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191.
Olga N. Pestova Andrey Yu. Efimov Lyubov A. Myund Andrei G. Kudrev Vasiliy D. Khripun Anna G. Davidian Valeria E. Baranauskaite 《Journal of solution chemistry》2017,46(9-10):1854-1870
A new approach has been proposed to study the structure of aqueous electrolyte solutions. NIR, Raman and attenuated total reflectance, Fourier transform infra-red (ATR FTIR) spectra have been measured for aqueous calcium perchlorate solutions in the 0.22–4.3 mol·L?1 (0.22–7.46 mol·kg?1) concentration range at 25 °C. By the methods of principal component analysis (PCA) and multivariate curve resolution—alternating least squares (MCR-ALS) the number, spectra and concentration profiles have been determined for spectroscopically distinguishable forms of water and ClO 4 ? ion in solutions. The results have been analyzed using a phenomenological model, establishing thereby: concentration ranges for structural rearrangements of the solution, the nature of structural microirregularities and different states of the ClO 4 ? ion in the areas of domination of the natural water structure, and of cybotactic groups of calcium perchlorate hexa and tetra hydrates. 相似文献
192.
Roman N. Naumov Artem V. Kozlov Santiago Gómez-Ruiz Evamarie Hey-Hawkins Andrey A. Karasik 《Tetrahedron letters》2010,51(7):1034-1037
The rac stereoisomer of a novel cryptand containing two bridgehead nitrogen and four asymmetric phosphorus atoms in the 16-membered core cycle was obtained stereoselectively via the reaction of bis(mesitylphosphino)propane, formaldehyde, and meta-xylylenediamine in the course of a covalent self-assembly process. 相似文献
193.
Ludmila V. Chepeleva Alexander Yu. Matsakov Zhanna A. Kondratyuk Fedor G. Yaremenko Andrey O. Doroshenko 《Journal of photochemistry and photobiology. A, Chemistry》2010,209(2-3):163-173
Two isomeric pyrazole derivatives of 3-hydroxychromone (3HC) with and without the possibility of the multiple intramolecular hydrogen bonds formation were compared theoretically and experimentally with the aim to find out whether the excited state intramolecular proton transfer (ESIPT) reaction follows the traditional to the most of 3HCs “flavonol-like” direction towards the CO group oxygen or an “alternative” direction towards the heterocyclic nitrogen atom.Quantum-chemical modeling and comparative study of the experimental spectral parameters of the title compounds indicated the preferential realization of “flavonol-like” ESIPT to oxygen channel.The 3HC systems with the “alternative” intramolecular hydrogen bond to nitrogen were characterized as low fluorescent and practically unable to ESIPT with participation of the nitrogen containing heterocyclic unit. 相似文献
194.
A coarse grained model for flexible polymers end-grafted to repulsive spherical nanoparticles is studied for various chain lengths and grafting densities under good solvent conditions by molecular dynamics methods and density functional theory. With increasing chain length, the monomer density profile exhibits a crossover to the star polymer limit. The distribution of polymer ends and the linear dimensions of individual polymer chains are obtained, while the inhomogeneous stretching of the chains is characterized by the local persistence lengths. The results on the structure factor of both single chain and full spherical brush as well as the range of applicability of the different theoretical tools are presented. Finally, a brief discussion of the experiment is given. 相似文献
195.
Andrey I. Poddel’sky Ivan V. Smolyaninov Georgy K. Fukin Vladimir K. Cherkasov 《Journal of organometallic chemistry》2010,695(8):1215-8281
Novel functionalized triphenylantimony(V) catecholates - Ph3Sb[4-O(CH2CH2)2N-3,6-DBCat] (1), Ph3Sb[4-PhN(CH2CH2)2N-3,6-DBCat] (2), Ph3Sb[4-Ph2CHN(CH2CH2)2N-3,6-DBCat] (3), Ph3Sb[4,5-Piperaz-3,6-DBCat] (4) and binuclear bis-catecholate Ph3Sb[3,6-DBCat-4-N(CH2CH2)2N-4-3,6-DBCat]SbPh3 (5) were synthesized by the oxidative addition reaction of corresponding o-quinones with triphenylantimony. The [4-O(CH2CH2)2N-3,6-DBCat]2−, [4-PhN(CH2CH2)2N-3,6-DBCat]2−, [4-Ph2CHN(CH2CH2)2N-3,6-DBCat]2− and [4,5-Piperaz-3,6-DBCat]2− are 4-(morpholin-1-yl)-, 4-(4-phenyl-piperazin-1-yl)-, 4-(4-dephenylmethyl-piperazin-1-yl)-, and 4,5-(piperazin-1,4-diyl)-3,6-di-tert-butyl-catecholate dianionic ligands, correspondingly. Complexes 1-5 were characterized in details by IR-, 1H and 13C NMR spectroscopy and cyclic voltammometry. Molecular structure of 4·CH3OH was determined by X-ray crystallography to be a distorted tetragonal-pyramidal. The NMR spectroscopic and electrochemical investigations of complexes in the presence of air reveal the reactions of complexes with dioxygen leading to the formation of spiroendoperoxides of 1,2,4,3-trioxastibolane type in a NMR yield of 25-37%. 相似文献
196.
