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111.
In this paper and in a forthcoming one, we study difference equations in of the types (2) (4) (6) which are linked to families of conics, cubics and quartics, respectively. These equations generalize Lyness' one un+2un=a+un+1 studied in several papers, whose behavior was completely elucidated in [G. Bastien, M. Rogalski, in press] through methods which are transposed in the present paper for the study of (1) and (2), and in the forthcoming one for (3). In particular we prove in the present paper a form of chaotic behavior for solutions of difference equations (1) and (2), and find all the possible periods for these solutions. 相似文献
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114.
Clark JS Northall JM Marlin F Nay B Wilson C Blake AJ Waring MJ 《Organic & biomolecular chemistry》2008,6(21):4012-4025
The synthesis of 5-epi-hydroxycornexistin (44), a diastereoisomer of the herbicidal natural product hydroxycornexistin (2) has been completed. Palladium mediated sp(2)-sp(3) coupling of the stannane 25 and the chloride 31 and ring-closing metathesis of the resulting diene 32 has been used to construct the tricyclic lactone 34a, which possesses the nine-membered carbocyclic core found in the natural product, in good yield. The synthesis of 5-epi-hydroxycornexistin (44) has established the feasibility of using a furan as precursor for the cyclic anhydride unit present in the natural product and has demonstrated the viability of other late-stage transformations that will be used to prepare hydroxycornexistin (2). 相似文献
115.
[reaction: see text] The ubiquity of the sialic acid alpha(2-3) galactose linkage in oligosaccharides of biological relevance necessitates a building block for the incorporation of this motif into oligosaccharides prepared by modular synthesis. The linear synthesis of the sialyl Lewis X tumor-associated antigen (1) has been accomplished in good yield using a sialic acid alpha(2-3) galactose disaccharide building block. The disaccharide building block was synthesized efficiently from readily available galactal by a high-yielding and selective sialylation reaction. 相似文献
116.
Bastien Mussard 《Molecular physics》2017,115(1-2):161-173
ABSTRACTWe investigate fractional-charge and fractional-spin errors in range-separated density-functional theory (DFT). Specifically, we consider the range-separated hybrid (RSH) method which combines long-range Hartree-Fock (HF) exchange with a short-range semilocal exchange-correlation density functional, and the RSH+MP2 method which adds long-range, second-order Møller-Plesset (MP2) correlation. Results on atoms and molecules show that the fractional-charge errors obtained in RSH are much smaller than in the standard Kohn-Sham (KS) scheme applied with semilocal or hybrid approximations, and also generally smaller than in the standard HF method. The RSH+MP2 method tends to have smaller fractional-charge errors than standard MP2 for the most diffuse systems, but larger fractional-charge errors for the more compact systems. Even though the individual contributions to the fractional-spin errors in the H atom coming from the short-range exchange and correlation density-functional approximations are smaller than the corresponding contributions for the full-range exchange and correlation density-functional approximations, RSH gives fractional-spin errors that are larger than in the standard KS scheme and only slightly smaller than in standard HF. Adding long-range MP2 correlation only leads to infinite fractional-spin errors. This work clarifies the successes and limitations of range-separated DFT approaches for eliminating self-interaction and static-correlation errors. 相似文献
117.
Bastien Belzunces Sophie Hoyau Fabienne Bessac 《Journal of computational chemistry》2019,40(14):1449-1462
Metamitron (Meta), an herbicide, and fenhexamid (Fen), a fungicide, are authorized by the European Union to be used in agriculture. This article reports theoretical calculations about Meta and Fen in interaction with a clay surface: a Ca-montmorillonite (Mont). Conformational searches have been performed thanks to Car–Parrinello molecular dynamics simulations from which geometries have been extracted. Interaction and adsorption energies have been calculated for isomers of Meta or Fen in interaction with Mont to understand the relative stability of various kinds of complexation. Substantial adsorption energies are comparable for Meta and Fen: around −40 kcal/mol. For Fen-Mont, the CO monodentate family is surprisingly the lowest in energy. Moreover, the 10 lowest-energy isomers involve complexation on Fen carbonyl oxygens. The Meta-Mont lowest-energy family, N-N, does not involve π delocalization breaking within Meta. At the same time, the stronger the interaction energy is, the larger the structural modifications within Mont are, particularly concerning the interacting cation distance to the surface. The non-negligible charge transfer and the magnitude of the adsorption energy speak in favor of the chemisorption of the pesticide on the surface. © 2019 Wiley Periodicals, Inc. 相似文献
118.
Karlhofer Bastien Kędra Jarek Marcinkowski Michał Trost Alexander 《Geometriae Dedicata》2021,213(1):523-530
Geometriae Dedicata - We investigate the geometry of word metrics on fundamental groups of manifolds associated with the generating sets consisting of elements represented by closed geodesics. We... 相似文献
119.
F. Feyza
zgen Michael E. Runda Bastien O. Burek Peter Wied Jonathan Z. Bloh Robert Kourist Sandy Schmidt 《Angewandte Chemie (International ed. in English)》2020,59(10):3982-3987
In this study, we coupled a well‐established whole‐cell system based on E. coli via light‐harvesting complexes to Rieske oxygenase (RO)‐catalyzed hydroxylations in vivo. Although these enzymes represent very promising biocatalysts, their practical applicability is hampered by their dependency on NAD(P)H as well as their multicomponent nature and intrinsic instability in cell‐free systems. In order to explore the boundaries of E. coli as chassis for artificial photosynthesis, and due to the reported instability of ROs, we used these challenging enzymes as a model system. The light‐driven approach relies on light‐harvesting complexes such as eosin Y, 5(6)‐carboxyeosin, and rose bengal and sacrificial electron donors (EDTA, MOPS, and MES) that were easily taken up by the cells. The obtained product formations of up to 1.3 g L?1 and rates of up to 1.6 mm h?1 demonstrate that this is a comparable approach to typical whole‐cell transformations in E. coli. The applicability of this photocatalytic synthesis has been demonstrated and represents the first example of a photoinduced RO system. 相似文献
120.
Dr. Chunyang Li Dr. Anne-Doriane Manick Dr. Yuxi Zhao Dr. Fengbo Liu Dr. Bastien Chatelet Roselyne Rosas Prof. Didier Siri Dr. Didier Gigmes Dr. Valerie Monnier Prof. Laurence Charles Dr. Julie Broggi Prof. Simin Liu Prof. Alexandre Martinez Dr. Anthony Kermagoret Dr. David Bardelang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(64):e202201656
The globular and monocationic guest molecule trimethyl-azaphosphatrane ( AZAP , a protonated Verkade superbase) was shown to form a host:guest 1 : 1 complex with the cucurbit[10]uril (CB[10]) macrocycle in water. Molecular dynamics calculations showed that CB[10] adopts an 8-shape with AZAP occupying the majority of the internal space, CB[10] contracting around AZAP and leaving a significant part of the cavity unoccupied. This residual space was used to co-include planar and monocationic co-guest ( CG ) molecules, affording heteroternary CB[10]⋅ AZAP ⋅ CG complexes potentially opening new perspectives in supramolecular chemistry. 相似文献