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53.
E. Galichet F. Gulminelli D. C. R. Guinet M. F. Rivet J. F. Lecolley R. Bougault G. Auger B. Borderie B. Bouriquet A. Buta J. L. Charvet A. Chbihi J. Colin D. Cussol R. Dayras D. Durand J. D. Frankland B. Guiot S. Hudan P. Lautesse F. Lavaud N. Le Neindre O. Lopez L. Manduci J. Marie L. Nalpas J. Normand M. Pârlog P. Paw lowski E. Plagnol E. Rosato J. C. Steckmeyer B. Tamain A. Van Lauwe E. Vient C. Volant J. P. Wieleczko INDRA Collaboration 《The European Physical Journal A - Hadrons and Nuclei》2003,18(1):75-86
The transport properties of the 36Ar +58Ni system at
measured with the INDRA array, are studied within the BNV kinetic equation. A general protocol of comparison between the N-body experimental fragment information and the one-body distribution function is developed using global variables, with a special focus on charge density. This procedure avoids any definition of sources and any use of an afterburner in the simulation. We shall discuss the feasibility of such an approach and the distortions induced by the finite detection efficiency and the completeness requirements of the data selection. The sensitivity of the different global observables to the macroscopic parameters of the effective nuclear interaction will be studied in detail.Received: 21 January 2003, Published online: 5 August 2003PACS:
25.70.-z Low and intermediate energy heavy-ion reactions - 24.10.-i Nuclear reaction models and methodsN. Le Neindre: Permanent address: Institut de Physique Nuclaire, IN2P3-CNRS, F-91406 Orsay cedex, France. 相似文献
54.
G. Durand F. Spiegelmann 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,13(2):237-243
The stability against fragmentation and possible relaxation of the lowest excited states of the Na5F4 cluster (representative of cubic non stoechiometric clusters with an excess sodium atom, also called sodium-tail) is investigated
by means of one-electron pseudopotential calculations with particular reference to photoabsorption processes from the ground
state. Whereas the equilibrium configuration of the ground state has C3v symmetry, the doubly degenerate 12E excited state is affected by a conical intersection and a Jahn-Teller effect associated with the rotation of the sodium
tail around the C3-axis. This yields a “Mexican hat" topology for the lowest sheet with three equivalent Cs minima. Alternatively the 22A1 state has a minimum retaining the C3v symmetry. The dissociation paths of the cluster along the C3-axis into respectively Na4F4 + Na and Na4F3 + NaF are also investigated. Among the former paths, the excited states are found adiabatically stable with respect to the
products. However in the A1 symmetry, fragmentation into NaF exhibits an interesting avoided crossing between configurations correlated respectively
with Na4F3
+ + NaF- and Na4F3 + NaF. Such interaction, similar to the well-known charge exchange processes in elementary molecules might induce non adiabatic
predissociation of the 22A1 state. This mechanism is invoked to explain the differences between R2PI and depletion spectra, correlated with the dissociation
or relaxation of the excited states.
Received 24 March 2000 and Received in final form 11 July 2000 相似文献
55.
Nelly Durand Bruno Ameduri Bernard Boutevin 《Journal of polymer science. Part A, Polymer chemistry》2011,49(1):82-92
The synthesis and characterizations of fluorinated telomers based on vinylidene fluoride (VDF) by iodine transfer polymerization (ITP) are presented. These telomers were prepared in the presence of ω‐iodoperfluorinated functional chain transfer agents, C6F13I or C4F9I. ITPs were initiated by thermal decomposition of bis(4‐tert‐butylcyclohexyl) peroxydicarbonate (BBCHPDC), in solution (in the presence of acetonitrile). The obtained telomers were characterized by different analyses such as elemental analyses, nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy, size exclusion chromatography, X‐ray diffraction (XRD), and finally by thermal analyses such as differential scanning calorimetry (DSC) and thermogravimetric analyses. These technical analyses enabled one to assess their chemical structures, various thermal properties, and their crystalline forms. The assignments of the characteristic signals obtained by 19F NMR spectroscopy enabled one to calculate the average degrees of polymerization (DPn) and percentages of ? CH2CF2I end group functionalities that depend on the initiator and the fractionation process after reaction. A good control of polymerization was shown by the absence of reversed ? CH2CF2? CF2CH2? (VDF–VDF dyads) and narrow polydispersity indices (<1.2). The XRD and DSC evidenced the influence of the chain length of the telomers on the crystallinity rate (>70%) and indicated two crystalline forms, α and β, that depended on DPn values. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010 相似文献
56.
