全文获取类型
收费全文 | 3237篇 |
免费 | 298篇 |
国内免费 | 123篇 |
专业分类
电工技术 | 214篇 |
综合类 | 177篇 |
化学工业 | 489篇 |
金属工艺 | 216篇 |
机械仪表 | 195篇 |
建筑科学 | 185篇 |
矿业工程 | 74篇 |
能源动力 | 93篇 |
轻工业 | 344篇 |
水利工程 | 35篇 |
石油天然气 | 170篇 |
武器工业 | 12篇 |
无线电 | 254篇 |
一般工业技术 | 453篇 |
冶金工业 | 302篇 |
原子能技术 | 43篇 |
自动化技术 | 402篇 |
出版年
2024年 | 24篇 |
2023年 | 72篇 |
2022年 | 147篇 |
2021年 | 179篇 |
2020年 | 116篇 |
2019年 | 93篇 |
2018年 | 110篇 |
2017年 | 129篇 |
2016年 | 106篇 |
2015年 | 114篇 |
2014年 | 144篇 |
2013年 | 216篇 |
2012年 | 195篇 |
2011年 | 204篇 |
2010年 | 181篇 |
2009年 | 155篇 |
2008年 | 151篇 |
2007年 | 132篇 |
2006年 | 147篇 |
2005年 | 92篇 |
2004年 | 93篇 |
2003年 | 75篇 |
2002年 | 78篇 |
2001年 | 50篇 |
2000年 | 66篇 |
1999年 | 78篇 |
1998年 | 87篇 |
1997年 | 65篇 |
1996年 | 61篇 |
1995年 | 60篇 |
1994年 | 38篇 |
1993年 | 28篇 |
1992年 | 16篇 |
1991年 | 18篇 |
1990年 | 9篇 |
1989年 | 6篇 |
1988年 | 11篇 |
1987年 | 5篇 |
1986年 | 5篇 |
1985年 | 10篇 |
1984年 | 7篇 |
1983年 | 9篇 |
1982年 | 6篇 |
1980年 | 6篇 |
1979年 | 7篇 |
1978年 | 10篇 |
1977年 | 10篇 |
1976年 | 13篇 |
1974年 | 5篇 |
1972年 | 5篇 |
排序方式: 共有3658条查询结果,搜索用时 0 毫秒
41.
The present paper investigates the 3D medial axis transform of objects bounded by freeform surfaces via the saddle point programming method, a mathematical programming approach used to identify the saddle points of a function. After exploring the local geometry and saddle point property of 3D medial axis transform, the mathematical programming method is employed to construct the saddle point programming models. Based on the optimality conditions that the optimal solutions should satisfy, a generic algorithm for computing various medial axis points is developed. In order to identify the junction points and localize the problem, the boundary and the skeletal curves are divided into skeletal segments, and it is proved to be efficient and accurate by numerical examples. 相似文献
42.
43.
机电一体化茶青超声波清洗机的设计开发 总被引:1,自引:0,他引:1
介绍了一种基于PIC单片机控制的超声波茶青清洗设备,给出了系统及结构的设计、单片机控制电路和功率放大电路的设计,并较详细地阐述了几种换能器的性能比较和控制器的工作原理及结构,使其具有(超声波加气泡发生器)的恒功率清洗功能,满足了茶青表面杂质清洗及去除农残的要求。经试验证明:超声波清洗速度快、效果好、容易实现工业控制,能保持恒定输出功率,且可以方便地调节。 相似文献
44.
Presented is a new microplane model for concrete, labeled M5, which improves the representation of tensile cohesive fracture by eliminating spurious excessive lateral strains and stress locking for far postpeak tensile strains. To achieve improvement, a kinematically constrained microplane system simulating hardening nonlinear behavior (nearly identical to previous Model M4 stripped of tensile softening) is coupled in series with a statically constrained microplane system simulating solely the cohesive tensile fracture. This coupling is made possible by developing a new iterative algorithm and by proving the conditions of its convergence. The special aspect of this algorithm (contrasting with the classical return mapping algorithm for hardening plasticity) is that the cohesive softening stiffness matrix (which is not positive definite) is used as the predictor and the hardening stiffness matrix as the corrector. The softening cohesive stiffness for fracturing is related to the fracture energy of concrete and the effective crack spacing. The postpeak softening slopes on the microplanes can be adjusted according to the element size in the sense of the crack band model. Finally, an incremental thermodynamic potential for the coupling of statically and kinematically constrained microplane systems is formulated. The data fitting and experimental calibration for tensile strain softening are relegated to a subsequent paper in this issue, while all the nonlinear triaxial response in compression remains the same as for Model M4. 相似文献
45.
研究RH-KTB系统的故障种类及特点,进行故障树分析,找出故障间的关系并建立了原始样本采集系统.利用决策树理论对炉外精练大型真空冶金系统的约简集进行快速学习和分类.最后,提出一种基于粗糙集-决策树理论的炉外精炼大型真空冶金系统故障诊断模型.从理论上保证及时对干扰数据进行排除并实现快速诊断.基于该模型开发了一套智能故障诊断系统并应用于大型真空冶金系统,应用效果良好. 相似文献
46.
中国钢铁生产量及其能源需求和CO2排放量情景分析 总被引:8,自引:0,他引:8
从预测中国的钢铁需求量开始,利用情景分析,预测了钢铁业将来的能源需求和CO2排放量。预测结果表明,中国的钢产量还将继续增长,但应特别注意废钢回用,降低铁钢比,以减少能源需求和CO2排放。 相似文献
47.
The transfer of mass flow between ironmaking and steelmaking process at Baoshan Iron and Steel Co. Ltd. has been analyzed. The mathematic-physical models of transport scheduling for hot metal manufacturing have been researched combined with the practical problem in the metallurgical manufacture procedure. Taking into account these models, the scheduling software has been designed, programmed and tested on-line. The new automation system of production scheduling has been implemented successfully at Baosteel, which produces a great economic benefit. 相似文献
48.
移动智能代理系统提供了一个新的计算方式,程序以软件代理的形式出现,它能在一台主机上停止它的执行,通过移动到另一台主机上来恢复执行。随着移动软件混合性的增加,也伴随着对安全的威胁,该文论述了agent主机面临的安全问题,同时提出了对agent主机的保护方法。 相似文献
49.
Lee Dongwook; LoGalbo Anthony P.; Ba?os James H.; Novack Thomas A. 《Canadian Metallurgical Quarterly》2004,49(2):167
Objective: To evaluate the ability of the Cognitive Log (Cog-Log) to predict neuropsychological outcome at 1 year after traumatic brain injury (TBI). Study Design: The Orientation Log (O-Log) and Cog-Log were administered during morning rounds, and a battery of neuropsychological tests was administered at 1 year postinjury. Setting: Acute rehabilitation hospital. Participants: Fifty rehabilitation inpatients. Main Outcome Measures: Composite scores for processing speed, attention, language, memory, executive functioning, and visuospatial abilities. Results: The Cog-Log was found to significantly predict 1-year outcome in attention, executive functioning, and visuospatial abilities. The O-Log contributed significantly to memory outcome. The Disability Rating Scale was not a significant predictor. Conclusions: The Cog-Log has utility as a predictor of neuropsychological outcome, particularly when used with its companion instrument, the O-Log. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
50.