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51.
Stowers MA van Wuijckhuijse AL Marijnissen JC Scarlett B van Baar BL Kientz CE 《Rapid communications in mass spectrometry : RCM》2000,14(10):829-833
Matrix-assisted laser desorption/ionization (MALDI) mass spectra were obtained from single biological aerosol particles using an aerosol time-of-flight mass spectrometer (ATOFMS). The inlet to the ATOFMS was coupled with an evaporation/condensation flow cell that allowed the aerosol to be coated with matrix material as the sampled stream entered the spectrometer. Mass spectra were generated from aerosol composed either of gramicidin-S or erythromycin, two small biological molecules, or from aerosolised spores of Bacillus subtilis var niger. Three different matrices were used: 3-nitrobenzyl alcohol, picolinic acid and sinapinic acid. A spectrum of gramicidin-S was generated from approximately 250 attomoles of material using a molar ratio of 3-nitrobenzyl alcohol to analyte of approximately 20:1. A single peak, located at 1224 Da, was obtained from the bacterial spores. The washing liquid and extract solution from the spores were analyzed using electrospray mass spectrometry and subsequent MS/MS product ion experiments. This independent analysis suggests that the measured species represents part of the B. subtilis peptidoglycan. The on-line addition of matrix allows quasi-real-time chemical analysis of individual, aerodynamically sized particles, with an overall system residence time of less than 5 seconds. These results suggest that a MALDI-ATOFMS can provide nearly real-time identification of biological aerosols. Copyright 2000 John Wiley & Sons, Ltd. 相似文献
52.
Vijay Janyani Ana Vukovic Trevor Benson John Paul Phillip Sewell 《Optical and Quantum Electronics》2007,39(9):709-716
Fibre Bragg gratings (FBGs) are an integral component of optical fibre based communication systems for signal processing.
Uniform FBGs and phase-shifted FBGs find major applications as add-drop filters in dense wavelength division multiplexing
(DWDM) systems where these are used to filter out channels and to shape the signal spectrum. We investigate numerically the
spatiotemporal deformation of pulses as they propagate through the gratings. In particular, the effect on the pulse dynamics
of phase shift or defect present in the gratings, often introduced intentionally in a grating to generate a narrow transmission
spike within the stopband, is studied in time domain. This study is of significance since the deformation in the pulse in
time limits the maximum bit rate achievable, and hence the pulse duration and shape need to be analysed and controlled accurately.
A time domain numerical tool based on the Transmission Line Modelling (TLM) method is developed to study the pulse dynamics.
The results obtained give useful information about the signal dynamics in gratings with defects, including the signal oscillations
trapped in the defect, to be considered in applications such as while designing spectral filters. 相似文献
53.
Geoffrey L. Sewell 《Physics Reports》1980,57(5):307-342
We survey a body of work, containing some new material, concerning the characterisation of equilibrium and metastable states of large assemblies of particles in terms of a variety of stability conditions. The theory is formulated in the thermodynamic limit and is based on the premise that the former states are those that are stable against all dynamical and thermodynamical perturbations, whereas the latter ones are endowed with only limited stability, sufficing to guarantee their long lifetimes and good thermodynamical behaviour. The Kubo-Martin-Schwinger (KMS) fluctuation-dissipation conditions play a central role in the developments stemming from this viewpoint, since it turns out that these conditions represent stability against localised disturbances of both the dynamical and thermo-dynamical kinds. Consequently, the stability arguments invoked here lead us to the following principal conclusions: (1) The equilibrium states are those that minimise the free energy density of the system and also satisfy the KMS conditions. This substantiates Gibbs's hypothesis that these states correspond to the standard ensembles. (2) Metastable states are of two kinds, that we term “ideal” and “normal”. Those of the former type satisfy the KMS conditions but minimise only the restriction of the free energy density to some reduced state space: those of the latter type are characterised by a still lower grade of stability. (3) The conditions on the forces under which ideal metastable states can exist are very restrictive, and thus the normal ones generally correspond to those observed in nature. 相似文献
54.
