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71.
72.
Alessandro D’Aprano Bianca Sesta Noemi Proietti Vincenzo Mauro 《Journal of solution chemistry》1997,26(6):649-662
Conductivity measurements, focused on the counterion binding of lithium perfluorononanoate (LiPFN) micelles in pure water
and in the presence of poly(vinyl pyrrolidone) (PVP), have been carried out. An abrupt decrease of the conductance of the
LiPFN in pure water, due to the self aggregation of anions and to dynamic linkage of cations on the micellar surface, has
been found. Analysis of the conductometric data indicates that about 50% of the stoichiometric concentration of Li+ interacts with the head groups of the perfluorinated anions involved in micellar assembly. Conductometric data of LiPFN-water-PVP
systems reveals a favorable influence of the PVP on the micellization process modulated by the concentration and by the molecular
weight of the polymer. Analysis of these data shows that in presence of PVP the degree of binding of lithium ion to the micellar
assemblies linked to the polymer is smaller than in pure water. By increasing the amount of surfactant in solution up to the
concentration where the polymer becomes saturated by LiPFN micelles, the binding of lithium ion in the system becomes slightly
greater than that observed in LiPFN-water system. This finding can be interpreted in terms of additional binding of lithium
ion to the polymer chains. Conductivity measurements carried out on LiClO4 and KClO4 in water + PVP support this interpretation. 相似文献
73.
Ribicki Ariane Caroline Chemin Bianca Gurski Van Haandel Viviane Jandira Winiarski João Paulo de Castro Rozada Thiago Pessoa Christiana Andrade Estrada Ruben Auccaise Fiorin Barbara Celânia Fujiwara Sérgio Toshio 《Journal of Sol-Gel Science and Technology》2018,87(1):216-229
Journal of Sol-Gel Science and Technology - A silsesquioxane based on a silica matrix and 4-(aminomethyl)pyridine group was successfully synthesized using the sol–gel process with the... 相似文献
74.
Scrimin P Tecilla P Tonellato U Verzini M Andreini BP Coutant JE Zerilli LF 《The Journal of organic chemistry》1996,61(18):6268-6272
The thermodynamics and kinetics of binding of model tripeptides epsilon-N-acetyl-alpha-N-dansyl-L-Lys-D-Ala-D-Ala (ADLAA) or alpha-N,epsilon-N-diacetyl-L-Lys-D-Ala-D-Ala (AALAA) to teicoplanin (1a) and a series of semisynthetic derivatives with (1b-f) or devoid of (2a-g) the glycidic side arms and modified at the terminal amino acids of the peptide backbone have been studied by fluorescence or UV spectroscopy. The binding process is suggested to occur via a two-step mechanism. The first, fast process is likely governed by an electrostatic interaction between the C- and N-termini of the peptide chain of the substrate and of the antibiotic, respectively, while the second slower one, accounts for the formation of the hydrogen bonds responsible of the major contribution to the overall binding energy. The binding constants with all modified derivatives are smaller than that with native teicoplanin. Larger modification of the overall binding constant are observed when the sugar residues are removed and, to a lower extent, when the N-terminus of the peptide chain is acylated. The kinetic process is very little affected by the modifications introduced. 相似文献
75.
A simple and rapid method was developed for the determination of 20 antibiotics (sulfonamides, tetacyclines, and flumequine) in honey by liquid chromatography tandem mass spectrometry. The proposed method is sensitive (limit of detection 0.5 to 10 ppb for the various antibiotics) and selective. A hydrolysis step ensures the liberation of sugar-bound sulfonamides. The approach has been used to analyze some 300 honey samples. A number of them were found to have exceeded the Swiss limit of 50 ppb. 相似文献
76.
