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951.
Two-dimensional cellular automata 总被引:11,自引:0,他引:11
A largely phenomenological study of two-dimensional cellular automata is reported. Qualitative classes of behavior similar to those in one-dimensional cellular automata are found. Growth from simple seeds in two-dimensiona! cellular automata can produce patterns with complicated boundaries, characterized by a variety of growth dimensions. Evolution from disordered states can give domains with boundaries that execute effectively continuous motions. Some global properties of cellular automata can be described by entropies and Lyapunov exponents. Others are undecidable.This work was supported in part by the U.S. Office of Naval Research under Contract No. N00014-80-C-0657. 相似文献
952.
H. Nagahiro S. Hirenzaki E. Oset M.J. Vicente Vacas 《Physics letters. [Part B]》2005,620(3-4):125-130
We present results on the production of bound states of Θ+ in nuclei using the (K+,π+) reaction. By taking into account the states obtained within a wide range of strength of the Θ+ nucleus optical potential, plus the possibility to replace different nucleons of the nucleus, we obtain an excitation spectra with clearly differentiated peaks. The magnitude of the calculated cross sections is well within reachable range. 相似文献
953.
The activation of CO2 in thin potassium layers adsorbed on Cu(1 1 1) has been studied with time-evolved Fourier transform-infrared reflection absorption spectroscopy. The growth of thin layers by reactive evaporation of potassium in a CO2 atmosphere permits control of the K:CO2 stoichiometry, which strongly affects the selectivity in the formation of intermediates and the decomposition pathways of the layer. Layers grown in a CO2 rich atmosphere exhibit the preferential growth of stoichiometric potassium oxalate K2C2O4 (D2h). The molecular identity of oxalate with D2h symmetry is confirmed by vibrational spectra utilizing isotopic substitution methods (13CO2 and C18O2) and by the use of isotopic mixtures of CO2/C18O2 and CO2/13CO2. A comparison of the isotope data with theoretical calculations gives an estimated OCO bond angle in oxalate of 132°. Far-IR spectra obtained with synchrotron radiation indicate the equivalent interaction of all oxygen atoms with the potassium. A comparison of the vibrational data with theoretical ab initio calculations confirms the structural model of an oxalate species that is bulk coordinated with no strong directional bonding and all oxygen atoms equally interacting with potassium.At medium and low CO2:K ratios, very complex vibrational spectra are observed, indicating the formation of an oxalate surface species with C2v symmetry in addition to D2h− oxalate, CO2− and CO22− species. 相似文献
954.
Kent M. Pumphrey Constantinos V. Chrysikopoulos 《Colloids and surfaces. A, Physicochemical and engineering aspects》2004,240(1-3):199-209
This work focuses on the mechanisms of non-aqueous phase liquid (NAPL) drop formation within a single fracture fed from a NAPL reservoir by way of a circular orifice, such as a pore. The fracture is assumed to be fully saturated, the relative wettability of the system is assumed water-wet, and the water velocity profile within the fracture is described by a Poiseuille flow. The size of the NAPL drops is investigated for various water flow velocities and NAPL entrance diameters. A force balancing method was used to determine the radii of detached drops. The drop sizes calculated from the model developed here are shown to be in agreement with available experimental drop size data. It is shown that at low Reynolds numbers the buoyancy force is the dominant force acting on the drop during the formation process and at high Reynolds numbers the viscous forces dominate. A simplified expression relating the geometry of the fractured system to the drop radii is developed from the model equations, and it is shown to predict drop radii that match well with both the model simulations and the available experimental data. 相似文献
955.
Aaron Luntala Nsakanda Wilson L. Price Moustapha Diaby Marc Gravel 《European Journal of Operational Research》2007
The entropy-based measure has been used in previous works to compute the population diversity in solving the cell formation problem with the genetic algorithm. Population diversity is crucial to the genetic algorithm’s ability to continue fruitful exploration as it may be used in choosing an initial population, in defining a stopping criterion, in evaluating the population convergence, and in making the search more efficient throughout the selection of crossover operators or the adjustment of various control parameters (e.g., crossover or mutation rate, population size). We show in this note that, when a non-ordinal chromosome representation corresponding to the allocation of machines to cells is used, the current way of measuring the population diversity is inaccurate. Consequently, it leads to wrong conclusions when, at various iterations, carrying out fruitful exploration or an efficient search of the solution space is guided by the perceived population diversity degree. An alternative approach based on computing the distance and the similarity between chromosomes is discussed. 相似文献
956.
A. Wucher 《Applied Surface Science》2006,252(19):6482-6489
A brief review is given regarding the application of cluster ion beams as desorption probes in molecular SIMS. The general observation is that the efficiency of secondary ion formation, particularly that of complex molecular species, is significantly enhanced if polyatomic projectiles are employed instead of atomic species. Apart from the sensitivity increase, cluster bombardment also appears to allow for molecular depth profiling studies without the accompanying damage accumulation normally associated with atomic projectiles. A few fundamental aspects are addressed in an attempt to highlight the physics behind these observations. It appears that much of the benefit associated with cluster bombardment is connected to the fact that these projectiles give access to very high sputter yields which are not accessible with atomic primary ions. 相似文献
957.
Rudolf Berghammer Agnieszka Rusinowska Harrie de Swart 《European Journal of Operational Research》2007
We present an application of relational algebra to coalition formation. This leads to specifications, which can be executed with the help of the RelView tool after a simple translation into the tool’s programming language. As an example we consider a simplification of the situation in Poland after the 2001 elections. 相似文献
958.
We consider here the morphogenesis (pattern formation) problem for some genetic network models. First, we show that any given spatio‐temporal pattern can be generated by a genetic network involving a sufficiently large number of genes. Moreover, patterning process can be performed by an effective algorithm. We also show that Turing's or Meinhardt's type reaction–diffusion models can be approximated by genetic networks. These results exploit the fundamental fact that the genes form functional units and are organized in blocks. Due to this modular organization, the genes always are capable to construct any new patterns and even any time sequences of new patterns from old patterns. Computer simulations illustrate some analytical results. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
959.
Yoshio Hayasaki Yoshihito Yuasa Hirotsugu Yamamoto Nobuo Nishida 《Optics Communications》2003,220(4-6):281-287
Flow of a spontaneously formed optical pattern in a nonlinear optical feedback system consisting of a liquid crystal optically addressable spatial light modulator with feedback is induced by a lateral wave-front shift of the feedback light. We demonstrate the dependency of the flow speed on the wave-front shift by tilting an optical flat inserted in the feedback loop. We also demonstrate the application to real-time, high-sensitivity detection of small tilt angles of optical components. 相似文献
960.
The aim of this investigation was to study the influence of electrolytes on a reaction of triiodide complex formation. Investigation
of the salt effect as concerns the thermodynamics of I
3
−
formation in methanol, ethanol and n-propanol solutions revealed regularities of the influence of the electrolyte on triiodide
complex formation connected with a multifactorial effect of the ionic medium. The quasichemical model presented was used to
calculate parameters reflecting the overall salt effect.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献