全文获取类型
收费全文 | 316篇 |
免费 | 14篇 |
专业分类
化学 | 150篇 |
晶体学 | 1篇 |
力学 | 14篇 |
数学 | 14篇 |
物理学 | 151篇 |
出版年
2023年 | 2篇 |
2022年 | 2篇 |
2021年 | 5篇 |
2020年 | 6篇 |
2019年 | 3篇 |
2018年 | 2篇 |
2017年 | 6篇 |
2016年 | 7篇 |
2014年 | 6篇 |
2013年 | 14篇 |
2012年 | 14篇 |
2011年 | 22篇 |
2010年 | 10篇 |
2009年 | 16篇 |
2008年 | 14篇 |
2007年 | 16篇 |
2006年 | 13篇 |
2005年 | 6篇 |
2004年 | 9篇 |
2003年 | 6篇 |
2002年 | 4篇 |
2001年 | 6篇 |
2000年 | 7篇 |
1999年 | 6篇 |
1998年 | 6篇 |
1997年 | 3篇 |
1996年 | 4篇 |
1995年 | 8篇 |
1994年 | 6篇 |
1993年 | 12篇 |
1992年 | 10篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 5篇 |
1987年 | 2篇 |
1986年 | 5篇 |
1985年 | 8篇 |
1984年 | 4篇 |
1983年 | 6篇 |
1982年 | 9篇 |
1981年 | 5篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1977年 | 5篇 |
1976年 | 2篇 |
1975年 | 4篇 |
1973年 | 3篇 |
1967年 | 1篇 |
排序方式: 共有330条查询结果,搜索用时 31 毫秒
71.
72.
73.
Baudelet F. Collin G. Dartyge E. Fontaine A. Kappler J. P. Krill G. Itie J. P. Jegoudez J. Maurer M. Monod Ph. Revcolevschi A. Tolentino H. Tourillon G. Verdaguer M. 《Zeitschrift für Physik B Condensed Matter》1987,69(2-3):141-149
X-ray absorption spectroscopy has been used to probe the Cu environment of the new highT
c
YBa2Cu3O7– superconductor. Evidences of other valencies than two are found for copper. Besides Cu1+ which is localized on Cu1 sites when the unit cell is oxygendeficient, one invokes a ground state which merges bivalent 3d
9 to 3d
9
L configurations as proposed in a recent paper (L stands for a ligand hole in the CuO bond) very similar to that observed in many light rare earth oxides. 相似文献
74.
The mild oxidation of bactericidal sulphonamides by hydrogen peroxide in acidic medium at room temperature in daylight, is reported. The oxidation products have been isolated by classical chromatography and purified, and their purity has been determined by HPLC. They have been identified by spectroscopy, chiefly by infrared and mass spectroscopy. An oxidation product not previously reported has been isolated and identified. An oxidation mechanism and the kinetics are discussed. 相似文献
75.
Céline Lucchesi Sagrario Pascual Alain Jouanneaux Gilles Dujardin Laurent Fontaine 《Journal of polymer science. Part A, Polymer chemistry》2007,45(16):3677-3686
Azlactone‐functionalized microporous polystyrene resins were synthesized by suspension polymerization of styrene, divinylbenzene and N‐(p‐vinylbenzyl)‐4,4‐dimethylazlactone (VBM). A fractional factorial design of experiments (DOE) has been used to evaluate the influence of several parameters (factors) on the physical and chemical properties (responses) of the resins. Six factors were considered: (i) the organic/aqueous phase ratio, (ii) the amount of the functional monomer N‐(p‐vinylbenzyl)‐4,4‐dimethylazlactone, (iii) the amount of stabilizer, (iv) the amount of initiator, (v) the stirring speed, and (vi) the equilibration time. The process responses were the yield of polymerization, the diameter of the beads and their polydispersity, their swelling ratio in dichloromethane and the accessibility ratio of the immobilized azlactone sites. This methodology enables the determination of an optimal combination of the six factors to synthesize beads in high yield (92%) with remarkable properties for SPOS applications (azlactone sites loading = 1.57 mmol/g, swelling ratio in dichloromethane = 5.0 mL/g and 100% accessibility ratio). © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3677–3686, 2007 相似文献
76.
