全文获取类型
收费全文 | 379篇 |
免费 | 14篇 |
国内免费 | 3篇 |
专业分类
化学 | 270篇 |
晶体学 | 2篇 |
力学 | 18篇 |
数学 | 41篇 |
物理学 | 65篇 |
出版年
2024年 | 1篇 |
2023年 | 3篇 |
2022年 | 12篇 |
2021年 | 11篇 |
2020年 | 14篇 |
2019年 | 16篇 |
2018年 | 10篇 |
2017年 | 4篇 |
2016年 | 15篇 |
2015年 | 16篇 |
2014年 | 16篇 |
2013年 | 21篇 |
2012年 | 32篇 |
2011年 | 47篇 |
2010年 | 20篇 |
2009年 | 22篇 |
2008年 | 22篇 |
2007年 | 25篇 |
2006年 | 23篇 |
2005年 | 14篇 |
2004年 | 19篇 |
2003年 | 9篇 |
2002年 | 13篇 |
2001年 | 2篇 |
1998年 | 1篇 |
1995年 | 1篇 |
1992年 | 6篇 |
1991年 | 1篇 |
排序方式: 共有396条查询结果,搜索用时 0 毫秒
31.
The predictions of a nonequilibrium schematic mode-coupling theory developed to describe the nonlinear rheology of soft glassy materials have been numerically tested in a sheared binary Lennard-Jones mixture. In this Letter, we focus on the existence, behavior, and properties of an effective temperature T(eff) for the slow modes of the fluid, as defined from a generalized fluctuation-dissipation theorem. New, simple experimental protocols to access T(eff) are proposed, and one such experiment is numerically performed. Our results give strong support to the thermodynamic interpretation of T(eff) and make it experimentally accessible in a very direct way. 相似文献
32.
Bruno Therrien Ludovic Vieille-Petit Yoshihisa Sei 《Journal of organometallic chemistry》2004,689(17):2820-2826
The hydrogen-bonded systems formed between monocarboxylic acid derivatives and the trinuclear arene-ruthenium cluster cation [H3Ru3(C6H6)(C6Me6)2(O)]+ (1) have been studied in solution by cold-spray ionisation mass spectroscopy (CSI-MS) and in the solid state by single-crystal X-ray structure analysis of the tetrafluoroborate salts. The presence of 1:1 (acid:cluster) adducts in acetone solution has been clearly demonstrated by CSI-MS. Single-crystal X-ray structure analyses of selected acid-cluster complexes show that in every case the hydroxyl of the acid function interacts strongly with the μ3-oxo ligand of cation 1, the O ? O distance ranging from 2.499(9) to 2.595(11) Å. 相似文献
33.
Carole Diederichs David Taj Thimothe Lecomte Crisitiano Ciuti Philippe Roussignol Claude Delalande Aristide Lemaître Ludovic Largeau Olivia Mauguin Jacqueline Bloch Charles Leyder Alberto Bramati Elisabeth Giacobino Jrme Tignon 《Comptes Rendus Physique》2007,8(10):1198-1204
We report the realization of a monolithic vertical-cavity, surface emitting micro-optical parametric conversion nanostructure, triply resonant with the parametric frequencies, allowing parametric oscillation with ultra-low pump power threshold. The photonic phase-space naturally provides triple resonance for the parametric frequencies, together with built-in cavity phase-matching for the pump wave at normal incidence. Parametric oscillation is observed in both the strong and weak exciton–photon coupling regime, allowing a high operating temperature. Signal and idler beams can be collected at 0° or at finite angles. The OPO threshold is low enough to envisage the realization of an all-semiconductor electrically-pumped micro-parametric oscillator. To cite this article: C. Diederichs et al., C. R. Physique 8 (2007). 相似文献
34.
Clementine Cailleteau Ludovic Micallef Clemence Lepage Philippe Jean-Paul Cardot Jean-Louis Beneytout Bertrand Liagre Serge Battu 《Analytical and bioanalytical chemistry》2010,398(3):1273-1283
Differentiation therapy could be one strategy for stopping cancer cell proliferation. A plant steroid, diosgenin, is known
to induce megakaryocytic differentiation in human erythroleukemia (HEL) cells. In recent studies, the use of sedimentation
field-flow fractionation (SdFFF) allowed the preparation of subpopulations that may differ in regard to sensitivity to differentiation
induction. The specific goal of this study was to determine the relationship between cell cycle stage and sensitivity to megakaryocytic
differentiation induction of HEL cells. After first confirming the capacity of diosgenin to specifically select targets, hyperlayer
SdFFF cell sorting was used to prepare fractions according to cell cycle position from crude HEL cells. The sensitivities
of these fractions to diosgenin-induced differentiation were then tested. The coupling of SdFFF cell separation to imaging
flow cytometry showed that G1-phase cells were more sensitive to differentiation induction than S/G2M-phase cells, confirming
the relationship between cell status at the start of induction, the extent of the biological event, and the potential of SdFFF
in cancer research. 相似文献
35.
