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41.
Chel-Jong Choi Sung-Young Chang Young-Woo Ok Tae-Yeon Seong H. Gan G. Z. Pan K. N. Tu 《Journal of Electronic Materials》2003,32(10):1072-1078
Transmission electron microscopy (TEM), secondary ion mass spectroscopy (SIMS), and x-ray photoemission spectroscopy (XPS)
have been used to investigate the nucleation, growth, and ripening behavior of nickel-disilicide precipitates formed by Ni
implantation in an amorphous-Si layer on (100) Si and followed by a two-step annealing treatment. The TEM and XPS results
show that amorphous-disilicide precipitates are formed in a depth of ∼21 nm in the amorphous-Si layer when pre-annealed at
380°C for 30 sec. It is also shown that the second-step annealing at temperatures in the range of 450–600°C causes the amorphous
precipitates to transform to randomly oriented crystalline ones embedded in the amorphous-Si layer. Annealing above 550°C
is shown to induce the crystallization of amorphous Si by solid-phase epitaxial growth (SPEG). It is further shown that, in
a prolonged annealing at high temperatures, the disilicide has dissolved and reprecipitated on the Si surface. Based on the
roles of the silicide-mediated crystallization (SMC), the dissolution and reprecipitation of silicides, and SPEG, possible
mechanisms are given to explain how the surface-disilicide islands are formed during annealing at temperatures of 550–950°C. 相似文献
42.
A. Nazarenko K. J. E. Vos S. Haas E. Dagotto R. J. Gooding 《Journal of Superconductivity》1995,8(5):671-672
Recent angle resolved photoemission (ARPES) measurements for the insulating cuprate Sr2CuO2Cl2 have provided the first experimental data which can be directly compared to the (theoretically) well-studied problem of a single hole propagating in an antiferromagnet. Some discrepancies withthe familiar 2D t— J model were observed. Here we discuss a comparison between the ARPES results and the quasiparticle dispersion of both (i) the extended t— t— J Hamiltonian and (ii) the three-band Hubbard model. 相似文献
43.
We continue to study Bi2Sr2CaCu2O8+ with angle-resolved photoemission spectroscopy, in order to gain detailed knowledge of the high-temperature superconductors' electronic structure. While the photoemission community has already established some important general characteristics of this material, continued investigation reveals a rich variety of details. In the superconducting state, we have looked for details in the gap anisotropy. In the normal state, we have concentrated on the evolution of the Fermi surface as the carrier doping is reduced. 相似文献
44.
We summarize some of the main results on photoemission spectroscopy in the field of high-T
c superconductivity, beginning with a discussion of several open questions. We then briefly analyze our experiments that illustrate the role of doping and of intentionally introduced disorder (by electron bombardment) in Bi2Sr2CaCu2O8+x
single crystals. 相似文献
45.
N. D. Jäger A. K. Verma P. Dreszer N. Newman Z. Liliental-Weber M. van Schilfgaarde E. R. Weber 《Journal of Electronic Materials》1993,22(12):1499-1502
Nonstoichiometric arsenic-rich GaAs grown at low temperatures by molecular beam epitaxy (LT-GaAs) has been found to be semi-insulating
after high-temperature annealing. The origin of this technologically important conversion is not yet fully understood. In
order to study this effect, we performed photocurrent measurements on p-LT GaAs-n diodes in the spectral range between 0.75
and 1.5eV at 8K. The photocurrent spectra revealed the following features which are unique to the EL2 level: photoquenching,
characteristic photoionization transitions to conduction band minima and a presence of a broad band due to the effect of auto-ionization
from the excited state. Moreover, modeling of the optical excitation process using realistic band structure demonstrates that
these features cannot be explained by “internal photoemission” originating from As precipitates, as the “buried Schottky barrier
model” predicts. This is the first direct experimental evidence for the existence of EL2-like defect levels and their importance
for understanding the optical and electronic properties of annealed LT-GaAs. 相似文献
46.
