全文获取类型
收费全文 | 172921篇 |
免费 | 14727篇 |
国内免费 | 11457篇 |
专业分类
电工技术 | 29415篇 |
技术理论 | 7篇 |
综合类 | 16283篇 |
化学工业 | 9038篇 |
金属工艺 | 6607篇 |
机械仪表 | 15983篇 |
建筑科学 | 14891篇 |
矿业工程 | 7020篇 |
能源动力 | 4698篇 |
轻工业 | 4583篇 |
水利工程 | 5434篇 |
石油天然气 | 5607篇 |
武器工业 | 2643篇 |
无线电 | 12996篇 |
一般工业技术 | 7981篇 |
冶金工业 | 7818篇 |
原子能技术 | 1191篇 |
自动化技术 | 46910篇 |
出版年
2024年 | 721篇 |
2023年 | 1945篇 |
2022年 | 3137篇 |
2021年 | 3911篇 |
2020年 | 4730篇 |
2019年 | 3726篇 |
2018年 | 3316篇 |
2017年 | 4872篇 |
2016年 | 5419篇 |
2015年 | 5998篇 |
2014年 | 11533篇 |
2013年 | 9915篇 |
2012年 | 12551篇 |
2011年 | 13478篇 |
2010年 | 10186篇 |
2009年 | 10485篇 |
2008年 | 10457篇 |
2007年 | 12905篇 |
2006年 | 11561篇 |
2005年 | 10103篇 |
2004年 | 8374篇 |
2003年 | 7400篇 |
2002年 | 5925篇 |
2001年 | 4912篇 |
2000年 | 4238篇 |
1999年 | 3407篇 |
1998年 | 2605篇 |
1997年 | 2307篇 |
1996年 | 1833篇 |
1995年 | 1489篇 |
1994年 | 1271篇 |
1993年 | 911篇 |
1992年 | 730篇 |
1991年 | 550篇 |
1990年 | 417篇 |
1989年 | 368篇 |
1988年 | 261篇 |
1987年 | 156篇 |
1986年 | 112篇 |
1985年 | 109篇 |
1984年 | 154篇 |
1983年 | 118篇 |
1982年 | 113篇 |
1981年 | 79篇 |
1980年 | 53篇 |
1979年 | 64篇 |
1978年 | 48篇 |
1977年 | 48篇 |
1964年 | 13篇 |
1959年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Statistical process control (SPC) is a conventional means of monitoring software processes and detecting related problems,
where the causes of detected problems can be identified using causal analysis. Determining the actual causes of reported problems
requires significant effort due to the large number of possible causes. This study presents an approach to detect problems
and identify the causes of problems using multivariate SPC. This proposed method can be applied to monitor multiple measures
of software process simultaneously. The measures which are detected as the major impacts to the out-of-control signals can
be used to identify the causes where the partial least squares (PLS) and statistical hypothesis testing are utilized to validate
the identified causes of problems in this study. The main advantage of the proposed approach is that the correlated indices
can be monitored simultaneously to facilitate the causal analysis of a software process.
Ching-Pao Chang is a PhD candidate in Computer Science & Information Engineering at the National Cheng-Kung University, Taiwan. He received his MA from the University of Southern California in 1998 in Computer Science. His current work deals with the software process improvement and defect prevention using machine learning techniques. Chih-Ping Chu is Professor of Software Engineering in Department of Computer Science & Information Engineering at the National Cheng-Kung University (NCKU) in Taiwan. He received his MA in Computer Science from the University of California, Riverside in 1987, and his Doctorate in Computer Science from Louisiana State University in 1991. He is especially interested in parallel computing and software engineering. 相似文献
Chih-Ping ChuEmail: |
Ching-Pao Chang is a PhD candidate in Computer Science & Information Engineering at the National Cheng-Kung University, Taiwan. He received his MA from the University of Southern California in 1998 in Computer Science. His current work deals with the software process improvement and defect prevention using machine learning techniques. Chih-Ping Chu is Professor of Software Engineering in Department of Computer Science & Information Engineering at the National Cheng-Kung University (NCKU) in Taiwan. He received his MA in Computer Science from the University of California, Riverside in 1987, and his Doctorate in Computer Science from Louisiana State University in 1991. He is especially interested in parallel computing and software engineering. 相似文献
992.
This paper investigates an intelligent adaptive control system for multiple-input–multiple-output (MIMO) uncertain nonlinear systems. This control system is comprised of a recurrent-cerebellar-model-articulation-controller (RCMAC) and an auxiliary compensation controller. RCMAC is utilized to approximate a perfect controller, and the parameters of RCMAC are on-line tuned by the derived adaptive laws based on a Lyapunov function. The auxiliary compensation controller is designed to suppress the influence of residual approximation error between the perfect controller and RCMAC. Finally, two MIMO uncertain nonlinear systems, a mass–spring–damper mechanical system and a Chua’s chaotic circuit, are performed to verify the effectiveness of the proposed control scheme. The simulation results confirm that the proposed intelligent adaptive control system can achieve favorable tracking performance with desired robustness. 相似文献
993.
Design of variable structure control for fuzzy nonlinear systems 总被引:1,自引:0,他引:1
In this paper, the variable structure control problem is presented for Takagi–Sugeno fuzzy systems with uncertainties and external disturbances. The sliding surfaces for the T–S fuzzy system are proposed by using a Lyapunov function and a fuzzy Lyapunov function, respectively. And we design the variable structure controllers such that the global T–S fuzzy system confined on the sliding surfaces is asymptotically stable. Two examples are given to illustrate the effectiveness of our proposed methods. 相似文献
994.