Andrey I. Poddel’sky Ivan V. Smolyaninov Nadezhda T. Berberova Gleb A. Abakumov 《Journal of organometallic chemistry》2010,695(4):530-522
Triphenylantimony(III) and triethylantimony(III) readily react with 4,5-(1,1,4,4-tetramethyl-butane-1,4-diyl)-o-benzoquinone to form catecholato complexes R3Sb(4,5-Cat) (R = Ph (1), Et (2); 4,5-Cat is dianionic 4,5-(1,1,4,4-tetramethyl-butane-1,4-diyl)-catecholate). In polar solvents (CHCl3, acetone) complex 1 transforms easily to ionic complex compound [Ph4Sb]+[Ph2Sb(4,5-Cat)2]− (3) with diphenyl-bis-[4,5-(1,1,4,4-tetramethyl-butane-1,4-diyl)-catecholato]antimony(V) complex anion. Complexes were characterized by IR, 1H, 13C NMR spectroscopy, cyclic voltammometry. Molecular structure of 3·CHCl3 was confirmed by X-ray analysis. Cyclic voltammometry of 1 and 3 shows that both complexes undergo reversible one-electron oxidation to quite stable paramagnetic o-semiquinonato species [Ph3Sb(4,5-SQ)]+ and [Ph2Sb(4,5-SQ)(4,5-Cat)] (0.75 and 0.49 V in CH2Cl2 vs. Ag/AgCl/KCl, respectively). 相似文献
197.
We study the molecular mechanisms of alkali halide ion interactions with the single‐wall carbon nanotube surface in water by means of fully atomistic molecular dynamics simulations. We focus on the basic physical‐chemical principles of ion–nanotube interactions in aqueous solutions and discuss them in light of recent experimental findings on selective ion effects on carbon nanotubes. 相似文献
198.
Bronstein LM Shtykova EV Malyutin A Dyke JC Gunn E Gao X Stein B Konarev PV Dragnea B Svergun DI 《The journal of physical chemistry. C, Nanomaterials and interfaces》2010,114(50):21900-21907
Iron oxide nanoparticles (NPs) with a diameter 21.6 nm were coated with poly(maleic acid-alt-1-octadecene) (PMAcOD) modified with grafted 5,000 Da poly(ethyelene glycol) (PEG) or short ethylene glycol (EG) tails. The coating procedure utilizes hydrophobic interactions of octadecene and oleic acid tails, while the hydrolysis of maleic anhydride moieties as well as the presence of hydrophilic PEG (EG) tails allows the NP hydrophilicity. The success of the NP coating was found to be independent of the degree of grafting which was varied between 20 and 80% of the -MacOD-units, but depended on the length of the grafted tail. The NP coating and hydrophilization did not occur when the modified copolymer contained 750 Da PEG tails independently of the grafting degree. To explain this phenomenon the micellization of the modified PMAcOD copolymers in water was analyzed by small angle x-ray scattering (SAXS). The PMAcOD molecules with the grafted 750 Da PEG tails form compact non-interacting disk-like micelles, whose stability apparently allows for no interactions with the NP hydrophobic shells. The PMAcOD containing the 5,000 Da PEG and EG tails form much larger aggregates capable of an efficient coating of the NPs. The coated NPs were characterized using transmission electron microscopy, dynamic light scattering, ζ-potential measurements, and thermal gravimetry analysis. The latter method demonstrated that the presence of long PEG tails in modified PMAcOD allows the attachment of fewer macromolecules (by a factor of ~20) compared to the case of non-modified or EG modified PMAcOD, emphasizing the importance of PEG tails in NP hydrophilization. The NPs coated with PMAcOD modified with 60% (towards all -MAcOD- units) of the 5,000 PEG tails bear a significant negative charge and display good stability in buffers. Such NPs can be useful as magnetic cores for virus-like particle formation. 相似文献
199.
Ganna A. Senchyk Andrey B. Lysenko Eduard B. Rusanov Alexander N. Chernega Konstantin V. Domasevitch 《Acta Crystallographica. Section C, Structural Chemistry》2010,66(7):m180-m183
In the structures of the CdII pseudohalide coordination polymer poly[[diaquabis[μ2‐3,3′‐bis(1,2,4‐triazol‐4‐yl)‐1,1′‐biadamantane‐κ2N1:N1′]cadmium(II)] dithiocyanate dihydrate], {[Cd(C24H32N6)2(H2O)2](NCS)2·2H2O}n, (I), and the isomorphous selenocyanate analogue, {[Cd(C24H32N6)2(H2O)2](NCSe)2·2H2O}n, (II), the CdII cations occupy inversion centres and have octahedral CdN4O2 environments, completed by four N atoms of the organic ligands [Cd—N = 2.316 (2) and 2.361 (2) Å for (I), and 2.313 (3) and 2.372 (3) Å for (II)] and two trans‐coordinated aqua ligands [Cd—O = 2.3189 (15) Å for (I) and 2.323 (2) Å for (II)]. In each compound, the ligand displays a bidentate N1:N1′‐bridging mode, connecting the metal centres at a distance of 14.66 Å into two‐dimensional nets of (4,4)‐topology, while the uncoordinated thio(seleno)cyanate anions reside inside the net cavities. Hydrogen bonding between the water molecules, anions and 1,2,4‐triazole N atoms supports the tight packing, with an interlayer distance of 6.09 Å. 相似文献
200.