全文获取类型
收费全文 | 90590篇 |
免费 | 8703篇 |
国内免费 | 4833篇 |
专业分类
电工技术 | 6075篇 |
技术理论 | 4篇 |
综合类 | 6542篇 |
化学工业 | 14209篇 |
金属工艺 | 5161篇 |
机械仪表 | 6219篇 |
建筑科学 | 8049篇 |
矿业工程 | 2693篇 |
能源动力 | 2446篇 |
轻工业 | 6657篇 |
水利工程 | 1913篇 |
石油天然气 | 4428篇 |
武器工业 | 843篇 |
无线电 | 11184篇 |
一般工业技术 | 10174篇 |
冶金工业 | 3860篇 |
原子能技术 | 1097篇 |
自动化技术 | 12572篇 |
出版年
2024年 | 442篇 |
2023年 | 1684篇 |
2022年 | 3217篇 |
2021年 | 4325篇 |
2020年 | 3234篇 |
2019年 | 2591篇 |
2018年 | 2725篇 |
2017年 | 3202篇 |
2016年 | 2875篇 |
2015年 | 4006篇 |
2014年 | 4996篇 |
2013年 | 5869篇 |
2012年 | 6356篇 |
2011年 | 6965篇 |
2010年 | 6224篇 |
2009年 | 6007篇 |
2008年 | 5769篇 |
2007年 | 5196篇 |
2006年 | 4840篇 |
2005年 | 3972篇 |
2004年 | 2581篇 |
2003年 | 2174篇 |
2002年 | 2083篇 |
2001年 | 1890篇 |
2000年 | 1640篇 |
1999年 | 1664篇 |
1998年 | 1277篇 |
1997年 | 1123篇 |
1996年 | 1078篇 |
1995年 | 928篇 |
1994年 | 753篇 |
1993年 | 560篇 |
1992年 | 394篇 |
1991年 | 327篇 |
1990年 | 229篇 |
1989年 | 198篇 |
1988年 | 159篇 |
1987年 | 102篇 |
1986年 | 86篇 |
1985年 | 55篇 |
1984年 | 36篇 |
1983年 | 41篇 |
1982年 | 32篇 |
1981年 | 24篇 |
1980年 | 31篇 |
1979年 | 21篇 |
1962年 | 42篇 |
1961年 | 39篇 |
1960年 | 16篇 |
1951年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
基于蚁群算法的网格资源发现模型研究 总被引:1,自引:0,他引:1
本文通过对传统的网格资源发现存在的问题进行分析,针对其不足,引入蚁群算法,提出基于蚁群算法的网格资源发现模型(AA_GRRM),设计并分析AA_GRRM的体系结构,并对其关键模块分析设计,以提高网格资源发现效率。 相似文献
102.
Jun Liang Long Chen Xian-yi Cheng Xian-bo Chen 《Simulation Modelling Practice and Theory》2010,18(8):1092-1103
Distance-between-vehicle-measurement is the only factor in traditional car rear-end alarm system. To address the above problem, this paper proposes an alarming model based on multi-agent systems (MAS) and driving behavior. It consists of four different types of agents that can either work alone or collaborate through a communications protocol on the basis of the extended KQML. The rear-end alarming algorithm applies the Bayes decision theory to calculate the probability of collision and prevent its occurrence real-time. The learning algorithm of driving behavior based on ensemble artificial neural network (ANN) and the decision procedure based on Bayes’ theory are also described in this paper. Both autonomy and reliability are enhanced in the proposed system. The effectiveness and robustness of the model have been confirmed by the simulated experiments. 相似文献
103.
Partner selection is a major issue in the formation of a virtual enterprise. In practice, in the partner selection process, the information about the candidates and their performances are incomplete and uncertain. Vague sets theory is one of the methods used to deal with uncertain information. In this paper, a new method based on vague sets is proposed to deal with the partner selection problem in the formation of a virtual enterprise while the factors of satisfaction degree, due date, cost and the precedence of tasks are taken into account. On the basis of the agreement index of satisfaction degree, the formulated partner selection problems are interpreted so as to maximize the minimum agreement index. To solve the problem, an improved particle swarm optimization (PSO) algorithm is proposed. Finally, the simulation of a numerical example demonstrates that the method is effective. 相似文献
104.
In this paper, we consider the following nonlinear fractional three-point boundary value problem
105.
Lei Ye Zhijun Wang Hao Che Henry B.C. Chan Constantino M. Lagoa 《Computer Communications》2009,32(5):800-805
Understanding the TCP congestion control mechanism from a global optimization point of view is not only important in its own right, but also crucial to the design of other transport layer traffic control protocols with provable properties. In this paper, we derive a global utility function and the corresponding optimal control law, known as TCP control law, which maximizes the global utility. The TCP control law captures the essential behaviors of TCP, including slow start, congestion avoidance, and the binary nature of congestion feedback in TCP. We find that the utility function of TCP is linear in the slow start phase and is proportional to the additive increase rate and approaches the well-known logarithm function as the data rate becomes large in the congestion avoidance phase. We also find that understanding the slow start phase with a fixed threshold is critical to the design of new transport layer control protocols to enable quality of service features. Finally, as an application, we design a Minimum Rate Guaranteed (MRG) traffic control law that shares the same utility function as the TCP control law. Our simulation study of the MRG control law indicates that it is indeed TCP friendly and can provide minimum rate guarantee as long as the percentage of network resource consumed by the MRG flows is moderately small. 相似文献
106.
Since color recording and color representing abilities of various media are very different, color information is often lost or misrepresented in the process of image transmission and reproduction. A Color Management System (CMS) based on iCAM color appearance model is presented in this paper. It can be used either in computer operation system software or application software for obtaining color consistency across different software applications, imaging devices, imaging media and viewing conditions. 相似文献
107.
Liming Lee Kit Ian Kou Wentao Zhang Jinling Liang 《International journal of systems science》2016,47(10):2466-2474
In this paper, we consider finite-time control problems for linear multi-agent systems subject to exogenous constant disturbances and impulses. Some sufficient conditions are obtained to ensure the finite-time boundedness of the multi-agent systems, which could be then reduced to a feasibility problem involving linear matrix inequalities. Numerical examples are given to illustrate the results. 相似文献
108.
109.
Hu Changhui Lu Xiaobo Ye Mengjun Zeng Weili Du Yijun 《Multimedia Tools and Applications》2017,76(24):26523-26550
Multimedia Tools and Applications - The extended sparse representation classifier (ESRC) is one of the state-of-the-art solutions for single sample face recognition, but it performs... 相似文献
110.
多元分析法在沉淀滴定中的应用 总被引:1,自引:0,他引:1
将多元分析法应用于沉淀滴定之中 ,提出固定电位的方法 ,建立了沉淀滴定中各组分浓度与体积之间关系的数学模型 ,对卤素和硫氰酸盐混合体系进行了测定。 相似文献