivachev Bonka M. Terzijska Andrzej J. Zaleski Halina Misiorek Valdek Mikli 《Central European Journal of Physics》2009,7(1):84-88
Sintering effects in YBa2Cu3Oz samples with quasi-equal rare earth substitution have been investigated. It has been shown that the Y-123 type compound can
be formed when gadolinium is partially substituted (in this case 50% atomic substitution) for yttrium. The superconducting
compound was obtained by the optimized ceramic method, including solid-state reaction, melting and sintering, controlled by
X-ray diffraction. The microstructure was investigated by SEM and energy dispersive X-ray analyses. An AC susceptibility measurement
has shown that T
c
=93 K. Temperature-dependece of the thermal conductivity (4.5–300 K) of the polycrystalline Y0.5Gd0.5Ba2Cu3O6.94 sample was also measured.
相似文献
147.
148.
Summary: Surface properties of poly(vinyl alcohol) (PVA) with low content of FeCl3 (1, 5 wt.%) were studied by measurements of contact angles and atomic force microscopy. The results of contact angles and the surface free energy calculations revealed that the hydrophilicity of the surface of PVA films depended on the content of iron (III) chloride in these polymeric films. Introduced salt also affected photochemical reactions in poly(vinyl alcohol). Photooxidation of PVA was more effective in the presence of FeCl3 because of formation of reactive chlorine atoms, which were capable of initiating new reactions. Also the morphology and roughness parameters of PVA film changed when iron (III) chloride was added. 相似文献
149.