全文获取类型
收费全文 | 122541篇 |
免费 | 12215篇 |
国内免费 | 7704篇 |
专业分类
电工技术 | 9459篇 |
技术理论 | 5篇 |
综合类 | 10271篇 |
化学工业 | 18012篇 |
金属工艺 | 7620篇 |
机械仪表 | 7867篇 |
建筑科学 | 9811篇 |
矿业工程 | 3684篇 |
能源动力 | 3831篇 |
轻工业 | 8829篇 |
水利工程 | 2903篇 |
石油天然气 | 5944篇 |
武器工业 | 1366篇 |
无线电 | 14424篇 |
一般工业技术 | 12890篇 |
冶金工业 | 5435篇 |
原子能技术 | 1598篇 |
自动化技术 | 18511篇 |
出版年
2024年 | 531篇 |
2023年 | 1805篇 |
2022年 | 3441篇 |
2021年 | 4873篇 |
2020年 | 3732篇 |
2019年 | 3190篇 |
2018年 | 3403篇 |
2017年 | 3971篇 |
2016年 | 3592篇 |
2015年 | 5051篇 |
2014年 | 6321篇 |
2013年 | 7307篇 |
2012年 | 8678篇 |
2011年 | 9068篇 |
2010年 | 8598篇 |
2009年 | 8150篇 |
2008年 | 7998篇 |
2007年 | 7549篇 |
2006年 | 7069篇 |
2005年 | 5808篇 |
2004年 | 4714篇 |
2003年 | 4985篇 |
2002年 | 5966篇 |
2001年 | 5075篇 |
2000年 | 2920篇 |
1999年 | 2183篇 |
1998年 | 1234篇 |
1997年 | 1108篇 |
1996年 | 989篇 |
1995年 | 782篇 |
1994年 | 620篇 |
1993年 | 418篇 |
1992年 | 335篇 |
1991年 | 224篇 |
1990年 | 192篇 |
1989年 | 147篇 |
1988年 | 107篇 |
1987年 | 72篇 |
1986年 | 61篇 |
1985年 | 38篇 |
1984年 | 35篇 |
1983年 | 27篇 |
1982年 | 20篇 |
1981年 | 18篇 |
1980年 | 21篇 |
1979年 | 10篇 |
1978年 | 2篇 |
1975年 | 3篇 |
1959年 | 10篇 |
1951年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 8 毫秒
991.
992.
基于SIP家庭网关和Web Service的智能家居系统 总被引:1,自引:0,他引:1
提出了一种将 SIP 家庭网关技术和 Web Service 技术相结合的智能家居系统的设计和实现方案,详细介绍了系统各功能模块,给出了在 PDA 上调用基于 SIP 家庭网关的 Web 服务来监控家中各电器状态的实现结果。该技术可以向用户提供智能家居管理、远程监控等具体服务。 相似文献
993.
Emergency medical service (EMS) providers continually seek ways to improve system performance particularly the response time to incidents. The demand for ambulances fluctuate throughout the week, depending on the day of week, and even the time of day, therefore EMS operators can improve system performance by dynamic relocation/redeployment of ambulances in response to fluctuating demand patters. The objective of the model is to determine the minimum number of ambulances and their locations for each time cluster in which significant changes in demand pattern occur while meeting coverage requirement with a predetermined reliability. The model is further enhanced by calculating ambulance specific busy probabilities and validated by a comprehensive simulation model. Computational results on experimental data sets and data from an EMS agency are provided. 相似文献
994.
The job shop scheduling problem (JSP) is one of the most notoriously intractable NP-complete optimization problems. Over the last 10–15 years, tabu search (TS) has emerged as an effective algorithmic approach for the JSP. However, the quality of solutions found by tabu search approach depends on the initial solution. To overcome this problem and provide a robust and efficient methodology for the JSP, the heuristics search approach combining simulated annealing (SA) and TS strategy is developed. The main principle of this approach is that SA is used to find the elite solutions inside big valley (BV) so that TS can re-intensify search from the promising solutions. This hybrid algorithm is tested on the standard benchmark sets and compared with the other approaches. The computational results show that the proposed algorithm could obtain the high-quality solutions within reasonable computing times. For example, 17 new upper bounds among the unsolved problems are found in a short time. 相似文献
995.
996.
In this paper, a new algorithm, named VICUR, is presented for curve reconstruction problem. From a set of unorganized points, the proposed algorithm can construct curves that look natural to human vision. The VICUR algorithm is based on two connectivity criteria: proximity and good continuation from the prominent Gestalt principles of perception. Experimental results are presented to show the effectiveness of VICUR. 相似文献
997.
998.
Scalability is a key factor of the design of distributed systems and parallel algorithms and machines. However, conventional scalabilities are designed for homogeneous parallel processing. There is no suitable and commonly accepted definition of scalability metric for heterogeneous systems. Isospeed scalability is a well-defined metric for homogeneous computing. This study extends the isospeed scalability metric to general heterogeneous computing systems. The proposed isospeed-efficiency model is suitable for both homogeneous and heterogeneous computing. Through theoretical analyses, we derive methodologies of scalability measurement and prediction for heterogeneous systems. Experimental results have verified the analytical results and confirmed that the proposed isospeed-efficiency scalability works well in both homogeneous and heterogeneous environments. 相似文献
999.
The eigenvector associated with the smallest eigenvalue of the autocorrelation matrix of input signals is called minor component. Minor component analysis (MCA) is a statistical approach for extracting minor component from input signals and has been applied in many fields of signal processing and data analysis. In this letter, we propose a neural networks learning algorithm for estimating adaptively minor component from input signals. Dynamics of the proposed algorithm are analyzed via a deterministic discrete time (DDT) method. Some sufficient conditions are obtained to guarantee convergence of the proposed algorithm. 相似文献
1000.
Xiaoyu Wang Wen Wang Yong Huang Nhan Nguyen Kalmanje Krishnakumar 《Journal of Intelligent Manufacturing》2008,19(4):383-396
Hard turning with cubic boron nitride (CBN) tools has been proven to be more effective and efficient than traditional grinding
operations in machining hardened steels. However, rapid tool wear is still one of the major hurdles affecting the wide implementation
of hard turning in industry. Better prediction of the CBN tool wear progression helps to optimize cutting conditions and/or
tool geometry to reduce tool wear, which further helps to make hard turning a viable technology. The objective of this study
is to design a novel but simple neural network-based generalized optimal estimator for CBN tool wear prediction in hard turning.
The proposed estimator is based on a fully forward connected neural network with cutting conditions and machining time as
the inputs and tool flank wear as the output. Extended Kalman filter algorithm is utilized as the network training algorithm
to speed up the learning convergence. Network neuron connection is optimized using a destructive optimization algorithm. Besides
performance comparisons with the CBN tool wear measurements in hard turning, the proposed tool wear estimator is also evaluated
against a multilayer perceptron neural network modeling approach and/or an analytical modeling approach, and it has been proven
to be faster, more accurate, and more robust. Although this neural network-based estimator is designed for CBN tool wear modeling
in this study, it is expected to be applicable to other tool wear modeling applications. 相似文献