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81.
82.
Kinetics of redox polymer-mediated enzyme electrodes 总被引:1,自引:0,他引:1
Oxygen-reducing enzyme electrodes are prepared from laccase of Trametes versicolor and a series of osmium-based redox polymer mediators covering a range of redox potentials from 0.11 to 0.85 V. Experimentally obtained current density generated by the film electrodes is analyzed using a one-dimensional numerical model to obtain kinetic parameters. The bimolecular rate constant for mediation is found to vary with mediator redox potential from 250 s(-1) M(-1) when mediator and enzyme are close in redox potential to 9.4 x 10(4) s(-1) M(-1) when the redox potential difference is large. The value of the bimolecular rate constant for the simultaneously occurring laccase-oxygen reaction is found to be 2.4 x 10(5) s(-1) M(-1). The relationship between mediator-enzyme overpotential and bimolecular rate constant is used to determine the optimum mediator redox potential for maximum power output of a hypothetical biofuel cell with a planar cathode and a reversible hydrogen anode. For laccase of T. versicolor (E(e)(0) = 0.82), the optimum mediator potential is 0.66 V (SHE), and a molecular structure is presented to achieve this result. 相似文献
83.
Finocchio E Busca G Forzatti P Groppi G Beretta A 《Langmuir : the ACS journal of surfaces and colloids》2007,23(20):10419-10428
The effect of pretreatments as well as of rhodium precursor and of the support over the morphology of Rh nanoparticles were investigated by Fourier transform infrared (FT-IR) spectroscopy of adsorbed CO. Over a Rh/alumina catalyst, both metallic Rh particles, characterized by IR bands in the range 2070-2060 cm-1 and 1820-1850 cm-1, and highly dispersed rhodium species, characterized by symmetric and asymmetric stretching bands of RhI(CO)2 gem-dicarbonyl species, are present. Their relative amount changes following pretreatments with gaseous mixtures, representative of the catalytic partial oxidation (CPO) reaction process. The Rh metal particle fraction decreases with respect to the Rh highly dispersed fraction in the order CO approximately CO/H2 > CH4/H2O, CH4/O2 > CH4 > H2. The metal particle dimensions decrease in the order CH4/O2 > H2 > CH4/H2O > CO > CO/H2. Grafting from a carbonyl rhodium complex also increases the amount and the dimensions of Rh0 particles at the catalyst surface. Increasing the ratio (extended rhodium metal particles/highly dispersed Rh species) allows a shorter conditioning process. The surface reconstruction phenomena going on during catalytic activity are related to this effect. 相似文献
84.
Inke Jess Tristan Neumann Huayna Terraschke Gianpiero Gallo Robert Dinnebier Christian Näther 《无机化学与普通化学杂志》2020,646(14):1046-1054
Reaction of MX2 (M = Cd, Zn; X = Cl, Br, I) with 2-cyanopyrazine leads to the formation of compounds with the composition CdX2(2-cyanopyrazine)2 (X = Cl; CdCl , X = Br; CdBr and X = I; CdI ) and ZnX2(2-cyanopyrazine)2 (X = Cl; ZnCl , X = Br; ZnBr and X = I; ZnI/I ). In the crystal structures of the Cd compounds and in ZnCl , the metal cations are octahedrally coordinated and are linked into chains by the halide anions via common edges. In contrast, in the crystal structures of ZnBr and ZnI/I the metal cations are tetrahedrally coordinated into discrete complexes. Further investigations show that a second modification of ZnCl2(2-cyanopyrazine)2 exists ( ZnI/II ), which is formed by kinetic control. The thermal properties of the 2-cyanopyrazine rich compounds were investigated by TG-DTA and temperature dependent XRPD measurements. Upon heating the Cd compounds, all 2-cyanopyrazine ligands are removed in a single step with no indication of the formation of a 2-cyanopyrazine deficient phase. A similar behavior is observed for ZnI , whereas for ZnCl and ZnBr , TG-DTA measurements suggest the formation of a 2-cyanopyrazine deficient phase that, in case of ZnBr , cannot be isolated and, for ZnCl , cannot be obtained pure. The emission of these compounds is shifted from the blue to orange depending on the crystal structure and the nature of the halide anion. 相似文献
85.