The stability of Al, Cr and Fe hydroxy-fluorides MF3−x(OH)x which adopt the hexagonal-tungsten-bronze (HTB)-type structure has been discussed by considering the lability of water coordinated to metals from a kinetic point of view. Thus, in the case of Al or Fe compounds, the easy departure of water contributes to the stabilization of fluoride ions as well as isolated hydroxyl groups around the metal, leading to the formation of the HTB structure. The stabilization of the HTB structure with respect to another structural type, the pyrochlore, with a lower density, is governed by this kinetic feature as well as the ability of fluorinated salts used as precursors to attract hydroxyls. Al(III) and Fe(III) represent the strongest acidic cations and the associated HTB-type structure containing isolated OH groups can easily be stabilized. In the case of Cr, a mixture of pyrochlore and HTB-type structure is generally obtained. We have succeeded in preparing, using supercritical medium, new (Fe, Cr) oxyhydroxy-fluorides which exhibit edge-shared octahedra and large 1D tunnels. These compounds can be considered as potential candidates for acid catalysts. 相似文献
57.
The problem of estimating the number of hidden states in a hidden Markov model is considered. Emphasis is placed on cross-validated
likelihood criteria. Using cross-validation to assess the number of hidden states allows to circumvent the well-documented
technical difficulties of the order identification problem in mixture models. Moreover, in a predictive perspective, it does
not require that the sampling distribution belongs to one of the models in competition. However, computing cross-validated
likelihood for hidden Markov models for which only one training sample is available, involves difficulties since the data
are not independent. Two approaches are proposed to compute cross-validated likelihood for a hidden Markov model. The first
one consists of using a deterministic half-sampling procedure, and the second one consists of an adaptation of the EM algorithm
for hidden Markov models, to take into account randomly missing values induced by cross-validation. Numerical experiments
on both simulated and real data sets compare different versions of cross-validated likelihood criterion and penalised likelihood
criteria, including BIC and a penalised marginal likelihood criterion. Those numerical experiments highlight a promising behaviour
of the deterministic half-sampling criterion. 相似文献
58.
A. Burr F. M. Berberich Sprinkmeyer Diedrichs E. Ackermann C. Valencien E. Müller-Hössly G. Cornalba Wuyt Courtoy F. Bordas F. Touplain R. Sanfelici G. Knappe H. Durand W. Gero R. Eichloff H. Bleçkmann L. Mathieu L. Ferré W. D. Kooper E. Oertel A. Kling P. Roy L. Ronnet L. Vandam R. Ledent E. Comanducci T. Jona Tillmans und Schneehagen 《Fresenius' Journal of Analytical Chemistry》1920,59(5-6):266-273
Ohne Zusammenfassung 相似文献
59.
Erwann Guénin Marc Lecouvey Julie Hardouin 《Rapid communications in mass spectrometry : RCM》2009,23(9):1395-1400
1‐Hydroxymethylene‐1,1‐bisphosphonic acids (or bisphosphonates) are compounds that have interesting pharmacological applications. However, few mass spectrometric investigations have been carried out to determine their fragmentation patterns. Herein, we evaluated different matrices for the study by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOFMS) of the formation and fragmentation of the protonated, the cationized (MNa+ and MK+) and the deprotonated bisphosphonates. Some in‐source fragmentations were observed both in positive and in negative ion modes. The fragmentation patterns obtained in post‐source decay mode are also discussed. In contrast to previous electrospray ionization/multi‐stage mass spectrometry (ESI‐MSn) studies, some new fragmentation pathways were deduced and the effects of alkali ions on the fragmentation patterns were shown. The results summarized here completed the data previously recorded by ESI‐MSn and could be used for the characterization of bisphosphonates as alkali complexes in biological mixtures. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
60.