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51.
P. Álvarez-Iglesias M. F. Araújo A. Gouveia T. Drago 《Journal of Radioanalytical and Nuclear Chemistry》2009,281(2):237-240
Two sediment cores (~30 m long) were retrieved at the mouth of the Minho Estuary to assess its palaeoenvironmental evolution
for the last millennia. Samples were characterized by Energy-Dispersive X-Ray Fluorescence Spectrometry and Instrumental Neutron
Activation Analysis, complemented by sedimentological analyses. Provenance of major and trace element contents (lithogenic
or biogenic, continental or marine) is assessed. The influence of grain size effect on total element concentration is discussed.
Most of the samples present a negative Eu anomaly. Sedimentological and geochemical parameters allow differentiating four
geological units––fluvial, marine, estuarine and sand barrier––which reflects the temporal evolution of the Minho Estuary. 相似文献
52.
Bénédicte Lepoittevin Ludovic Costa Sylvain Pardoue Diana Dragoé Sandra Mazerat Philippe Roger 《Journal of polymer science. Part A, Polymer chemistry》2016,54(17):2689-2697
Poly(ethylene terephthalate) (PET) is a semiaromatic thermoplastic polyester used in many fields. For specific applications, controlled of the surface wettability (hydrophily/hydrophoby) could be a great challenge. Aminolysis of PET surfaces with branched polyethylenimine gives amino functional groups on the surface with high grafting density. Then, in a second step, atom transfer radical polymerization (ATRP) initiator was grafted by reaction with 2‐bromoisobutyryl bromide. Surface initiated ATRP of 2‐lactobionamidoethyl methacrylate (LAMA) was performed in solution in the presence of a sacrificial initiator or an appropriate amount of Cu(II) species that act as deactivator. The efficiency of all reactions was confirmed by X‐ray photoelectron spectroscopy. Wetting properties and surface energy were found to vary systematically depending to the type of functionalization and grafting. The quantity of grafted carbohydrate was determined by phenol/sulfuric acid colorimetric titration. The sugar graft density was observed to vary according to the ratio (monomer)/(free initiator). High graft density could be obtained yielding to superhydrophilic polymer brushes. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2689–2697 相似文献
53.
54.
Christos Levcopoulos Drago Krznaric 《Journal of Algorithms in Cognition, Informatics and Logic》1998,27(2):303-338
This article settles the following two longstanding open problems:
- • What is the worst case approximation ratio between the greedy triangulation and the minimum weight triangulation?
- • Is there a polynomial time algorithm that always produces a triangulation whose length is within a constant factor from the minimum?
55.
Antonio Drago 《Fresenius' Journal of Analytical Chemistry》1990,337(2):220-224
Summary An new insight into the history of chemistry is outlined. The underlying mathematical principles are discussed and the specific tradition of analytical chemistry is emphasized. 相似文献
56.
A. R. Osborne L. Bergamasco M. Serio L. Bianco L. Cavaleri M. Drago L. Iovenitti D. Viezzoli 《Il Nuovo Cimento C》1996,19(1):151-176
Summary We study nonlinear interactions in measured surface wave trains obtained in the Northern Adriatic Sea about 16 kilometres
from Venice, Italy.Nonlinear Fourier analysis is discussed in terms of the exact spectral solution to the Korteweg-deVries (KdV) equation as given by theinverse scattering transform (IST). For the periodic and/or quasi-periodic boundary conditions assumed herein, the approach may be viewed as a nonlinear,
broad-banded generalization of the ordinary, linear Fourier transform. In particular, we study solition interactions, their
properties and the nonlinear dynamics of the radiation (or oscillation) modes as found from the inverse scattering transform
analysis. We also conduct a number of computer experiments in which measured wave trains are numerically propagated forward
in time toward shallow water and backward in time into deep water in order to assess how the nonlinear wave dynamics are influenced
by propagation over variable bathymetry. On this basis we develop a scenario for the evolution of nonlinear wave trains, initially
far offshore in deep water, as they propagate into shallow water regions. The deep-water waves have a small Ursell number
and are hence not very nonlinear; as they propagate toward shallow water, the Ursell number gradually increases in the numerical
experiments by about an order of magnitude. A useful parameterization of nonlinearity in these studies is the ?spectral modulus,?
a number between 0 and 1, which is associated with each IST spectral frequency. Small values of the modulus mean that a particular
spectral component is linear (a sine wave); large values of the modulus (≈1) indicate that the component is nonlinear (a soliton).
There is a systematic increase of the modulus as the waves propagate into shallow water where nonlinear effects predominate;
we describe how the modulus varies as a function of spectral frequency during this shoaling process. The results suggest that
the effect of increasing nonlinearity ?saturates? the IST spectrum (i.e. the modulus ≈1 for all frequencies) to that virtually all spectral components become solitons in sufficiently shallow water. 相似文献
57.
58.
Phase relations in the system Bi2O3CdO were studied in the composition range from 90-30 mole% Bi2O3. A new phase, Bi2O3 · CdO, was found to exist up to 925 K. At this temperature it decomposes to form CdO and the 5Bi2O3 · 3CdO phase. The 5Bi2O3 · 3CdO phase is stable between 925 and 963 K and melts incongruently. Below 925 K it decomposes to Bi2O3 · CdO and 6Bi2O3 · CdO. The phase 5Bi2O3 · 3CdO has cubic symmetry. The Sillenite-type bcc phase 6Bi2O3 · CdO forms above 897 K from oxide mixtures in the solid state or from fused oxide mixtures, but the compound could never be prepared as a single phase. 相似文献
59.
Letters in Mathematical Physics - The existence of a real linear space structure on the set of observables of a quantum system—i.e., the requirement that the linear combination of two... 相似文献
60.
A model-based optimisation of the process of printed circuit board laser structuring is presented. For this purpose, a comprehensive theoretical model of the interaction between the travelling pulsed laser beam and conductive layer, as well as between the laser beam and the induced plasma plume is employed. The model is used to calculate process speed. Based on the process speed determined, the influence of pulse power, duration, and frequency on process speed is analysed. In addition, an optimal range of process parameters with respect to process speed and quality is defined. 相似文献