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排序方式: 共有89条查询结果,搜索用时 720 毫秒
1.
Mireille Richard-Plouet Jean-Louis Guille Yves Frere Louis Danicher 《Journal of Sol-Gel Science and Technology》2002,25(3):207-213
A new process to control the distribution of metal nanoparticles is proposed. It involves the use of complexing microcapsules obtained by interfacial polycondensation. The latter are hollow spheres constituted of a polymer membrane, containing an insoluble active ingredient, such as a polyacrylic acid, which can complex Co2+ ions. These capsules are dispersed in a silica sol followed by thermal treatments and reduction under H2 which results in metallic Co nanoparticles confined in the capsules domains. The particles do not diffuse in the matrix. 相似文献
2.
Corbellini F Mulder A Sartori A Ludden MJ Casnati A Ungaro R Huskens J Crego-Calama M Reinhoudt DN 《Journal of the American Chemical Society》2004,126(51):17050-17058
A molecular capsule based on ionic interactions between two oppositely charged calix[4]arenes, 1 and 2, was assembled both in solution and on a surface. In solution, the formation of the equimolar assembly 1.2 was studied by (1)H NMR, ESI-MS, and isothermal titration calorimetry, giving an association constant (K(a)) of 7.5 x 10(5) M(-1). A beta-cyclodextrin self-assembled monolayer (beta-CD SAM) on gold was used as a molecular printboard to anchor the tetraguanidinium calix[4]arene (2). The binding of tetrasulfonate calix[4]arene 1 was monitored by surface plasmon resonance spectroscopy. Rinsing of the surface with a high ionic strength aqueous solution allows the removal of the tetrasulfonate calix[4]arene (1), while by rinsing with 2-propanol it is possible to achieve the complete desorption of the tetraguanidinium calix[4]arene (2) from the beta-CD SAM. The K(a) for the capsule formation on a surface is 3.5 x 10(6) M(-1), thus comparing well with the K(a) determined in solution. 相似文献
3.
Manon Catherin Olatz Uranga-Barandiaran Arnaud Brosseau Dr. Rémi Métivier Dr. Gabriel Canard Dr. Anthony D'Aléo Dr. David Casanova Prof. Frédéric Castet Dr. Elena Zaborova Prof. Frédéric Fages 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(17):3818-3828
We describe the synthesis of a series of covalently linked dimers of quadrupolar curcuminoid-BF2 dyes and the detailed investigation of their solvent-dependent spectroscopic and photophysical properties. In solvents of low polarity, intramolecular folding induces the formation of aggregated chromophores, the UV/Vis absorption spectra of which display the optical signature characteristic of weakly-coupled H-aggregates. The extent of folding and, in turn, of ground-state aggregation is strongly dependent on the nature of the flexible linker. Steady-state and time-resolved fluorescence emission spectroscopies show that the Frenkel exciton relaxes into a fluorescent symmetrical excimer state with a long lifetime. Furthermore, our in-depth studies show that a weakly emitting excimer lies on the pathway toward a photocyclomer. Two-dimensional 1H NMR spectroscopy and density functional theory (DFT) allowed the structure of the photoproduct to be established. To our knowledge, this represents the first example of a [2π+2π] photodimerization of the curcuminoid chromophore. 相似文献
4.
Fatimata Nea Michel Boni Bitchi Manon Genva Allison Ledoux Alembert Tiabou Tchinda Christian Damblon Michel Frederich Zanahi Flix Tonzibo Marie-Laure Fauconnier 《Molecules (Basel, Switzerland)》2021,26(4)
Lantana rhodesiensis Moldenke is a plant widely used to treat diseases, such as rheumatism, diabetes, and malaria in traditional medicine. To better understand the traditional uses of this plant, a phytochemical study was undertaken, revealing a higher proportion of polyphenols, including flavonoids in L. rhodesiensis leaf extract and moderate proportion in stem and root extracts. The antioxidant activity of the extracts was also determined using three different assays: the radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity, the FRAP method (Ferric-reducing antioxidant power) and the β-carotene bleaching test. The anti-malarial activity of each extract was also evaluated using asexual erythrocyte stages of Plasmodium falciparum, chloroquine-sensitive strain 3D7. The results showed that the leaf extract exhibited higher antioxidant and anti-malarial activities in comparison with the stem and root extracts, probably due to the presence of higher quantities of polyphenols including flavonoids in the leaves. A positive linear correlation was established between the phenolic compound content (total polyphenols including flavonoids and tannins; and total flavonoids) and the antioxidant activity of all extracts. Furthermore, four flavones were isolated from leaf dichloromethane and ethyl acetate fractions: a new flavone named rhodescine (5,6,3′,5′-tetrahydroxy-7,4′-dimethoxyflavone) (1), 5-hydroxy-6,7,3′,4′,5′-pentamethoxyflavone (2), 5-hydroxy-6,7,3′,4′-tetramethoxyflavone (3), and 5,6,3′-trihydroxy-7,4′-dimethoxyflavone (4). Their structures were elucidated by 1H, 13CNMR, COSY, HSQC, HMBC, and MS-EI spectral methods. Aside from compound 2, all other molecules were described for the first time in this plant species. 相似文献
5.
