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81.
Cristian E. Lacey Alex G. Novoselov Michael E. Mueller 《Proceedings of the Combustion Institute》2021,38(2):2673-2680
Reduced-order manifold approaches to turbulent combustion modeling traditionally involve precomputation of manifold solutions and pretabulation of the thermochemical database versus a small number of manifold variables. However, additional manifold variables are required as the complexity of turbulent combustion processes increases through consideration of, for example, multi-modal, non-adiabatic, or non-isobaric combustion, or combustion featuring multiple and/or inhomogeneous inlets. This increase in the number of manifold variables comes with an increase in the computational cost of precomputing a greater number of manifold solutions, most of which are never actually utilized in a CFD calculation. The memory required to store the pretabulated high-dimensional thermochemical database also increases, practically limiting the complexity of manifold-based combustion models. In this work, a new In-Situ Adaptive Manifolds (ISAM) approach is developed that overcomes this limitation by combining ‘on-the-fly’ calculation of manifold solutions with In-Situ Adaptive Tabulation (ISAT), enabling the use of more complex manifold-based turbulent combustion models. The performance of ISAM is evaluated via LES of turbulent nonpremixed jet flames with both hydrogen and hydrocarbon fuels. A performance assessment indicates that the computational overhead associated with ISAM compared to pretabulation ranges from negligible up to a factor of two, with most of this overhead associated with convolution of the thermochemical state against a presumed subfilter PDF. In addition, the memory requirements of ISAM are more than two orders of magnitude less than conventional tabulation. These results demonstrate the potential for ISAM to accommodate significantly more complex manifold-based combustion models. 相似文献
82.
Ecaterina Matei Claudia Drăgan Cristian Pantilimon Cristian Predescu 《Analytical letters》2017,50(17):2822-2838
ABSTRACTTwo nanostructured hybrid materials are reported that include uncoated magnetic nanoiron oxides and magnetic nanoiron oxides treated with rose leaf extract. Atomic and molecular absorption spectrometry were used to evaluate the sensitivity of these materials for the isolation of Cr(VI), Zn(II), Pb(II), and Ca(II) from aqueous solution. The structure and physicochemical properties of the resulting nanohybrids were characterized by scanning electron microscopy coupled with energy-dispersive spectroscopy, atomic force microscopy, and X-ray diffraction. The results show that following 15?min of contact in acidic solution, the uncoated magnetic nanoiron oxides removed approximately 90% of Cr(VI), while the magnetic nanoiron oxides coated with rose leaf extract removed 92% of the analyte. These correspond to most industrial wastewater conditions. For the removal of Ca(II) and Zn(II), it was necessary to adjust the pH to neutral to maximize the efficiency. Pb(II) showed maximum removal efficiency when the solution is basic. The simple rose extract suspension was also used for metal removal with high capacity. The results demonstrate that the magnetic nanoiron oxides were uniformly distributed in the rose leaf extract. The extract served as a capping agent due to the presence of polyphenolics. 相似文献
83.
Cristian Rodrigo Muzzio Nicolás Gabriel Dini Adrián César Razzitte 《Physics and Chemistry of Liquids》2017,55(4):506-521
Highly concentrated electrolyte solutions were studied through a Monte Carlo-based simulator, developed to consider the water molecules not a homogeneous dielectric as usual, but as dipoles that can move and rotate within a 3D lattice. This approach allowed fast calculations of detailed interactions between the particles, which were described from mechanistic potentials including dipole–dipole, ion–dipole, ion–ion, and hydrogen bonding (HB) interactions. A good agreement was found between experimental data and simulated results. The study also provides new insights about the balance of the different interactions in systems with or without electrolytes, and the effects of the electrolytes addition on the original water structure. The proposed model was also compared with previous explicit models. 相似文献
84.
85.
Hans J. Breunig Tim Koehne Ana Maria Preda Cristian Silvestru Luis F. Piedra-Garza 《Journal of organometallic chemistry》2010,695(9):1307-1313
The syntheses and spectroscopic (NMR, MS) investigations of the antimonates [Ph4P]+[Me2SbCl4]− (1), [Me4Sb]+[Me2SbCl4]− (2), [Et4N]+[Ph2SbCl4]− (3), [Bu4N]+[Ph2SbCl4]− (4), [Me4Sb]+[Ph2SbCl4]− (5), [Et3MeSb]+[Ph2SbCl4]− (6), [Et4N]+[Ph2SbF4]− (7) and [Et4N]+[Ph2SbBr4]− (8) are reported. Halogen scrambling reactions of Et4NBr or Ph4EBr (E = P, Sb) with R2SbCl3 (R = Me, Ph) produce mixtures of compounds from which crystals of [Et4N]+[Ph2SbBr1.24Cl2.76]− (9), [Et4N]+[Ph2SbBr2.92Cl1.08]− (10) or [Ph4Sb]+[Me2SbCl4]− (11) were isolated. The crystal and molecular structures of 1 and 3-11 are reported. 相似文献
86.
