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181.
C. Dölle C. Reinhardt P. Simon B. Wellegehausen 《Applied physics. B, Lasers and optics》2002,75(6-7):629-634
. Investigations of the efficient generation of powerful coherent radiation at 82.8 nm by frequency tripling of short-pulse
KrF laser radiation are presented. Argon gas is selected as nonlinear medium due to the resonantly enhanced 3rd-order susceptibility
χ(3)(-3ω,ω,ω,ω). Pulse energies of 100 μJ at 82.8 nm have been measured for a pump pulse energy of 14 mJ. An upscaling to more
than 500 μJ is expected with available more powerful pump lasers. Features of this XUV source and possible applications are
discussed.
Received: 26 July 2002 / Published online: 15 November 2002
RID="*"
ID="*"Corresponding author. Fax: +49-511/7622211, E-mail: reinhardt@iqo.uni-hannover.de 相似文献
182.
Lhoëst G Zey T Verbeeck RK Wallemacq P Maton N De Houx JP Latinne D 《Journal of mass spectrometry : JMS》1999,34(1):28-32
It was demonstrated that rapamycin is metabolized in vitro by pig liver microsomes under the influence of the cytochrome P450-dependent mixed function oxygenase system to a rapamycin tris-epoxide metabolite, as demonstrated by electrospray tandem mass spectrometry. The in vitro immunosuppressive activity of this metabolite was found to be lower than that of rapamycin, probably because the rapamycin effector sector was structurally modified. The effector region of rapamycin was recognized to include the conjugated double bonds of this compound and metabolic reactions affecting this region may change the binding affinity of the rapamycin-FKBP binary complex towards another pharmacological receptor bound to the binary complex. Moreover, metabolic modifications in the effector region are probably able to induce a change in the binding affinities of the rapamycin-FKBP binary complex, including the pipecolic acid moiety and the lactone function of the parent drug. 相似文献
183.
A photon echo experiment in Tm(3+):YAG is reported that shows, for the first time to the authors' knowledge, the time-domain equivalent of the transition from near- to far-field diffraction, including Talbot self-imaging effects. The experiment demonstrates the huge dispersion capability of photon echoes and opens the way to further exploration of space-time duality. 相似文献
184.
V. Parfait-Pignol G. Le Caër R. Delannay 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,4(4):499-511
The topological and metric properties of a few natural 2D random cellular structures, namely an armadillo shell structure
and young soap froths, which are formed from two classes of cells, large and small, have been characterized. The topological
properties of a model generated from a Kagome tiling, which mimics such random binary structures, have also been exactly calculated.
The distribution of the number of cell sides is bimodal for the structures investigated. In contrast to the classical Aboav-Weaire
law for homogeneous 2D random cellular structures, nm(n), the mean total number of edges of neighbouring cells of cells with n sides does not vary linearly with n. Only the nm(i, n) (i=1,2) determined separately for every class of cells are linear in n for all investigated structures. Topological properties and correlations between metric and topological properties are finally
compared with the predictions of various literature models.
Received: 24 December 1997 / Revised: 7 April 1998 / Accepted: 20 April 1998 相似文献
185.
Infrared absorption intensities of fundamental bands of propyl halides n-C3 H7 Cl, n-C3H7 Br and n-C3H7I were measured in the pure liquid state. In order to obtain L matrix data necessary for the intensity computation, normal frequencies of the rotational isomers were calculated, and LSFF force constants were determined by the least squares method so as to attain the best fit between the observed and calculated frequencies. By applying the absolute intensity method, energy differences between the rotational isomers were evaluated, which are in quite good agreement with values obtained by the temperature variation method. 相似文献
186.
Ph. Cahuzac J. L. LeGouët P. E. Toschek R. Vetter 《Applied physics. B, Lasers and optics》1979,20(1):83-88
Laser induced nonlinear absorption profiles in a three-level system have been recorded to study the effect of elastic collisions
upon optical coherences. In our particular system, the signal is due to a pure double-quantum term, where we have separated
the effect of phase-interrupting collisions from the effect of velocity-changing collisions. Experimental results show that
the effect of velocity-changing collisions is very small, and that broadening of the signal is due to phase-interrupting collisions
mainly. We are able to determine the increase of the decay rate of the coherent superposition (the “coherence”) of two levels
of same parity [Dγ
13/dp=(6.5±1) MHz/Torr] and an upper limit for the mean velocity change (ũ≲5m/s). 相似文献
187.
188.
189.
Photoemission measurements have been performed on Li covered Si samples. The Li layer is formed: (i) by adsorption, (ii) by segregation of dissolved Li to the Si surface.These two methods of activation give comparable results: the photoemissive quantum yield is about 10 per cent at 5 eV and the threshold is 2.5 eV for p type Si. Moreover, the surface layer obtained by segregation seems highly pure and uniform. The segregation kinetics are analyzed using a simple theoretic model. 相似文献
190.
Rapenne G 《Organic & biomolecular chemistry》2005,3(7):1165-1169
Technomimetic molecules are molecules designed to imitate macroscopic objects at the molecular level, also transposing the motions that these objects are able to undergo. This article focuses on technomimetic molecules with rotary motions, including gears, wheelbarrows and motors. Following the bottom-up approach the synthesis of technomimetic molecules grants access to the study of mechanical properties at the molecular level. These molecules are designed to operate as single molecules on surfaces under the control of the tip of a scanning tunneling microscope or atomic force microscope. 相似文献