全文获取类型
收费全文 | 12059篇 |
免费 | 1272篇 |
国内免费 | 1126篇 |
专业分类
电工技术 | 776篇 |
技术理论 | 4篇 |
综合类 | 1765篇 |
化学工业 | 304篇 |
金属工艺 | 250篇 |
机械仪表 | 912篇 |
建筑科学 | 1127篇 |
矿业工程 | 193篇 |
能源动力 | 272篇 |
轻工业 | 332篇 |
水利工程 | 143篇 |
石油天然气 | 257篇 |
武器工业 | 96篇 |
无线电 | 822篇 |
一般工业技术 | 817篇 |
冶金工业 | 698篇 |
原子能技术 | 52篇 |
自动化技术 | 5637篇 |
出版年
2024年 | 107篇 |
2023年 | 243篇 |
2022年 | 420篇 |
2021年 | 392篇 |
2020年 | 363篇 |
2019年 | 293篇 |
2018年 | 241篇 |
2017年 | 253篇 |
2016年 | 349篇 |
2015年 | 346篇 |
2014年 | 617篇 |
2013年 | 689篇 |
2012年 | 724篇 |
2011年 | 754篇 |
2010年 | 709篇 |
2009年 | 742篇 |
2008年 | 744篇 |
2007年 | 887篇 |
2006年 | 840篇 |
2005年 | 717篇 |
2004年 | 688篇 |
2003年 | 588篇 |
2002年 | 490篇 |
2001年 | 408篇 |
2000年 | 356篇 |
1999年 | 315篇 |
1998年 | 185篇 |
1997年 | 123篇 |
1996年 | 124篇 |
1995年 | 146篇 |
1994年 | 120篇 |
1993年 | 96篇 |
1992年 | 74篇 |
1991年 | 63篇 |
1990年 | 46篇 |
1989年 | 58篇 |
1988年 | 39篇 |
1987年 | 18篇 |
1986年 | 16篇 |
1985年 | 13篇 |
1984年 | 7篇 |
1980年 | 3篇 |
1979年 | 5篇 |
1968年 | 3篇 |
1966年 | 3篇 |
1965年 | 3篇 |
1963年 | 4篇 |
1962年 | 4篇 |
1960年 | 3篇 |
1958年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
Segmenting the heart in medical images is a challenging and important task for many applications. In particular, segmenting the heart in CT images is very useful for cardiology and oncological applications such as radiotherapy. Although the majority of methods in the literature are designed for ventricle segmentation, there is a real interest in segmenting the heart as a whole in this modality. In this paper, we address this problem and propose an automatic and robust method, based on anatomical knowledge about the heart, in particular its position with respect to the lungs. This knowledge is represented in a fuzzy formalism and it is used both to define a region of interest and to drive the evolution of a deformable model in order to segment the heart inside this region. The proposed method has been applied on non-contrast CT images and the obtained results have been compared to manual segmentations of the heart, showing the good accuracy and high robustness of our approach. 相似文献
12.
Jen‐te Yu 《Asian journal of control》2009,11(1):1-10
A new Coulomb friction compensator is proposed for servo control systems in this paper. The novelty of the new approach lies in its capability of assigning the eigenvalues of the resulting closed loop system while attacking the problem. First, based on the standard backstepping methodology, an implicit Lyapunov function, with part of the components being only symbolically constructed at the very beginning, is utilized. To increase the robustness of the system against disturbance and model inaccuracy, an integral term is employed in the design. Using part of the variable gradient method, we are able to turn the implicit Lyapunov function into an explicit one, which is positive definite, and whose time‐derivative is negative definite. Second, it will be shown that the resulting closed loop error system is a switched linear system with two possible active modes that share the same set of eigenvalues, which is at our disposal. Unlike the common adaptive control design methods, such as the Control Lyapunov Function approach, in which the gains are typically positive but otherwise arbitrary, and are hence difficult to choose and have a lack of connection with the system's performance, our new scheme imposes two further constraints on the gains. It turns out that we can then match these gains with the coefficients of the desired characteristic equation of the closed loop system. In this respect, the gains are linked to the system's overall performance, which is a new and very appealing feature for such a scheme. Finally, a procedure of constructing a common Lyapunov function is provided to prove exponential stability of the aforementioned switched linear system. In addition, using the invariance principle, we will show the convergence of the estimated Coulomb friction coefficient to its real value. Numerical simulations are given to validate the effectiveness of the design and its robustness against friction time‐variations. Compared to existing results, the proposed scheme is much simpler, hence, much more advantageous computationally. Copyright © 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society 相似文献
13.
