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31.
This contribution concerns the mechanics of materials with random network microstructures. It develops a general homogenization approach that allows to link the microscopic deformation of fibers in the disordered network with the macroscopic response of the continuous solid. This link is established by a novel micro-macro relation based on the kinematics of maximal advance paths that constrains the unknown microscopic stretch of fibers with respect to the macroscopic strain. This relation accounts for the topology of the network, in particular, its connectivity and takes for the tetrafunctional networks a clearly interpretable tensorial form. In line with the principle of the minimum averaged free energy the elastic response of the network is obtained by the relaxation of the variable fiber stretch subjected to the kinematic constraint. (© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
32.
Shaotang Song Lulu Wang Jie Su Zhen Xu Chia-Hsiu Hsu Chenqiang Hua Pin Lyu Jing Li Xinnan Peng Takahiro Kojima Shunpei Nobusue Mykola Telychko Yi Zheng Feng-Chuan Chuang Hiroshi Sakaguchi Ming Wah Wong Jiong Lu 《Chemical science》2021,12(35):11659
Deciphering rich non-covalent interactions that govern many chemical and biological processes is crucial for the design of drugs and controlling molecular assemblies and their chemical transformations. However, real-space characterization of these weak interactions in complex molecular architectures at the single bond level has been a longstanding challenge. Here, we employed bond-resolved scanning probe microscopy combined with an exhaustive structural search algorithm and quantum chemistry calculations to elucidate multiple non-covalent interactions that control the cohesive molecular clustering of well-designed precursor molecules and their chemical reactions. The presence of two flexible bromo-triphenyl moieties in the precursor leads to the assembly of distinct non-planar dimer and trimer clusters by manifold non-covalent interactions, including hydrogen bonding, halogen bonding, C–H⋯π and lone pair⋯π interactions. The dynamic nature of weak interactions allows for transforming dimers into energetically more favourable trimers as molecular density increases. The formation of trimers also facilitates thermally-triggered intermolecular Ullmann coupling reactions, while the disassembly of dimers favours intramolecular cyclization, as evidenced by bond-resolved imaging of metalorganic intermediates and final products. The richness of manifold non-covalent interactions offers unprecedented opportunities for controlling the assembly of complex molecular architectures and steering on-surface synthesis of quantum nanostructures.A real-space characterization of dynamic non-covalent interactions in molecular assemblies and chemical reactions at the atomic bond level. 相似文献
33.
Perepichka DF Kondratenko M Bryce MR 《Langmuir : the ACS journal of surfaces and colloids》2005,21(19):8824-8831
Nitrofluoren-9-one and nitrofluoren-9-dicyanomethylene electron acceptors 7, 8, and 11 functionalized with a terminal thioctic acid unit have been synthesized from 2,4,5,7-tetranitrofluorenone. The self-assembled monolayers (SAMs) of these compounds on gold, formed via gold-sulfur interaction, have been fully characterized by electrochemical, FTIR, ellipsometry, and contact angle measurements. Cyclic voltammetry of SAMs reveals two reversible single-electron reduction waves for fluorenone derivatives 7a,b and 11, and three single-electron reductions for the dicyanomethylene-fluorene 8b, providing the first observation of a radical trianion species in SAMs. The tendency of the thioctic anchor to form multilayers via disulfide links is noted. 相似文献
34.
Mykola Kolotylo Volodymyr Holovatiuk Julia Bondareva Oleg Lukin Vladimir Rozhkov 《Tetrahedron letters》2019,60(4):352-354
The synthesis of dendrimers and a chlorosulfo-dendron possessing a unique combination of 1?→?2 and 1?→?4 branching types is described. The procedure consists of a two-step preparation of 3,5-dinitrobenzene-1-sulfonyl chloride, which was used for the persulfonylation of p-toluidine and 4-(benzylthio)aniline. The obtained tetranitro compounds were reduced to the corresponding tetraamines. The latter were decorated with eight 4-toluene sulfonyl groups each to furnish the corresponding dendrimers. Oxidation of the dendrimer possessing a 4-(benzylthio)phenylene core with N-chlorosuccinimide resulted in the formation of a dendron with a sulfonyl chloride functionality at the focal point. 相似文献
35.
Kostiantyn Kulyk Valentyna Ishchenko Borys Palyanytsya Volodymyr Khylya Mykola Borysenko Tetiana Kulyk 《Journal of mass spectrometry : JMS》2010,45(7):750-761
The interactions between coumarins and the surface of fumed SiO2, CeO2/SiO2, TiO2/SiO2 and Al2O3/SiO2 were assessed by means of temperature‐programed desorption mass spectrometry. The different stages of the thermolysis of coumarin were identified and an analysis of the underlying reactions was performed. The kinetic parameters of the involved reactions were thus obtained. The decomposition of thiazolyl‐substituted coumarins was found to proceed through a ‘thiazole–thiazine’ ring expansion in the adsorbed state. A linear correlation between the sigma constants (Σσ) of the coumarin substituents and the activation energy of CO2 formation was obtained. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
36.