Ania Alik Chafiaa Bouguechtouli Manon Julien Wolfgang Bermel Rania Ghouil Sophie Zinn‐Justin Francois‐Xavier Theillet 《Angewandte Chemie (International ed. in English)》2020,59(26):10411-10415
Abundant phosphorylation events control the activity of nuclear proteins involved in gene regulation and DNA repair. These occur mostly on disordered regions of proteins, which often contain multiple phosphosites. Comprehensive and quantitative monitoring of phosphorylation reactions is theoretically achievable at a residue‐specific level using 1H‐15N NMR spectroscopy, but is often limited by low signal‐to‐noise at pH>7 and T>293 K. We have developed an improved 13Cα‐13CO correlation NMR experiment that works equally at any pH or temperature, that is, also under conditions at which kinases are active. This allows us to obtain atomic‐resolution information in physiological conditions down to 25 μm . We demonstrate the potential of this approach by monitoring phosphorylation reactions, in the presence of purified kinases or in cell extracts, on a range of previously problematic targets, namely Mdm2, BRCA2, and Oct4. 相似文献
6.
Bone matrix like assemblies of collagen: from liquid crystals to gels and biomimetic materials 总被引:3,自引:0,他引:3
Skeletal tissues associate in close interaction, a dense organic matrix and a mineral network. In bone, the major structural protein is type I collagen, associated with inorganic crystals of hydroxyapatite. The three-dimensional arrangement of collagen fibrils in compact bone forms regularly ordered networks and a parallel was evidenced between these structures and molecular assemblies described in liquid crystals. Similar structures are now obtained in vitro. Indeed, when purified type I collagen is highly concentrated in an acid soluble state, the protein spontaneously assembles into ordered liquid crystalline phases. After a sol/gel transition triggered by pH increase, biomimetic materials are formed which resemble the exact compact bone matrix architecture over distances reaching centimetres and more. The properties of these highly ordered materials will be reviewed recalling their supramolecular arrangement and the corresponding patterns when visualised in polarised light microscopy (birefringence) and transmission electron microscopy (TEM). The association of inorganic phases (amorphous silica) to form chiral hybrid materials will also be described so as the behaviour of cells (fibroblast adhesion and migration) when seeded on these dense biomimetic matrices. 相似文献
7.
Huskens J Mulder A Auletta T Nijhuis CA Ludden MJ Reinhoudt DN 《Journal of the American Chemical Society》2004,126(21):6784-6797
A model has been described for interpreting the binding of multivalent molecules to interface-immobilized monovalent receptors through multiple, independent interactions. It is based on the concept of effective concentration, C(eff), which has been developed before for multivalent binding in solution and which incorporates effects of lengths and flexibilities of linkers between interacting sites. The model assumes: (i). the interactions are independent, (ii). the maximum number of interactions, p(max), is known, (iii). C(eff) is estimated from (simple) molecular models. Simulations of the thermodynamics and kinetics of multivalent host-guest binding to interfaces have been discussed, and competition with a monovalent competitor in solution has been incorporated as well. The model was successfully used to describe the binding of a divalent guest to self-assembled monolayers of a cyclodextrin host. The adsorption data of more complex guest-functionalized dendrimers, for which p(max) was not known beforehand, was interpreted as well. Finally, it has been shown that the model can aid to deconvolute contributions of multivalency and cooperativity to stability enhancements observed for the adsorption of multivalent molecules to interfaces. 相似文献
8.
9.
Chrystelle Brignone Caroline Grygar Manon Marcu Gaëlle Perrin Frédéric Triebel 《Journal of immune based therapies and vaccines》2007,5(1):5-15
Background
LAG-3 (CD223) is a natural high affinity ligand for MHC class II. The soluble form (sLAG-3) induces maturation of monocyte-derived dendritic cells in vitro and is used as a potent Th1-like immune enhancer with many antigens in animal models. To extend this observation to human, a proof of concept study was conducted with a clinical-grade sLAG-3, termed IMP321, coinjected with alum-non-absorbed recombinant hepatitis B surface antigen. 相似文献10.
Jeremy Drapeau Manon Rossano Didier Touraud Ulla Obermayr Martin Geier Andreas Rose Werner Kunz 《Comptes Rendus Chimie》2011,14(7-8):629-635
A simple and efficient method was developed for the synthesis of para-Menthane-3,8-diol (PMD), a well-known repellent active against mosquitoes, from Eucalyptus citriodora essential oil by a treatment of citric acid in a biphasic medium (H2O/essential oil). The E. citriodora contains as main component (+)-citronellal (74% in the present case), which cyclises (Prins reaction) to form cis/trans PMD isomers. As an example, an emulsion containing an aqueous solution of 7% citric acid and E. citriodora oil at 50°, conducted after 15 h stirring to 82% conversion of (+)-citronellal with a selectivity of 80% with the remaining presence of monoterpenes and sesquiterpenes in the medium. Investigations of lasting protection on human volunteers are carried out using a cage test bioassay protocol and Aedes aegypti mosquitoes. At 20% in iPrOH, the new reaction mixture showed a complete protection of 303 min compared to 22 min with the pure essential oil. The modified oil was compared with N,N-diethyl-m-methylbenzamide (DEET), the most popular active used in repellent formulations. Thermogravimetric analyses (TGA) of E. citriodora, the modified oil, PMD, DEET, and (+)-citronellal were performed and showed a slow evaporation rate for PMD and DEET as well as for the modified oil, which may explain their long lasting protection action. 相似文献