Angelo Albert Francesco Paolo Colonna Maurizio Guerra Bianca F. Bonini Germana Mazzanti Zoltàn Dinya Gian Franco Pedulli 《Journal of organometallic chemistry》1981,221(1):47-55
The radical adducts resulting from the reaction between group IVB organometallic radicals MR3 (M = Si, Ge, Sn; R = alkyl or aryl) and a number of thioketones of the chromone and flavone series have been investigated by ESR spectroscopy. The spectral parameters obtained for these species have been compared with those of similar adducts of the corresponding ketones. Both classes of radicals adopt an orthogonal conformation, and the differences between the former and the latter paramagnetic species can be accounted for by the different electronegativity of oxygen and sulphur. the effects of substitution of the heterocyclic oxygen with a sulphur or selenium atom on the spin density distribution are likewise explained. INDO calculations have been carried out on the model systems CH2XSiH3 (X = O, S). 相似文献
77.
Bruna Bovio
Sandro Calogero
Friedrich E. Wagner
Alfredo Burini
Bianca Rosa Pietroni 《Journal of organometallic chemistry》1994,470(1-2):275-283Reactions of the trinuclear [Au3Rim3] compound (Rim = [μ-1-benzylimidazolato-N3,C2] with several reagents capable of oxidative addition have been investigated by 197Au Mössbauer spectroscopy. The reaction products are either AuI carbene mononuclear and binuclear complexes or trinuclear AuIII and mixed-valence compounds. The X-ray crystal structure of the mixed-valence complex [AuIIIAuI2Rim3I2] has been determined. Two two-coordinate AuI centres show average Au---C and Au---N distances of 2.02(3) and 2.04(2) Å and average C---Au---N angles of 175.0(1.2)°, whereas the four-coordinate AuIII centre gives Au---C and Au---N 1.96(4) and 1.91(3) Å with the C---Au---N angle 170.5(1.6)°, and Au---I average distances 2.598(3) Å, with an I---Au=I angle 175.8(1)°. The Au---Au intramolecular distances [Au(1) Au(2) 3.432(3), Au(1) Au(3) 3.508(3), Au(2) Au(3) 3.464(3) Å] indicate a weak metal-metal interaction. 相似文献
78.
79.
Manuel W. Thesen Bianca Höfer Marc Debeaux Silvia Janietz Armin Wedel Anna Köhler Hans‐Hermann Johannes Hartmut Krueger 《Journal of polymer science. Part A, Polymer chemistry》2010,48(15):3417-3430
A series of novel styrene derived monomers with triphenylamine‐based units, and their polymers have been synthesized and compared with the well‐known structure of polymer of N,N′‐bis(3‐methylphenyl)‐N,N′‐diphenylbenzidine with respect to their hole‐transporting behavior in phosphorescent polymer light‐emitting diodes (PLEDs). A vinyltriphenylamine structure was selected as a basic unit, functionalized at the para positions with the following side groups: diphenylamine, 3‐methylphenyl‐aniline, 1‐ and 2‐naphthylamine, carbazole, and phenothiazine. The polymers are used in PLEDs as host polymers for blend systems with the following device configuration: glass/indium–tin–oxide/PEDOT:PSS/polymer‐blend/CsF/Ca/Ag. In addition to the hole‐transporting host polymer, the polymer blend includes a phosphorescent dopant [Ir(Me‐ppy)3] and an electron‐transporting molecule (2‐(4‐biphenyl)‐5‐(4‐tert‐butylphenyl)‐1,3,4‐oxadiazole). We demonstrate that two polymers are excellent hole‐transporting matrix materials for these blend systems because of their good overall electroluminescent performances and their comparatively high glass transition temperatures. For the carbazole‐substituted polymer (Tg = 246 °C), a luminous efficiency of 35 cd A?1 and a brightness of 6700 cd m?2 at 10 V is accessible. The phenothiazine‐functionalized polymer (Tg = 220 °C) shows nearly the same outstanding PLED behavior. Hence, both these polymers outperform the well‐known polymer of N,N′‐bis(3‐methylphenyl)‐N,N′‐diphenylbenzidine, showing only a luminous efficiency of 7.9 cd A?1 and a brightness of 2500 cd m?2 (10 V). © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3417–3430, 2010 相似文献
80.