全文获取类型
收费全文 | 569篇 |
免费 | 16篇 |
国内免费 | 57篇 |
专业分类
电工技术 | 4篇 |
综合类 | 13篇 |
化学工业 | 74篇 |
金属工艺 | 102篇 |
机械仪表 | 9篇 |
建筑科学 | 1篇 |
矿业工程 | 4篇 |
能源动力 | 12篇 |
轻工业 | 5篇 |
石油天然气 | 2篇 |
武器工业 | 1篇 |
无线电 | 195篇 |
一般工业技术 | 179篇 |
冶金工业 | 27篇 |
原子能技术 | 11篇 |
自动化技术 | 3篇 |
出版年
2024年 | 1篇 |
2023年 | 4篇 |
2022年 | 11篇 |
2021年 | 8篇 |
2020年 | 5篇 |
2019年 | 5篇 |
2018年 | 7篇 |
2017年 | 13篇 |
2016年 | 10篇 |
2015年 | 10篇 |
2014年 | 19篇 |
2013年 | 18篇 |
2012年 | 23篇 |
2011年 | 42篇 |
2010年 | 18篇 |
2009年 | 38篇 |
2008年 | 29篇 |
2007年 | 42篇 |
2006年 | 41篇 |
2005年 | 23篇 |
2004年 | 28篇 |
2003年 | 32篇 |
2002年 | 22篇 |
2001年 | 25篇 |
2000年 | 29篇 |
1999年 | 11篇 |
1998年 | 41篇 |
1997年 | 14篇 |
1996年 | 11篇 |
1995年 | 10篇 |
1994年 | 5篇 |
1993年 | 5篇 |
1992年 | 4篇 |
1991年 | 3篇 |
1990年 | 7篇 |
1989年 | 9篇 |
1988年 | 4篇 |
1987年 | 5篇 |
1986年 | 2篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1982年 | 4篇 |
排序方式: 共有642条查询结果,搜索用时 375 毫秒
51.
52.
G. Ottaviani R. Tonini D. Giubertoni A. Sabbadini T. Marangon G. Queirolo F. La Via 《Microelectronic Engineering》2000,50(1-4):153-158
The C49C54 TiSi2 polymorphic transformation has been investigated trying to elucidate the relative role played by nucleation and growth in silicide formation. Samples having an amorphous layer and C54 seeds have been made by heat treatment of a Ti/Si bi-layer structure and subsequent suitable Ar ion implantation. In situ resistance measurements performed during heat treatments in controlled and purified atmosphere at constant heating rates and ex situ X-ray diffraction, MeV 4He+ backscattering spectrometry and cross-section transmission electron microscopy have been used to characterize the samples. The results show that in a sample with C49 the C54 nucleation occurs at 800°C; when C54 seeds are present the growth is appreciable already at temperatures as low as 400–500°C. It has also been shown that nucleation and growth of the C49 phase is a process competitive to the growth of the C54 phase. 相似文献
53.
Quasi-continuous-wave operation of GaAs/AlGaAs quantum-cascade lasers with high average optical power is demonstrated. Double X-ray diffraction has been used to investigate the quality of the epitaxial material. The compositional gradients and the interface quality are controlled effectively. The corrected average power of per facet about 17 mW and temperature tuning coefficient of the gain peak about 0.91 nm/K from 83 K to 140 K is achieved in pulse operation. Best value of threshold current density is less than 3.0 kA/cm2 at 83 K. 相似文献
54.
55.
56.
The effect of lateral dimensional scaling on the thermal stability of polycrystalline cobalt disilicide wires reacted on Si (001) has been studied down to 0.6 μm linewidth. An unpatterned silicide has been used as a reference sample. The annealing processes were performed in N2 environment, between 900 and 1050°C, on both blanket and patterned silicide. Transmission electron microscopy analyses in plan-view and cross-section allowed us to study the morphology of lines before and after high-temperature processes. Resistance measurements showed a better thermal stability in blanket silicide layer compared to narrow lines. The electrical behaviour of the lines has been explained in terms of both lateral roughness and hole formation in the silicide layer. 相似文献
57.
