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61.
Recently, many polarizable force fields have been devised to describe induction effects between molecules. In popular polarizable models based on induced dipole moments, atomic polarizabilities are the essential parameters and should be derived carefully. Here, we present a parameterization scheme for atomic polarizabilities using a minimization target function containing both molecular and atomic information. The main idea is to adopt reference data only from quantum chemical calculations, to perform atomic polarizability parameterizations even when relevant experimental data are scarce as in the case of electronically excited molecules. Specifically, our scheme assigns the atomic polarizabilities of any given molecule in such a way that its molecular polarizability tensor is well reproduced. We show that our scheme successfully works for various molecules in mimicking dipole responses not only in ground states but also in valence excited states. The electrostatic potential around a molecule with an externally perturbing nearby charge also exhibits a near‐quantitative agreement with the reference data from quantum chemical calculations. The limitation of the model with isotropic atoms is also discussed to examine the scope of its applicability. © 2012 Wiley Periodicals, Inc. 相似文献
62.
Jong-Bong Kim Hyunho Shin Woong Lee Kyong Yop Rhee 《Archive of Applied Mechanics (Ingenieur Archiv)》2008,78(10):811-819
Deflection criterion for oblique cracks terminating at a bi-material interface was established numerically based on a remote
loading condition where the crack deflection event took place well within the K-dominant stress field. The criterion was described in terms of the ratio of the energy release rate of a deflected crack
(G
d) to the maximum energy release rate of a penetrated crack (). The criterion was markedly more conservative than the existing solution based on wedge loading which did not converge with
respect to limited number of a/L ratios in the literature (a is the size of the putative crack; L is the loading distance). Further, the criterion established herein for the cracks slightly oblique from the normal direction
to the interface was more conservative than the crack normal to the interface. 相似文献
63.
The elastic deformation of host layers is calculated by constructing a model where the host layers, regarded as continuous
two-dimensional elastic sheets, are infinitely stacked and compressible intercalants, represented by harmonic springs, are
intercalated into them. If we treat the intercalants as being rigid relative to the soft host layers in the stage-1 graphite
intercalation compound, LixC6 (0≤x≤1), the calculated average gallery spacing agrees well with the experiments, without using any adjustable parameter.
Received: 14 April 2000 / Accepted: 17 April 2000 / Published online: 23 August 2000 相似文献
64.
Sun-Jae Kim E.G. Lee S.D. Park C.J. Jeon Y.H. Cho C.K. Rhee W.W. Kim 《Journal of Sol-Gel Science and Technology》2001,22(1-2):63-74
The photocatalytic characteristics of nanostructured TiO2 ultrafine powder with rutile phase produced using the homogeneous precipitation process at low temperatures (HPPLT) were compared with those of commercial P-25 TiO2 powder by flame hydrolysis. The TiO2 powder by the HPPLT showed much higher photoactivity in the removal rate, showing lower pH values in the solution than the P-25 powder when eliminating metal ions such as Pb and Cu from the aqueous metal-EDTA solutions. This can be inferred as the more rapid photo-oxidation or -reduction of metal ions from the aqueous solution, together with relatively higher efficiencies in the use of an electron-hole pair formed on the surface of the TiO2 particles under UV light irradiation. Also, in the view of the TiO2 particle morphology, compared to the well-dispersed spherical P-25 particles, the agglomerated TiO2 secondary particles by the HPPLT consist of acicular typed primary particles with a thickness in the range of 3–7 nm and the primary particles radialize in all directions, which would be more effective to photocatalytic reactions without the large electron-hole recombination on the surface of the TiO2 particle under UV light irradiation. It can be, therefore, thought that the higher photoactivity of the rutile TiO2 powder by the HPPLT in the aqueous solutions results mainly from having a larger surface area by the acicular shaped primary particles with very thin thickness and radialization in all directions. 相似文献
65.