M. Calicchio O. Erriquez M.T. Fogli-Muciaccia S. Natali S. Nuzzo F. Romano F. Ruggieri R. Belusevic D.C. Colley G.T. Jones S. ONeale S.J. Sewell M.F. Votruba D. Bertrand P. Marage J. Moreels J. Sacton F.W. Bullock 《Physics letters. [Part B]》1980,93(4):521-524
An event with the decay chain Σc+ → Λc+ + π0, Λc+ → K? + p + π+, has been observed in an exposure of BEBC, equipped with a track sensitive target, to the wide band neutrino beam from the SPS at CERN. The event has a unique three constraint kinematic fit to the ΔS = ?ΔQ reaction v + p → μ? + p + K? + π+ + π+ + π0 with both gammas from the π0 decay detected. The proton and other final state particles are identified. The masses are M(Λc+) = 2290 ± 3 MeV/c2, M(Σc+) = 2457 ± 4 MeV/c2 and M(Σc+) ? M(Λc+) = 168 ± 3 MeV/c2. Including other data one obtains M (Σc++) ? M(Σc+) = 0 ± 4 MeV/c2. 相似文献
55.
In this paper, we introduce the notions of (∈, ∈∨q)-fuzzy subnear-ring, (∈, ∈∨q)-fuzzy ideal and (∈, ∈∨q)-fuzzy quasi-ideal of near-rings and find more generalized concepts than those introduced by others. The characterization of such (∈, ∈ ∨q)-fuzzy ideals are also obtained. 相似文献
56.
Various polymeric materials commonly used domestically have been subjected to temperatures ranging from 600 to 1000° under laboratory conditions and the amounts of nitrogen oxides evolved have been measured. In general, the amounts formed are small (from 0·2 to 2·0 per cent calculated on the original weight of sample). The results show little dependence on the nitrogen content of the sample. 相似文献
57.
O. Erriquez S. Natali S. Nuzzo A. Pullia F. Romano D.C. Colley G.T. Jones L. Lowe S. ONeale S.J. Sewell G. Bertrand-Coremans H. Mulkens J. Sacton C. Vander Velde-Wilquet J. Wickens V. Brisson P. Petiau T.W. Jones 《Physics letters. [Part B]》1978,77(2):227-232
For e+ energy > 0.3 GeV and 10 GeV < visible energy < 100 GeV we find that: (i) ; (ii) 1.2 ± 0.5 neutral strange particles are produced per μ?e+ event; (iii) the lifetime of possible positron-parent particles is < 3 × 10?10 s (90% C.L.); (iv) the cross section for direct e+ production via the neutral current is < 0.2 times that via the charged current (90% C.L.); (v) the cross section for producing heavy leptons, L+, decaying into e+ … is < 0.7 × 10?3 times that for μ?production, implying M(L+) > 10 GeV. 相似文献
58.
G.L Sewell 《Annals of Physics》1976,97(1):55-79
We formulate a characterization of equilibrium and metastable states of classical hard-core continuous systems in terms of certain global and local stability conditions. The equilibrium states are assumed to be those that are both locally and globally stable; the metastable states are assumed to be those that are locally, but not globally, stable, and that possess also a certain restricted global stability. It is found that a certain specified class of systems with appropriately weakly tempered, or long range forces, can support metastable states, possessing bona fide thermodynamic properties, whose pressure functions are real analytic continuations in the chemical potential of those of some equilibrium phases. This result is complementary to that of Lanford and Ruelle, concerning the absence of metastable states of systems with strongly tempered forces. 相似文献
59.
60.
Geoffrey L. Sewell 《Communications in Mathematical Physics》1977,55(1):63-66
We extend the characterisation of metastability, as given in [1] for classical systems, to show that quantal lattice systems with suitable long range forces can support metastable states. 相似文献