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71.
Valeria Califano Francesco Bloisi Luciano R.M. Vicari Paolo Colombi Laura E. Depero 《Applied Surface Science》2008,254(22):7143-7148
Double layers of polyethylene glycol (PEG) and 3-(3,4-dihydroxyphenyl)-2-methyl-l-alanine (m-DOPA) thin films were obtained by matrix assisted pulsed laser evaporation (MAPLE) technique, by depositing a first layer of m-DOPA on Si substrate and a second layer of PEG on top of it. The films were characterized by low angle X-ray diffraction (LAXRD), X-ray reflectivity (XRR), atomic force microscopy (AFM), and micro-Raman spectroscopy. From these analyses it resulted that PEG was deposited without any relevant damage both in terms of chemical structure and molecular weight. Furthermore, PEG chains were mostly in the extended conformation, although PEG micelles appeared. 相似文献
72.
Giorgia Oliviero Nicola Borbone Vincenzo Piccialli Gennaro Piccialli Luciano Mayol 《Tetrahedron》2010,66(10):1931-6144
We report here an efficient solid-phase synthesis of N-1-alkyl-substituted analogues of cyclic inosine-diphosphate-ribose (cIDPR), a mimic of cyclic ADP-ribose (cADPR). Our synthetic strategy makes use of a polystyrene support to which inosine was bonded through a 2′,3′-acetal linkage. Insertion of a ω-hydroxy-polymethylene chain of variable length on N-1, followed by conversion into N-1-alkylinosine-bis-phosphate derivatives and cyclization, allowed to obtain analogues of cIDPR of various ring size. The cyclization step was carried out both in solid-phase and in solution by pyrophosphate bond formation. The effect of the N-1-polymethylene chain length on the cyclization yields as well as the reaction conditions, which led to the solid-phase pyrophosphate bond formation, were thoroughly investigated. 相似文献
73.
Silvia Tavazzi Dr. Leonardo Silvestri Dr. Luciano Miozzo Dr. Antonio Papagni Prof. Peter Spearman Dr. Sandra Ianelli Dr. Alberto Girlando Prof. Andrea Camposeo Dr. Marco Polo Dr. Dario Pisignano Dr. 《Chemphyschem》2010,11(2):429-434
Blue amplified spontaneous emission at room temperature is demonstrated from the exposed face of the strongly emitting organic semiconductor 1,1,4,4‐tetraphenyl‐1,3‐butadiene in single crystal form. The symmetry of the crystal and calculation of lattice sums indicate the J‐type organization of the molecular transition moments. The minimum in the lowest exciton dispersion branch, from which emission takes place, is found at the edge of the Brillouin zone leading to a dominant vibronic emission since the zero‐phonon line is forbidden. The observed gain narrowed line is attributed to the vibronic replica which becomes amplified with increased pumping. The reported emission is along the normal to the exposed crystal face, important for the development of vertical cavity geometry lasers based on organic single crystals. The threshold excitation fluence of 400 μJ cm?2 is comparable to other organic crystalline systems, even if the amplification path is much reduced as a consequence of the vertical geometry. Considering these relevant aspects, the optical characterization of this material is provided. The polarized absorption spectra are reported and the properties of the lowest‐energy excitonic state investigated. Calculation of the electronic transitions for the isolated molecule, lattice sums for the transition at lowest energy, and the symmetry of the crystal allow attributing the largest face of the samples and the observed optical bands in the spectra. Polarized time‐resolved spectra are also reported allowing to identify the intrinsic excitonic emission. 相似文献
74.
Andre L. Barbieri G.F. de Arruda Francisco A. Rodrigues Odemir M. Bruno Luciano da Fontoura Costa 《Physica A》2011,390(3):512-518
An entropy-based image segmentation approach is introduced and applied to color images obtained from Google Earth. Segmentation refers to the process of partitioning a digital image in order to locate different objects and regions of interest. The application to satellite images paves the way to automated monitoring of ecological catastrophes, urban growth, agricultural activity, maritime pollution, climate changing and general surveillance. Regions representing aquatic, rural and urban areas are identified and the accuracy of the proposed segmentation methodology is evaluated. The comparison with gray level images revealed that the color information is fundamental to obtain an accurate segmentation. 相似文献
75.
