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141.
142.
A semi-analytical solution is obtained for a rotating stress-free edge disk of constant thickness and density. In the plastic
range, the Hill’s quadratic orthotropic yield criterion is adopted. In the elastic range, the Hooke’s law holds with thermal
effects included. The analysis of singularities performed may be used for correct implementation of numerical codes and preliminary
engineering design. 相似文献
143.
Jaume Llibre Paulo R. da Silva Marco A. Teixeira 《Journal of Dynamics and Differential Equations》2007,19(2):309-331
Singular perturbations problems in dimension three which are approximations of discontinuous vector fields are studied in
this paper. The main result states that the regularization process developed by Sotomayor and Teixeira produces a singular
problem for which the discontinuous set is a center manifold. Moreover, the definition of sliding vector field coincides with
the reduced problem of the corresponding singular problem for a class of vector fields.
相似文献
144.
Paulo H. P. Macaúbas Hideo Kawamoto Masaoki Takahashi Kenzo Okamoto Toshikazu Takigawa 《Rheologica Acta》2007,46(7):921-932
Shape recovery of a droplet of liquid crystalline polymer (LCP) hydroxypropylcellulose in a matrix of poly(dimethyl siloxane) subjected to a step shear strain has been studied via optical microscopy. Just after application of a large strain, the LCP droplet shape is flat ellipsoid, and then the droplet takes cylindrical shape and band texture perpendicular to the flow direction appears. The band texture fades away before emergence of poly-domain structure. In the final process with the shape of spheroid, poly-domain structure recovers very slowly. Except for the final process, the shape change is identical with that of isotropic droplet at strains smaller than 3, when the LCP viscosity in Region II is taken as an equivalent viscosity for normalization. For a 20:80 blend, the excess relaxation modulus is calculated based on the Doi-Ohta theory, taking account of the distribution of droplet size and compared with experimental modulus data. 相似文献
145.
Amperometric Folic Acid Quantification Using a Supramolecular Tetraruthenated Nickel Porphyrin µ‐Peroxo‐Bridged Matrix Modified Electrode Associated to Batch Injection Analysis
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Luís M. C. Ferreira Paulo R. Martins Koiti Araki Henrique H. Toma Lúcio Angnes 《Electroanalysis》2015,27(10):2322-2328
A supramolecular Nickel (II) porphyrin complex containing four pyridyl‐bis(2,2′‐bipyridyl)chloro ruthenium meso substituents was submitted to successive voltammetric cycles in high alkaline media to produce a supramolecular matrix with Nickel centers linked by µ‐peroxo bridges, producing a highly stable thin film able to act as redox mediator for electrocatalytic oxidation of folic acid. The characterization of electrode surface material was performed by Scanning Electron Microscopy and Electrochemical Impedance Spectroscopy. The modified electrode was inserted into a batch injection electrochemical cell used for the rapid and precise quantification of folic acid in pharmaceutical products. The favorable hydrodynamic conditions provided by amperometry‐BIA association allowed a very high throughput with good linear range (1 to 200 µmol L?1) and low detection limit (7.37×10?7 mol L?1). The electrochemical method was applied to the quantification of folic acid in different tablet samples. The results were comparable with values indicated by the manufacturer and those found using high HPLC according to the Brazilian Pharmacopoeia; commercial samples were submitted to a procedure in order to remove lactose of tablets, since carbohydrates act as interfering species. This procedure together with the electrochemical method showed to be simple, rapid, efficient and an appropriate alternative for quantifying this compound in real samples. 相似文献
146.
147.
Formulation of Aluminum Chloride Phthalocyanine in Pluronic™ P‐123 and F‐127 Block Copolymer Micelles: Photophysical properties and Photodynamic Inactivation of Microorganisms
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Bruno Henrique Vilsinski Adriana Passarella Gerola Junior Adalberto Enumo Katieli da Silva Souza Campanholi Paulo Cesar de Souza Pereira Gustavo Braga Noboru Hioka Elza Kimura André Luiz Tessaro Wilker Caetano 《Photochemistry and photobiology》2015,91(3):518-525
Aluminum Chloride Phthalocyanine (AlPcCl) can be used as a photosensitizer (PS) for Photodynamic Inactivation of Microorganisms (PDI). The AlPcCl showed favorable characteristics for PDI due to high quantum yield of singlet oxygen (ΦΔ) and photostability. Physicochemical properties and photodynamic inactivation of AlPcCl incorporated in polymeric micelles of tri‐block copolymer (P‐123 and F‐127) against microorganisms Staphylococcus aureus, Escherichia coli and Candida albicans were investigated in this work. Previously, it was observed that the AlPcCl undergoes self‐aggregation in F‐127, while in P‐123 the PS is in a monomeric form suitable for PDI. Due to the self‐aggregation of AlPcCl in F‐127, this formulation did not show any effect on these microorganisms. On the other hand, AlPcCl formulated in P‐123 was effective against S. aureus and C. albicans and the death of microorganisms was dependent on the PS concentration and illumination time. Additionally, it was found that the values of PS concentration and illumination time to eradicate 90% of the initial population of microorganisms (IC90 and D90, respectively) were small for the AlPcCl in P‐123, showing the effectiveness of this formulation for PDI. 相似文献
148.
149.
Mariana R. Almeida Deleon N. Correa Jorge J. Zacca Lucio Paulo Lima Logrado Ronei J. Poppi 《Analytica chimica acta》2015
The aim of this study was to develop a methodology using Raman hyperspectral imaging and chemometric methods for identification of pre- and post-blast explosive residues on banknote surfaces. The explosives studied were of military, commercial and propellant uses. After the acquisition of the hyperspectral imaging, independent component analysis (ICA) was applied to extract the pure spectra and the distribution of the corresponding image constituents. The performance of the methodology was evaluated by the explained variance and the lack of fit of the models, by comparing the ICA recovered spectra with the reference spectra using correlation coefficients and by the presence of rotational ambiguity in the ICA solutions. The methodology was applied to forensic samples to solve an automated teller machine explosion case. Independent component analysis proved to be a suitable method of resolving curves, achieving equivalent performance with the multivariate curve resolution with alternating least squares (MCR-ALS) method. At low concentrations, MCR-ALS presents some limitations, as it did not provide the correct solution. The detection limit of the methodology presented in this study was 50 μg cm−2. 相似文献
150.
Vivian E. Cornelio Mariele M. Pedroso André S. Afonso João B. Fernandes M.Fátima G.F. da Silva Ronaldo C. Faria Paulo C. Vieira 《Analytica chimica acta》2015
The hemoglobin (Hb) released from erythrocytes is a primary nutritive component for many blood-feeding parasites. The aspartic protease cathepsin D is a hemoglobinase that is involved in the Hb degradation process and is considered an interesting target for chemotherapy intervention. However, traditional enzymatic assays for studying Hb degradation utilize spectrophotometric techniques, which do not allow real-time monitoring and can present serious interference problems. Herein, we describe a biosensor using simple approach for the real-time monitoring of Hb hydrolysis as well as an efficient screening method for natural products as enzymatic inhibitors using a quartz crystal microbalance (QCM) technique. Hemoglobin was anchored on the quartz crystal surface using mixed self-assembled monolayers. The addition of the enzyme caused a mass change (frequency shift) due to Hb hydrolysis, which was monitored in real time. From the frequency change patterns of the Hb-functionalized QCM, we evaluated the enzymatic reaction by determining the kinetic parameters of product formation (kcat). The QCM enzymatic assay using immobilized human Hb was shown to be an excellent approach for screening possible inhibitors in complex mixtures, opening up a new avenue for the discovery of novel inhibitors. 相似文献