全文获取类型
收费全文 | 12332篇 |
免费 | 1023篇 |
国内免费 | 639篇 |
专业分类
电工技术 | 1387篇 |
综合类 | 1032篇 |
化学工业 | 387篇 |
金属工艺 | 1019篇 |
机械仪表 | 2080篇 |
建筑科学 | 553篇 |
矿业工程 | 513篇 |
能源动力 | 217篇 |
轻工业 | 269篇 |
水利工程 | 136篇 |
石油天然气 | 213篇 |
武器工业 | 264篇 |
无线电 | 1316篇 |
一般工业技术 | 679篇 |
冶金工业 | 550篇 |
原子能技术 | 240篇 |
自动化技术 | 3139篇 |
出版年
2024年 | 44篇 |
2023年 | 147篇 |
2022年 | 228篇 |
2021年 | 309篇 |
2020年 | 345篇 |
2019年 | 214篇 |
2018年 | 249篇 |
2017年 | 380篇 |
2016年 | 367篇 |
2015年 | 450篇 |
2014年 | 678篇 |
2013年 | 653篇 |
2012年 | 894篇 |
2011年 | 923篇 |
2010年 | 640篇 |
2009年 | 661篇 |
2008年 | 613篇 |
2007年 | 875篇 |
2006年 | 813篇 |
2005年 | 685篇 |
2004年 | 579篇 |
2003年 | 570篇 |
2002年 | 434篇 |
2001年 | 333篇 |
2000年 | 335篇 |
1999年 | 294篇 |
1998年 | 250篇 |
1997年 | 213篇 |
1996年 | 170篇 |
1995年 | 133篇 |
1994年 | 99篇 |
1993年 | 74篇 |
1992年 | 71篇 |
1991年 | 32篇 |
1990年 | 43篇 |
1989年 | 39篇 |
1988年 | 23篇 |
1987年 | 22篇 |
1986年 | 12篇 |
1985年 | 14篇 |
1984年 | 5篇 |
1983年 | 14篇 |
1982年 | 11篇 |
1981年 | 7篇 |
1979年 | 5篇 |
1975年 | 5篇 |
1964年 | 3篇 |
1963年 | 4篇 |
1959年 | 7篇 |
1958年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
André M. Eberle 《International Journal of Parallel, Emergent and Distributed Systems》2016,31(5):405-419
Traditionally, computer programs have been developed using the sequential programming paradigm. With the advent of parallel computing systems, such as multicore processors and distributed environments, the sequential paradigm became a barrier to the utilisation of the available resources, since the program is restricted to a single processing unit. To address this issue, we propose a transparent automatic parallelisation tool with a binary rewriter. The steps of our approach are: the disassembly of the Intel x86 application, its transformation into an intermediary language; the analysis of this intermediary representation to obtain the flow and dependency graphs; the partitioning of the application into parallel units, using the obtained graphs; and, finally, the reassembly of the application back into the original Intel x86 architecture. By transforming the compiled application software, we aim at obtaining a program which can better explore the parallel resources, with no extra effort required from users or developers. 相似文献
72.
The train stop control is a typical set‐point control task, where only the final state (i.e., the terminal train stop position) is of concern and specified. For such a control problem, an optimal terminal iterative learning control (TILC) approach is presented in this paper, where the stopping position and initial braking speed are chosen as the terminal system output and the control input, respectively. The controller design only depends on the measured input/output (I/O) data without requiring any modeling information of the train operation system, and the learning gain is updated by the system I/O data iteratively to accommodate the system uncertainties. The monotonic convergence of the terminal tracking error is guaranteed by rigorous mathematical analysis. Extensive simulation results are provided to show the applicability and effectiveness of the proposed approach. 相似文献
73.