In this article, a new methodology for developing discrete geometric conservation law (DGCL) compliant formulations is presented. It is carried out in the context of the finite element method for general advective–diffusive systems on moving domains using an ALE scheme. There is an extensive literature about the impact of DGCL compliance on the stability and precision of time integration methods. In those articles, it has been proved that satisfying the DGCL is a necessary and sufficient condition for any ALE scheme to maintain on moving grids the nonlinear stability properties of its fixed‐grid counterpart. However, only a few works proposed a methodology for obtaining a compliant scheme. In this work, a DGCL compliant scheme based on an averaged ALE Jacobians formulation is obtained. This new formulation is applied to the θ family of time integration methods. In addition, an extension to the three‐point backward difference formula is given. With the aim to validate the averaged ALE Jacobians formulation, a set of numerical tests are performed. These tests include 2D and 3D diffusion problems with different mesh movements and the 2D compressible Navier–Stokes equations. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
76.
Jasquer A. Sehnem Priscila Milani Vanessa Nascimento Leandro H. Andrade Luciano Dorneles Antonio L. Braga 《Tetrahedron: Asymmetry》2010,21(8):997-1003
N-Trifluoracyl β-chalcogeno amides and N-perfluoracyl β-thio amide ligands were prepared by a simple and efficient reaction sequence. These new ligands were evaluated in palladium-catalyzed alkylation of rac-(E)-1,3-diphenyl-2-propenyl acetate in the presence of dimethyl malonate and an enantioselectivity of up to 99% was obtained. After catalysis, the fluorous ligand can be easily recovered by liquid–liquid extraction and reused without loss in the activity. 相似文献
77.
The Kalman-Yakubovich-Popov theorem for stabilizable hyperbolic boundary control systems 总被引:1,自引:0,他引:1
L. Pandolfi 《Integral Equations and Operator Theory》1999,34(4):478-493
In this paper we present a version of the Kalman-Yakubovich-Popov theorem for a class of boundary control systems of hyperbolic type. Unstable, controllable systems are considered and stabilizability withunbounded feedbacks is permitted.Paper partially supported by the Italian MINISTERO DELLA RICERCA SCIENTIFICA E TECNOLOGICA within the program of GNAFA-CNR and by NATO CRG program SA.5-2-05 (CRG940161). 相似文献
78.
79.
Maurizio Pandolfi 《Meccanica》1973,8(4):236-242
Summary A numerical technique used in gasdynamics is here applied to the solution of one-dimensional unsteady flows in channels in
the spirit of the shallow water theory. Its most important feature is the explicit treatment of imbedded bores generated in
the flow by coalescence of characteristics. Four numerical examples are presented to show possible applications of the method.
Sommario Si mostra qui l'applicazione al calcolo di correnti non stazionarie in canali, secondo la formulazione della “shallow water theory”, di metodologie numeriche già usate in gasdinamica. Il trattamento esplicito di risalti, formati per coalescenza di caratteristiche, costituisce il punto particolare del lavoro. Vengono quindi presentati quattro esempi di applicazione della metodologia numerica.相似文献
80.
Growth under Visible Light Increases Conidia and Mucilage Production and Tolerance to UV‐B Radiation in the Plant Pathogenic Fungus Colletotrichum acutatum
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Henrique D. de Menezes Nelson S. Massola Jr Stephan D. Flint Geraldo J. Silva Jr Luciano Bachmann Drauzio E. N. Rangel Gilberto U. L. Braga 《Photochemistry and photobiology》2015,91(2):397-402
Light conditions can influence fungal development. Some spectral wavebands can induce conidial production, whereas others can kill the conidia, reducing the population size and limiting dispersal. The plant pathogenic fungus Colletotrichum acutatum causes anthracnose in several crops. During the asexual stage on the host plant, Colletototrichum produces acervuli with abundant mucilage‐embedded conidia. These conidia are responsible for fungal dispersal and host infection. This study examined the effect of visible light during C. acutatum growth on the production of conidia and mucilage and also on the UV tolerance of these conidia. Conidial tolerance to an environmentally realistic UV irradiance was determined both in conidia surrounded by mucilage on sporulating colonies and in conidial suspension. Exposures to visible light during fungal growth increased production of conidia and mucilage as well as conidial tolerance to UV. Colonies exposed to light produced 1.7 times more conidia than colonies grown in continuous darkness. The UV tolerances of conidia produced under light were at least two times higher than conidia produced in the dark. Conidia embedded in the mucilage on sporulating colonies were more tolerant of UV than conidia in suspension that were washed free of mucilage. Conidial tolerance to UV radiation varied among five selected isolates. 相似文献