全文获取类型
收费全文 | 307604篇 |
免费 | 18299篇 |
国内免费 | 9520篇 |
专业分类
电工技术 | 13215篇 |
技术理论 | 24篇 |
综合类 | 16047篇 |
化学工业 | 49470篇 |
金属工艺 | 17634篇 |
机械仪表 | 17329篇 |
建筑科学 | 19651篇 |
矿业工程 | 8015篇 |
能源动力 | 7449篇 |
轻工业 | 16845篇 |
水利工程 | 4804篇 |
石油天然气 | 16920篇 |
武器工业 | 1648篇 |
无线电 | 33781篇 |
一般工业技术 | 42564篇 |
冶金工业 | 15312篇 |
原子能技术 | 2484篇 |
自动化技术 | 52231篇 |
出版年
2024年 | 998篇 |
2023年 | 3806篇 |
2022年 | 6495篇 |
2021年 | 9129篇 |
2020年 | 7097篇 |
2019年 | 6026篇 |
2018年 | 20072篇 |
2017年 | 19910篇 |
2016年 | 15969篇 |
2015年 | 9438篇 |
2014年 | 11478篇 |
2013年 | 13463篇 |
2012年 | 17197篇 |
2011年 | 24333篇 |
2010年 | 21270篇 |
2009年 | 17885篇 |
2008年 | 18785篇 |
2007年 | 19292篇 |
2006年 | 12457篇 |
2005年 | 11911篇 |
2004年 | 8324篇 |
2003年 | 7344篇 |
2002年 | 5984篇 |
2001年 | 4984篇 |
2000年 | 5603篇 |
1999年 | 6495篇 |
1998年 | 5492篇 |
1997年 | 4481篇 |
1996年 | 4237篇 |
1995年 | 3509篇 |
1994年 | 2827篇 |
1993年 | 1976篇 |
1992年 | 1550篇 |
1991年 | 1248篇 |
1990年 | 933篇 |
1989年 | 740篇 |
1988年 | 546篇 |
1987年 | 336篇 |
1986年 | 278篇 |
1985年 | 196篇 |
1984年 | 139篇 |
1983年 | 114篇 |
1982年 | 125篇 |
1981年 | 98篇 |
1980年 | 70篇 |
1968年 | 47篇 |
1966年 | 43篇 |
1965年 | 48篇 |
1955年 | 64篇 |
1954年 | 68篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Sankaralingam K. Nagarajan R. Haiming Liu Changkyu Kim Jaehyuk Huh Burger D. Keckler S.W. Moore C. 《Micro, IEEE》2003,23(6):46-51
The Tera-op reliable intelligently adaptive processing system (TRIPS) architecture seeks to deliver system-level configurability to applications and runtime systems. It does so by employing the concept of polymorphism, which permits the runtime system to configure the hardware execution resources to match the mode of execution and demands of the compiler and application. 相似文献
72.
73.
M. Del C. Ruiz J. A. González J. B. Rivarola 《Metallurgical and Materials Transactions B》2004,35(3):439-448
The mechanism and kinetics of β-Ta2O5 chlorination, mixed with sucrose carbon, have been studied by a thermogravimetric technique. The investigated temperature
range was 500 °C to 850 °C. The reactants and reaction residues were analyzed by scanning electronic microscopy (SEM), X-ray
diffraction (XRD), and Brunauer-Emmett-Teller method for surface area (BET). The effect of various experimental parameters
was studied, such as carbon percentage, temperature, chlorine partial pressure, and flow, use of the multiple sample method,
and carbon previous oxidation. The carbon percentage and previous treatment have an effect on the system reactivity. The temperature
has a marked effect on the reaction rate. In the 500 °C to 600 °C temperature interval, the apparent activation energy is
144 kJ/mol of oxide, while at higher temperatures, the activation energy decreases. With high chorine partial pressures, the
order of reaction is near zero. The kinetic contractile plate model, X=kt, considering carbon oxidation as the controlling stage, is the one with the best fit to the experimental data. A probable
mechanism for the carbochlorination of β-Ta2O5 is proposed: (1) activation of chlorine on the carbon surface, (2) chlorination of Ta2O5, (3) oxidation of carbon, and (4) recrystallization of β-Ta2O5. 相似文献
74.
75.
76.
77.
Voltage switching induced by long-wavelength infrared light from a CO2 laser was observed using a double-barrier resonant tunneling diode (RTD) biased in the bistable region and the intersubband transition (IT) between the quantum confined states. Possible optoelectronic and all-optical switching applications involving hysteresis are proposed and discussed 相似文献
78.
79.
80.
This paper reports the findings of a detailed study of Web-based systems design (WBSD) practices in Ireland based on data
collected over a 3-year period (2002–2005), the objectives of which were to (1) contribute towards a richer understanding
of the current “real-world” context of WBSD by characterising the profile of a typical project (team size, timeframe, nature
of requirements, etc.) and identifying the key challenges, constraints, and imperatives (i.e. “mediating factors”) faced by
Web-based system designers, and (2) understand how those contextual parameters and mediating factors influence the activity
of WBSD as regards the selection and enactment of whatever design practices are therefore engaged (i.e. the use of methods,
procedures, etc.). Data was gathered through a survey which yielded 165 usable responses, and later through a series of semi-structured
qualitative interviews. Using grounded theory, an explanatory conceptual framework is derived, based on an extension of the
“method-in-action” model, the application of which to WBSD has not been previously investigated in depth. It is proposed that
this framework of WBSD issues is valuable in a number of ways to educators, researchers, practitioners, and method engineers. 相似文献