全文获取类型
收费全文 | 7061篇 |
免费 | 258篇 |
国内免费 | 11篇 |
专业分类
电工技术 | 182篇 |
综合类 | 9篇 |
化学工业 | 1711篇 |
金属工艺 | 121篇 |
机械仪表 | 145篇 |
建筑科学 | 251篇 |
矿业工程 | 5篇 |
能源动力 | 253篇 |
轻工业 | 798篇 |
水利工程 | 49篇 |
石油天然气 | 45篇 |
无线电 | 659篇 |
一般工业技术 | 963篇 |
冶金工业 | 1047篇 |
原子能技术 | 58篇 |
自动化技术 | 1034篇 |
出版年
2024年 | 12篇 |
2023年 | 63篇 |
2022年 | 148篇 |
2021年 | 232篇 |
2020年 | 125篇 |
2019年 | 160篇 |
2018年 | 185篇 |
2017年 | 151篇 |
2016年 | 230篇 |
2015年 | 126篇 |
2014年 | 242篇 |
2013年 | 441篇 |
2012年 | 367篇 |
2011年 | 440篇 |
2010年 | 330篇 |
2009年 | 350篇 |
2008年 | 340篇 |
2007年 | 277篇 |
2006年 | 206篇 |
2005年 | 195篇 |
2004年 | 170篇 |
2003年 | 168篇 |
2002年 | 155篇 |
2001年 | 121篇 |
2000年 | 101篇 |
1999年 | 122篇 |
1998年 | 409篇 |
1997年 | 251篇 |
1996年 | 164篇 |
1995年 | 127篇 |
1994年 | 115篇 |
1993年 | 96篇 |
1992年 | 61篇 |
1991年 | 51篇 |
1990年 | 43篇 |
1989年 | 63篇 |
1988年 | 44篇 |
1987年 | 31篇 |
1986年 | 34篇 |
1985年 | 33篇 |
1984年 | 36篇 |
1983年 | 33篇 |
1982年 | 22篇 |
1981年 | 33篇 |
1980年 | 27篇 |
1979年 | 27篇 |
1978年 | 28篇 |
1977年 | 36篇 |
1976年 | 52篇 |
1974年 | 14篇 |
排序方式: 共有7330条查询结果,搜索用时 15 毫秒
91.
In this paper, we introduce the concept of an exoskeleton as a new abstraction of arbitrary shapes that succinctly conveys both the perceptual and the geometric structure of a 3D model. We extract exoskeletons via a principled framework that combines segmentation and shape approximation. Our method starts from a segmentation of the shape into perceptually relevant parts and then constructs the exoskeleton using a novel extension of the Variational Shape Approximation method. Benefits of the exoskeleton abstraction to graphics applications such as simplification and chartification are presented. 相似文献
92.
This paper introduces a method for automatically generating continuous line illustrations, drawings consisting of a single line, from a given input image. Our approach begins by inferring a graph from a set of edges extracted from the image in question and obtaining a path that traverses through all edges of the said graph. The resulting path is then subjected to a series of post‐processing operations to transform it into a continuous line drawing. Moreover, our approach allows us to manipulate the amount of detail portrayed in our line illustrations, which is particularly useful for simplifying the overall illustration while still retaining its most significant features. We also present several experimental results to demonstrate that our approach can automatically synthesize continuous line illustrations comparable to those of some contemporary artists. 相似文献
93.
We prove several decidability and undecidability results for ν-PN, an extension of P/T nets with pure name creation and name management. We give a simple proof of undecidability of reachability, by reducing reachability in nets with inhibitor arcs to it. Thus, the expressive power of ν-PN strictly surpasses that of P/T nets. We encode ν-PN into Petri Data Nets, so that coverability, termination and boundedness are decidable. Moreover, we obtain Ackermann-hardness results for all our decidable decision problems. Then we consider two properties, width-boundedness and depth-boundedness, that factorize boundedness. Width-boundedness has already been proven to be decidable. Here we prove that its complexity is also non-primitive recursive. Then we prove undecidability of depth-boundedness. Finally, we prove that the corresponding “place version” of all the boundedness problems is undecidable for ν-PN. These results carry over to Petri Data Nets. 相似文献
94.