Chun-Liang Lin Chun-Hsiung Chen Bing-Min Shiu 《Journal of Intelligent Manufacturing》2008,19(4):407-419
In practical electro-pneumatic or hydraulic servo mechanism, there is usually an unavoidable operating delay time in the solenoid
valves. This may sometimes cause closed-loop instability if the time delay is not treated carefully in the control system
designs. Furthermore, pneumatic actuators can offer high performance at low cost, but are often suffered from external disturbances
depending on the operating conditions. This paper proposes a non-model-based design approach for pneumatic actuating systems.
In the proposed control system, a gain scheduled fuzzy-PID controller ensures tracking performance an adaptable wavelet neuro
compensator compensates for time-delay of the control valve, and a disturbance rejecter diminishes influence from load changes.
A condition ensuring the closed-loop stability is derived. The proposed design is experimentally verified to show its effectiveness. 相似文献
995.
In the present and next generation wireless networks, cellular system remains the major method of telecommunication infrastructure. Since the characteristic of the resource constraint, call admission control is required to address the limited resource problem in wireless network. The call dropping probability and call blocking probability are the major performance metrics for quality of service (QoS) in wireless network. Many call admission control mechanisms have been proposed in the literature to decrease connection dropping probability for handoffs and new call blocking probability in cellular communications. In this paper, we proposed an adaptive call admission control and bandwidth reservation scheme using fuzzy logic control concept to reduce the forced termination probability of multimedia handoffs. Meanwhile, we adopt particle swarm optimization (PSO) technique to adjust the parameters of the membership functions in the proposed fuzzy logic systems. The simulation results show that the proposed scheme can achieve satisfactory performance when performance metrics are measured in terms of the forced termination probability for the handoffs, the call blocking probability for the new connections and bandwidth utilization. 相似文献
996.
在无线传感器网络的拓扑控制(TC)中,基于Cell的TC算法被认为是一类可以节省传感器节点能量并延长网络生命周期的方法,但是其需要较多的骨干网节点并且无法保证连通性.通过分析现今算法的内在局限性,提出了一种1-Con思想:当一个Cell的头节点被加入当前骨干网时,所有其可以连接的Cell使用该节点连入拓扑结构,然后此新骨干网递归地继续扩大.基于此思想,设计了一种基于可连Cell的拓扑控制算(CCTC),并从理论上证明:1)CCTC可以保证其所形成的拓扑结构维持网络连通;2)每一轮用于形成骨干网的工作节点非常少.CCTC的计算复杂度是线性的,空间复杂度和信息交换量都是常数量级.仿真实验同样显示,CCTC可以在提供良好鲁棒性和较少的消息交换的情况下,更有效地节省节点能耗并延长网络生命周期. 相似文献
997.
Sampled-data based average consensus with measurement noises: convergence analysis and uncertainty principle 总被引:1,自引:0,他引:1
In this paper, sampled-data based average-consensus control is considered for networks consisting of continuous-time first-order
integrator agents in a noisy distributed communication environment. The impact of the sampling size and the number of network
nodes on the system performances is analyzed. The control input of each agent can only use information measured at the sampling
instants from its neighborhood rather than the complete continuous process, and the measurements of its neighbors’ states
are corrupted by random noises. By probability limit theory and the property of graph Laplacian matrix, it is shown that for
a connected network, the static mean square error between the individual state and the average of the initial states of all
agents can be made arbitrarily small, provided the sampling size is sufficiently small. Furthermore, by properly choosing
the consensus gains, almost sure consensus can be achieved. It is worth pointing out that an uncertainty principle of Gaussian
networks is obtained, which implies that in the case of white Gaussian noises, no matter what the sampling size is, the product
of the steady-state and transient performance indices is always equal to or larger than a constant depending on the noise
intensity, network topology and the number of network nodes. 相似文献
998.
Recently, international academic circles advanced a class of new stochastic control models of a geometric Brownian motion
which is an important kind of impulse control models whose cost structure is different from the others before, and it has
a broad applying background and important theoretical significance in financial control and management of investment. This
paper generalizes substantially the above stochastic control models under quite extensive conditions and describes the models
more exactly under more normal theoretical system of stochastic process. By establishing a set of proper variational equations
and proving the existence of its solution, and applying the means of stochastic analysis, this paper proves that the generalized
stochastic control models have optimal controls. Meanwhile, we also analyze the structure of optimal controls carefully. Besides,
we study the solution function of variational equations in a relatively deep-going way, which constitutes the value function
of control models to some extent. Because the analysis methods of this paper are greatly different from those of original
reference, this paper possesses considerable originality to some extent. In addition, this paper gives the strict proof to
the part of original reference which is not fairly well-knit in analyses, and makes analyses and discussions of the model
have the exactitude of mathematical sense.
Supported by the National Natural Science Foundation of China (Grant No. 19671004) 相似文献
999.
电子白板是虚拟教室中的一个重要工具。该文介绍了基于JAVA语言设计的一个电子白板系统,并对电子白板的设计与实现过程当中的各种关键技术进行了讨论。 相似文献
1000.
This paper reports on recent results in a series of the work of the authors on the stability and nonlinear control for general
dynamical systems described by retarded functional differential and difference equations. Both internal and external stability
properties are studied. The corresponding Lyapunov and Razuminkhin characterizations for input-to-state and input-to-output
stabilities are proposed. Necessary and sufficient Lyapunov-like conditions are derived for robust nonlinear stabilization.
In particular, an explicit controller design procedure is developed for a new class of nonlinear time-delay systems. Lastly,
sufficient assumptions, including a small-gain condition, are presented for guaranteeing the input-to-output stability of
coupled systems comprised of retarded functional differential and difference equations. 相似文献