Ontologies are structures, used for knowledge representation, which model domain knowledge in the form of concepts, roles, instances and their relationships. This knowledge can be exploited by an assessment system in the form of multiple choice questions (MCQs). The existing approaches, which use ontologies expressed in the Web Ontology Language (OWL) for MCQ generation, are limited to simple concept related questions — “What is C?” or “Which of the following is an example of C?” (where is a concept symbol) — or analogy type questions involving roles. There are no efforts in the literature which make use of the terminological axioms in the ontology such as existential, universal and cardinality restrictions on concepts and roles for MCQ generation. Also, there are no systematic methods for generating incorrect answers (distractors) from ontologies. Distractor generation process has to be given much importance, since the generated distractors determine the quality and hardness of an MCQ. We propose two new MCQ generation approaches, which generate MCQs that are very useful and realistic in conducting assessment tests, and the corresponding distractor generating techniques. Our distractor generation techniques, unlike other methods, consider the open-world assumption, so that the generated MCQs will always be valid (falsity of distractors is ensured). Furthermore, we present a measure to determine the difficulty level (a value between 0 and 1) of the generated MCQs. The proposed system is implemented, and experiments on specific ontologies have shown the effectiveness of the approaches. We also did an empirical study by generating question items from a real-world ontology and validated our results with the help of domain experts. 相似文献
74.
为准确给出移动干扰源的位置与速度,依据多普勒频移原理分别计算了干扰源经主星、邻星链路到达观测站的频率,并由此给出了频率差(FDOA)与时间差(TDOA)表达式,利用FDOA、TDOA表达式以及移动干扰源的位置关系建立了移动干扰源双星定位模型。利用最小二乘法给出了模型计算方法与步骤,最后通过实例计算验证了模型的有效性。 相似文献
75.
Kuo‐Chung Huang Yi‐Heng Chou Lang‐chin Lin Hoang Yan Lin Fu‐Hao Chen Ching‐Chiu Liao Yi‐Han Chen Kuen Lee Wan‐Hsuan Hsu 《Journal of the Society for Information Display》2013,21(6):263-270
The optimal viewing distance was proposed as a parameter for designing a parallax barrier 3D display. It can be designed based on simple geometric method and by considering the pitches of image display pixels and parallax barrier, or even including the aperture ratios of the image display pixels and parallax barrier. It can be analyzed by using ray tracing method. By considering the optical refraction index of the cover glass, the angular behavior of the system becomes more realistic; however, the geometric method is difficult to be used. We propose a revised method for estimating the view distance and angular behavior. In this paper, we have demonstrated a designated eye position (DEP) for each view and shown that multiple DEPs make a circular curve around the center of the display. We prove the new concept by comparing the optical ray tracing calculations and optical measurement. 相似文献
76.
结合杭州市清泰水厂净水技术改造工程,介绍了膜处理自控系统的特点和要求,就三个膜处理自控系统方案进行了分析和总结。通过对比,选用了方案三,该方案实现了每一膜组的冗余热备控制,较好地达到了设计要求,可靠性高。 相似文献
77.
针对具有霍尔传感器的无刷直流电动机,以dsPIC30F3010为核心控制芯片,绘制出系统的总体设计框图,同时采用空间矢量调制法生成六路SVPWM信号,从而实现无刷直流电机的正弦波驱动.实验结果表明采用空间矢量脉宽调制法,可以实现正弦波驱动无刷直流电机的平稳运行. 相似文献
78.
目前,很多蜂拥控制算法都是基于智能体通信半径为一个固定的值且既考虑多智能体之间的相对位置,又考虑它们的相对速度来设计的,然而,实际的情况往往不会有那么理想。文中试图在基于通信半径不同的混合多智能体控制策略的设计过程中减少考虑的控制因素的个数(只考虑位置信息),提出一种分布式的控制算法。此控制算法能实现多智能体跟随一个速度固定的虚拟领航者,形成聚合、无碰撞的队列。给出了算法的可行性理论分析,并针对20个智能体跟踪一个速度固定的虚拟领导者的情形给出了计算机仿真,用以验证算法的可行性。 相似文献
79.
80.
在蚕种生产中引进白控系统,以改善老式蚕种培育方法效率低的问题。文中详细的介绍了自控系统的整体架构和蚕种生产的工艺流程,并就系统的安全性采取了远程/就地控制和冗余设计。系统通过上位机组态和网络发布,使操作人员和管理者能对生产现场状态进行实时监控和管理。 相似文献