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991.
Riccardo Colini-Baldeschi Marco Scarsini Stefano Vaccari 《Methodology and Computing in Applied Probability》2018,20(3):919-933
Motivated by the problem of utility allocation in a portfolio under a Markowitz mean-variance choice paradigm, we propose an allocation criterion for the variance of the sum of n possibly dependent random variables. This criterion, the Shapley value, requires to translate the problem into a cooperative game. The Shapley value has nice properties, but, in general, is computationally demanding. The main result of this paper shows that in our particular case the Shapley value has a very simple form that can be easily computed. The same criterion is used also to allocate the standard deviation of the sum of n random variables and a conjecture about the relation of the values in the two games is formulated. 相似文献
992.
Stefano Zanini Claudia Riccardi Elisa Grimoldi Claudia Colombo Anna Maria Villa Antonino Natalello Pietro Gatti-Lafranconi Marina Lotti Silvia Maria Doglia 《Journal of colloid and interface science》2010,341(1):53-58
This work deals with the optimization of argon plasma-induced graft-polymerization of polyethylene glycol acrylate (PEGA) on polypropylene (PP) films in order to obtain surfaces with a reduced protein adsorption for possible biomedical applications. To this end, we examined the protein adsorption on the treated and untreated surfaces. The graft-polymerization process consisted of four steps: (a) plasma pre-activation of the PP substrates; (b) immersion in a PEGA solution; (c) argon plasma-induced graft-polymerization; (d) washing and drying of the samples. The efficiency of these processes was evaluated in terms of the amount of grafted polymer, coverage uniformity and substrates wettability. The process was monitored by contact angle measurements, attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), X-ray Photoelectron Spectroscopy (XPS) and atomic force microscopy (AFM) analyses. The stability of the obtained thin films was evaluated in water and in Phosphate Buffer Saline (PBS) at 37 °C. The adsorption of fibrinogen and green fluorescent protein (GFP) – taken as model proteins – on the differently prepared surfaces was evaluated through a fluorescence approach using laser scanning confocal microscopy with photon counting detection. After plasma treatments of short duration, the protein adsorption decreases by about 60–70% with respect to that of the untreated film, while long plasma exposure resulted in a higher protein adsorption, due to damaging of the grafted polymer. 相似文献
993.
Claudia Bendazzoli Elisabetta Mileo Marco Lucarini Stefano Olmo Vanni Cavrini Roberto Gotti 《Mikrochimica acta》2010,169(1-2):23-31
The micellization of the ionic surfactant sodium dodecyl sulfate (SDS) has been investigated in the presence of neutral cyclodextrins by means of capillary electrophoresis (CE). The measurements of electric current allowed the determination of the critical micelle concentration of SDS in the presence of α-, β- and γ-cyclodextrin, and of (2-hydroxypropyl)-β-cyclodextrin and (2,6-di-O-methyl)-β-cyclodextrin. Measurements of the CE current also yields information on the binding of SDS by cyclodextrins. The results are supported by electronic paramagnetic resonance spectroscopy and suggest that the methylated cyclodextrin affects the micellization of SDS in an unconventional way compared to other considered cyclodextrins. The combination of SDS with methylated cyclodextrin can have a profound effect on the reliable application of cyclodextrin-modified micellar electrokinetic chromatography. 相似文献
994.
Giuliana Cardillo Luca Gentilucci Elisa Mosconi Alessandra Tolomelli Stefano Troisi Eusebio Juaristi 《Tetrahedron》2010,66(27-28):4994-4999
A pratical, highly enantioselective method for the synthesis of dehydro-β-amino acids was developed starting from easily accessible enantiopure allylic carbonates. The substitution with amines for C–N bond formation on these substrates bearing substituents on the Cα, Cβ, and Cγ position of the allylic system has received, until now, little attention. The reactions, carried out under palladium-catalyzed conditions, resulted in good yields and complete regioselectivity. Moreover, starting from enantiopure carbonates, complete retention of the configuration could be observed, affording enantiopure allylic amines. 相似文献
995.