Baylet A Marécot P Duprez D Castellazzi P Groppi G Forzatti P 《Physical chemistry chemical physics : PCCP》2011,13(10):4607-4613
Reduction of Pd° and decomposition of palladium oxide supported on γ-alumina were studied at atmospheric pressure under different atmospheres (H(2), CH(4), He) over a 4 wt% Pd/Al(2)O(3) catalyst (mean palladium particle size: 5 nm with 50% of small particles of size below 5 nm). During temperature programmed tests (reduction, decomposition and oxidation) the crystal domain behaviour of the PdO/Pd° phase was evaluated by in situ Raman spectroscopy and in situ XRD analysis. Under H(2)/N(2), the reduction of small PdO particles (<5 nm) occurs at room temperature, whereas reduction of larger particles (>5 nm) starts at 100 °C and is achieved at 150 °C. Subsequent oxidation in O(2)/N(2) leads to reoxidation of small crystal domain at ambient temperature while oxidation of large particles starts at 300 °C. Under CH(4)/N(2), the small particle reduction occurs between 240 and 250 °C while large particle reduction is fast and occurs between 280 and 290 °C. Subsequent reoxidation of the catalyst reduced in CH(4)/N(2) shows that small and large particle oxidation of Pd° starts also at 300 °C. Under He, no small particle decomposition is observed probably due to strong interactions between particles and support whereas large particle reduction occurs between 700 and 750 °C. After thermal decomposition under He, the oxidation starts at 300 °C. Thus, the reduction phenomenon (small and large crystal domain) depends on the nature of the reducing agent (H(2), CH(4), He). However, whatever the reduction or decomposition treatment or the crystal domain, Pd° oxidation starts at 300 °C and is completed only at temperatures higher than 550 °C. Under lean conditions, with or without water, the palladium consists of reduced sites of palladium (Pd°, Pd(δ+) with δ < 2 or PdO(x) with x < 1) randomly distributed on palladium particles. 相似文献
86.
87.
C Ye I Drachuk R Calabrese H Dai DL Kaplan VV Tsukruk 《Langmuir : the ACS journal of surfaces and colloids》2012,28(33):12235-12244
We studied the pH-responsive behavior of layer-by-layer (LbL) microcapsules fabricated from silk fibroin chemically modified with different poly amino acid side chains: cationic (silk-poly l-lysine, SF-PL) or anionic (silk-poly-l-glutamic acid, SF-PG). We observed that stable ultrathin shell microcapsules can be assembled with a dramatic increase in swelling, thickness, and microroughness at extremely acidic (pH < 2.5) and basic (pH > 11.0) conditions without noticeable disintegration. These changes are accompanied by dramatic changes in shell permeability with a 2 orders of magnitude increase in the diffusion coefficient. Moreover, the silk ionomer shells undergo remarkable softening with a drop in Young's modulus by more than 1 order of magnitude due to the swelling, stretching, and increase in material porosity. The ability to control permeability and mechanical properties over a wide range for the silk-based microcapsules, with distinguishing stability under harsh environmental conditions, provides an important system for controlled loading and release and applications in bioengineering. 相似文献
88.
Fabio Gosetti Ugo Chiuminatto Eleonora Mazzucco Giorgio Calabrese Maria Carla Gennaro Emilio Marengo 《Analytica chimica acta》2012
The study deals with the identification of the degradation products formed by simulated sunlight photoirradiation in a beverage that contains Allura Red AC (E129) dye. An UHPLC–MS/MS method that makes use of high resolution quadrupole-time-of-flight mass spectrometer, was developed. For the identification of the degradation products the software tool Information Dependent Acquisition (IDA) was used to automatically obtain information about the high resolution MS and MS/MS spectra of the species present. 相似文献
89.
Gianpiero Gervino Andrea Lavagno Daniele Pigato 《Central European Journal of Physics》2012,10(3):594-601
We investigate the relativistic equation of state of hadronic matter and quark-gluon plasma at finite temperature and baryon
density in the framework of the non-extensive statistical mechanics, characterized by power-law quantum distributions. We
impose the Gibbs conditions on the global conservation of baryon number, electric charge and strangeness number. For the hadronic
phase, we study an extended relativistic mean-field theoretical model with the inclusion of strange particles (hyperons and
mesons). For the quark sector, we employ an extended MIT-Bag model. In this context we focus on the relevance of non-extensive
effects in the presence of strange matter. 相似文献
90.
Lauren N. McHugh Angela Terracina Paul S. Wheatley Gianpiero Buscarino Martin W. Smith Russell E. Morris 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(34):11873-11877
Metal–organic frameworks (MOFs) are a class of porous materials that show promise in the removal of toxic industrial chemicals (TICs) from contaminated airstreams, though their development for this application has so far been hindered by issues of water stability and the wide availability and low cost of traditionally used activated carbons. Here a series of three MOF‐activated carbon composite materials with different MOF to carbon ratios are prepared by growing STAM‐17‐OEt crystals inside the commercially available BPL activated carbon. The composite materials display excellent water stability and increased uptake of ammonia gas when compared to unimpregnated carbon. Such properties make these composites very promising in the fields of air purification and personal protective equipment. 相似文献