The p-doping effect of the fluorinated fullerene C60 F36 doped into organic thin films of N,N,N′,N′-tetrakis(4-methoxyphenyl)-benzidine (MeO-TPD) of different purification grades is systematically investigated by photoemission spectroscopy. By reducing the molar doping ratio to MR = 2.9 × 10?4, the Fermi-level shift upon doping is resolved in particular at very low doping concentrations. In comparison to four times sublimated MeO-TPD, 5 times more C60F36 molecules have to be doped into unpurified MeO-TPD films to shift the Fermi-level just above its intrinsic position. This finding is discussed in terms of a statistical model, showing that narrow deep hole-trap states are additionally present in the unpurified host material which are hindering an efficient generation of free charge carriers at molar doping ratios below MR = 0.002. 相似文献
47.
A chemical approach to controlling the work function of few‐layer graphene is investigated. Graphene films are synthesized on Cu foil by chemical vapor deposition. Six metal chlorides, AuCl3, IrCl3, MoCl3, OsCl3, PdCl2, and RhCl3, are used as dopants. The sheet resistance of the doped graphene decreases from 1100 Ω/sq to ≈500–700 Ω/sq and its transmittance at 550 nm also decreases from 96.7% to 93% for 20 mM AuCl3 due to the formation of metal particles. The sheet resistance and transmittance are reduced with increasing metal chloride concentration. The G peak in the Raman spectra is shifted to a higher wavenumber after metal chloride doping, which indicates a charge transfer from graphene to metal ions. The intensity ratio of IC?C/IC?C increases with doping, indicating an electron transfer from graphene sheets to metal ions. Ultraviolet photoemission spectroscopy data shows that the work function of graphene increases from 4.2 eV to 5.0, 4.9, 4.8, 4.68, 5.0, and 5.14 eV for the graphene with 20 mM AuCl3, IrCl3, MoCl3, OsCl3, PdCl2, and RhCl3, respectively. It is considered that spontaneous charge transfer occurs from the specific energy level of graphene to the metal ions, thus increasing the work function. 相似文献
48.
肖特基势垒红外焦平面阵列 总被引:1,自引:0,他引:1
介绍肖特基势垒IRCCD的结构和工作原理,制作工艺,目前国内外发展的状况和提高器件性能的各种措施. 相似文献
49.
Guillaume Vidon Pia Dally Mirella Al-Katrib Daniel Ory Minjin Kim Etienne Soret Eva Rangayen Marie Legrand Alexandre Blaizot Philip Schulz Jean-Baptiste Puel Daniel Suchet Jean-François Guillemoles Arnaud Etcheberry Muriel Bouttemy Stefania Cacovich 《Advanced functional materials》2023,33(45):2304730
Understanding the effects of X-rays on halide perovskite thin films is critical for accurate and reliable characterization of this class of materials, as well as their use in detection systems. In this study, advanced optical imaging techniques are employed, both spectrally and temporally resolved, coupled with chemical characterizations to obtain a comprehensive picture of the degradation mechanism occurring in the material during photoemission spectroscopy measurements. Two main degradation pathways are identified through the use of local correlative physico-chemical analysis. The first one, at low X-Ray fluence, shows minor changes of the surface chemistry and composition associated with the formation of electronic defects. Moreover, a second degradation route occurring at higher fluence leads to the evaporation of the organic cations and the formation of an iodine-poor perovskite. Based on the local variation of the optoelectronic properties, a kinetic model describing the different mechanisms is proposed. These findings provide valuable insight on the impact of X-rays on the perovskite layers during investigations using X-ray based techniques. More generally, a deep understanding of the interaction mechanism of X-rays with perovskite thin films is essential for the development of perovskite-based X-ray detectors and solar for space applications. 相似文献
50.
银氧铯光电阴极至今仍为一种重要的实用光电阴极,本文以银氧铯光电阴极为例,利用吴全德提出的有关模型和量子力学微扰论的结果,讨论了它的光强依赖关系,并导出了必要的公式;既为对实验结果的一种预测,也与现有实验结果符合很好。 相似文献