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81.
82.
Low tropospheric wind measurement with Mie Doppler Lidar 总被引:3,自引:0,他引:3
A double edge Mie Doppler lidar at 1064 nm was developed in Hefei, China in 2005 for low tropospheric wind measurement. Intercomparison
experiments with a wind profiler and a wiresonde were held. Intercomparisons of concurrent lidar and other instrument observations
show good agreement with expected measurement accuracy. The examples of validated lidar wind profiles obtained during these
experiments as well as an example of continuous wind observations are presented. The instrument has demonstrated the capability
of atmospheric wind field measurement from 0.2 to 5 km altitude, achieving below 2 m/s accuracy with 1 min averaging and 21.2
m vertical resolution. 相似文献
83.
Alfredo De Rossi Gaetano Assanto Stefano Trillo William E. Torruellas 《Optics Communications》1998,150(1-6):390-398
We have identified a family of (2+1)D spatial solitary waves which can stably propagate in bulk media in the presence of coexisting diffraction, self-focusing Kerr and quadratic nonlinearities. In a conspicuous range of excitation conditions close to the stationary solutions, the emerging wavepackets are immune to the detrimental occurrence of filamentation and collapse, typical of pure Kerr media. The presence of a second-order contribution to the cubic nonlinear response is, therefore, able to prevent optical damage in applications relying on self-guidance. We show that the cross-phase modulation plays an important effect on stability. Our estimate shows that the effects of the cubic susceptibility cannot be neglected below a certain beam size in realistic crystals (e.g. KTP or similar). 相似文献
84.
Twenty high energy nuclear interactions produced in the graphite units of an emulsion chamber were recorded. The emulsion
chamber was exposed to cosmic rays at an atmospheric depth of 10 g cm−2 for about 7 hr over Hyderabad, India. Fourteen interactions which radiated energyΣ E
r⩾1000 GeV in the form ofγ-rays were analysed in detail. The median energy 〈Σ E
r〉 of the interactions was 1600 GeV. Results concerning the multiplicity, the transverse and longitudinal momentum distributions,
and the fractional energy distribution ofγ-rays in these interactions are presented. The average transverse momentum ofπ
0—mesons <pt
π
0> is found to increase very slowly with the primary energyE
0 and it can be approximated by the function <pt
π
0>=0·238E
0
0.06
. 相似文献
85.
Paston S. A. Prokhvatilov E. V. Franke V. A. 《Theoretical and Mathematical Physics》2004,139(3):807-822
We briefly describe problems of the Hamiltonian approach for quantizing gauge fields on the light front for space–time bounded by the inequality |x
–|L with periodic boundary conditions in the variable x
– imposed on all fields (the DLCQ method). With these restrictions, we consider the gauge-invariant ultraviolet regularization by passing to a lattice in transverse coordinates. We remove the remaining ultraviolet divergences in the longitudinal momentum p
– by imposing a gauge-invariant finite-mode regularization. It turns out that the canonical formalism on the light front with such a regularization imposed does not contain the usual most complicated second-class constraints between zero and nonzero modes of fields. The described scheme can be used both to regularize the standard gauge theory and to provide a gauge-invariant formulation of effective low-energy models on the light front. Because the manifest Lorentz invariance is broken in our formalism, the vacuum state is poorly defined. We discuss this problem, in particular, in relation to the problem of passing to the continuous space limit. 相似文献
86.
We investigate the motion of high-energy particles in a crystal with regard to their interaction with the thermal vibrations of the lattice atoms using analytic methods in the theory of Markov processes including the local Fokker–Planck equation. We construct a local matrix of random actions, which is used to introduce the main kinetic functions in the traverse-energy space, namely, the function a() of energy losses due to the dynamic friction and the diffusion function b(). We show that the singularities of the functions a() and b() are related to the distinction between the contributions to the kinetics from particles moving in three different regimes, namely, in the channeling, quasichanneling, and chaotic motion modes. 相似文献
87.
Acceleration waves propagating in isotropic solids at finite temperatures are studied by applying the method of singular surfaces to a new continuum model derived statistical-mechanically from a three-dimensional lattice model. The continuum model explicitly takes into account the microscopic thermal vibrations of the constituent atoms as one of the field variables. The propagation speeds and the ratios of mechanical and thermal amplitudes for both longitudinal and transverse waves are consistently determined. The differential equations that govern the time variation of the amplitudes of the waves are also derived. The analytical results, which are valid over a wide temperature range that includes the melting point, are evaluated numerically for several materials, and their physical implications are discussed. One of the findings to be emphasized is that of the singularities of the characteristic quantities at the melting point.Received: 13 March 2003, Accepted: 20 June 2003PACS:
62.30. + d, 65.40.-bM. Sugiyama: Correspondence to
Dedicated to Prof. Ingo Müller on the occasion of his 65th birthday. 相似文献
88.
We introduce the concept of para-Hopf algebroid and define their cyclic cohomology in the spirit of Connes–Moscovici cyclic cohomology for Hopf algebras. Para-Hopf algebroids are closely related to, but different from, Hopf algebroids. Their definition is motivated by attempting to define a cyclic cohomology theory for Hopf algebroids in general. We show that many of Hopf algebraic structures, including the Connes–Moscovici algebra
, are para-Hopf algebroids 相似文献
89.
C. A. Morales 《Transactions of the American Mathematical Society》2003,355(2):735-745
Let be an Axiom A flow with a transverse torus exhibiting a unique orbit that does not intersect . Suppose that there is no null-homotopic closed curve in contained in either the stable or unstable set of . Then we show that has either an attracting periodic orbit or a repelling periodic orbit or is transitive. In particular, an Anosov flow with a transverse torus is transitive if it has a unique periodic orbit that does not intersect the torus.
90.
Matthew Harris 《Journal of Theoretical Probability》2001,14(2):299-317
We consider a Poisson point process on
with intensity , and at each Poisson point we place a two sided mirror of random length and orientation. The length and orientation of a mirror is taken from a fixed distribution, and is independent of the lengths and orientations of the other mirrors. We ask if light shone from the origin will remain in a bounded region. We find that there exists a
with 0 <
< for which, if
<
, light leaving the origin in all but a countable number of directions will travel arbitrariliy far from the origin with positive probability. Also, if
>
, light from the origin will almost surely remain in a bounded region. 相似文献