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991.
We consider the harmonic and anharmonic chains of oscillators with self-consistent stochastic reservoirs and derive an integral
representation (à la Feynman-Kac) for the correlations, in particular, for the heat flow. For the harmonic chain, we give
a new proof that its thermal conductivity is finite in the steady state. Based on this integral representation for the correlations
and a perturbative analysis, the approach is quite general and can be extended to more intricate systems.
__________
Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 156, No. 1, pp. 138–146, July, 2008. 相似文献
992.
A theoretical study of the possible protonation sites of simple molecules formed by C, N, Si, P, B and Al that present a triple
bond between those atoms has been carried out. The calculations performed include MP2 and CCSD(T) methods with the aug-cc-pVTZ
basis set. The nature of the protonated species has been analyzed with the Atoms In Molecules methodology.
To Serafin, a free spirit and a good friend.
Contribution to the Serafin Fraga Memorial Issue. 相似文献
993.
Javier Garín Enrique Melndez Francisco L. Merchn Pedro Merino Jesús Orduna Toms Tejero 《Journal of heterocyclic chemistry》1990,27(5):1345-1349
The title compounds 3 were synthesized in one step from bisdithiocarbamates 2 , and their structures were confirmed by two independent syntheses. Alkylation and hydrolysis of 3 gives 3,3′-arylenebis(2,4-dioxo-1,2,3,4-tetrahydroquinazolines) 8 . 相似文献
994.
Krzysztof Pomorski José M. Blanco Pavel V. Kostryukov Artur Dobrowolski Bo?ena Nerlo-Pomorska Micha? Warda Zhi-Gang Xiao Yong-Jing Chen Li-Le Liu Jun-Long Tian Xin-Yue Diao Qiang-Hua Wu 《中国物理C(英文版)》2021,45(5):054109-054109-11
Fission properties of the actinide nuclei are deduced from theoretical analysis. We investigate potential energy surfaces and fission barriers and predict the fission fragment mass yields of actinide isotopes. The results are compared with experimental data where available. The calculations were performed in the macroscopic-microscopic approximation with the Lublin-Strasbourg Drop (LSD) for the macroscopic part, and the microscopic energy corrections were evaluated in the Yukawa-folded potential. The Fourier nuclear shape parametrization is used to describe the nuclear shape, including the non-axial degree of freedom. The fission fragment mass yields of the nuclei considered are evaluated within a 3D collective model using the Born-Oppenheimer approximation. 相似文献
995.
Maurya S. K. Pradhan Anirudh Tello-Ortiz Francisco Banerjee Ayan Nag Riju 《The European Physical Journal C - Particles and Fields》2021,81(9):1-11
The European Physical Journal C - Baryon inhomogeneities are generated early in the universe. These inhomogeneities affect the phase transition dynamics of subsequent phase transitions, they also... 相似文献
996.
Alex Virgilio Renata Stabile Amais Daniela Schiavo José Anchieta Gomes Neto Joaquim de Araújo Nóbrega 《Analytical letters》2017,50(5):842-852
A procedure for the determination of As, Cd, Cr, Ni, Pb, and V in phytotherapy medicines by inductively coupled plasma–tandem mass spectrometry is reported. The use of tandem mass spectrometry with oxygen into an octopole reaction system at various gas flow rates and the combination of on-mass and mass-shift modes was evaluated. Cadmium, Cr, Ni, and Pb were determined as free atomic ions while As and V were determined as the oxides AsO+ and VO+ in the same run. Samples were prepared by microwave-assisted digestion with dilute nitric acid and hydrogen peroxide. Two plant-certified reference materials (apple leaves and tomato leaves) were used to check the accuracy. For tandem mass spectrometry with 0.5?mL min?1 O2, recoveries in the 85–113% were typically obtained and no statistical differences were observed at the 95% confidence level (t-test) in comparison with the certified values. Using these conditions, the limits of detection for the method were 0.01, 0.0002, 0.008, 0.008, 0.003, and 0.002?µg g?1 for As, Cd, Cr, Ni, Pb, and V, respectively. The procedure was used for the analysis of four phytotherapic drugs and the determined concentrations were up to 0.168?µg g?1 As, 0.03?µg g?1 Cd, 0.82?µg g?1 Cr, 1.18?µg g?1 Ni, 0.52?µg g?1 Pb, and 2.4?µg g?1 V with average precision values of 8% as the relative standard deviation. The found concentrations were compared with limits proposed in official guidelines and, in most cases, the values were below the maximum limits allowed. 相似文献
997.
