全文获取类型
收费全文 | 19823篇 |
免费 | 1528篇 |
国内免费 | 1113篇 |
专业分类
电工技术 | 404篇 |
综合类 | 769篇 |
化学工业 | 4479篇 |
金属工艺 | 3027篇 |
机械仪表 | 566篇 |
建筑科学 | 78篇 |
矿业工程 | 187篇 |
能源动力 | 849篇 |
轻工业 | 744篇 |
水利工程 | 12篇 |
石油天然气 | 132篇 |
武器工业 | 68篇 |
无线电 | 3198篇 |
一般工业技术 | 6959篇 |
冶金工业 | 576篇 |
原子能技术 | 187篇 |
自动化技术 | 229篇 |
出版年
2024年 | 50篇 |
2023年 | 314篇 |
2022年 | 266篇 |
2021年 | 462篇 |
2020年 | 479篇 |
2019年 | 455篇 |
2018年 | 516篇 |
2017年 | 612篇 |
2016年 | 627篇 |
2015年 | 664篇 |
2014年 | 876篇 |
2013年 | 1216篇 |
2012年 | 1273篇 |
2011年 | 1758篇 |
2010年 | 1268篇 |
2009年 | 1356篇 |
2008年 | 1221篇 |
2007年 | 1360篇 |
2006年 | 1179篇 |
2005年 | 883篇 |
2004年 | 846篇 |
2003年 | 774篇 |
2002年 | 729篇 |
2001年 | 618篇 |
2000年 | 496篇 |
1999年 | 347篇 |
1998年 | 327篇 |
1997年 | 324篇 |
1996年 | 196篇 |
1995年 | 167篇 |
1994年 | 155篇 |
1993年 | 102篇 |
1992年 | 120篇 |
1991年 | 115篇 |
1990年 | 76篇 |
1989年 | 45篇 |
1988年 | 36篇 |
1987年 | 26篇 |
1986年 | 22篇 |
1985年 | 23篇 |
1984年 | 16篇 |
1983年 | 11篇 |
1982年 | 11篇 |
1981年 | 5篇 |
1979年 | 3篇 |
1978年 | 6篇 |
1976年 | 7篇 |
1975年 | 6篇 |
1974年 | 9篇 |
1957年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
In this paper, we examine, both experimentally and theoretically, the kinetics of formation and microstructure of product
phases in thin film reactions, using the Nb/Al and Ti/Al systems as our prototypes. The results of calorimetry and microscopy
studies are interpreted using simple kinetic and morphology models. In particular, the kinetic models employed here focus
on the nucleation and growth components of the phase formation process and the morphology models provide a starting point
for the classification of product grain structures.
An erratum to this article is available at . 相似文献
52.
A vibrating Kelvin probe in form of a platinum wire loop is used to measure the surface potential Us on electron-irradiated free-floating metal and insulator specimens as a function of electron energy E. This allows an accurate measurement of the critical electron energy E2 for no charging. At energies below E2, the positive charging increases with decreasing energy to Us=2–5 eV at E=0.5 keV and switching off the collector bias of the Everhart-Thornley detector. A two-to threefold increase of Us is observed when the bias is switched on. For E > E2, the strong increase of a negative surface potential can be measured. Insulating films free-supported on a conductive substrate show a steep decrease to small positive and negative Us when the film thickness becomes lower than the electron range at a critical energy E3 > E2. At insulating specimen the temporal decrease of charging can be measured when the electron beam is switched off. 相似文献
53.
54.
张庆瑜 《真空科学与技术学报》1996,(1)
着重讨论了TiNx薄膜俄歇电子谱的定量分析方法和X射线光电子谱中线形的变化。利用已知组元强度定量分析技术和Ti的LMV俄歇电子峰,探讨TiNx薄膜中N含量的定量方法。由该方法给出的定量结果与X射线光电子谱定量结果相一致。同时,利用X射线光电子谱测定了TiN和Ti2N2p轨道的结合能。并针对Ti2p峰形随N含量的变化,给出新的解释。 相似文献
55.
56.
The dye-sensitized TiO2 complex films were prepared by the dye coat onto TiO2 surfaces,and the sensitizing mechanism and adsorption properties of the dye-sensitized TiO2 complex films were inverstigated.The influence of the application conditions of dye adsorbed on TiO2 films on the amount of dye adsorption was discussed.Experimental results show that the concentration,the temperature of dye solutions and the dipping time of TiO2 films in the dye solutions have a significant influence on the amount of dye adsorption.Cell test indicates that the conversion efficiency of light to electricity increases with the amount of dye adsorption. 相似文献
57.
对无明胶重铬酸盐全息记录软片(NGD)的光正性抗蚀特性进行了分析研究,通过对溶解度的分析及红外光谱的测定,首次提出NGD是一种新型的紫外正性光抗蚀材科,给出了实验及分析结果。 相似文献
58.
Kiyotaka Wasa 《Bulletin of Materials Science》1993,16(6):643-663
Sputter deposition is currently being widely used in the microelectronics industry for the production of silicon integrated
circuits. Recently interest has been focused on sputter deposition as a new materials processing technique. The highly energetic
sputtered atoms enhance crystal growth and/or sintering during film growth. This results in lowering of the growth temperature
of high temperature materials including cubic diamonds. Single crystals of complex ceramics materials could be prepared by
sputter deposition through epitaxial growth process. Atomically controlled deposition using multi-target sputter enables to
make man-made superlattice including high-T
C superconductors of layered perovskite. At present sputter deposition is one of key materials technologies for the coming
century. 相似文献
59.
Thin CdTe films were deposited by hot-wall epitaxy (HWE) on (111) HgCdTe and CdZnTe substrates at temperatures from about 140 to 335°C. X-ray rocking curves were used to show that crystal quality of the CdTe (111)B films improved as substrate temperature increased from 140 to about 250°C. Rocking curve values for full width at half maximum (FWHM) decreased from 2–4 degrees at 140–150°C to less than 100 arc-s at 250°C, and a FWHM of 59 arc-s was the lowest value observed near 250°C. The FWHM of the HWE CdTe was found to be insensitive to growth rate below about 400Å/min, but increased to four degrees at 1250Å/min. X-ray diffraction confirmed that films grown on the B-face at higher temperatures were epitaxial, but contained a significant volume fraction, 35% to 50%, of rotational in-plane twins. Electron microscopy confirmed a coarse twin density, and photoluminescence spectra showed an absence of excitonic emission in the HWE films. Simultaneous growth on two (111) HgCdTe substrates with different surface polarities between 230°C and 335°C showed that deposition rate on the A-face decreased relative to that on the B-face as temperature increased. Films grown on the B-face exhibited better surface morphologies than those grown on the A-face. 相似文献
60.
The partial oxidation of methanol to formaldehyde was studied over YBa2Cu3O7-x catalyst in a flow reactor. The structural change of YBa2Cu3O7-x before and after the reaction was measured by means of XRD and iodometric titration method. The catalytic characteristics
of YBa2Cu3O7-x for the partial oxidation of methanol to formaldehyde was due to copper ions. It was found that Cu+2 was responsible for the higher selectivity for formaldehyde. 相似文献