Niculina D. Bogdan Dr. Mihaela Matache Veronika M. Meier Dr. Cristian Dobrotă Dr. Ioana Dumitru Gheorghe D. Roiban Dr. Daniel P. Funeriu Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(7):2170-2180
Herein we describe the design and synthesis of the first series of di‐functional ligands for the directed construction of inorganic‐protein frameworks. The synthesized ligands are composed of a metal‐ion binding moiety (terpyridine‐based) conjugated to an epoxysuccinyl peptide, known to covalently bind active cysteine proteases through the active‐site cysteine. We explore and optimize two different conjugation chemistries between the di‐functionalized metal‐ion ligand and the epoxysuccinyl‐containing peptide moiety: peptide‐bond formation (with limited success) and CuI‐catalysed click chemistry (with good results). Further, the complexation of the synthesized ligands with FeII and NiII ions is investigated: the di‐functional ligands are confirmed to behave similarly to the parent terpyridine. As designed, the peptidic moiety does not interfere with the complexation reaction, in spite of the presence of two triazole rings that result from the click reaction. ES‐MS together with NMR and UV/Vis studies establish the structure, the stoichiometry of the complexation reactions, as well as the conditions under which chemically sensitive peptide‐containing polypyridine ligands can undergo the self‐assembly process. These results establish the versatility of our approach and open the way to the synthesis of di‐functional ligands containing more elaborated polypyridine ligands as well as affinity labels for different enzyme families. As such, this paper is the first step towards the construction of robust supramolecular species that cover a size‐regime and organization level previously unexplored. 相似文献
87.
In this review, we provide an organized summary of the theoretical and computational results that are available for polymers subject to spatial or topological constraints. Because of the interdisciplinary character of the topic, we provide an accessible, non-specialist introduction to the main topological concepts, polymer models, and theoretical/computational methods used to investigate dense and entangled polymer systems. The main body of our review deals with (i) the effect that spatial confinement has on the equilibrium topological entanglement of one or more polymer chains and (ii) the metric and entropic properties of polymer chains with fixed topological states. These problems have important technological applications and implications for life sciences. Both aspects, especially the latter, are amply covered. A number of selected open problems are finally highlighted. 相似文献
88.
Cristian?E.?BotezEmail author Abdul?W.?Bhuiya Ronald?J.?Tackett 《Applied Physics A: Materials Science & Processing》2011,104(1):177-181
We have used temperature- and frequency-resolved ac-susceptibility measurements to investigate the magnetic relaxation of
a Co0.2Fe2.8O4 magnetic fluid above the freezing point of the liquid carrier. Our data show that both the Néel and the Brown relaxation mechanisms are operative
at temperatures in the vicinity of the out-of-phase (imaginary) susceptibility peak. We separate the contributions of the
two mechanisms to the overall relaxation time, and demonstrate that Brownian relaxation plays a dominant role at all temperatures
within this high-dissipation regime. 相似文献
89.
We give conditions on the kernel function (or activation function) for the family of radial basis function (RBF) neural networks obtained upon replacing the usual translation by the Delsarte one, with not necessarily the same smoothing factor in all kernel nodes, to have the universal approximation property in suitable weighted Lp-spaces (1?p<∞). A complete characterization of such kernels for p=1 and p=2 is provided. 相似文献
90.
Mamie Sancy Jorge Pavez Miguel A. Gulppi Ivanildo Luiz de Mattos Ramiro Arratia‐Perez Cristian Linares‐Flores Maritza Paez Tebello Nyokong José H. Zagal 《Electroanalysis》2011,23(3):711-718
We have studied the trends in catalytic activity of several Co macrocyclics confined on the surface graphite electrodes for the oxidation of thiocyanate. A plot of log i (at constant E) versus the formal potential of the catalyst gives a volcano correlation, indicating that the Co(II/I) redox potential needs to be tuned, in order to achieve maximum reactivity. Graphite electrodes modified with Co phthalocyanine at pH 4 exhibit linear amperometric response for thiocyanate concentration in the range 10?7 and 10?3 M. Theoretical calculations show that electrocatalytic activity (as log i at constant E) plotted versus the energy of the LUMO of the Co complex also gives a volcano correlation. 相似文献