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881.
We investigate flux front penetration in a disordered type-II superconductor by molecular dynamics simulations of interacting vortices and find scaling laws for the front position and the density profile. The scaling can be understood by performing a coarse graining of the system and writing a disordered nonlinear diffusion equation. Integrating numerically the equation, we observe a crossover from flat to fractal front penetration as the system parameters are varied. The value of the fractal dimension indicates that the invasion process is described by gradient percolation. 相似文献
882.
Celeste de Jesus Pereira Franco Oberdan Oliveira Ferreira Jorddy Neves Cruz Everton Luiz Pompeu Varela ngelo Antnio Barbosa de Moraes Lidiane Diniz do Nascimento Mrcia Moraes Cascaes Antnio Pedro da Silva Souza Filho Rafael Rodrigues Lima Sandro Percrio Mozaniel Santana de Oliveira Eloisa Helena de Aguiar Andrade 《Molecules (Basel, Switzerland)》2022,27(15)
The essential oil (EO) of Calycolpus goetheanus (Myrtaceae) specimens (A, B, and C) were obtained through hydrodistillation. The analysis of the chemical composition of the EOs was by gas chromatography coupled with mass spectrometry CG-MS, and gas chromatography coupled with a flame ionization detector CG-FID. The phytotoxic activity of those EOs was evaluated against two weed species from common pasture areas in the Amazon region: Mimosa pudica L. and Senna obtusifolia (L.) The antioxidant capacity of the EOs was determined by (DPPH•) and (ABTS•+). Using molecular docking, we evaluated the interaction mode of the major EO compounds with the molecular binding protein 4-hydroxyphenylpyruvate dioxygenase (HPPD). The EO of specimen A was characterized by β-eudesmol (22.83%), (E)-caryophyllene (14.61%), and γ-eudesmol (13.87%), while compounds 1,8-cineole (8.64%), (E)-caryophyllene (5.86%), δ-cadinene (5.78%), and palustrol (4.97%) characterize the chemical profile of specimen B’s EOs, and specimen C had α-cadinol (9.03%), δ-cadinene (8.01%), and (E)-caryophyllene (6.74%) as the majority. The phytotoxic potential of the EOs was observed in the receptor species M. pudica with percentages of inhibition of 30%, and 33.33% for specimens B and C, respectively. The EOs’ antioxidant in DPPH• was 0.79 ± 0.08 and 0.83 ± 0.02 mM for specimens A and B, respectively. In the TEAC, was 0.07 ± 0.02 mM for specimen A and 0.12 ± 0.06 mM for specimen B. In the results of the in silico study, we observed that the van der Waals and hydrophobic interactions of the alkyl and pi-alkyl types were the main interactions responsible for the formation of the receptor–ligand complex. 相似文献
883.
Andrade LH Lima SM Novatski A Udo PT Astrath NG Medina AN Bento AC Baesso ML Guyot Y Boulon G 《Physical review letters》2008,100(2):027402
This Letter reports the formation of Ti3+ in OH- free aluminosilicate glass melted under vacuum condition, with a very long lifetime (170 micros) and broad emission band shifted towards the visible region. This lifetime value was attributed to the trapping of the excited electrons by the glass defects and detrapping by thermal energy, and it is 2 orders of magnitude higher than those published for Ti3+ doped materials. Our results suggest that this glass is a promising system to overcome the challenge of extending the spectral range of traditional tunable solid state lasers towards the visible region. 相似文献
884.
L. R. Calixto D. M. Lima R. S. Queiroz A. N. S. Rastelli V. S. Bagnato M. F. Andrade 《Laser Physics》2008,18(11):1365-1369
The purpose of this study was to evaluate the polymerization effectiveness of a composite resin (Z-250) utilizing microhardness testing. In total, 80 samples with thicknesses of 2 and 4 mm were made, which were photoactivated by a conventional halogen light-curing unit, and light-curing units based on LED. The samples were stored in water distilled for 24 h at 37°C. The Vickers microhardness was performed by the MMT-3 microhardness tester. The microhardness means obtained were as follows: G1, 72.88; G2, 69.35; G3, 67.66; G4, 69.71; G5, 70.95; G6, 75.19; G7, 72.96; and G8, 71.62. The data were submitted to an analysis of variance (ANOVA’s test), adopting a significance level of 5%. The results showed that, in general, there were no statistical differences between the halogen and LED light-curing units used with the same parameters. 相似文献
885.
