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321.
R. H. Giles A. J. Gatesman J. Waldman 《International Journal of Infrared and Millimeter Waves》1990,11(11):1299-1302
The far-infrared optical properties of Rexolite 1422 were characterized at the University of Lowell Research Foundation using Fourier transform spectroscopy. The spectroscopic transmission measurements were performed on a 0.0236 thick sample of material over the submillimeter wavelength region from 10 cm–1 to 360 cm–1. Using multiple reflection theory for transmission through an etalon, the frequency dependent complex refractive index of Rexolite is reported. 相似文献
322.
Giles K Pringle SD Worthington KR Little D Wildgoose JL Bateman RH 《Rapid communications in mass spectrometry : RCM》2004,18(20):2401-2414
The use of radio-frequency (RF)-only ion guides for efficient transport of ions through regions of a mass spectrometer where the background gas pressure is relatively high is widespread in present instrumentation. Whilst multiple collisions between ions and the background gas can be beneficial, for example in inducing fragmentation and/or decreasing the spread in ion energies, the resultant reduction of ion axial velocity can be detrimental in modes of operation where a rapidly changing influx of ions to the gas-filled ion guide needs to be reproduced at the exit. In general, the RF-only ion guides presently in use are based on multipole rod sets. Here we report investigations into a new mode of ion propulsion within an RF ion guide based on a stack of ring electrodes. Ion propulsion is produced by superimposing a voltage pulse on the confining RF of an electrode and then moving the pulse to an adjacent electrode and so on along the guide to provide a travelling voltage wave on which the ions can surf. Through appropriate choice of the travelling wave pulse height, velocity and gas pressure it will be shown that the stacked ring ion guide with the travelling wave is effective as a collision cell in a tandem mass spectrometer where fast mass scanning or switching is required, as an ion mobility separator at pressures around 0.2 mbar, as an ion delivery device for enhancement of duty cycle on an orthogonal acceleration time-of-flight (oa-TOF) mass analyser, and as an ion fragmentation device at higher wave velocities. 相似文献
323.
A model of the formation, detachment, and rise of a bubble from a submerged orifice is derived, based upon a study using a modified form of the Rayleigh–Plesset equation. Similar models have previously been proposed by Oguz and Prosperetti (1), Avramidis and Jiang (2), and also Chakraborty and Tuteja (3). We seek to re-examine these models and implement a number of additional physical features. In particular, we demonstrate the relative importance of the surface dilatational viscosity of surfactant added to the liquid in the growth and detachment of the bubble from the orifice. It is found that “large” surface dilatational viscosities significantly increase the time to detachment of the bubble. In addition, through a drastic reduction in the rate of radial expansion of the bubble in the early stages of development (given an initial condition on the radial velocity for “fast” bubble growth), the rise velocity of the bubble centroid at this time is greater with a large surface dilatational viscosity than when this property is neglected. 相似文献
324.
D. Gihwala I. S. Giles C. Olivier M. Peisach 《Journal of Radioanalytical and Nuclear Chemistry》1978,46(2):333-341
The prompt gamma-ray of 871 keV emitted during the bombardment of steels by 5 MeV alpha particles were used to determine nitrogen
by means of the reaction14N(α, pγ)17O. The method is non-destructive, rapid and experimentally simple. It has a sensitivity of about 7 μg·g−1. In the nitrogen concentration range of 101–102 μg·g−1 the relative precision of the method is about 3%. The accuracy of the method compares with that of other nuclear methods.
Presented at the 5th Symposium on Recent Developments in Activation Analysis, Oxford, 17–21 July, 1978. 相似文献
325.
Under simulated environmental (atmospheric) conditions, chloropicrin vapor was readily converted in light to phosgene, which remained stable, and nitrosyl chloride which was subsequently photolyzed to nitric oxide and chlorine; a portion of the nitric oxide was oxidized to nitrogen dioxide and dinitrogen tetroxide. The unexpected dependence of the reaction upon oxygen, the initial photoproducts, and the incorporation of 18O when the photolysis occurred in the presence of 18O2 suggest an intramolecular rearrangement involving a trioxazole N-oxide. 相似文献
326.