14.
Although Berman and Hafner [Berman 1989, pp. 928–938] presented the possibility to adapt the model of reasoning of development of an expert system for medical diagnosis to the reasoning of a judge when he/she sentences criminals does not resemble the reasoning found in the decisions of physicians, mathematicians or statisticians.When a lawyer reasons, he/she not only looks for the solution of a case; he/she simultaneously looks for the bases on which his/her reasoning can rest [Galindo 1992, pp. 363–367]. That is to say, he/she not only needs to find the solution but moreover he/she has to find the references (laws, jurisprudence and bibliography) that allow him/her to argue the solution.In many cases, computer solutions to these reasoning processes have been made in a separated way: the solution to the cases using expert systems, and the search of documentation using information retrieval systems.This paper presents the ARPO-2 prototype, a solution integrating the two aspects of legal reasoning: an expert system which is able to simultaneously find the solution to a problem and to give the necessary references so that the lawyer argues the solution. The subject on which the prototype solves problems is the breach of building contracts.In this paper, we describe the process of development of an expert system for solving, justification and documentation of breach of contracts, giving details on the way how the objects that intervene in the case were defined as well as on the reasoning followed.This paper was funded in part by DGICYT, Spanish Civil Law Computerization Project: PB870-632. 相似文献
15.
针对我校信息对抗技术专业的发展方向和培养定位,结合我校办学特色,提出该专业的知识体系和实践教学体系。通过对当前现状和存在问题的分析,研究探讨符合实际的专业教学和人才培养模式。 相似文献
16.
Abstract: Enterprise production is becoming more and more knowledge oriented nowadays and knowledge management is playing a key role in making commercial profit and maintaining enterprise competence. Knowledge characterization and measurement are the bases of knowledge management, and this paper aims to develop a method for characterizing and measuring knowledge in a comprehensive and practical way. Knowledge in its static state is modelled as a vector, whose values vary with the situation, and changes in state are modelled as a finite state machine. 相似文献
17.
It is argued that robotic platforms are the way forward towards building intelligent systems, where multiple sensors and manipulation are used for cognitive processes. It is also argued that the cue for developing the right architecture for such a system is human language. 相似文献
18.
机械基础课因其内容通俗、知识面覆盖广的特点,对此本文通过多年来的教学实践,在如何有效组织本课程的教学,提高教学质量和教学效果,既能使学生轻松而又系统地掌握知识点,又能激发学生主动学习机械类相关专业知识的积极性进行了深入探索和实践,从而确定了较为合理的教学手段和方法。 相似文献
19.
利用单向导粗集((one direction singular rough sets)与它的动态特性,给出F-阶梯知识、F-阶梯度的概念。利
用这些概念,提出F-阶梯知识分辩定理、最小F-阶梯知识挖据发现定理、最大F-阶梯知识挖掘一发现定理、知识发现
依赖一筛选定理与F-阶梯知识内潜藏原理,给出F-阶梯知识挖掘一发现准则及应用。这些结果是单向导粗集的新特性
与单向导粗集的动态特性的新应用。 相似文献
20.
全面分析了目前知识处理系统所存在的弊病,提出了下一代语义激活系统,探讨了新一代知识系统所应提供的服务;并将之运用于图形处理系统,阐明了图形数据从统一表示到有效存储、建模、再现和检索等一系列智能处理过程;进而提出了图形信息的语义表示和智能推理模型. 相似文献