Fedor I. Zubkov Julya D. Ershova Mykola D. Obushak Ekaterina A. Sokolova Alexey V. Varlamov 《Tetrahedron letters》2010,51(52):6822-6824
1-(2-Furyl)-3,4-dihydroisoquinolines, easily prepared from readily available phenethylamines, undergo tandem alkylation/[4+2]-cycloaddition with allyl halides. The reaction proceeds via 2-allyl-1-furyl-3,4-dihydroisoquinolinium salt formation and subsequent intramolecular exo-Diels-Alder reaction of furan with the allyl fragment (IMDAF reaction). The adducts formed include the basic structural element of the isoindolo[1,2-a]isoquinoline alkaloids jamtine and hirsutine. 相似文献
37.
The study of electrogenerated chemiluminescence (ECL) in aqueous and non-aqueous media with tetraphenylborate anion as a co-reactant is reported. The obtained results indicate that tetraphenylborate acts according to an oxidative reduction scheme and forms a strong reducer after being homogeneously oxidized by a radical cation or dication of luminophore. Spectral measurements prove that light emission originates from the luminophore present in solution and practically no emission occurs when only tetraphenylborate ion is oxidized at the electrode. Since the tetraphenylborate ion is a well known analytical reactant and precipitates a number of metal and organic cations its electrochemiluminescent detection can be used for their assay. It can also be applied as an efficient co-reactant for electrogenerated chemiluminescence excitation both in aqueous and non-aqueous media. 相似文献
38.
Volodymyr?DibrivnyiEmail author Iryna?Sobechko Marian?Puniak Yuriy?Horak Mykola?Obushak Yuriy?Van-Chin-Syan Marshalek?Andriy Nadiia?Velychkivska 《Chemistry Central journal》2015,9(1):67
Background
The aim of the current work was to determine thermo dynamical properties of 5(2-nitro phenyl)-furan-2-carbaldehyde, 5(3-nitro phenyl)-furan-2-carbaldehyde and 5(4-nitro phenyl)-furan-2-carbaldehyde.Results
The temperature dependence of saturated vapor pressure of 5(2-nitro phenyl)-furan-2-carbaldehyde, 5(3-nitro phenyl)-furan-2-carbaldehyde and 5(4-nitro phenyl)-furan-2-carbaldehyde was determined by Knudsen’s effusion method. The results are presented by the Clapeyron–Clausius equation in linear form, and via this form, the standard enthalpies, entropies and Gibbs energies of sublimation and evaporation of compounds were calculated at 298.15 K. The standard molar formation enthalpies of compounds in crystalline state at 298.15 K were determined indirectly by the corresponding standard molar combustion enthalpy, obtained using bomb calorimetry combustion.Conclusions
Determination of the thermodynamic properties for these compounds may contribute to solving practical problems pertaining optimization processes of their synthesis, purification and application and it will also provide a more thorough insight regarding the theoretical knowledge of their nature.
39.
Yuri V. Ostapiuk Mykola D. Obushak Vasyl S. Matiychuk Marek Naskrent Andrzej K. Gzella 《Tetrahedron letters》2012,53(5):543-545
It was found that the reaction of 2-chloroacetamido/chloropropioamido-5-benzylthiazole with potassium thiocyanate gave, via rearrangement, 2-[(5-benzyl-1,3-thiazol-2-yl)imino]-1,3-thiazolidin-4-ones. 相似文献
40.
Nazariy T. Pokhodylo Vasyl S. Matiychuk Mykola D. Obushak 《Phosphorus, sulfur, and silicon and the related elements》2013,188(7):850-858
Abstract Two synthetic pathways for the preparation of 2-mercapto-3-arylpropanoic acids were developed. First, by the reaction of arenediazonium bromides with acrylic esters in the presence of CuBr, alkyl (2-bromo-3-aryl)propanoates were formed. Their cyclization with thiourea produced 5-(R-benzyl)-2-imino-4-thiazolidinones, which yielded 3-aryl-2-mercaptopropanoic acids by alkaline hydrolysis. Second, direct Meerwein arylation of acrylates in the presence of S-nucleophile (NaSH) allowed isolation of 3-phenyl-2-mercaptopropanoic acid in 8% yield. Such acids were used for cyclization with cyanoguanidine and phenyl isothiocyanate yielding 1-[5-(R-benzyl)-4-oxo-1,3-thiazolidin-2-ylidene]guanidines and new 5-(R-benzyl)-3-phenyl-2-thioxo-1,3-thiazolidin-4-one (rhodanine) derivatives correspondingly. 相似文献