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81.
Magnetization measurements have been made on a Sm2Fe14B single crystal in magnetic fields up to 140 kOe. The easy direction of the magnetization lies along [100] in the tetragonal structure P42/mnm. Magnetic anisotropy energies at 290K along [110] and [001] have been estimated to be 5.8×106 and 1.1×108 erg/cm3, respectively, both becoming much larger at lower temperature. No evidence of the spin canting of Nd2Fe14B type is observed even at 4.2K.  相似文献   
82.
Single-mode cw dye laser excitation spectra of the (0, 00, 0)-(0, 00, 0), (1, 00, 0)-(1, 00, 0), (0, 11, 0)-(0, 11, 0) bands of the 611- to 607-nm system of SrOH and SrOD were observed and assigned. The spectrum is consistent with a 2Σ-2Σ system where the molecule is linear in both electronic states. The rotational analysis is obtained by measuring P-R separations in the excitation spectrum. A technique which greatly aided in the spectral assignment that utilizes a monochromator as a bandpass filter in obtaining excitation spectra is described. A new spin-rotation constant, γ(+) - γ(?), was found necessary to fit the l-type doubling of the (0, 11, 0) mode in B2Σ+ of SrOH. This new constant is assumed to arise from two 2Σ12 vibronic states, split by Renner-Teller interaction, of the (0, 11, 0) mode of A2Π. From a perturbation treatment of this electronic interaction, 2 of the (0, 11, 0) mode of A2Π was found to be 14 cm?1. The linear structure of SrOH and SrOD in both electronic states is consistent with the model, in the one-electron approximation, in that the transition involves the promotion of the unpaired 5s to the 5p orbital localized on the strontium.  相似文献   
83.
The intensity anomaly of the B2Σ-X2Σ system of SrF was analyzed based on the interaction between the A2Π and B2Σ states. The theoretical relative intensity was calculated from overlap integrals and spectroscopic constants previously obtained. Comparison between theoretical and observed intensities showed that the electronic transition moment of the B-X system is the same order of magnitude as that of the A-X system.  相似文献   
84.
85.
We report frequency stabilization of diode lasers using modulation transfer spectroscopy of an acetylene transition (13C2H2, 1+3, P(16)) at 1542 nm. We realize modulation-free acetylene-stabilized lasers with a frequency stability of about 10–11 and an absolute frequency accuracy of about 20 kHz.This revised version was published online in March 2005. In the previous version, the published online date was missing  相似文献   
86.
We prepared Au/gamma-Fe2O3 composite nanoparticles by sonochemically reducing Au(III) ions employing no stabilizer in the aqueous solution to form stable Au nanoparticles and allowing them to attach onto the surface of gamma-Fe2O3 particles with an average size of 21 nm. Size of the formed Au nanoparticle depended on the initial concentration of Au(III) ions. The number of the Au nanoparticles, supported on each gamma-Fe2O3 particle was controlled by changing the relative amounts of Au(III) ions and gamma-Fe2O3 particles. The composite nanoparticles exhibited a high affinity with glutathione, a tripeptide with mercapto group so that separation and manipulation of glutathione in aqueous solutions could be performed by application of external magnetic field. Because the surfaces of the Au nanoparticles were not shielded by any stabilizers, or naked, sonochemically prepared Au/gamma-Fe2O3 composite nanoparticles seemed to show stronger affinity to the glutathione than those by the radiochemical method.  相似文献   
87.
Elastic wave scattering off a layer containing a single set of vertical periodic fractures is examined using a numerical technique based on the work of Hennion et al. [J. Acoust. Soc. Am. 87, 1861-1870 (1990)]. This technique combines the finite element method and plane wave method to simulate three-dimensional scattering off a two-dimensional fractured layer structure. Each fracture is modeled explicitly, so that the model can simulate both discrete arrivals of scattered waves from individual fractures and multiply scattered waves between the fractures. Using this technique, we examine changes in scattering characteristics of plane elastic waves as a function of wave frequency, angle of incidence, and fracture properties such as fracture stiffness, height, and regular and irregular spacing.  相似文献   
88.
Vicinal 4H and 6H-SiC(0001) surfaces have been investigated using atomic force microscopy and cross-sectional high-resolution transmission electron microscopy. We observed the characteristic self-ordering of nanofacets on any surface, regardless of polytypes and vicinal angles, after gas etching at high temperature. Two facet planes are typically revealed: (0001) and high index (112;n) that are induced by equilibrium surface phase separation. A (112;n) plane may have a free energy minimum due to attractive step-step interactions. The differing ordering distances in 4H and 6H polytypes imply the existence of SiC polytypic dependence on nanofaceting. Thus, it should be possible to control SiC surface nanostructures by selecting a polytype, a vicinal angle, and an etching temperature.  相似文献   
89.
Laser-supported propulsion of a micro-airplane with a water-covered ablator is demonstrated. The repetitive use of an overlay structure is experimentally demonstrated with a specially designed water supply. Various transparent overlays are investigated by the CIP-based hydrodynamic code and by experiments using a pendulum and using a semi-conductor load cell. A momentum-coupling efficiency of ∼104 N s/MJ is achieved by water–exotic-target experiments, in agreement with the simulation code, which predicts a maximum efficiency of ∼105 N s/MJ. The concept of laser-supported propulsion can also be used for driving a Mach 5 airplane in the stratosphere, a micro-ship inside the human body, and a robot in a nuclear power reactor accident, during which large numbers of neutrons make electronic devices useless. Received: 7 October 2002 / Accepted: 20 January 2003 / Published online: 28 May 2003 RID="*" ID="*"Corresponding author. Fax: +81-3/5734-2165, E-mail: yabe@mech.titech.ac.jp  相似文献   
90.
N-Allylic difluoroenamines exhibited unusual behaviors under thermal conditions; N-allyl difluoroenamines in refluxing xylene afforded not only aza-Claisen rearrangement products, but also 2-azabicyclo[2.1.1]hexanes, whose formation could be explained via intramolecular [2+2]-cycloaddition, whilst N-prenyl difluoroenamine underwent an ene reaction to give the pyrrolidine as a sole product.  相似文献   
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