The oxide film formed on nickel base alloys at high temperature and high pressure water exhibits semi-conducting properties evidenced by photocurrent generation when exposed to monochromatic light. The use of macro- and micro-photoelectrochemical techniques (PEC and MPEC) aims to identify the different semiconductor phases and their distribution in the oxide film.Three different nickel base alloys were corroded in recirculation loop at 325 °C in pressurised water reactor primary coolant conditions for different exposition durations.PEC experiments on these materials enable to obtain macroscopic energy spectra showing three contributions. The first one, with a band gap around 2.2 eV, was attributed to the presence of nickel hydroxide and/or nickel ferrite. The second one, with a band gap around 3.5 eV, was attributed to Cr2O3. The last contribution, with a band gap in the range of 4.1-4.5 eV, was attributed to the spinel phase Ni1−xFexCr2O4. In addition, macroscopic potential spectra recorded at different energies highlight n-type semi-conduction behaviours for both oxides, Cr2O3 and Ni1−xFexCr2O4.Moreover, MPEC images recorded at different energies exhibit contrasted regions in photocurrent, describing the distribution of nickel hydroxide and/or nickel ferrite and Cr2O3 in the oxide film at a micron scale.It is concluded that PEC techniques represent a sensitive and powerful way to locally analyse the various semiconductor phases in the oxide scale. 相似文献
58.
《Ceramics International》2023,49(13):21839-21847
This article presents a study on the manufacturing of three-phase TaSi2–TaC–SiC ceramics through self-propagating high-temperature synthesis (SHS) and their subsequent chemical conversion to TaC–SiC carbide composites during transient liquid-phase hot pressing (HP). The effect of carbon black doping, ranging from 0% to 7%, on the degree of chemical conversion, structure, mechanical, and thermophysical properties of the ceramics was investigated. Our results showed that the proportionate increase of carbide content and decrease of TaSi2 content in hot-pressed samples was achieved through carbon black doping. The increase of TaSi2 content during hot pressing led to an increase in porosity from 4.3% to 23.8%, while the density decreased from 6.3 to 4.6 g/cm3. Superior mechanical properties were obtained when SHS-powder was doped with 1.5% carbon black (HV = 15.2 GPa, KIC = 4.8 MPa × m1/2, and σbend = 331 MPa). The structure of the ceramics was characterized by a TaSi2–SiC matrix and highly dispersed TaC grains predominantly residing inside TaSi2, with the TaC–TaSi2 and TaSi2–SiC interface being incoherent, as demonstrated through TEM studies. Complete conversion of TaSi2 to TaC and SiC was achieved through 7% carbon black doping, resulting in the hot-pressed sample consisting solely of carbide grains. Two-stage hot pressing was employed to enhance the relative density of the two-phase TaC–SiC sample, resulting in ceramics characterized by HV up to 22.3 GPa, KIC up to 6.1 MPa × m1/2, σbend up to 256 MPa, and λ up to 36 W/(m × K). 相似文献
59.
采用料浆烧结法在TZM钼合金表面制备Mo层,再通过包埋渗法制得双层结构的MoSi2厚涂层。利用内热法在大气环境下测试了钼合金Si-Mo涂层在1 600 ℃下的高温抗氧化性能。结果表明,涂层由多孔MoSi2外层和致密MoSi2内层组成,Mo粉细化对涂层组织致密化和高温抗氧化性能提升有益,平均粒度9.8 μm和2.2 μm的Mo粉制备的涂层在1 600 ℃下的高温抗氧化寿命分别为5.1 h和14.8 h,高温氧化后涂层结构转变为SiO2氧化层-多孔MoSi2层-致密层-Mo5Si3层。随着氧化持续进行,SiO2层和Mo5Si3层不断增厚,而MoSi2层持续减薄并转化为Mo5Si3,硅元素的持续贫化导致涂层最终失效。 相似文献
60.
V. S. Pershenkov V. V. Belyakov S. V. Cherepko I. N. Shvetzov-Shilovsky V. V. Abramov 《Microelectronics Reliability》1999,39(1):133
The work is concerned with the properties of conventional MOSFET in bipolar mode of operation. It is shown that the base current can provide useful information about interface trap density at the Si–SiO2 interface. The new device characteristics are found promising for use in low-voltage low-power logic circuits. 相似文献