全文获取类型
收费全文 | 20729篇 |
免费 | 1234篇 |
国内免费 | 692篇 |
专业分类
电工技术 | 1009篇 |
综合类 | 1293篇 |
化学工业 | 2789篇 |
金属工艺 | 2427篇 |
机械仪表 | 1440篇 |
建筑科学 | 2533篇 |
矿业工程 | 367篇 |
能源动力 | 1628篇 |
轻工业 | 358篇 |
水利工程 | 275篇 |
石油天然气 | 1007篇 |
武器工业 | 155篇 |
无线电 | 1345篇 |
一般工业技术 | 3879篇 |
冶金工业 | 921篇 |
原子能技术 | 883篇 |
自动化技术 | 346篇 |
出版年
2024年 | 26篇 |
2023年 | 141篇 |
2022年 | 325篇 |
2021年 | 397篇 |
2020年 | 463篇 |
2019年 | 328篇 |
2018年 | 387篇 |
2017年 | 492篇 |
2016年 | 544篇 |
2015年 | 568篇 |
2014年 | 1181篇 |
2013年 | 1097篇 |
2012年 | 1370篇 |
2011年 | 1739篇 |
2010年 | 1248篇 |
2009年 | 1245篇 |
2008年 | 1123篇 |
2007年 | 1305篇 |
2006年 | 1181篇 |
2005年 | 1086篇 |
2004年 | 830篇 |
2003年 | 839篇 |
2002年 | 747篇 |
2001年 | 588篇 |
2000年 | 558篇 |
1999年 | 491篇 |
1998年 | 434篇 |
1997年 | 378篇 |
1996年 | 275篇 |
1995年 | 240篇 |
1994年 | 190篇 |
1993年 | 157篇 |
1992年 | 125篇 |
1991年 | 112篇 |
1990年 | 103篇 |
1989年 | 82篇 |
1988年 | 63篇 |
1987年 | 45篇 |
1986年 | 33篇 |
1985年 | 27篇 |
1984年 | 30篇 |
1983年 | 16篇 |
1982年 | 11篇 |
1981年 | 2篇 |
1980年 | 11篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1961年 | 1篇 |
1959年 | 7篇 |
1951年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
P. PetrouI. Raptis S. KakabakosTh. Speliotis A. GerardinoN. Papanikolaou 《Microelectronic Engineering》2011,88(8):1845-1848
We have fabricated sub-quarter-micron-patterned Au templates with electron beam lithography, and studied their effect on the fluorescence intensity of immobilized, anti-rabbit IgG antibody labeled with AlexaFluor® 546. Varying the geometry of the structured surface, the plasmon resonances are tuned to match the fluorescence wavelengths and achieve significant fluorescence enhancement. Full electrodynamic simulations were used to understand the optical response and access the quality of the fabricated structures for surface plasmon excitation. 相似文献
82.
The formation of individual graphene foils (GF) has been evidenced in the present study inside multi-walled carbon nanotubes. The graphene foils are attached on one side to a catalyst nanoparticle and on the other side to the internal walls of the nanotube. Moreover, results suggest that a necking process occurs in which internal carbon walls are deformed until formation of the graphene foil. A possible mechanism for the GF formation is then proposed. 相似文献
83.
L. Baldini M. Pesce-Rollins C. Sgr For the FERMI LAT Collaboration 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2011,630(1):273
Successfully launched into a low-Earth orbit on June 11, 2008, the Fermi Large Area Telescope (LAT) is a pair conversion telescope specifically designed to survey the gamma-ray sky with unprecedented sensitivity and resolution. The broad list of exciting scientific results that the observatory has achieved in the first year of operation, though, is not limited to photon science, as it includes the first high-statistics measurement of the cosmic-ray electron spectrum for energies above 20 GeV. Here we thoroughly discuss the main aspects of the data analysis underlying this measurement and present the ongoing study aimed at lowering the energy threshold of the primary spectrum (measured by the LAT) as well as exploring the properties of the electron albedo population. 相似文献
84.
85.
L. Viskari Y. CaoM. Norell G. SjöbergK. Stiller 《Materials Science and Engineering: A》2011,528(6):2570-2580
The correlation between grain boundary microstructure and fatigue crack growth with hold-times was investigated for two conditions of the superalloy Allvac 718Plus; a Standard condition with the recommended distribution of grain boundary phases and a Clean condition with virtually no grain boundary phases. Fatigue testing was performed at 704 °C using 10 Hz cyclic load with intermittent hold-times of 100 s at maximum tensile load. Microstructural characterization and fractography were conducted using scanning- and transmission electron microscopy techniques. Auger electron- and X-ray photoelectron spectroscopy techniques were used for oxide analyses on fracture surfaces. It was found that in the Standard condition crack growth is mostly transgranular for 10 Hz loading and intergranular for hold-times, while for the Clean condition crack growth is intergranular in both load modes. The lower hold-time crack growth rates in the Standard condition are attributed to grain boundary δ-phase precipitates. No effect of δ-phase was observed for 10 Hz cyclic loading crack growth rates. Two different types of oxides and oxide colours were found on the fracture surfaces in the Standard condition and could be correlated to the different loading modes. For cyclic loading a bright thin Cr-enriched oxide was dominate and for hold-times a dark and slightly thicker Nb-enriched oxide was dominant These oxide types could be related to the oxidation of δ-phase and the matrix respectively. The influence of δ-phase precipitates on crack propagation is discussed. 相似文献
86.
87.
CUI Peng LI Jie & LIU DeSheng Maglev Engineering Center National University of Defense Technology Changsha China 《中国科学:信息科学(英文版)》2010,(4)
Aiming at the lateral dislocation between the electromagnets and the rails on a horizontal curve,we investigated a single magnetic bogie of the maglev train in this paper.The magnetic levitation and guidance forces supplied by the suspension modules were deduced by the flux tube method.According to the dynamic equilibrium equations of the maglev train on the curved track with cant,several major factors that influence the carrying capacity were analyzed,and the formula of the carrying capacity was presented.... 相似文献
88.
凝汽器管板和水室的防腐 总被引:1,自引:0,他引:1
根据凝汽器水室和管板的腐蚀机理,提出用环氧煤沥青做防腐涂层。本文介绍了环氧煤沥青的主要成分、性能以及凝汽器用环氧煤沥青防腐的施工工艺及涂层质量的检测方法等。 相似文献
89.
90.