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991.
We characterize the eigenvalues of [X,A]=XA?AX, where A is an n by n fixed matrix and X runs over the set of the matrices of the same size. 相似文献
992.
Prof. Rocío Domínguez Prof. Mónica Moral Prof. M. Paz Fernández-Liencres Prof. Tomás Peña-Ruiz Prof. Juan Tolosa Prof. Jesús Canales-Vázquez Prof. Joaquín C. García-Martínez Prof. Amparo Navarro Prof. Andrés Garzón-Ruiz 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(15):3373-3384
This work is focused on unraveling the mechanisms responsible for the aggregation-induced enhanced emission and solid-state luminescence enhancement effects observed in star-shaped molecules based on 1,3,5-tris(styryl)benzene and tri(styryl)-s-triazine cores. To achieve this, the photophysical properties of this set of molecules were analyzed in three states: free molecules, molecular aggregates in solution, and the solid state. Different spectroscopy and microscopy experiments and DFT calculations were conducted to scrutinize the causative mechanisms of the luminescence enhancement phenomenon observed in some experimental conditions. Enhanced luminescence emission was interpreted in the context of short- and long-range excitonic coupling mechanisms and the restriction of intramolecular vibrations. Additionally, we found that the formation of π-stacking aggregates could block E/Z photoisomerization through torsional motions between phenylene rings in the excited state, and hence, enhancing the luminescence of the system. 相似文献
993.
Technologies Employed in the Treatment of Water Contaminated with Glyphosate: A Review 总被引:1,自引:0,他引:1
Patricio J. Espinoza-Montero Carolina Vega-Verduga Paulina Alulema-Pullupaxi Lenys Fernndez Jose L. Paz 《Molecules (Basel, Switzerland)》2020,25(23)
Glyphosate [N-(phosphonomethyl)-glycine] is a herbicide with several commercial formulations that are used generally in agriculture for the control of various weeds. It is the most used pesticide in the world and comprises multiple constituents (coadjutants, salts, and others) that help to effectively reach the action’s mechanism in plants. Due to its extensive and inadequate use, this herbicide has been frequently detected in water, principally in surface and groundwater nearest to agricultural areas. Its presence in the aquatic environment poses chronic and remote hazards to human health and the environment. Therefore, it becomes necessary to develop treatment processes to remediate aquatic environments polluted with glyphosate, its metabolites, and/or coadjutants. This review is focused on conventional and non-conventional water treatment processes developed for water polluted with glyphosate herbicide; it describes the fundamental mechanism of water treatment processes and their applications are summarized. It addressed biological processes (bacterial and fungi degradation), physicochemical processes (adsorption, membrane filtration), advanced oxidation processes—AOPs (photocatalysis, electrochemical oxidation, photo-electrocatalysis, among others) and combined water treatment processes. Finally, the main operating parameters and the effectiveness of treatment processes are analyzed, ending with an analysis of the challenges in this field of research. 相似文献
994.
Santos Hugo L. S. Corradini Patricia G. Andrade Marcos A. S. Mascaro Lucia Helena 《Journal of Solid State Electrochemistry》2020,24(8):1899-1908
Journal of Solid State Electrochemistry - Copper oxides are considered to be very promising materials for promoting a hydrogen evolution reaction (HER). However, some CuO features, such as the... 相似文献
995.
996.
997.
Oel Guzmán Francisco Hernández Paz del Angel Alberto Velez 《Reaction Kinetics and Catalysis Letters》1994,52(2):475-480
The influence of the seed nature upon the crystalline and textural characteristics and the catalytic performance of ZSM-5 samples obtained from different seed crystals has been determined. Differences in catalytic behavior can be related to the size of the crystalline agglomerates obtained. 相似文献
998.
Counterpoise estimates of the BSSE in the evaluation of protonation energies have been calculated for basis sets ranging from minimal to split-valence plus polarization quality. Three-, five- and six-membered-ring heterocycles have been chosen as suitable model compounds for this study. Counterpoise corrections are significant, at the minimal basis set and 3–21G levels, when considering both, absolute and relative protonation energies and depend on the nature of the centre which undergoes protonation. In general, second- and third-order counterpoise corrections to the protonation energies are comparable to the corresponding SCF values. BSSE depend not only on the size of the basis sets but also on their quality. The presence in the basis of quite diffuse functions (either sp or d) leads to lower protonation energies and greater BSSE. Relative protonation energies are not substantially affected by BSSE or correlation effects. 相似文献
999.
R. Andrade A. Lisser N. Maculan G. Plateau 《Computational Optimization and Applications》2004,29(2):127-146
The expansion of telecommunication services has increased the number of users sharing network resources. When a given service is highly demanded, some demands may be unmet due to the limited capacity of the network links. Moreover, for such demands, telecommunication operators should pay penalty costs. To avoid rejecting demands, we can install more capacities in the existing network. In this paper we report experiments on the network capacity design for uncertain demand in telecommunication networks with integer link capacities. We use Poisson demands with bandwidths given by normal or log-normal distribution functions. The expectation function is evaluated using a predetermined set of realizations of the random parameter. We model this problem as a two-stage mixed integer program, which is solved using a stochastic subgradient procedure, the Barahona's volume approach and the Benders decomposition. 相似文献
1000.
M.S. Dopico-García A. Fique L. Guerra J.M. Afonso O. Pereira P. Valento P.B. Andrade R.M. Seabra 《Talanta》2008,75(5):1190-1202
Phenolic profile of 10 different varieties of red “Vinho Verde” grapes (Azal Tinto, Borraçal, Brancelho, Doçal, Espadeiro, Padeiro de Basto, Pedral, Rabo de ovelha, Verdelho and Vinhão), from Minho (Portugal) were studied. Nine Flavonols, four phenolic acids, three flavan-3-ols, one stilben and eight anthocyanins were determined. Malvidin-3-O-glucoside was the most abundant anthocyanin while the main non-coloured compound was much more heterogeneous: catechin, epicatechin, myricetin-3-O-glucoside, quercetin-3-O-glucoside or syringetin-3-O-glucoside. Anthocyanin contents ranged from 42 to 97%. Principal component analysis (PCA) was applied to analyse the date and study the relations between the samples and their phenolic profiles. Anthocyanin profile proved to be a good marker to characterize the varieties even considering different origin and harvest. “Vinhão” grapes showed anthocyanins levels until twenty four times higher than the rest of the samples, with 97% of these compounds. 相似文献