An unsteady numerical simulation was performed for locally forced separated and reattaching flow over a backward-facing step. The local forcing was given to the separated and reattaching flow by means of a sinusoidally oscillating jet from a separation line. A version of the k––fμ model was employed, in which the near-wall behavior without reference to distance and the nonequilibrium effect in the recirculation region were incorporated. The Reynolds number based on the step height (H) was fixed at ReH=33 000, and the forcing frequency was varied in the range 0StH2. The predicted results were compared and validated with the experimental data of Chun and Chun. It was shown that the unsteady locally forced separated and reattaching flows are predicted reasonably well with the k––fμ model. To characterize the large-scale vortex evolution due to the local forcing, numerical flow visualizations were carried out. 相似文献
66.
Kwang-Min Lee Chang-Hoon Rhee Choong-Kyung Kang Jung-Hoe Kim 《Applied biochemistry and biotechnology》2006,135(1):81-100
The medium formulation and robust process modeling for anti-HIV peptide (T-20) production by recombinant Escherichia coli overexpression were studied by employing a crossed experimental design. The crossed design, a mixture design combined with
process factor (induction duration), was used to find the optimal medium formulation and process time. The optimal settings
for three major components, (7.75 mL of NPK sources, 5.5 mL of glucose, and 11.75 mL of MgSO4) characterized by %T-20 (14.45%), the proportion of peptide to the total protein, were observed in a total of 100 mL of medium
inducted at an optical density of 0.67 with 0.7 mM isopropyl-β-d-thiogalactopyranoside) for a 3-h induction duration at shake-flask scale. These conditions were further investigated to find
robust, process conditions (8.2 mL of NPK sources, 5.6 mL of glucose, and 11.3 mL of MgSO4, and a 3.5-h induction duration time) for T-20 production (13.9%) by applying propagation of error.
Coauthors 相似文献
67.
Liu C.J. Moon-Jhong Rhee 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1995,23(3):235-238
Simple empirical scaling laws that can be applied universally are determined for breakdown voltage characteristics of single-gap and multigap pseudosparks. For the single-gap pseudospark, the breakdown voltage is found to be a function of the product of the gas pressure squared, the anode-cathode gap distance, and the hollow cavity diameter, p2dD, and a function of the product pd for a gap distance less than and greater than three times the cavity diameter, respectively. For the multigap pseudospark, however, the breakdown voltage is found to be only a function of the product p2dD 相似文献
68.
We show a simple way how asymptotic convergence results can be conveyed from a simple Jacobi method to a block Jacobi method. Our pilot methods are the well known symmetric Jacobi method and the Paardekooper method for reducing a skew-symmetric matrix to the real Schur form. We show resemblance in the quadratic and cubic convergence estimates, but also discrepances in the asymptotic assumptions. By numerical tests we confirm that our asymptotic assumptions for the Paardekooper method are most general. 相似文献
69.
Dendrimers, well-defined hyper-branched macromolecules with characteristic globular structure, have emerged as an attractive material in the field of catalysis and have been considered as a new type of host for the accommodation of guest molecules by virtue of their three-dimensional structure having interior void space. In line with the prospect of dendrimer as a nanoreactor, various metal nanoparticles have been successfully prepared via encapsulation in or formation of particles surrounded by dendrimer branches. However, it is worth noting that most of the previous studies have been confined to the monometallic nanoparticles, and bimetallic nanoparticles have been scarcely exploited yet. In this article, we present the synthesis and characterization of dendrimer-templated bimetallic nanoparticles and their application to catalysis. 相似文献
70.
Park H Kwon DH Rhee Y 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2004,60(14):259-3309
Based on laser absorption spectroscopy (LAS), we developed a vapor density monitor for controlling the vaporization rate of Yb using a tunable diode laser. The laser source consisted of an extended cavity violet diode laser which has an emission wavelength of 398.8 nm coincident with the Yb absorption transition line, 6s(2) 1S(0)-6s6p 1P(1). The light emitted from the diode laser was transmitted across an atomic vapor column generated by heating the Yb metal, while the laser frequency was scanned across the atomic transition line. By comparing the amount of incident light to the amount of light transmitted after the light passed through the vapor column, the vapor density was determined using the Beer's law. From the experimental results, we demonstrated that the diode-laser-based LAS operated successfully for the real-time monitoring of the Yb vapor density. 相似文献