Fragment-based and classical quantitative structure–activity relationships for a series of hydrazides as antituberculosis agents 总被引:1,自引:1,他引:0
Andrade CH Salum Lde B Castilho MS Pasqualoto KF Ferreira EI Andricopulo AD 《Molecular diversity》2008,12(1):47-59
Worldwide, tuberculosis (TB) is the leading cause of death among curable infectious diseases. Multidrug-resistant Mycobacterium tuberculosis is an emerging problem of great importance to public health, and there is an urgent need for new anti-TB drugs. In the present work, classical 2D quantitative structure-activity relationships (QSAR) and hologram QSAR (HQSAR) studies were performed on a training set of 91 isoniazid derivatives. Significant statistical models (classical QSAR, q (2) = 0.68 and r (2) = 0.72; HQSAR, q (2) = 0.63 and r (2) = 0.86) were obtained, indicating their consistency for untested compounds. The models were then used to evaluate an external test set containing 24 compounds which were not included in the training set, and the predicted values were in good agreement with the experimental results (HQSAR, [Formula: see text] ; classical QSAR, [Formula: see text]). 相似文献
886.
B. A. Mello V. M.C.S. Souza D. O. Cajueiro R. F.S. Andrade 《The European Physical Journal B - Condensed Matter and Complex Systems》2010,76(1):147-156
The minority game (MG) is used as a source of information to design complex networks where the nodes represent the playing
agents. Differently from classical MG consisting of independent agents, the current model rules that connections between nodes
are dynamically inserted or removed from the network according to the most recent game outputs. This way, preferential attachment
based on the concept of social distance is controlled by the agents wealth. The time evolution of the network topology, quantitatively
measured by usual parameters, is characterized by a transient phase followed by a steady state, where the network properties
remain constant. Changes in the local landscapes around individual nodes depend on the parameters used to control network
links. If agents are allowed to access the strategies of their network neighbors, a feedback effect on the network structure
and game outputs is observed. Such effect, known as herding behavior, considerably changes the dependence of volatility σ on memory size: it is shown that the absolute value of σ as well as the corresponding value of memory size depend both on the network topology and on the way along which the agents
make their playing decisions in each game round. 相似文献
887.
R. V. Ferreira I. L. S. Pereira L. C. D. Cavalcante L. F. Gamarra S. M. Carneiro E. Amaro Jr. J. D. Fabris R. Z. Domingues A. L. Andrade 《Hyperfine Interactions》2010,195(1-3):265-274
Magnetic nanoparticles coated with silica have been subjected of extensive, and, in many aspects, also intensive investigations because of their potential application in different technological fields, particularly in biomedicine. This work was conceived and is being carried out in two main parts: (1) synthesis of the ferrimagnetic nanoparticles, specifically magnetite, and (2) coating these particles with tetraethyl orthosilicate (TEOS). The nanosized magnetite sample was prepared by the reduction–precipitation and the nanomagnetite particles were coated by the sol-gel method, based on the hydrolysis of tetraethyl orthosilicate (TEOS). The so obtained materials were characterized with powder X-ray diffraction (XRD), FTIR spectroscopy, saturation magnetization measurements, and 57Fe Mössbauer spectroscopy at room temperature. 相似文献
888.
889.
Lee Y Andrade JS Buldyrev SV Dokholyan NV Havlin S King PR Paul G Stanley HE 《Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics》1999,60(3):3425-3428
We study traveling time and traveling length for tracer dispersion in two-dimensional bond percolation, modeling flow by tracer particles driven by a pressure difference between two points separated by Euclidean distance r. We find that the minimal traveling time t(min) scales as t(min) approximately r(1.33), which is different from the scaling of the most probable traveling time, t* approximately r(1.64). We also calculate the length of the path corresponding to the minimal traveling time and find l(min) approximately r(1.13) and that the most probable traveling length scales as l* approximately r(1.21). We present the relevant distribution functions and scaling relations. 相似文献
890.
A broad chemometric study was made on structural data from non-fused and non-pi-complexed pentafulvenes obtained both from the Cambridge structural database (CSD) and from several studies to synthesise new fulvene compounds. Three main differentiated pentafulvene groups can be established considering bond distances extracted from the CSD database. Structural data for the new 1-mono and 1,4-disubstituted 2,3,6-trioxypentafulvenes and 1,4-disubstituted-6-amino-2, 3-dioxypentafulvenes reveal different structural behaviours due to their high functionality. The chemometric techniques employed comprise principal component analysis, cluster analysis, selection of essential variables (Procrustes rotation) and isoprobability curves, all of them giving essentially the same general chemical conclusions. 相似文献