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71.
The dynamics of an ensemble of identically prepared two-qubit systems is investigated which is subjected to the iteratively applied measurements and conditional selection of a typical entanglement purification protocol. The resulting dynamics exhibits strong sensitivity to initial conditions. For one class of initial states two types of islands characterize the asymptotic limit. They correspond to a separable and a fully entangled two-qubit state, respectively, and their boundaries form fractal-like structures. In the presence of incoherent noise an additional stable asymptotic cycle appears. 相似文献
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The purpose of this paper is to elaborate a procedure, based on a mathematical model, for the setting of the pulling rate, capillary and thermal conditions, in order to grow a cylindrical rod with prescribed radius and length, by edge-defined film-fed growth (EFG) method. First, in the case of an axisymmetric meniscus, we use simultaneously the catching and the angle fixation conditions in order to find a formula, which describes the fluctuation of the angle between the horizontal axis Or and the tangent line to the free surface of the meniscus at the three phase point. This angle appears in the system of differential equations which describes the evolution of the radius of the rod. During the growth this angle can fluctuate due to the fluctuations of the crystal radius, or crystallization front level, or pressure, respectively. In the second part of the paper it is shown in which kind this formula together with the energy balance equation at the crystallization front level can be used for setting the pulling rate, the thermal and capillary conditions to grow a cylindrical rod with prescribed radius and length. Numerical illustration and simulation are presented for rods having thermo-physical properties similar to NdYAG and InSb. This type of results can be useful for the experiment planning, since personal computer simulation is less expensive than experiment. With this aim the present study was undertaken. 相似文献
74.
The semiarcs are generalizations of semiovals. Estimates on the sizes of semiarcs, some characterization theorems of semiarcs with large collinear subsets, of semiarcs contained in the union of three concurrent lines and the complete classification of strong semiovals in PG(2, q), q odd, are given. 相似文献
75.
Salmoun M Braekman JC Ranarivelo Y Rasamoelisendra R Ralambomanana D Dewelle J Darro F Kiss R 《Natural product research》2007,21(2):111-120
Four calamenene sequiterpenes, (+)-(7R,10S)-15-hydroxycalamenene (3), (+)-(7R,10S)-2,15-dihydroxycalamenene (4), (+)-(7R,10S)-2-hydroxy-15-calamenal (5), (+)-(7R,10S)-15-calamenal (6), along with the amorphane sesquiterpene (+)-(1S,6R,7R,10S)-1-hydroxy-3-oxo-amorph-4-ene (16), have been isolated from the Madagascan shrub Tarenna madagascariensis (Rubiaceae) and their structures determined by spectroscopic methods and chemical correlations. Furthermore, five known related sesquiterpenes [(+)-(7R,10S)-2-hydroxycalamenene (1), (+)-(7R,10S)-3-hydroxycalamenene (2), (-)-alpha-cadinol (13), cadinenal (14), 6-epicadinenal (15)], and three known lignans [(-)-hinokinin, (-)-dihydrocubebin, (-)-cubebin] were also isolated from the same plant. This is the first report of compounds 3, 4, 5, 6, and 16 from a natural source. 相似文献
76.
Dr. Gert Kiss Dr. Nihan Çelebi‐Ölçüm Dr. Rocco Moretti Prof. Dr. David Baker Prof. Dr. Dr. K. N. Houk 《Angewandte Chemie (International ed. in English)》2013,52(22):5700-5725
Recent developments in computational chemistry and biology have come together in the “inside‐out” approach to enzyme engineering. Proteins have been designed to catalyze reactions not previously accelerated in nature. Some of these proteins fold and act as catalysts, but the success rate is still low. The achievements and limitations of the current technology are highlighted and contrasted to other protein engineering techniques. On its own, computational “inside‐out” design can lead to the production of catalytically active and selective proteins, but their kinetic performances fall short of natural enzymes. When combined with directed evolution, molecular dynamics simulations, and crowd‐sourced structure‐prediction approaches, however, computational designs can be significantly improved in terms of binding, turnover, and thermal stability. 相似文献
77.
The adsorption and dissociation of CH2I2 were studied at 110 K with the aim of generating CH2 species on the Ru(001) surface. The methods used included X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), temperature programmed desorption (TPD), Auger electron spectroscopy (AES) and work function measurements. Adsorption of CH2I2 is characterized by a work function decrease (0.96 eV at monolayer), indicating that adsorbed CH2I2 has a positive outward dipole moment. Three adsorption states were distinguished: a multilayer (Tp=200 K), a weakly bonded state (Tp=220 K) and an irreversibly adsorbed state. A new feature is the formation of CH3I, which desorbs with Tp=160 K. The adsorption of CH2I2 at 110 K is dissociative at submonolayer, but molecular at higher coverages. Dissociation of the monolayer to CH2 and I proceeded at 198–230 K, as indicated by a shift in the I(3d5/2) binding energy from 620.6 eV to 619.9 eV. A fraction of adsorbed CH2 is self-hydrogenated into CH4 (Tp=220 K), and another one is coupled to di-σ-bonded ethylene, which — instead of desorption — is converted to ethylidyne at 220–300 K. Illumination of the adsorbed CH2I2 initiated the dissociation of CH2I2 monolayer even at 110 K, and affected the reaction pathways of CH2. 相似文献
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