A predictive reactivity of Cp2An(IV)Me2 (with An = uranium [U], neptunium [Np] and plutonium [Pu]) with pyridine N-oxide has been studied at the theoretical level. The predictive reaction, which consists in the formation of a formaldehyde complex, begins after the initial formation of a cyclometalated complex produced by a C-H activation of the pyridine N-oxide. A difference of reactivity between U/Pu and Np has been observed and has been attributed to the presence of a more covalent bond between Np and the carbene group in the transition state of formation of a transient carbene intermediate. 相似文献
36.
Badr Benmansour Ludovic Stephan Jean-Yves Cabon Laure Deschamps Philippe Giamarchi 《Journal of fluorescence》2011,21(3):843-850
This work presents spectroscopic properties of some Endocrine Disrupting Compounds (EDCs), frequently found in food and in
natural water. Studied molecules belong to the groups of phenolic and phthalate EDCs. In a first part, we have examined their
absorption and fluorescence properties. Fluorescence emission wavelengths are about 300 nm for phenolic compounds and 360 nm
for phtalate compounds; main excitation wavelengths being comprised between 210 nm and 230 nm. Fluorescence lifetimes measured
are short (about 4 ns) and the fluorescence quantum yield has been determined. In a second part, to avoid the time consuming
solvent extraction step, an analytical application to evaluate the performance of a direct analysis by laser induced fluorescence
spectroscopy of ECDs traces in tap water and in raw water is presented. Good detection limits have been obtained, i.e.: 0.35 μg.L−1 of chlorophenol in tap water, which are always lower than the reported Predictive Non Efficient Concentration (PNEC). 相似文献
37.
We analyze the large-scale structure and fluctuations of jammed packings of size-disperse spheres, produced in a granular experiment as well as numerically. While the structure factor of the packings reveals no unusual behavior for small wave vectors, the compressibility displays an anomalous linear dependence at low wave vectors and vanishes when q→0. We show that such behavior occurs because jammed packings of size-disperse spheres have no bulk fluctuations of the volume fraction and are thus hyperuniform, a property not observed experimentally before. Our results apply to arbitrary particle size distributions. For continuous distributions, we derive a perturbative expression for the compressibility that is accurate for polydispersity up to about 30%. 相似文献
38.
Landrieu I Lacosse L Leroy A Wieruszeski JM Trivelli X Sillen A Sibille N Schwalbe H Saxena K Langer T Lippens G 《Journal of the American Chemical Society》2006,128(11):3575-3583
The phosphorylation of the neuronal Tau protein modulates both its physiological role of microtubule binding and its aggregation into paired helical fragments observed in Alzheimer's diseased neurons. However, detailed knowledge of the role of phosphorylation at specific sites has been hampered by the analytical difficulties to evaluate the level of site-specific phosphate incorporation. Even with recombinant kinases, mass spectrometry and immunodetection are not evident for determining the full phosphorylation pattern in a qualitative and quantitative manner. We show here that heteronuclear NMR spectroscopy on a 15N labeled Tau sample modified by the cAMP dependent kinase allows identification of all phosphorylation sites, measures their level of phosphate integration, and yields kinetic data for the enzymatic modification of the individual sites. Filtering through the 15N label discards the necessity of any further sample purification and allows the in situ monitoring of kinase activity at selected sites. We finally demonstrate that the NMR approach can equally be used to evaluate potential kinase inhibitors in a straightforward manner. 相似文献
39.
Mireia Segado Centellas Madeleine Piot Raphaël Salles Anna Proust Ludovic Tortech Dalil Brouri Sbastien Hupin Benjamin Abcassis David Landy Carles Bo Guillaume Izzet 《Chemical science》2020,11(40):11072
The formation of hierarchical nanostructures using preformed dumbbell-like species made of covalent organic–inorganic polyoxometalate (POM)-based hybrids is herein described. In this system, the presence of charged subunits (POM, metal linkers, and counter ions) in the complex molecular architecture can drive their aggregation, which results from a competition between the solvation energy of the discrete species and intermolecular electrostatic interactions. We show that the nature of the POM and the charge of the metal linker are key parameters for the hierarchical nanoorganization. The experimental findings were corroborated with a computational investigation combining DFT and molecular dynamics simulation methods, which outlines the importance of solvation of the counter ion and POM/counter ion association in the aggregation process. The dumbbell-like species can also form gels, in the presence of a poorer solvent, displaying similar nanoorganization of the aggregates. We show that starting from the designed molecular building units whose internal charges can be controlled by redox trigger we can achieve their implementation into soft nanostructured materials through the control of their supramolecular organization.The formation of hierarchical nanostructures using supramolecular dumbbell-like species made of organic–inorganic polyoxometalate-based hybrids is investigated by combination of SAXS and computational methods. 相似文献
40.
The synthesis of imidazolinium salts from the reaction of formamidines and (2-bromoethyl)diphenylsulfonium triflate is described. A variety of symmetrical and unsymmetrical imidazolinium triflate salts were synthesized in high yield in short reaction times under mild conditions. Aromatic and aliphatic N-substituents work well. The reaction is proposed to proceed via generation of a vinyl sulfonium salt intermediate from the bromoethylsulfonium triflate. 相似文献