327.
Giles Auchmuty 《Numerische Mathematik》1992,61(1):1-6
Summary This paper describes upper and lowerp-norm error bounds for approximate solutions of the linear system of equationsAx=b. These bounds imply that the error is proportional to the quantity
wherer is the residual andq is the conjugate index top. The constant of proportionality is larger than 1 and lies in a specified range. Similar results are obtained for approximations toA
–1 and solutions of nonsingular linear equations on general spaces.Research was partially supported by NSF Grant DMS8901477 相似文献
328.
Ryf R. Su Y. Moller L. Chandrasekhar S. Xiang Liu Neilson D.T. Giles C.R. 《Lightwave Technology, Journal of》2005,23(1):54-61
This work presents a high-resolution (13.2 GHz) channel-blocking optical filter, suitable for use as a reconfigurable optical add/drop multiplexer (ROADM), which seamlessly supports data rates from 2.5 to 160 Gb/s. The filter consists of a linear array of 64 MEMS micromirrors and a high-dispersion echelle grating. The demonstrated device had an insertion loss of 9 dB, a loss ripple of 1.2 dB, and a group delay ripple of 15 ps. Data transmission through the device with various mixed data rate scenarios ranging from 2.5 to 160 Gb/s showed negligible penalty, except at 40 Gb/s where a maximum penalty of 1.5 dB was observed due to a phase coherence with the blocker filter ripple. 相似文献
329.
E. Mané J. Billowes K. Blaum P. Campbell B. Cheal P. Delahaye K. T. Flanagan D. H. Forest H. Franberg C. Geppert T. Giles A. Jokinen M. Kowalska R. Neugart G. Neyens W. N?rtersh?user I. Podadera G. Tungate P. Vingerhoets D. T. Yordanov 《The European Physical Journal A - Hadrons and Nuclei》2009,42(3):503-507
A gas-filled segmented linear Paul trap has been installed at the focal plane of the high-resolution separator (HRS) at CERN-ISOLDE. As well as providing beams with a reduced transverse emittance, this device is also able to accumulate the ions and release the sample in bunches with a well-defined time structure. This has recently permitted collinear laser spectroscopy with stable and radioactive bunched beams to be demonstrated at ISOLDE. Surface-ionized 39, 44, 46K and 85Rb beams were accelerated to 30keV, mass separated and injected into the trap for subsequent extraction and delivery to the laser setup. The ions were neutralized in a charge exchange cell and excited with a co-propagating laser. The small ion beam emittance allowed focussing in the ion-laser overlap region, which is essential to achieve the best experimental sensitivity. Fluorescent photons were detected by a photomultiplier tube as a frequency scan was taken. A gate (typically 7-12μs wide) was set on the photomultiplier signal to accept the fluorescent photons within the time window defined by the bunch. Thus, using accumulation times of 100ms, the dominant contribution to background due to continuous laser scattering could be reduced by a factor of up to 4×104 . 相似文献
330.
E. D. Johnson G. V. Rogachev V. Z. Goldberg S. Brown D. Robson A. M. Crisp P. D. Cottle C. Fu J. Giles B. W. Green K. W. Kemper K. Lee B. T. Roeder R. E. Tribble 《The European Physical Journal A - Hadrons and Nuclei》2009,42(2):135-139
The structure of the 18O nucleus at excitation energies above the $ \alpha$ decay threshold was studied using 14C + $ \alpha$ resonance elastic scattering. A number of states with large $ \alpha$ reduced widths have been observed, indicating that the $ \alpha$ -cluster degree of freedom plays an important role in this N $ \ne$ Z nucleus. A 0+ state with an $ \alpha$ reduced width exceeding the single-particle limit was identified at an excitation energy of 9.9±0.3 MeV. We discuss evidence that states of this kind are common in light nuclei and give possible explanations of this feature. 相似文献