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101.
Enhanced rate of arene hydrogenation with imidazolium functionalized bipyridine stabilized rhodium nanoparticle catalysts 总被引:1,自引:0,他引:1
The imidazolium functionalized bipyridine compounds, {4,4'-bis[7-(2,3-dimethylimidazolium)heptyl]-2,2'-bipyridine}(2+) ([BIHB](2+)) and {4,4'-bis[(1,2-dimethylimidazolium)methyl]-2,2'-bipyridine}(2+) ([BIMB](2+)), were prepared and used as Rh nanoparticle stabilizers. The dispersed Rh nanoparticles were used as catalysts in the biphasic hydrogenation of various arene substrates. The catalytic activity was strongly influenced by the stabilizer employed and followed the trend [BIHB](2+) > bipy > [BIMB](2+). The steric and electronic characteristics of the imidazolium functionalized bipyridine ligands were assessed via the synthesis of rhenium carbonyl complexes, which facilitated the rationalization of the catalytic properties of the nanoparticles. 相似文献
102.
Pilar Cabildo Concepción López Marta Pérez-Torralba M. Rosario Torres José Elguero 《Journal of Molecular Structure》2011,985(1):75-81
3-Bromo-1-methyl-7-nitro-1H-indazole (1), 3-bromo-2-methyl-7-nitro-2H-indazole (2) and 3,7-dinitro-1(2)H-indazole (3) have been synthesized and characterized by X-ray diffraction, 13C and 15N NMR spectroscopy in solution and in solid-state. The dihedral angles obtained in the crystal structures are in good agreement with the molecular parameters calculated using DFT B3LYP calculations employing the 6-311++G(d,p) basis set. Compounds 1 and 2 present intermolecular halogen bonds between the bromine and the oxygen atoms of the nitro group and in compound 3 inter- and intramolecular hydrogen bonding exists. 相似文献
103.
María DS Farrán MÁ García MÁ Pinilla E Torres MR Elguero J Claramunt RM 《The Journal of organic chemistry》2011,76(16):6780-6788
Four hosts (7-10) containing 2,6-bisamidopyridine- and 2,5-bisamidopyrrole-bearing pyridyl or 1,8-naphthyridyl groups have been prepared and their structures studied by a combination of multinuclear NMR spectroscopy and X-ray crystallography. Their behavior in molecular recognition of urea derivatives, including (+)-biotin methyl ester, has been approached by molecular modeling (Monte Carlo conformational search, AMBER force field). The minimum energy values for the complexes are correlated with the experimental binding energies determined by means of (1)H NMR titrations. 相似文献
104.
Vergara J Barberá J Serrano JL Ros MB Sebastián N de la Fuente R López DO Fernández G Sánchez L Martín N 《Angewandte Chemie (International ed. in English)》2011,50(52):12523-12528
What a core-ker! By the appropriate combination of promesogenic bent-core structures and the C(60) unit, lamellar polar liquid-crystal phases were induced. The supramolecular organization of the functional fullerene-based assemblies, the temperature range of the soft phase, the stabilization of the mesophase-like order at room temperature, and the molecular switching under an electric field can be tuned, depending on the molecular structure. 相似文献
105.
Caruso R Gambino GL Scordino M Sabatino L Traulo P Gagliano G 《Natural product communications》2011,6(12):1939-1943
The influence of the wine distillation process on methanol content has been determined by quantitative analysis using gas chromatographic flame ionization (GC-FID) detection. A comparative study between direct injection of diluted wine and injection of distilled wine was performed. The distillation process does not affect methanol quantification in wines in proportions higher than 10%. While quantification performed on distilled samples gives more reliable results, a screening method for wine injection after a 1:5 water dilution could be employed. The proposed technique was found to be a compromise between the time consuming distillation process and direct wine injection. In the studied calibration range, the stability of the volatile compounds in the reference solution is concentration-dependent. The stability is higher in the less concentrated reference solution. To shorten the operation time, a stronger temperature ramp and carrier flow rate was employed. With these conditions, helium consumption and column thermal stress were increased. However, detection limits, calibration limits, and analytical method performances are not affected substantially by changing from normal to forced GC conditions. Statistical data evaluation were made using both ordinary (OLS) and bivariate least squares (BLS) calibration models. Further confirmation was obtained that limit of detection (LOD) values, calculated according to the 3sigma approach, are lower than the respective Hubaux-Vos (H-V) calculation method. H-V LOD depends upon background noise, calibration parameters and the number of reference standard solutions employed in producing the calibration curve. These remarks are confirmed by both calibration models used. 相似文献
106.
Rolando Gonzlez-Pea Rosa María Cibrin-Ortiz de Anda Angel J Pino-Velzquez Yhoama Gonzlez-Jorge Rosario Salvador-Palmer 《Optics and Lasers in Engineering》2003,39(5-6):609-618
Speckle photography (SP) is a powerful tool that is adequate to determine small displacements in micrometer range. This information shows other characteristics of structure deformation under loads and can be determined as stress and strain distribution. In this paper we present the results of the application of the SP technique used to study the behaviour of discontinuities in a shearwall model. These structural elements are very important to the stability of buildings. The displacement whole field around the discontinuities and loading points was determined using the pointwise method. This allows us to determine stress distribution at the point of interest by means of the suitable equations. We also present the stress distribution obtained through the finite element method in order to compare the results obtained by means of these two techniques. Good correspondence was found between the displacements determined by both techniques (r=0.982) and also between the stress values we obtained. 相似文献
107.
Paolo Facchi Rosario Fazio Giuseppe Florio Saverio Pascazio Tetsuya Yoneda 《Foundations of Physics》2006,36(4):500-511
Decoherence is one of the most serious drawback in quantum mechanical applications. We discuss the effects of noise in superconducting devices (Josephson junctions) and suggest a decoherence-control strategy based on the quantum Zeno effect. 相似文献
108.
María del Carmen Barral Rodrigo González-Prieto Santiago Herrero Reyes Jiménez-Aparicio José Luis Priego Elia del Carmen Royer María Rosario Torres Francisco Alejandro Urbanos Felix Zamora 《Journal of Cluster Science》2008,19(1):219-230
Two new complexes, based on the unit Ru2Cl(μ-O2CC4H4N)4 (1) (O2CC4H4N = pyrrole-2-carboxylate), Ru2Cl(μ-O2CC4H4N)4(H2O)·4H2O [1(H
2
O)·4H
2
O], and Ru2Cl(μ-O2CC4H4N)4(Me2CO) [1(Me
2
CO)], are synthesized and structurally characterized. The physical properties of these complexes are studied and compared with
those previously reported for Ru2Cl(μ-O2CC4H4N)4(thf)·thf·H2O [1(thf)·thf·H
2
O]. The nature of the solvent molecule bonded to the axial position of the dimetallic unit determines the supramolecular interactions
leading to different arrangements in the solid state. The presence of NH groups in the pyrrolic rings favours the existence
of hydrogen bond interactions that are present in the three complexes. In addition, complex 1(Me
2
CO) shows π–π stacking interactions through pyrrolic rings of different dimetallic units.
Dedicated to the memory of Prof. F. Albert Cotton. 相似文献
109.
The [Ni(CN)2(CO)2]2? anion (I) reacts with either one or two equivalents of benzyl bromide in either water/acetone or anhydrous acetonitrile to produce mainly 1,3-diphenyl-2-propanone. Excess carbon monoxide inhibits the reaction. These results are interpreted as indicating that I is an intermediate in the reaction of K4[Ni2(CN)6] with CO and PhCH2Br to form 1,3-diphenyl-2-propanone. 相似文献
110.