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61.
Vito Fragnelli Joaquín Sánchez-Soriano Rodica Branzei 《Journal of Mathematical Analysis and Applications》2010,362(1):200-209
In this paper we study convex games with an infinite countable set of agents and provide characterizations of this class of games. To do so, and in order to overcome some shortcomings related to the difficulty of dealing with infinite orderings, we need to use a continuity property. Infinite sequencing situations where the number of jobs is infinite countable can be related to convex cooperative TU games. It is shown that some allocations turn out to be extreme points of the core of an infinite sequencing game. 相似文献
62.
A simple and efficient stereoselective synthesis of polysubstituted beta,gamma-epoxyhydroxylamines and 4-hydroxyalkyl-1,2-oxazetidines, based on the addition of alpha-lithiated aryloxiranes to nitrones and subsequent cyclization of the corresponding intermediates in a 4-exo-tet mode, is described. 相似文献
63.
N-Trifluoromethylsulfonyl-propiolamides have been prepared by two methods: a) N-triflation of secondary acetylenic carboxanilides, prepared in two steps from terminal alkynes, with triflic anhydride (Tf2O) and b) from terminal alkynes and an aryl or alkyl isocyanate followed by Tf2O in a consecutive one-pot reaction. The title compounds are bench-stable and insensitive to water and alcohols but amenable to transamidation reactions with a wide range of amine nucleophiles. Conversely, they are excellent reagents for the propynoylation of ammonia, primary and secondary amines, anilines, and hydrazines. 相似文献
64.
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66.
A short and efficient synthesis of tetrahydroindenofuranones based on the Michael addition of ortho-lithiated aryloxiranes to alkylidene malonates followed by the nucleophilic oxirane ring-opening and subsequent lactonization is described. The methodology has been applied to the synthesis of a structural analogue of epipodophyllotoxins. 相似文献
67.
Foderà V Groenning M Vetri V Librizzi F Spagnolo S Cornett C Olsen L van de Weert M Leone M 《The journal of physical chemistry. B》2008,112(47):15174-15181
The fluorescent dye thioflavin T (ThT) is commonly used for in situ amyloid fibril detection. In this work, we focused on the spectroscopic properties and chemical stability of ThT in aqueous solution as a function of pH, temperature, and dye concentration. A reversible hydroxylation process occurs in alkaline solutions, which was characterized using a combination of UV-vis absorption spectroscopy, proton NMR, and density functional theory (DFT). On the basis of these studies, we propose a chemical structure for the hydroxylated form. Finally, by means of fluorescence spectroscopy, ThT hydroxylation effects on in situ amyloid detection have been investigated, providing new insights on the efficiency of the ThT assay for quantitative fibril evaluation at basic pH. 相似文献
68.
Gómez-Caravaca AM Verardo V Segura-Carretero A Caboni MF Fernández-Gutiérrez A 《Journal of chromatography. A》2008,1209(1-2):238-245
The aim of this work was to develop a capillary electrophoresis-mass spectrometry (CE-MS) method to identify and quantify phenolic and other related polar compounds in walnut samples. The extraction capacity of several solvent mixtures of phenolic compounds from walnut by conventional solid-liquid extractions was tested, and CE and electrospray ionization MS parameters were optimized. The finalized procedure is able to determine many well-known phenolic compounds present in walnuts and provide relevant information about the presence of minor polar compounds. A new compound in walnut ((2E,4E)-8-hydroxy-2,7-dimethyl-2,4-decadiene-1,10-dioic acid 6-O-beta-d-glucopiranosyl ester, [M-H](-) 403.161m/z) with a structure similar to glansreginins was also identified. Phenolic compounds correspond to 14-28% of total polar compounds quantified. Aglycone and glycosylated ellagic acid represent the principal components and account for 64-75% of total phenols in walnuts. However, the sum of glansreginins A, B and (2E,4E)-8-hydroxy-2,7-dimethyl-2,4-decadiene-1,10-dioic acid 6'-O-beta-d-glucopiranosyl ester was in the range of 72-86% of total quantified compounds. In addition, this is the first time that separation by CE with detection by electrospray ionization time-of-flight MS has been applied to the analysis of phenolic and other polar compounds in walnut samples, providing results in less than 15min. 相似文献
69.
Capriati V Florio S Luisi R Mazzanti A Musio B 《The Journal of organic chemistry》2008,73(8):3197-3204
The alpha-lithiation-trapping sequence of trans-N-alkyl-2,3-diphenylaziridines (s-BuLi or s-BuLi/TMEDA), taking place with a stereochemistry which dramatically depends on the solvent coordinating ability (inversion of configuration in THF and retention in toluene), has been carefully investigated. 1H,13C, and 7Li multinuclear NMR investigations at low temperature suggest that two differently configured lithiated aziridines (monomeric cis-1-Li in THF and dimeric trans-1-Li in toluene) are involved. 相似文献
70.
Dr. Michela Parafioriti Dr. Minghong Ni Maurice Petitou Dr. Courtney J. Mycroft-West Dr. Timothy R. Rudd Dr. Neha S. Gandhi Prof. Vito Ferro Prof. Jeremy E. Turnbull Dr. Marcelo A. Lima Dr. Mark A. Skidmore Prof. David G. Fernig Dr. Edwin A. Yates Dr. Antonella Bisio Dr. Marco Guerrini Dr. Stefano Elli 《Chemistry (Weinheim an der Bergstrasse, Germany)》2023,29(1):e202202599
Infection of host cells by SARS-CoV-2 begins with recognition by the virus S (spike) protein of cell surface heparan sulfate (HS), tethering the virus to the extracellular matrix environment, and causing the subunit S1-RBD to undergo a conformational change into the ‘open’ conformation. These two events promote the binding of S1-RBD to the angiotensin converting enzyme 2 (ACE2) receptor, a preliminary step toward viral-cell membrane fusion. Combining ligand-based NMR spectroscopy with molecular dynamics, oligosaccharide analogues were used to explore the interactions between S1-RBD of SARS CoV-2 and HS, revealing several low-specificity binding modes and previously unidentified potential sites for the binding of extended HS polysaccharide chains. The evidence for multiple binding modes also suggest that highly specific inhibitors will not be optimal against protein S but, rather, diverse HS-based structures, characterized by high affinity and including multi-valent compounds, may be required. 相似文献