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31.
32.
In-situ TEM observation of the evolution of helium bubbles in Mo during He+ irradiation and post-irradiation annealing 下载免费PDF全文
Yi-Peng Li 《中国物理 B》2021,30(8):86109-086109
The evolution of helium bubbles in purity Mo was investigated by in-situ transmission electron microscopy (TEM) during 30 keV He+ irradiation (at 673 K and 1173 K) and post-irradiation annealing (after 30 keV He+ irradiation with the fluence of 5.74×1016 He+/cm2 at 673 K). Both He+ irradiation and subsequently annealing induced the initiation, aggregation, and growth of helium bubbles. Temperature had a significant effect on the initiation and evolution of helium bubbles. The higher the irradiation temperature was, the larger the bubble size at the same irradiation fluence would be. At 1173 K irradiation, helium bubbles nucleated and grew preferentially at grain boundaries and showed super large size, which would induce the formation of microcracks. At the same time, the geometry of helium bubbles changed from sphericity to polyhedron. The polyhedral bubbles preferred to grow in the shape bounded by {100} planes. After statistical analysis of the characteristic parameters of helium bubbles, the functions between the average size, number density of helium bubbles, swelling rate and irradiation damage were obtained. Meanwhile, an empirical formula for calculating the size of helium bubbles during the annealing was also provided. 相似文献
33.
Nickel-based alloys have been considered as candidate structural materials used in generation IV nuclear reactors serving at high temperatures. In the present study, alloy 617 was irradiated with 180-keV helium ions to a fluence of 3.6×1017 ions/cm2 at room temperature. Throughout the cross-section transmission electron microscopy (TEM) image, numerous over-pressurized helium bubbles in spherical shape are observed with the actual concentration profile a little deeper than the SRIM predicted result. Post-implantation annealing was conducted at 700 ℃ for 2 h to investigate the bubble evolution. The long-range migration of helium bubbles occurred during the annealing process, which makes the bubbles of the peak region transform into a faceted shape as well. Then the coarsening mechanism of helium bubbles at different depths is discussed and related to the migration and coalescence (MC) mechanism. With the diffusion of nickel atoms slowed down by the alloy elements, the migration and coalescence of bubbles are suppressed in alloy 617, leading to a better helium irradiation resistance. 相似文献
34.
35.
T. S. Ramazanov T. T. Daniyarov S. A. Maiorov S. K. Kodanova M. K. Dosbolayev E. B. Zhankarashev 《等离子体物理论文集》2011,51(6):505-508
Ion heating in dusty plasma of noble gas mixtures is studied by the observation of dust particles in stratified glow discharge. The particles and their formations can be used as a “contact‐free” probe of the ion flows. It is shown that under condition of experiments transition of dust particles into crystalline state in pure gases occur at much lower pressures in comparison to the case of gas mixtures. This observation is also supported by the evaluation of “effective” kinetic temperature of dust particles as defined from the velocity distribution function at the same set of discharge parameters. Absolute value of temperature of dust component in the mixture of helium and argon indicates important role of argon ionization process (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
36.
Robens E. Keller J. U. Massen C. H. Staudt R. 《Journal of Thermal Analysis and Calorimetry》1999,55(2):383-387
In sorption measurements, volumetric or gravimetric procedures are commonly used to determine the amount adsorbed. At low
pressures, thermomolecular flow and pressure differences according to Knudsen's law disturb measurements. In volumetry, calibration
of the dead space is required; in gravimetry, the influence of buoyancy has to be taken into account. In both cases, adsorption
of the calibrating gas, usually helium, may disturb the measurements [1]. From the calibration measurements, the density of
the sample can in principle be calculated. However, it has been observed in many experiments that its value depends on the
calibrating gas.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
37.
Regimes of superfluid-helium boiling on structural-steel spheres 4.8 and 6.0 mm in diameter, with heaters installed inside, are examined. Experimental data on the evolution of vapor films formed on the
spherical surfaces are obtained.
__________
Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 47, No. 6, pp. 78–84, November–December, 2006. 相似文献
38.
Using a set of explicitly correlated trial wavefunctions that describe the three lowest singlet and triplet states of the helium atom with symmetry S, P, and D, we calculate the decay rates for all possible magnetic quadrupole (M2) transitions: m3P2→n1S0, m1P1→n3S1, m3D3→n1P1, and m1D2→n3P2. Our values are in excellent agreement with the best results in the literature. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011 相似文献
39.
Near 25 °C, ab initio calculations of the zero-density viscosity of helium gas η He have an uncertainty of approximately 0.001%, which is 1/40th of the uncertainty of the best measurements. The uncertainties of the published calculations for neon and argon are probably much larger. This paper presents new measurements of the viscosities of neon, argon, and krypton at 25 °C made with a capillary viscometer that was calibrated with helium. The resulting viscosity ratios are η Ne/η He?=?1.59836?±?0.00037, η Ar/η He?=?1.13763?±?0.00030, and η Kr/η He?=?1.27520?±?0.00040. The argon ratio agrees with a recent, unpublished calculation to within the combined uncertainty (measurement plus calculation) of 0.032%. The neon ratio is smaller than the calculated value by 0.13%. 相似文献
40.