For a connected graph G=(V,E), a subset U⊆V is a disconnected cut if U disconnects G and the subgraph G[U] induced by U is disconnected as well. A cut U is a k-cut if G[U] contains exactly k(≥1) components. More specifically, a k-cut U is a (k,?)-cut if V?U induces a subgraph with exactly ?(≥2) components. The Disconnected Cut problem is to test whether a graph has a disconnected cut and is known to be NP-complete. The problems k-Cut and (k,?)-Cut are to test whether a graph has a k-cut or (k,?)-cut, respectively. By pinpointing a close relationship to graph contractibility problems we show that (k,?)-Cut is in P for k=1 and any fixed constant ?≥2, while it is NP-complete for any fixed pair k,?≥2. We then prove that k-Cut is in P for k=1 and NP-complete for any fixed k≥2. On the other hand, for every fixed integer g≥0, we present an FPT algorithm that solves (k,?)-Cut on graphs of Euler genus at most g when parameterized by k+?. By modifying this algorithm we can also show that k-Cut is in FPT for this graph class when parameterized by k. Finally, we show that Disconnected Cut is solvable in polynomial time for minor-closed classes of graphs excluding some apex graph. 相似文献
95.
96.
A class of artificial neural networks with a two‐layer feedback topology to solve nonlinear discrete dynamic optimization problems is developed. Generalized recurrent neuron models are introduced. A direct method to assign the weights of neural networks is presented. The method is based on Bellmann's Optimality Principle and on the interchange of information which occurs during the synaptic chemical processing among neurons. A comparative analysis of the computational requirements is made. The analysis shows advantages of this approach as compared to the standard dynamic programming algorithm. The technique has been applied to several important optimization problems, such as shortest path and control optimal problems. 相似文献
97.
Codevelopmental learning between human and humanoid robot using a dynamic neural-network model. 总被引:1,自引:0,他引:1
Jun Tani Ryu Nishimoto Jun Namikawa Masato Ito 《IEEE transactions on systems, man, and cybernetics. Part B, Cybernetics》2008,38(1):43-59
This paper examines characteristics of interactive learning between human tutors and a robot having a dynamic neural-network model, which is inspired by human parietal cortex functions. A humanoid robot, with a recurrent neural network that has a hierarchical structure, learns to manipulate objects. Robots learn tasks in repeated self-trials with the assistance of human interaction, which provides physical guidance until the tasks are mastered and learning is consolidated within the neural networks. Experimental results and the analyses showed the following: 1) codevelopmental shaping of task behaviors stems from interactions between the robot and a tutor; 2) dynamic structures for articulating and sequencing of behavior primitives are self-organized in the hierarchically organized network; and 3) such structures can afford both generalization and context dependency in generating skilled behaviors. 相似文献
98.
Makoto Sakamoto Kaoru Kajisa Naoko Tomozoe Takao Ito Hiroshi Furutani Michio Kono Satoshi Ikeda 《Artificial Life and Robotics》2008,13(1):61-64
In 1997, C.R. Dyer and A. Rosenfeld introduced an acceptor on a two-dimensional pattern (or tape), called the pyramid cellular acceptor, and demonstrated that many useful recognition tasks are executed by pyramid cellular acceptors in time proportional to the
logarithm of the diameter of the input. They also introduced a bottom-up pyramid cellular acceptor which is a restricted version of the pyramid cellular acceptor, and proposed some interesting open problems of the bottom-up
pyramid cellular acceptors. On the other hand, we think that the study of threedimensional automata has been meaningful as
the computational model of three-dimensional information processing such as computer vision, robotics, and so forth. In this
paper, we investigate about bottom-up pyramid cellular acceptors with three-dimensional layers, and show their some accepting
powers.
This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January
31–February 2, 2008 相似文献
99.
The authors investigate complete system development using a Java machine aimed at FPGA devices. A new design strategy targets a single FPGA chip, within which the dedicated Java microcontroller-FemtoJava-is synthesized 相似文献
100.
Vivanco F Mas S Darde VM De la Cuesta F Alvarez-Llamas G Barderas MG 《Proteomics. Clinical applications》2007,1(9):1102-1122
The characterization of patients with acute coronary syndromes (ACS) at the molecular and cellular levels provides a novel vision for understanding the pathological and clinical expression of the disease. Recent advances in proteomic technologies permit the evaluation of systematic changes in protein expression in many biological systems and have been extensively applied to cardiovascular diseases (CVD). The cardiovascular system is in permanent intimate contact with blood, making blood-based biomarker discovery a particularly worthwhile approach. Thus, proteomics can potentially yield novel biomarkers reflecting CVD, establish earlier detection strategies, and monitor response to therapy. Here we review the different proteomic strategies used in the study of atherosclerosis and the novel proteins differentially expressed and secreted by atherosclerotic lesions which constitute novel potential biomarkers (HSP-27, Cathepsin D). Special attention is paid to MS-Imaging of atheroma plaque and the generation, for the first time, of 2-D images of lipids, showing the distribution of these molecules in the different areas of the atherosclerotic lesions. In addition new potential biomarkers have been identified in plasma (amyloid A1α, transtherytin), circulating cells (protein profile in monocytes from ACS patients) and individual cells constituents of atheroma plaques (endothelial, VSMC, macrophages) which provide novel insights into vascular pathophysiology. 相似文献