全文获取类型
收费全文 | 9996篇 |
免费 | 601篇 |
国内免费 | 326篇 |
专业分类
电工技术 | 296篇 |
综合类 | 559篇 |
化学工业 | 4812篇 |
金属工艺 | 679篇 |
机械仪表 | 177篇 |
建筑科学 | 251篇 |
矿业工程 | 387篇 |
能源动力 | 318篇 |
轻工业 | 711篇 |
水利工程 | 33篇 |
石油天然气 | 136篇 |
武器工业 | 5篇 |
无线电 | 339篇 |
一般工业技术 | 1521篇 |
冶金工业 | 523篇 |
原子能技术 | 78篇 |
自动化技术 | 98篇 |
出版年
2024年 | 21篇 |
2023年 | 139篇 |
2022年 | 210篇 |
2021年 | 291篇 |
2020年 | 233篇 |
2019年 | 208篇 |
2018年 | 201篇 |
2017年 | 374篇 |
2016年 | 336篇 |
2015年 | 291篇 |
2014年 | 439篇 |
2013年 | 515篇 |
2012年 | 659篇 |
2011年 | 857篇 |
2010年 | 601篇 |
2009年 | 574篇 |
2008年 | 490篇 |
2007年 | 648篇 |
2006年 | 535篇 |
2005年 | 433篇 |
2004年 | 440篇 |
2003年 | 352篇 |
2002年 | 333篇 |
2001年 | 238篇 |
2000年 | 258篇 |
1999年 | 245篇 |
1998年 | 159篇 |
1997年 | 121篇 |
1996年 | 113篇 |
1995年 | 119篇 |
1994年 | 91篇 |
1993年 | 71篇 |
1992年 | 79篇 |
1991年 | 55篇 |
1990年 | 47篇 |
1989年 | 22篇 |
1988年 | 27篇 |
1987年 | 24篇 |
1986年 | 21篇 |
1985年 | 14篇 |
1984年 | 8篇 |
1983年 | 9篇 |
1982年 | 7篇 |
1981年 | 6篇 |
1980年 | 4篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1951年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
Aluminum-doped zinc oxide (ZnO:Al, AZO) electrodes were covered with very thin (∼6 nm) Zn1−xMgxO:Al (AMZO) layers grown by atomic layer deposition. They were tested as hole blocking/electron injecting contacts to organic semiconductors. Depending on the ALD growth conditions, the magnesium content at the film surface varied from x = 0 to x = 0.6. Magnesium was present only at the ZnO:Al surface and subsurface regions and did not diffuse into deeper parts of the layer. The work function of the AZO/AMZO (x = 0.3) film was 3.4 eV (based on the ultraviolet photoelectron spectroscopy). To investigate carrier injection properties of such contacts, single layer organic structures with either pentacene or 2,4-bis[4-(N,N-diisobutylamino)-2,6-dihydroxyphenyl] squaraine layers were prepared. Deposition of the AMZO layers with x = 0.3 resulted in a decrease of the reverse currents by 1–2 orders of magnitude and an improvement of the diode rectification. The AMZO layer improved hole blocking/electron injecting properties of the AZO electrodes. The analysis of the current-voltage characteristics by a differential approach revealed a richer injection and recombination mechanisms in the structures containing the additional AMZO layer. Among those mechanisms, monomolecular, bimolecular and superhigh injection were identified. 相似文献
2.
Undoped and fluorine doped ZnO thin films were deposited onto glass substrates using successive ionic layer adsorption and reaction (SILAR) technique and then annealed at 350 °C in vacuum ambience. The F doping level was varied from 0 to 15 at% in steps of 5 at%. The XRD analysis showed that all the films are polycrystalline with hexagonal wurtzite structure and preferentially oriented along the (002) plane. Crystallite sizes were found to increase when 5 at% of F is doped and then decreased with further doping. It was seen from the SEM images that the doping causes remarkable changes in the surface morphology and the annealing treatment results in well-defined grains with an improvement in the grain size irrespective of doping level. All the films exhibit good transparency (>70%) after vacuum annealing. Electrical resistivity of the film was found to be minimum (1.32×10−3 Ω cm) when the fluorine doping level was 5 at%. 相似文献
3.
4.
5.
JFC磷酸酯的合成和应用 总被引:2,自引:0,他引:2
详述了JFC磷酸酯的合成工艺路线,以及它在织物前处理精练工艺中的应用。与其它磷酸酯类精练剂性能对比,证明它可作为一种性能优良的精练剂中的添加剂。 相似文献
6.
简述国内磷酸二铵的建设情况及不同的生产工艺、原有磷酸二铵装置改造选用的工艺及生产情况 ,重点介绍 Incro工艺在云南红河州磷肥厂年产 12万吨磷铵装置中的改造情况 ,经过比较认为原采用预中和槽流程磷酸二铵装置增产改造时选用 Incro工艺比较合适 相似文献
7.
Atmospheric corrosion of reference metals in Antarctic sites 总被引:1,自引:0,他引:1
Manuel Morcillo Beln Chico Daniel de la Fuente Elisabete Almeida Günter Joseph Susana Rivero Blanca Rosales 《Cold Regions Science and Technology》2004,40(3):165-178
This paper presents the results obtained at three Antarctic test sites participating in the “Ibero-American Map of Atmospheric Corrosiveness” (MICAT), a project on atmospheric corrosion carried out during the period 1988–1994 at some 70 sites distributed across 12 countries of the Latin-American region, Spain and Portugal. The three Antarctic sites are located near the coastline.The singular climatic characteristics of Antarctic regions are related with the purity of the air, the absence of rainfall and the formation of ice on the metallic surface during an important part of the exposure time. However, electrochemical activity is possible below ice layers. This situation affects the structure and morphology of corrosion product films and the resulting corrosion rates of metallic surfaces. 相似文献
8.
1Introduction Reconstructivesurgeryisoneofthehottestre searchedsubjectsthatdealingwithbonedefects.Thetra ditionalmethodisimplantationoffreshautograftbonebe causeofitsnon immunoreactiveproperty.Butautologousbonewasnotabundantinsomecases.Sowefoundbeta trica… 相似文献
9.
10.
Lei Liu Ying Kong Hong Xu Jin P. Li Jin X. Dong Zhi Lin 《Microporous and mesoporous materials》2008,115(3):624-628
A three-dimensional zinc phosphate compound with DFT topology, designated as ZnPO4-EU1, has been synthesized by an ionothermal approach from the system HF-ZnO–P2O5-choline chloride-imidazolidone. Ethylenediamine, derived from decomposition of the imidazolidone component of the deep-eutectic solvent (DES) itself, is delivered to the synthesis and serves as an appropriate template for ZnPO4-EU1. Experiments in which the synthesis conditions were varied showed that ZnPO4-EU1 may be prepared over a wide molar ratio of P/Zn = 0.55–13.0. Powder X-ray diffraction patterns have been obtained at intervals to track the crystallization process of this material. The experimental data show that Zn3(PO4)2 · 4H2O (a dense phase) was first isolated from the DES after reaction for 1 h. Subsequently, the pure phase of ZnPO4-EU1 was obtained with increasing crystallization time from 12 h to 72 h. The experimental results show that the nucleation and crystallization take place with relatively low levels of solvent degradation, demonstrating that zinc phosphate with a three-dimensional framework can be synthesized by in situ generation of an appropriate template using an unstable DES at high temperatures (150–200 °C). 相似文献