Carla F. C. Ruschel Marcelo C. A. Marcelo Francisco P. dos Santos Marco F. Ferrão 《Analytical letters》2017,50(11):1767-1777
Automotive fuel adulteration is an old and significant problem. One common type of fuel adulteration is the addition of diesel to gasoline. Unsupervised models were developed through hierarchical cluster and principal component analysis models. Supervised models through partial least square discriminant analysis using 1H nuclear magnetic resonance spectra as the input were used to classify samples as adulterated or unadulterated. Quantitative models were developed using partial least squares to determine the gasoline and diesel concentrations in the samples. This set contained samples composed of pure gasoline and anhydrous ethanol reproducing commercial gasoline and other samples treated with diesel. Hierarchical cluster and principal component analysis did not distinguish between adulterated and unadulterated samples except for the most adulterated materials. However, partial least square discriminant analysis classified 100% of the samples correctly. The partial least square algorithm provided excellent regression models for the gasoline and diesel content. The determination coefficient was 0.9920 for both models, whereas the root mean square error of cross-validation and root mean square error of prediction for the diesel model were 2.32 and 1.42%, respectively, and 2.40 and 1.38% for the gasoline model. 相似文献
998.
Confinement effects on the electronic structure of M‐shell atoms: A study with explicitly correlated wave functions
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Francisco J. Gálvez Enrique Buendía Antonio Sarsa 《International journal of quantum chemistry》2017,117(19)
The ground and some excited states of Na and Mg atoms confined at the center of a spherical box with impenetrable walls are studied. Variational wave functions including dynamic correlations and configuration mixing have been obtained. Level crossings induced by confinement have been analyzed in terms of the energy of the occupied orbitals of the M shell and the weight of the different configurations. Confinement effects on the correlation energy have been studied. The parameterized optimized effective potential and the variational Monte Carlo methods have been employed. A cut off‐factor has been included to account for the hard wall confinement. 相似文献
999.
José A. Murillo Pulgarín Luisa F. García Bermejo Armando Carrasquero Durán 《Analytical letters》2017,50(1):186-196
This study reports a simple and rapid method for the determination of the antioxidant activity of the phenolics present in plants of the Hibiscus genus. The protocol is based on the ability of the phenolic compounds to inhibit luminol chemiluminescence through the inactivation of free radicals in a flow injection system. Using the optimized operational conditions, the antioxidant activities of several phenolics were measured. The results were explained on the basis of structure–reactivity relationships. The antioxidant activities of dried flowers of Hibiscus rosa-sinensis and Hibiscus sabdariffa were evaluated. The protocol was validated by the 2,2-diphenyl-1-picrylhydrazyl-hydrate free radical assay. The differences in the antiradical activities were explained based on the concentrations of total polyphenol and flavonoid concentrations determined by spectrophotometric methods. It was concluded that the chemiluminescence method was complementary for the evaluation of hydrophilic antioxidants in plants. 相似文献
1000.
José Gustavo Ávila-Zárraga Ignacio Pérez Erick Beristain Irma Gavilan Moises Romero 《合成通讯》2017,47(4):364-367
Several new 6-(alkylamine)-6H-dibenz[c,e][1,2]oxaphosphinine-6-oxides were prepared through a one-pot reaction, starting with 2-phenylphenol, phosphorus trichloride, and a Zn catalyst, to form 6-chloro-6H-dibenz[c,e][1,2]oxaphosphine. The alkylamine derivatives were subsequently prepared through a nucleophilic substitution reaction involving aliphatic amines and H2O2 oxidation under soft conditions. This method has the advantages that it is a one-pot synthesis, does not require an inert atmosphere, and involves in situ catalyst formation. 相似文献