全文获取类型
收费全文 | 388篇 |
免费 | 18篇 |
国内免费 | 1篇 |
专业分类
化学 | 312篇 |
晶体学 | 5篇 |
力学 | 8篇 |
数学 | 17篇 |
物理学 | 65篇 |
出版年
2024年 | 1篇 |
2023年 | 5篇 |
2022年 | 4篇 |
2021年 | 11篇 |
2020年 | 4篇 |
2019年 | 11篇 |
2018年 | 12篇 |
2017年 | 10篇 |
2016年 | 16篇 |
2015年 | 10篇 |
2014年 | 14篇 |
2013年 | 38篇 |
2012年 | 27篇 |
2011年 | 33篇 |
2010年 | 19篇 |
2009年 | 10篇 |
2008年 | 19篇 |
2007年 | 22篇 |
2006年 | 23篇 |
2005年 | 15篇 |
2004年 | 15篇 |
2003年 | 22篇 |
2002年 | 16篇 |
2001年 | 3篇 |
1997年 | 2篇 |
1996年 | 3篇 |
1995年 | 7篇 |
1994年 | 9篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 3篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有407条查询结果,搜索用时 0 毫秒
401.
Chandra S Mitra S Laha D Bag S Das P Goswami A Pramanik P 《Chemical communications (Cambridge, England)》2011,47(30):8587-8589
A novel route has been developed to fabricate different carbon nanostructures having individual morphology of carbon nanoparticles: nanofullerene, nanocube, nanoleaf and porous nanorods, through the combustion of carbon xerogel with nitric acid. These fabricated nanostructures exhibited bright green fluorescence under the exposure of UV light. 相似文献
402.
A portable ultrahigh‐vacuum system for advanced synchrotron radiation studies of thin films and nanostructures: EuSi2 nano‐islands 下载免费PDF全文
Shyjumon Ibrahimkutty Anja Seiler Tim Prüßmann Tonya Vitova Ramu Pradip Olga Bauder Peter Wochner Anton Plech Tilo Baumbach Svetoslav Stankov 《Journal of synchrotron radiation》2015,22(1):91-98
A portable ultrahigh‐vacuum system optimized for in situ variable‐temperature X‐ray scattering and spectroscopy experiments at synchrotron radiation beamlines was constructed and brought into operation at the synchrotron radiation facility ANKA of the Karlsruhe Institute of Technology, Germany. Here the main features of the new instrument are described and its capabilities demonstrated. The surface morphology, structure and stoichiometry of EuSi2 nano‐islands are determined by in situ grazing‐incidence small‐angle X‐ray scattering and X‐ray absorption spectroscopy. A size reduction of about a factor of two of the nano‐islands due to silicide decomposition and Eu desorption is observed after sample annealing at 1270 K for 30 min. 相似文献
403.
404.
Ghosh D Ghosh P Tanemura M Haysahi A Hayashi Y Shinji K Miura N Yusop MZ Asaka T 《Chemical communications (Cambridge, England)》2011,47(17):4980-4982
Single-walled carbon nanotubes (SWNTs) have been used successfully to fabricate highly transparent and flexible field emission displays (FEDs). Field emission measurements indicated that SWNTs films have great potential to work as building blocks for next generation transparent and flexible FEDs. 相似文献
405.
Rajesh H. Bahekar Pradip A. Jadav Dipam N. Patel Vijay M. Prajapati Arun A. Gupta Mukul R. Jain Pankaj R. Patel 《Tetrahedron letters》2007,48(29):5003-5005
An improved method for the synthesis of Fmoc-N-methyl serine and threonine has been developed, which involves formation and subsequent reduction of the corresponding oxazolidinone with a Lewis acid under mild conditions, with improved yields and shorter reaction times. 相似文献
406.
The nucleophilic substitution reaction of S2O32− with [Ru(HaaiR′)2(OH2)2](ClO4)2 (1) [HaaiR′ = 1-alkyl-2-(phenylazo)imidazole] and [Ru(ClaaiR′)2(OH2)2](ClO4)2 (2) [ClaaiR′ = 1-alkyl-2-(chlorophenylazo)imidazole] [where R′ = Me(a), Et(b) or Bz(c)] in acetonitrile–water (50% v/v) medium to yield Na2[Ru(HaaiR′)2(S2O3)2] (3a, 3b or 3c) and Na2[Ru(ClaaiR′)2(S2O3)2] (4a, 4b or 4c) has been studied. The products were characterized by microanalytical data and spectroscopic techniques (UV–Vis, NMR and mass spectroscopy). The reaction proceeds in two consecutive steps (A → B → C); each step follows first order kinetics with respect to each complex and S2O32−, and the first step second order rate constant (k′2) is greater than the second step one (k″2). An increase in the π-acidity of the ligand increases the rate. Thermodynamic parameters, the standard enthalpy of activation (Δ‡H0) and the standard entropy of activation (Δ‡S0), have been calculated for both steps using the Eyring equation from variable temperature kinetic studies. The low Δ‡H0 and large negative Δ‡S0 values indicate an associative mode of activation for both aqua ligand substitution processes. 相似文献
407.
Patra AK Rowland JM Marlin DS Bill E Olmstead MM Mascharak PK 《Inorganic chemistry》2003,42(21):6812-6823
Three iron complexes of a pentadentate ligand N,N-bis(2-pyridylmethyl)amine-N-ethyl-2-pyridine-2-carboxamide (PaPy(3)H, H is the dissociable amide proton) have been synthesized. All three species, namely, two nitrosyls [(PaPy(3))Fe(NO)](ClO(4))(2) (2) and [(PaPy(3))Fe(NO)](ClO(4)) (3) and one nitro complex [(PaPy(3))Fe(NO(2))](ClO(4)) (4), have been structurally characterized. These complexes provide the opportunity to compare the structural and spectral properties of a set of isostructural [Fe-NO](6,7) complexes (2 and 3, respectively) and an analogous genuine Fe(III) complex with an "innocent" sixth ligand ([(PaPy(3))Fe(NO(2))](ClO(4)), 4). The most striking difference in the structural features of 2 and 3 is the Fe-N-O angle (Fe-N-O = 173.1(2) degrees in the case of 2 and 141.29(15) degrees in the case of 3). The clean (1)H NMR spectrum of 2 in CD(3)CN reveals its S = 0 ground state and confirms its [Fe-NO](6) configuration. The binding of NO at the non-heme iron center in 2 is completely reversible and the bound NO is photolabile. M?ssbauer data, electron paramagnetic resonance signal at g approximately 2.00, and variable temperature magnetic susceptibility measurements indicate the S = (1)/(2) spin state of the [Fe-NO](7) complex 3. Analysis of the spectroscopic data suggests Fe(II)-NO(+) and Fe(II)-NO(*) formulations for 2 and 3, respectively. The bound NO in 3 does not show any photolability. However, in MeCN solution, it reacts rapidly with dioxygen to afford the nitro complex 4, which has also been synthesized independently from [(PaPy(3))Fe(MeCN)](2+) and NO(2)(-). Nucleophilic attack of hydroxide ion to the N atom of the NO ligand in 2 in MeCN in the dark gives rise to 4 in high yield. 相似文献