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101.
A model, based on inverse gas chromatography experiments, has been developed for intermolecular interaction and its temperature dependence. The model ascribes to each substance a four-component solubility parameter; the four components reflect the van der Waals, polar, electron donor, and electron acceptor interactive properties. Their values depend on temperature in the same manner as does the cohesive energy. The latter was found to depend only on the critical temperature, the acentric factor, and the reduced temperature. The model was used for evaluation of the solubility parameters from polymer-solvent interaction coefficients and their temperature dependence with high accuracy. For binary solventsolvent mixtures, the free energy of mixing and its temperature dependence, as well as enthalpy of mixing can be derived from this model with a good accuracy. 相似文献
102.
Emerging supramolecular chemistry of gases 总被引:1,自引:0,他引:1
Rudkevich DM 《Angewandte Chemie (International ed. in English)》2004,43(5):558-571
Molecular recognition of gases is an emerging area of chemistry. Supramolecular chemistry helps us to understand how gases interact with biological molecules and offers delicate insights into the mechanisms of their physiological activity. Principles of molecular recognition have been used for gas sensing, and have provided fundamental knowledge about the structure and dynamics of receptor-analyte complexes, and novel materials for gas sensing and storage have been developed. Supramolecular chemistry is also enabling us to learn how to transform gases into synthetically useful reagents. The rational design of novel catalysts for gas conversion and, more recently, encapsulation complexes with gases open novel directions in preparative synthetic chemistry. 相似文献
103.
J.B Goodenough J.-S Zhou F Rivadulla E Winkler 《Journal of solid state chemistry》2003,175(1):116-123
Bond-length fluctuations in transition-metal oxoperovskites may give rise to two-phase fluctuations in what appears to be a single phase to a diffraction experiment. Orbital disorder at Jahn-Teller ions results in bond-length fluctuations that give 3D-ferromagnetic, vibronic Mn(III)-O-Mn(III) superexchange interactions and allow disproportionation into Mn(IV) and Mn(II) in LaMnO3; where orbitally ordered and disordered phases coexist, an external magnetic field stabilizes the orbitally disordered, ferromagnetic phase relative to the orbitally ordered, antiferromagnetic phase. Spin-lattice interactions in the paramagnetic phase of charge-transfer compounds give bond-length fluctuations arising from the semicovalent component of the superexchange interactions. At the crossover from localized to itinerant electronic behavior, the coexistence of two-phase fluctuations has been demonstrated in both the single-valent RNiO3 family (R=rare-earth, A=alkaline-earth) and the mixed-valent R0.5A0.5MnO3 perovskites. “Bad-metal” behavior is found to be associated with bond-length fluctuations. 相似文献
104.
Stereoselective molecularly imprinted polymers (MIPs) have been synthesised via ring-opening metathesis polymerisation, in essentially, quantitative yield. A covalent imprinting strategy was followed during the network formation of the chiral sorbent. Recognition of the substrate however involved non-covalent interactions; a combination of hydrogen bonding and the chiral environment presented by the imprinted cavities. The enantiomeric excess achievable with these new MIPs is solvent dependent and stereoselectivities of up to 20% e.e. (separation factor α=2.2) were found in batch equilibrations. 相似文献
105.
The origin of the elastic inconsistency ofdaf, mas andgtf models for non-cubic solids and the failure of their force constants to comply with all the rotational invariance conditions
are analysed by resolving the atomic displacements of face-centred tetragonal indium along three mutually perpendicular directions.
It is shown that a lattice dynamical model suffers from these deficiencies as a consequence of its neglect of three-body interactions
as well as the mixed neighbour interactions associated with the angular forces, while thecgw model which incorporates both these interactions is elastically consistent and its potential energy rotationally invariant.
The degree of equivalence that exists among the force constants ofdaf, mas, gtf andcgw models, the distortions introduced by the elastic inconsistency into the phonon dispersion curves of fct indium as well as
the consequences of imposing the rotational invariance conditions on the force constants of a lattice dynamical model are
discussed. 相似文献
106.
V. A. Al'fonsov I. A. Litvinov O. N. Kataeva D. A. Pudovik S. A. Katsyuba 《Russian Chemical Bulletin》1995,44(10):1897-1899
X-Ray study of (diethyldithiocarbomoyl)diphenylthiophosphinate was carried out. AZ-conformation of the diethyldithiocarbomoyl ligand, which results in a short nonvalent intramolecular P...S contact (3.315 Å), is realized in the molecule. Steric hindrances in the molecule increase the P-S-C bond angle to 106.39°.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1978–1980, October, 1995.The work was financially supported by the International Science Foundation (Gram RH1 000). 相似文献
107.
IntroductionConstructionoffunctionalmolecularunitsintostruc turallywell definedsupramolecularassemblieshasattract edgreatattentionduetotheirpotentialapplicationsincomplexelectronicstructuresandmoleculardevices .1 5Amongthevariousfunctionalorganicmolecules ,azoben zenederivativeshavebeenwidelystudiedbecauseoftheirinterestingphotoresponsivebehavior .6 11Extensivestudieshaveshownthatsuitablydesignedazobenzenederivativescanformlongrangeorderedarrangementoftwo orthree dimensionalmolecularlatticeat… 相似文献
108.
A porphyrin nanotube: size-selective inclusion of tetranuclear molybdenum-oxo clusters 总被引:2,自引:0,他引:2
Harada R Matsuda Y Okawa H Kojima T 《Angewandte Chemie (International ed. in English)》2004,43(14):1825-1828
109.
Ab initio supermolecular SCF calculations at the STO-3G level are reported for the diacetylene-hydrogen fluoride complexes. The reverse
σ-complex is predicted to have somewhat higher stability and H-bond strength than the π-complexes. 相似文献
110.
Four new stationary phases for HPLC were prepared by modifying silica gel with a trifrnctional aminoalkyl silane. A conjugated π-electron system was linked to the amino group either directly or with a carboxylic anhydride as a spacer in between. Characterization and dynamic measurements of the new stationary phases were performed by solid state NMR spectroscopy. The results of the 29si and 13C CP/MAS techniques were compared with the recently developed 1H MAS-only technique. Despite strong homonuclear dipole-dipole interactions it was possible to obtain well resolved 1H MAS spectra of those stationaru phases with a high degree of crosslinking. Limited mobility of the aromatic ligand fragments is common for all examined stationaryu phases. The chromatographic properties of the new phases were tested by their ability tio sepatate a mixture of eight PAHS. It could be shown that the π-π interaction mechanism is responsible for the separation of the eight PAHs, because the elution order of the PAHs did not changem despite the use of both a nonpolar mobile phase (n-heptane) and a polar mobile phase (methanol/ water mixture). 相似文献