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861.
F. F. Dedus L. I. Kulikova S. A. Makhortykh N. N. Nazipova A. N. Pankratov R. K. Tetuev 《Moscow University Computational Mathematics and Cybernetics》2007,31(2):49-53
The analysis problem for genetic sequences is formulated from the viewpoint of modern mathematical and information approaches. Statistical, correlative, entropic, and spectral approaches are considered. A brief introduction into the background of the problem is given. Genesis of a new interdisciplinary subject area, bioinformatics, a science considering application of computer methods in biological studies, is analyzed. New approaches to studying macromolecular systems on the basis of combined spectral-analytic technologies are proposed. Estimates of the algorithmic complexity of implementation of the proposed approaches are presented. 相似文献
862.
The passive systems for ensuring the thermal regime of space objects, which are in current use, can preserve the temperature
at the same level only under a certain orientation of spacecraft and at a constant heat release of the equipment. At a variable
orientation of the space object, its temperature may vary due to a possible illumination of the radiator-emitter of the system
for ensuring the thermal regime by the solar or planet radiation. At a variable heat release the object temperature changes
due to an off-design regime of the radiator operation. To compensate for the given effects the active elements are used —
the heaters and coolers. This reduces the reliability of thermal regulation system and, consequently, the reliability of the
entire spacecraft.
The solutions are proposed, which create in the absence of active elements in the thermal regulation system the internal mechanisms
enabling a compensation of the variability of heat fluxes both at a reorientation of the spacecraft and at a variation of
the internal heat release. 相似文献
863.
N. A. Zavolsky V. E. Zapevalov M. A. Moiseev 《Radiophysics and Quantum Electronics》2006,49(2):108-119
We study theoretically the influence of the spread of initial energies and velocities in the electron beam on the starting
conditions and efficiency of a gyrotron. We compare various analytical and numerical models and the results of experimental
studies of gyrotrons in which the interaction takes place at the first and second harmonics of the cyclotron frequency. The
aftercavity interaction of the electron beam with the high-frequency field in the output waveguide transition is taken into
account. The influence of the energy spread on the recuperation efficiency is estimated. Permissible spreads of the initial
energies and electron velocities are determined.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 49, No. 2, pp. 121–133, February 2006. 相似文献
864.
865.
At the ISOLDE on-line isotope separation facility, the resonance ionisation laser ion source (RILIS) can be used to ionise
reaction products as they effuse from the target. The RILIS process of laser step-wise resonance ionisation of atoms in a
hot metal cavity provides a highly element selective stage in the preparation of the radioactive ion beam. As a result, the
ISOLDE mass separators can provide beams of a chosen isotope with greatly reduced isobaric contamination. With the addition
of a new three-step ionisation scheme for gold, the RILIS is now capable of ionising 26 of the elements. The optimal scheme
was determined during an extensive study of the atomic energy levels and auto-ionising states of gold, carried out by means
of in-source resonance ionisation spectroscopy. Details of the ionisation scheme and a summary of the spectroscopy study are
presented. 相似文献
866.
N. K. Smolentsev 《Siberian Mathematical Journal》1989,30(3):451-457
Kemerovo. Translated from Sibirskii Matematicheskii Zhurnal, Vol. 30, No. 3, pp. 131–139, May–June, 1989. 相似文献
867.
S. Barth H. R. Ott F. N. Gygax B. Hitti E. Lippelt A. Schenck Z. Fisk 《Hyperfine Interactions》1989,50(1-4):709-716
μ+ SR-measurements in transversally applied magnetic fields of 2000 G and 4000 G on heavy-electron single crystal U2Zn17 are presented. They reveal that at least two types of interstitial sites are occupied by the positive muons. One of these
sites (1/3, 2/3, 5/6) could be identified via induced local dipolar fields which aboveT
N=9.7 K can exactly be derived from the magnetic susceptibility. The corresponding component of the μ+-signal exhibits a steplike decrease by about 40% atT
N which is caused by the onset of a very broad distribution of static internal magnetic fields (ΔB≈1000 G) with zero average. Such a field distribution is in distinct contrast to dipolar-field calculations performed for
the simple antiferromagnetic structure deduced from neutron diffraction. The remaining 60% of the muons contributing to this
component belowT
N are subject to a narrow static field distribution (ΔB≈1 G). The induced dipolar fields at the site (1/3, 2/3, 5/6) are temperature-independent belowT
N. A weak dipolar coupling to the U-moments renders similar observations for muons occupying the second type of interstitial
impossible. 相似文献
868.
869.
870.
I. N. Koprinarov U. Müller-Jahreis P. Thiele 《Applied Physics A: Materials Science & Processing》1996,62(6):565-570
The crystalline-amorphous transition in GaAs induced by Ar ions (energy 1–3 keV) has been investigated using single-wavelength ellipsometry. The experiments have been performed in-situ at room temperature. Ion damage straggling, amorphization threshold and critical energy density have been derived by means of a simple analytical model for the growth of the amorphous layer. This model is discussed and the corresponding calculations are found to be in satisfactory agreement with experimental data. 相似文献