Fontaine O Ghilane J Martin P Lacroix JC Randriamahazaka H 《Langmuir : the ACS journal of surfaces and colloids》2010,26(23):18542-18549
The electrochemical reduction of 4-nitrophenyl diazonium, NPD, in different ionic liquids presenting different viscosities has been investigated. The electrochemical studies show that the reduction of diazonium leading to the formation of its corresponding radical occurs whatever the viscosity of the grafting media. Following that, the presence of an organic layer attached to the electrode after electrochemical treatment was evidenced by cyclic voltammetry (CV) in acidic media thanks to the presence of nitro groups. Moreover, infrared spectroscopy (IR), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM) confirm the presence of a nitrophenyl (NP) layer attached to the electrode material. Next, the examination of the electrochemical data through the measurement of the charge, corresponding to the reduction of the attached nitrophenyl (NP) moieties, shows that the surface concentration of NP, Γ(NP), decreases when the viscosity, η, of the grafting media increases. Additionally, in the case of the more viscous ionic liquid, N-tributyl-N-methylammonium bis(trifluoromethylsulfonyl)imide [Bu(3)MeN] [NTf(2)], a cosolvent has been added leading to fine decrease of the viscosity. The IR and CV investigations of the modified electrodes demonstrate the decrease of the amount of the attached molecules when the viscosity of the grafting media increases. In addition, a correlation between Γ(NP) as function of 1/η was observed. Finally, XPS and AFM experiments lead to an estimate of the thickness of the attached layer. As a result, both methods are in perfect agreement and thicknesses of 4 and 1 nm are measured after grafting in acetonitrile and in pure ionic liquid [Bu(3)MeN] [NTf(2)], respectively. By comparison with classical solvent, the use of viscous ionic liquid for the grafting leads to a decrease in the amount of the attached molecules and conduce to the formation of thinner or less dense layer. 相似文献
77.
Bonn B Leandersson C Fontaine F Zamora I 《Rapid communications in mass spectrometry : RCM》2010,24(21):3127-3138
The identification of metabolites is almost exclusively done with liquid chromatography/tandem mass spectrometry (LC/MSMS) and despite the enormous progress in the development of these techniques and software for handling of data this is a time-consuming task. In this study the use of quadrupole time-of-flight (QTOF)-generated MS(E) and MS/MS data were compared with respect to rationalization of metabolites. In addition Mass-MetaSite, a semi-automated software for metabolite identification, was evaluated. The program combines the information from MS raw data, in the form of collision-induced dissociation spectra, with a prediction of the site of metabolism in order to assign the structure of a metabolite. The aim of the software is to mimic the rationalization of fragment ions performed by a biotransformation scientist in the process of structural elucidation. For this evaluation, metabolite identification in human liver microsomes was accomplished for 19 commercially available compounds and 15 in-house compounds. The results were very encouraging and for 96% of the metabolites the same structures were assigned using MS(E) compared with MSMS acquired data. The possibility of using MS(E) could considerably reduce the analysis time. Moreover, Mass-MetaSite performed well and the correct assigned structure, compared to manual inspection of the data, was picked in the first rank in ~80% of the cases. In conclusion MS(E) could be successfully used for metabolite identification in order to reduce time of analysis and Mass-MetaSite could alleviate the work of a biotransformation scientist and decrease the workload by assigning the structure for a majority of the metabolites. 相似文献
78.
Alexander MD Fontaine SD La Clair JJ Dipasquale AG Rheingold AL Burkart MD 《Chemical communications (Cambridge, England)》2006,(44):4602-4604
The undecenolide core of mycolactone was synthesized by ring-closing metathesis and the structure confirmed using single-crystal X-ray diffraction techniques. 相似文献
79.
Marius Murariu Anne Laure Dechief Yoann Paint Gaëlle Fontaine Philippe Dubois 《Polymer Degradation and Stability》2010,95(5):889-900
Composites have been produced by melt-blending biodegradable polylactide (PLA) with commercially available expanded graphite (EG). Using different techniques of addition, the manifold effects of EG on PLA molecular, thermo-mechanical and fire-retardant properties were evaluated. The EG nanofiller provides PLA composites with competitive functional properties. They have a high rigidity, with Young's modulus and storage modulus increasing with EG content. They also have excellent thermal stability while preserving the glass transition and melting temperature of the original PLA matrix. Purification and pre-dispersion of EG nanofiller proved beneficial for preserving PLA molecular weights and led to improved mechanical performance. The presence of dispersed graphene nanolayers in PLA significantly accelerated the polyester crystallization process. The flame retardant properties also displayed improvements with a large decrease in the maximum rate of heat release as recorded by cone calorimetry, whereas the horizontal burning test (UL94 HB) was successfully passed revealing non-dripping and char formation. 相似文献
80.
J.-X. Fontaine R. Molinié T. Tercé-Laforgue D. Cailleu B. Hirel F. Dubois F. Mesnard 《Comptes Rendus Chimie》2010,13(4):453-458
It is now well established that the GS/GOGAT cycle is the major route for ammonium assimilation in higher plants. However, it has often been argued that other enzymes, such as glutamate dehydrogenase, have the capacity to assimilate ammonium, leading to the hypothesis that alternative ammonium assimilatory pathways could operate under particular physiological conditions. The GDH enzyme is encoded by two distinct genes, GDH1 and GDH2. A third gene, GDH3, potentially encoding GDH has recently been identified by in silico studies performed on Arabidopsis thaliana. In order to precise its function, the metabolic profile of gdh3 knock out mutants were compared to wild type plants using the 1H-NMR technique. 1H-NMR spectra coupled with principal component analysis and partial least square-discriminant analysis were applied to identify changes of the metabolic profiles. These experiments were performed on roots, leaves and stems. In the gdh3 mutant, metabolic variations were observed for carboxylic acids, amino acids and carbohydrates content. 相似文献