全文获取类型
收费全文 | 13360篇 |
免费 | 1737篇 |
国内免费 | 1782篇 |
专业分类
电工技术 | 1612篇 |
综合类 | 1459篇 |
化学工业 | 189篇 |
金属工艺 | 153篇 |
机械仪表 | 745篇 |
建筑科学 | 315篇 |
矿业工程 | 116篇 |
能源动力 | 166篇 |
轻工业 | 104篇 |
水利工程 | 132篇 |
石油天然气 | 52篇 |
武器工业 | 105篇 |
无线电 | 2466篇 |
一般工业技术 | 1127篇 |
冶金工业 | 313篇 |
原子能技术 | 150篇 |
自动化技术 | 7675篇 |
出版年
2024年 | 51篇 |
2023年 | 250篇 |
2022年 | 343篇 |
2021年 | 415篇 |
2020年 | 493篇 |
2019年 | 507篇 |
2018年 | 502篇 |
2017年 | 617篇 |
2016年 | 661篇 |
2015年 | 643篇 |
2014年 | 900篇 |
2013年 | 1103篇 |
2012年 | 1017篇 |
2011年 | 1056篇 |
2010年 | 771篇 |
2009年 | 835篇 |
2008年 | 879篇 |
2007年 | 899篇 |
2006年 | 708篇 |
2005年 | 695篇 |
2004年 | 574篇 |
2003年 | 480篇 |
2002年 | 362篇 |
2001年 | 333篇 |
2000年 | 286篇 |
1999年 | 209篇 |
1998年 | 181篇 |
1997年 | 179篇 |
1996年 | 122篇 |
1995年 | 137篇 |
1994年 | 116篇 |
1993年 | 117篇 |
1992年 | 81篇 |
1991年 | 71篇 |
1990年 | 65篇 |
1989年 | 33篇 |
1988年 | 16篇 |
1987年 | 19篇 |
1986年 | 11篇 |
1985年 | 21篇 |
1984年 | 17篇 |
1983年 | 29篇 |
1982年 | 17篇 |
1981年 | 7篇 |
1980年 | 8篇 |
1979年 | 7篇 |
1976年 | 5篇 |
1964年 | 5篇 |
1962年 | 3篇 |
1958年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Wood inspection with non-supervised clustering 总被引:9,自引:0,他引:9
Abstract. The appearance of sawn timber has huge natural variations that the human inspector easily compensates for mentally when determining
the types of defects and the grade of each board. However, for automatic wood inspection systems these variations are a major
source for complication. This makes it difficult to use textbook methodologies for visual inspection. These methodologies
generally aim at systems that are trained in a supervised manner with samples of defects and good material, but selecting
and labeling the samples is an error-prone process that limits the accuracy that can be achieved. We present a non-supervised
clustering-based approach for detecting and recognizing defects in lumber boards. A key idea is to employ a self-organizing
map (SOM) for discriminating between sound wood and defects. Human involvement needed for training is minimal. The approach
has been tested with color images of lumber boards, and the achieved false detection and error escape rates are low. The approach
also provides a self-intuitive visual user interface.
Received: 16 December 2000 / Accepted: 8 December 2001
Correspondence to: O. Silvén 相似文献
72.
Qi Gong 《Automatica》2007,43(1):184-189
In this paper we address the practical tracking problem for a class of nonlinear systems by dynamic output feedback control. Unlike most of the existing results where the unmeasurable states in the nonlinear vector field can only grow linearly, we allow higher-order growth of unmeasurable states. The proposed controller makes the tracking error arbitrarily small and demonstrates nice properties such as robustness to disturbances and universal property to reference signals. 相似文献
73.
This paper considers the trajectory tracking problem for uncertain robot manipulators and proposes two adaptive controllers as solutions to this problem. The first controller is derived under the assumption that the manipulator state is measurable, while the second strategy is developed for those applications in which only position measurements are available. The adaptive schemes are very general and computationally efficient since they do not require knowledge of either the mathematical model or the parameter values of the manipulator dynamics, and are implemented without calculation of the robot inverse dynamics or inverse kinematic transformation. It is shown that the control strategies ensure uniform boundedness of all signals in the presence of bounded disturbances, and that the ultimate size of the tracking errors can be made arbitrarily small. Experimental results are presented for a PUMA 560 manipulator and demonstrate that accurate and robust trajectory tracking can be achieved by using the proposed controllers. 相似文献
74.
In this paper, we propose an ID-based non-interactive zero-knowledge proof system based on the 1-out-of-2 noninteractive oblivious transfer protocol. This zero-knowledge proof system is secure against a newly discovered cheating attack. 相似文献
75.
The goal of this article is to provide a construction of a homogeneous Lyapunov function
associated with a system of differential equations
, under the hypotheses: (1)
vanishes at x = 0 and is homogeneous; (2) the zero solution of this system is locally asymptotically stable. Moreover, the Lyapunov function
tends to infinity with x, and belongs to
, with
as large as wanted. As application to the theory of homogeneous systems, we present two well known results of robustness, in a slightly extended form, and with simpler proofs. 相似文献
76.
本文自行设计和制作了1.30μmDFB激光器组件的讨论了光隔离和光耦合原理。由于采用的激光器-光隔离器-光纤的一体化结构,大大增加了该组件的可用性。在实验中得到高达55%的耦合效率。 相似文献
77.
Precise timing and asynchronous I/O are appealing features for many applications. Unix kernels provide such features on a per‐process basis, using signals to communicate asynchronous events to applications. Per‐process signals and timers are grossly inadequate for complex multithreaded applications that require per‐thread signals and timers that operate at finer granularity. To respond to this need, we present a scheme that integrates asynchronous (Unix) signals with user‐level threads, using the ARIADNE system as a platform. This is done with a view towards support for portable, multithreaded, and multiprotocol distributed applications, namely the CLAM (connectionless, lightweight, and multiway) communications library. In the same context, we propose the use of continuations as an efficient mechanism for reducing thread context‐switching and busy‐wait overheads in multithreaded protocols. Our proposal for integrating timers and signal‐handling mechanisms not only solves problems related to race conditions, but also offers an efficient and flexible interface for timing and signalling threads. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
78.
席德明 《核电子学与探测技术》1993,(4)
本文提出了一种电荷灵敏放大器不用反馈高值电阻的新方法。对这种方法作了电路分析以及对实际电路的测量结果作了介绍。 相似文献
79.
A two-stage MMSE multiuser decision feedback detector using successive/parallel interference cancellation 总被引:1,自引:0,他引:1
In this paper, we present a novel two-stage minimum-mean-squared-error (MMSE) multiuser decision feedback detector (DFD) for code division multiple access systems working in the frequency-selective multipath fading environment. The first stage of the proposed cascaded structure is the noise-predictive successive DFD (NP-S-DFD), in which the active users are detected successively using the conventional bell labs layered space-time (BLAST) ordering criterion. The second stage includes an adaptive successive/parallel DFD (SP-DFD), which uses the tentative decisions obtained at the first stage for multiuser interference cancellation and data detection. Therefore, the proposed two-stage DFD may be called noise-predictive successive SP-DFD (NP-S-SP-DFD). Simulation results are presented to demonstrate the substantial improvement in the bit error rate performance of NP-S-SP-DFD over the conventional single-stage and cascaded DFDs. It may be inferred that the proposed DFD provides additional performance gain, when the order in which the users are detected is optimized according to the BLAST ordering based on MMSE criterion. 相似文献
80.