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排序方式: 共有209条查询结果,搜索用时 15 毫秒
1.
The kinetics of hydrolysis of a series of N-acylsulfamate esters p-XC6H4OSO2NHCOR as models for more complex, biologically important compounds has been examined. Structure-reactivity, solvent-reactivity, thermodynamic data, etc. support a bimolecular mechanism involving water in the transition state (TS). 相似文献
2.
Colette Deschamps-Vallet Jean-Baptiste Ilots Michle Meyer-Dayan Darius Molho 《Journal of heterocyclic chemistry》1982,19(1):97-101
3-Phenyl-1-benzopyrylium percholorates 1a, 1i react exculusively at C-2 with ethanol and isopropyl alcohol, affording mixed acetals 2a, 3a, 3i . Aqueous ammonia gives symmetrical secondary amines 4a, 4b or bis(3-phenyl-2H-1-benzopyran-2-yl)amines, while with aqueous aliphatic amines (40%) bis-acetals 5a, 5b or 2,2′-oxy-bis(3-phenyl-2H-1-benzopyrans) are characterized. In some other acidic conditions, 5a and 5b are also obtained. 相似文献
3.
4.
Hydrosilylation is an important process, not only in the silicon industry to produce silicon polymers, but also in fine chemistry. In this review, the development of rhenium-based catalysts for the hydrosilylation of unsaturated bonds in carbonyl-, cyano-, nitro-, carboxylic acid derivatives and alkenes is summarized. Mechanisms of rhenium-catalyzed hydrosilylation are discussed. 相似文献
5.
Linda Axelsson Jean-Baptiste VeronJonas Sävmarker Jonas LindhLuke R. Odell Mats Larhed 《Tetrahedron letters》2014
A palladium(II)-catalyzed decarboxylative protocol for the synthesis of aryl ketones has been developed. The addition of TFA was shown to improve the reaction yield and employing THF as solvent enabled the use of solid nitriles and in only a small excess. Using this method, five different benzoic acids reacted with a wide range of nitriles to produce 29 diverse (hetero)aryl ketone derivatives in up to 94% yield. 相似文献
6.
Ralf Seemann Jean-Baptiste Fleury Corinna C. Maass 《The European physical journal. Special topics》2016,225(11-12):2227-2240
Self-propelled droplets are a special kind of self-propelled matter that are easily fabricated by standard microfluidic tools and locomote for a certain time without external sources of energy. The typical driving mechanism is a Marangoni flow due to gradients in the interfacial energy on the droplet interface. In this article we review the hydrodynamic prerequisites for self-sustained locomotion and present two examples to realize those conditions for emulsion droplets, i.e. droplets stabilized by a surfactant layer in a surrounding immiscible liquid. One possibility to achieve self-propelled motion relies on chemical reactions affecting the surface active properties of the surfactant molecules. The other relies on micellar solubilization of the droplet phase into the surrounding liquid phase. Remarkable cruising ranges can be achieved in both cases and the relative insensitivity to their own ‘exhausts’ allows to additionally study collective phenomena. 相似文献
7.
Poullet JB Sima DM Van Huffel S Van Hecke P 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2007,186(2):293-304
Accurate and efficient filtering techniques are required to suppress large nuisance components present in short-echo time magnetic resonance (MR) spectra. This paper discusses two powerful filtering techniques used in long-echo time MR spectral quantitation, the maximum-phase FIR filter (MP-FIR) and the Hankel-Lanczos Singular Value Decomposition with Partial ReOrthogonalization (HLSVD-PRO), and shows that they can be applied to their more complex short-echo time spectral counterparts. Both filters are validated and compared through extensive simulations. Their properties are discussed. In particular, the capability of MP-FIR for dealing with macromolecular components is emphasized. Although this property does not make a large difference for long-echo time MR spectra, it can be important when quantifying short-echo time spectra. 相似文献
8.
Philippe Pinel Bertrand Thirion Sébastien Meriaux Antoinette Jobert Julien Serres Denis Le Bihan Jean-Baptiste Poline Stanislas Dehaene 《BMC neuroscience》2007,8(1):91
Background
Although cognitive processes such as reading and calculation are associated with reproducible cerebral networks, inter-individual variability is considerable. Understanding the origins of this variability will require the elaboration of large multimodal databases compiling behavioral, anatomical, genetic and functional neuroimaging data over hundreds of subjects. With this goal in mind, we designed a simple and fast acquisition procedure based on a 5-minute functional magnetic resonance imaging (fMRI) sequence that can be run as easily and as systematically as an anatomical scan, and is therefore used in every subject undergoing fMRI in our laboratory. This protocol captures the cerebral bases of auditory and visual perception, motor actions, reading, language comprehension and mental calculation at an individual level. 相似文献9.
Morgane Rosendale Jonathan Daniel Frdric Castet Paolo Pagano Jean-Baptiste Verlhac Mireille Blanchard-Desce 《Molecules (Basel, Switzerland)》2022,27(7)
Molecular-based Fluorescent Organic Nanoparticles (FONs) are versatile light-emitting nano-tools whose properties can be rationally addressed by bottom-up molecular engineering. A challenging property to gain control over is the interaction of the FONs’ surface with biological systems. Indeed, most types of nanoparticles tend to interact with biological membranes. To address this limitation, we recently reported on two-photon (2P) absorbing, red to near infrared (NIR) emitting quadrupolar extended dyes built from a benzothiadiazole core and diphenylamino endgroups that yield spontaneously stealth FONs. In this paper, we expand our understanding of the structure-property relationship between the dye structure and the FONs 2P absorption response, fluorescence and stealthiness by characterizing a dye-related series of FONs. We observe that increasing the strength of the donor end-groups or of the core acceptor in the quadrupolar (D-π-A-π-D) dye structure allows for the tuning of optical properties, notably red-shifting both the emission (from red to NIR) and 2P absorption spectra while inducing a decrease in their fluorescence quantum yield. Thanks to their strong 1P and 2P absorption, all FONs whose median size varies between 11 and 28 nm exhibit giant 1P (106 M−1.cm−1) and 2P (104 GM) brightness values. Interestingly, all FONs were found to be non-toxic, exhibit stealth behaviour, and show vanishing non-specific interactions with cell membranes. We postulate that the strong hydrophobic character and the rigidity of the FONs building blocks are crucial to controlling the stealth nano-bio interface. 相似文献
10.
Jean-Baptiste Hiriart-Urruty Jérôme Malick 《Journal of Optimization Theory and Applications》2012,153(3):551-577
Engineering sciences and applications of mathematics show unambiguously that positive semidefiniteness of matrices is the
most important generalization of non-negative real numbers. This notion of non-negativity for matrices has been well-studied
in the literature; it has been the subject of review papers and entire chapters of books. 相似文献