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排序方式: 共有222条查询结果,搜索用时 15 毫秒
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Antoine Meunier Michael L. Singleton Brice Kauffmann Thierry Granier Guillaume Lautrette Yann Ferrand Ivan Huc 《Chemical science》2020,11(44):12178
As metalloproteins exemplify, the chemical and physical properties of metal centers depend not only on their first but also on their second coordination sphere. Installing arrays of functional groups around the first coordination sphere of synthetic metal complexes is thus highly desirable, but it remains a challenging objective. Here we introduce a novel approach to produce tailored second coordination spheres. We used bioinspired artificial architectures based on aromatic oligoamide foldamers to construct a rigid, modular and well-defined environment around a metal complex. Specifically, aza-aromatic monomers having a tethered [2Fe–2S] cluster have been synthesized and incorporated in conical helical foldamer sequences. Exploiting the modularity and predictability of aromatic oligoamide structures allowed for the straightforward design of a conical architecture able to sequester the metal complex in a confined environment. Even though no direct metal complex–foldamer interactions were purposely designed in this first generation model, crystallography, NMR and IR spectroscopy concurred to show that the aromatic oligoamide backbone alters the structure and fluxional processes of the metal cluster.Wrapping a [2Fe–2S] metal complex in an aromatic foldamer helix is introduced as a new approach to tailor a second coordination sphere. 相似文献
3.
Aline Delamare Guillaume Naulet Brice Kauffmann Gilles Guichard Guillaume Compain 《Chemical science》2022,13(33):9507
The isobutyl side chain is a highly prevalent hydrophobic group in drugs, and it notably constitutes the side chain of leucine. Its replacement by a hexafluorinated version containing two CF3 groups may endow the target compound with new and advantageous properties, yet this modification remains overlooked due to the absence of a general and practical synthetic methodology. Herein, we report the first general method to introduce the hexafluoroisobutyl group into ketoesters, malonates, 1,3-diketones, Schiff base esters and malononitrile. We demonstrated that the reaction occurs through an elimination/allylic shift/hydrofluorination cascade process which efficiently overcomes the usual fluoride β-elimination observed with α-CF3-vinyl groups. We showed that with alkali metal bases, a pentafluorinated alkene is obtained predominantly, whereas the use of tetrabutylammonium fluoride (TBAF) allows hydrofluorination to occur. This tandem process represents a conceptually new pathway to synthesize bis-trifluoromethylated compounds. This methodology was applied to the multigram-scale synthesis of enantiopure (S)-5,5,5,5′,5′,5′-hexafluoroleucine.Hexafluoroisobutylation of ketoesters, malonates, diketones, Schiff base esters and malononitrile is reported. The reaction involves an elimination/allylic shift/hydrofluorination cascade process that efficiently overcomes the usual SN2′ mechanism. 相似文献
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Dendrimers are macromolecules characterized by high controlled size, shape and architecture, presence of inner cavities able to accommodate small molecules and many peripheral functional groups to bind target entities. They are of eminent interest for biomedical applications, including gene transfection, tissue engineering, imaging, and drug delivery. The well-known pharmacological activities of ursolic and oleanolic acids are limited by their small water solubility, non-specific cell distribution, low bioavailability, poor pharmacokinetics, and their direct administration could result in the release of thrombi. To overcome such problems, in this paper we described their physical incorporation inside amino acids-modified polyester-based dendrimers which made them highly water-soluble. IR, NMR, zeta potential, mean size of particles, buffer capacity and drug release profiles of prepared materials were reported. The achieved water-soluble complexes harmonize a polycationic character and a buffer capacity which presuppose efficient cell penetration and increased residence time with a biodegradable cell respectful scaffold, thus appearing as a promising team of not toxic prodrugs for safe administration of ursolic and oleanolic acids. 相似文献
6.
Dr. Brice Kauffmann Dr. Gilles Guichard 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(44):15684-15692
Anion binding properties of neutral helical foldamers consisting of urea type units in their backbone have been investigated. 1H NMR titration studies in various organic solvents including DMSO suggest that the interaction between aliphatic oligoureas and anions (CH3COO?, H2PO4?, Cl?) is site‐specific, as it largely involves the urea NHs located at the terminal end of the helix (positive pole of the helix), which do not participate to the helical intramolecular hydrogen‐bonding network. This mode of binding parallels that found in proteins in which anion‐binding sites are frequently found at the N‐terminus of an α‐helix. 1H NMR studies suggest that the helix of oligoureas remains largely folded upon anion binding, even in the presence of a large excess of the anion. This study points to potentially useful applications of oligourea helices for the selective recognition of small guest molecules. 相似文献
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Functionalization of a Ruthenium–Diacetylide Organometallic Complex as a Next‐Generation Push–Pull Chromophore 下载免费PDF全文
Samuel De Sousa Dr. Laurent Ducasse Dr. Brice Kauffmann Prof. Thierry Toupance Dr. Céline Olivier 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(23):7017-7024
The design and preparation of an asymmetric ruthenium–diacetylide organometallic complex was successfully achieved to provide an original donor–π–[M]–π–acceptor architecture, in which [M] corresponds to the [Ru(dppe)2] (dppe: bisdiphenylphosphinoethane) metal fragment. The charge‐transfer processes occurring upon photoexcitation of the push–pull metal–dialkynyl σ complex were investigated by combining experimental and theoretical data. The novel push–pull complex, appropriately end capped with an anchoring carboxylic acid function, was further adsorbed onto a semiconducting metal oxide porous thin film to serve as a photosensitizer in hybrid solar cells. The resulting photoactive material, when embedded in dye‐sensitized solar cell devices, showed a good spectral response with a broad incident photon‐to‐current conversion efficiency profile and a power conversion efficiency that reached 7.3 %. Thus, this material paves the way to a new generation of organometallic chromophores for photovoltaic applications. 相似文献
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Yella-Reddy Nelli Céline Douat-Casassus Paul Claudon Brice Kauffmann Claude Didierjean Gilles Guichard 《Tetrahedron》2012,68(23):4492-4500
A new N-Boc-protected monomer for the synthesis of oligourea foldamers containing the (1H-imidazolyl-4yl)methyl side chain of histidine, has been prepared in seven steps from Trt-His(τ-Trt)-OMe. This protecting group combination on histidine was found to be critical to ensure efficient access to the requisite activated building block. This new derivative, suitable for solid phase synthesis, expands the current arsenal of building blocks with proteinogenic side chains useful for the design of peptidomimetic oligourea foldamers. 相似文献
10.
Camille Thevenot Brice Vincent Sabu Thomas Didier Rouxel 《International Journal of Polymer Analysis and Characterization》2017,22(7):649-658
The purpose of this paper is to understand the mechanisms occurring during the ultrasonication of the copolymer poly(vinylidenedifluoride-trifluoroethylene). In these experimental conditions, the polymer adopts a core–shell structure and its hydrodynamic diameter is measured by dynamic light scattering. The results show that, without covalent bonds breakage, the hydrodynamic diameter decreases with ultrasonication time and a smaller size population appears. This evolution is reversible in a matter of days. A new two-step mechanism is proposed to describe this phenomenon: first the erosion of a core–shell structure and second the contraction of the core. Beyond shedding a new light on the phenomena occurring during the sonication of polymers used in nanocomposites elaboration, this work also strongly questions the traditional techniques used to study the degradation of polymers, which use the hydrodynamic diameter measurement to determine the molecular weight. 相似文献