Sharma RP Singh A Venugopalan P Dansby-Sparks R Xue ZL Rossetti S Ferretti V 《Journal of Coordination Chemistry》2010,63(17):3016-3027
A new complex salt of composition [Co(phen)(3)](3)(V(4)O(12))(2)Cl·27H(2)O (phen = 1,10-phenanthroline and [V(4)O(12)](4-) = tetrameric dodecaoxotetravanadate ion) was synthesized by reacting appropriate salts in aqueous medium. The complex salt has been characterized by elemental analyses, thermogravimetric analysis (TGA), cyclic voltammetry (CV), FT-IR and UV/Vis spectroscopies, solubility product and conductance measurements. Single crystal X-ray structure determination revealed ionic structure consisting of three complex cations, [Co(phen)(3)](3+), two [V(4)O(12)](4-) anions, one chloride and twenty seven lattice waters. Detailed structural and spectroscopic analyses of [Co(phen)(3)](3)(V(4)O(12))(2)Cl·27H(2)O show that the large anion is stabilized by the large cationic metal complex as there is preferred shape compatibility that leads to a large number of lattice stabilizing non-covalent interactions. 相似文献
996.
G. Della Ventura F. Bellatreccia A. Marcelli M. Cestelli Guidi M. Piccinini A. Cavallo M. Piochi 《Analytical and bioanalytical chemistry》2010,397(6):2039-2049
In this paper we describe recent applications of micro-infrared imaging in the Earth sciences. We address, in particular,
the use of Fourier-transform infrared (FTIR) spectroscopy in characterizing the zoning and speciation of H and C in a variety
of geological materials, including microporous minerals, nominally anhydrous volcanic minerals (NAMs), and crystal inclusions.
These investigations show that use of the modern techniques of FTIR imaging enables detection of the zoning of volatile species
across the studied samples, and possible configuration changes of structurally-bound carbon molecular species (e.g., CO2 vs CO3) during crystal growth. Such features, which are not accessible with other micro-analytical techniques, may provide information
about the physicochemical properties which act as constraints in the genesis of the samples, and important information about
the evolution of the geological system. Tests performed with focal-plane-array detectors (FPA) show that resolution close
to the diffraction limit can be achieved if the amounts of the target molecules in the sample are substantially different.
We also point out the possibility of using FTIR imaging for investigations under non-ambient conditions. 相似文献
997.
Yang L Caprasecca S Mennucci B Jang S 《Journal of the American Chemical Society》2010,132(47):16911-16921
A computational study is conducted on dithia-anthracenophane (DTA), for which there is experimental evidence for coherent resonance energy transfer dynamics, and on dimethylanthracene (DMA), a molecule representing the energy donor and the acceptor in DTA. Electronic excitation energies are calculated by configuration interaction singles (CIS) and time-dependent density functional theory (TD-DFT) methods and are compared to experimental ones. Electronic coupling constants are calculated between two DMAs embedded into the ground-state structure of DTA employing methods based on transition densities. The resulting values of electronic coupling provide a more consistent interpretation of experiments than those based on one-half the level spacing of DTA excitation energies. Solvation effects are studied based on the polarizable continuum model (PCM). Solvent-induced polarization and screening effects are shown to make opposite contributions, and the net electronic coupling is little different from the value in a vacuum. The likelihood of coherent population transfer is assessed on the basis of a recently developed theory of coherent resonance energy transfer. The time scale of bath is shown to have an important role in sustaining the quantum coherence. The combination of quantum chemical and dynamical data suggests that the electronic coupling in DTA is in the range of 50-100 cm(-1). The presence of oscillatory excitation population dynamics can be understood from the picture of polaronic excitation moderately dressed with dispersive vibrational modes. The effect of torsional modulation on the excitation energies of DTA and electronic coupling is examined on the basis of optimized structures with the torsional angle constrained. The result suggests that inelastic effect due to torsional motion cannot be disregarded in DTA. 相似文献
998.
Oliviero G Amato J Borbone N D'Errico S Galeone A Mayol L Haider S Olubiyi O Hoorelbeke B Balzarini J Piccialli G 《Chemical communications (Cambridge, England)》2010,46(47):8971-8973
The biophysical and biological properties of unprecedented anti-HIV aptamers are presented. The most active aptamer (1L) shows a significant affinity to the HIV protein gp120. 相似文献
999.
1000.
Fasoli E Arnone A Caligiuri A D'Arrigo P de Ferra L Servi S 《Organic & biomolecular chemistry》2006,4(15):2974-2978
1-O-Acyl-sn-glycero-3-phosphocholine and 1-O-acyl-sn-glycero-3-phosphoric acid have been prepared selectively and with high yields from the corresponding diols, glycerophosphoryl choline and glycerol-3-phosphate. Starting from the diols, the activated tin ketals were prepared in 2-propanol by reaction with dialkyltin oxide. The intermediates were acylated in the same solvent with long-chain fatty acid chlorides, giving the corresponding 1-acyl-lyso-phospholipids in high yield and with complete regioselectivity. The catalytic nature of the tin-mediated acylation and the relevance of the solvent are discussed. 相似文献