全文获取类型
收费全文 | 32574篇 |
免费 | 4265篇 |
国内免费 | 3229篇 |
专业分类
电工技术 | 4404篇 |
技术理论 | 1篇 |
综合类 | 5608篇 |
化学工业 | 1374篇 |
金属工艺 | 786篇 |
机械仪表 | 3117篇 |
建筑科学 | 1351篇 |
矿业工程 | 1243篇 |
能源动力 | 888篇 |
轻工业 | 1770篇 |
水利工程 | 1006篇 |
石油天然气 | 1200篇 |
武器工业 | 586篇 |
无线电 | 2699篇 |
一般工业技术 | 1695篇 |
冶金工业 | 577篇 |
原子能技术 | 105篇 |
自动化技术 | 11658篇 |
出版年
2024年 | 115篇 |
2023年 | 349篇 |
2022年 | 630篇 |
2021年 | 729篇 |
2020年 | 918篇 |
2019年 | 886篇 |
2018年 | 853篇 |
2017年 | 993篇 |
2016年 | 1166篇 |
2015年 | 1296篇 |
2014年 | 1940篇 |
2013年 | 2135篇 |
2012年 | 2408篇 |
2011年 | 2693篇 |
2010年 | 2061篇 |
2009年 | 2177篇 |
2008年 | 2231篇 |
2007年 | 2765篇 |
2006年 | 2508篇 |
2005年 | 2074篇 |
2004年 | 1636篇 |
2003年 | 1414篇 |
2002年 | 1167篇 |
2001年 | 1008篇 |
2000年 | 861篇 |
1999年 | 690篇 |
1998年 | 542篇 |
1997年 | 395篇 |
1996年 | 327篇 |
1995年 | 255篇 |
1994年 | 202篇 |
1993年 | 145篇 |
1992年 | 115篇 |
1991年 | 95篇 |
1990年 | 74篇 |
1989年 | 83篇 |
1988年 | 44篇 |
1987年 | 23篇 |
1986年 | 13篇 |
1985年 | 8篇 |
1984年 | 6篇 |
1983年 | 10篇 |
1982年 | 6篇 |
1981年 | 3篇 |
1980年 | 5篇 |
1979年 | 4篇 |
1977年 | 5篇 |
1976年 | 2篇 |
1973年 | 1篇 |
1951年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
961.
基于直觉模糊Petri网的加权直觉模糊推理 总被引:1,自引:0,他引:1
利用直觉模糊集合较好地表现不确定信息的能力和Petri网的并行处理能力,构建了直觉模糊Petri网模型。给出了输入权值、变迁阈值等多种约束条件下的直觉模糊推理算法。该算法将直觉模糊推理过程转化为矩阵的运算过程可充分利用直觉模糊Petri网的并行推理能力,有效地避免同一变迁不必要地重复激发从而节省推理时间。实例分析表明所给出的直觉模糊推理算法较已有算法更加合理并且高效。 相似文献
962.
飞行器姿态控制系统结构极其复杂,难以建立准确的数学模型。为了实现姿态的精确控制,将模糊控制方法应用于飞行器纵向通道姿态控制中,在模糊逻辑理论的框架下,根据姿态控制系统的输入输出量,提出了一种模糊规则优化设计方案,通过模糊推理,实现了对飞行器姿态的模糊控制。仿真结果表明,所设计的模糊控制器性能稳定,系统响应的调整时间在1s以内,超调量不超过3%,且小扰动情况下仍能保持较好的控制效果,有效提高了系统的稳态精度与动态品质。 相似文献
963.
964.
965.
基于超级电容器的太阳能汽车储能系统研究 总被引:1,自引:0,他引:1
针对太阳能汽车在启动时需要蓄电池提供瞬时大电流,制动时会使蓄电池承受大电流冲击,导致蓄电池寿命严重缩短这一问题,提出一种基于超级电容器的新型储能系统,并通过模糊控制使超级电容器与蓄电池协调工作。本设计在MATLAB平台上搭建了基于超级电容器的太阳能电动汽车混合储能系统的模型,进行相关的仿真实验,实验结果表明混合储能方式可以提高汽车启动速度,减少对蓄电池造成的损害。 相似文献
966.
This paper provides simple and effective linear matrix inequality (LMI) characterizations for the stability and stabilization conditions of discrete-time Takagi–Sugeno (T–S) fuzzy systems. To do this, more general classes of non-parallel distributed compensation (non-PDC) control laws and non-quadratic Lyapunov functions are presented. Unlike the conventional non-quadratic approaches using only current-time normalized fuzzy weighting functions, we consider not only the current-time fuzzy weighting functions but also the l-step-past (l?0) and one-step-ahead ones when constructing the control laws and Lyapunov functions. Consequently, by introducing additional decision variables, it can be shown that the proposed conditions include the existing ones found in the literature as particular cases. Examples are given to demonstrate the effectiveness of the approaches. 相似文献
967.
Research on the robustness of fuzzy logic systems (FLSs), an imperative factor in the design process, is very limited in the literature. Specifically, when a system is subjected to small deviations of the sampling points (operating points), it is of great interest to find the maximum tolerance of the system, which we refer to as the system’s robustness. In this paper, we present a methodology for the robustness analysis of interval type-2 FLSs (IT2 FLSs) that also holds for T1 FLSs, hence, making it more general. A procedure for the design of robust IT2 FLSs with a guaranteed performance better than or equal to their T1 counterparts is then proposed. Several examples are performed to demonstrate the effectiveness of the proposed methodologies. It was concluded that both T1 and IT2 FLSs can be designed to achieve robust behavior in various applications, and preference one or the other, in general, is application-dependant. IT2 FLSs, having a more flexible structure than T1 FLSs, exhibited relatively small approximation errors in the several examples investigated. The methodologies presented in this paper lay the foundation for the design of FLSs with robust properties that will be very useful in many practical modeling and control applications. 相似文献
968.
In this paper we propose an entropy measure for interval-valued intuitionistic fuzzy sets, which generalizes three entropy measures defined independently by Szmidt, Wang and Huang, for intuitionistic fuzzy sets. We also give an approach to construct similarity measures using entropy measures for interval-valued intuitionistic fuzzy sets. In particular, the proposed entropy measure for interval-valued intuitionistic fuzzy sets can yield a similarity measure. Several illustrative examples are given to demonstrate the practicality and effectiveness of the proposed formulas. We apply the similarity measure to solve problems on pattern recognitions, multi-criteria fuzzy decision making and medical diagnosis. 相似文献
969.
Methods of fuzzy rule extraction based on rough set theory are rarely reported in incomplete interval-valued fuzzy information systems. Thus, this paper deals with such systems. Instead of obtaining rules by attribute reduction, which may have a negative effect on inducting good rules, the objective of this paper is to extract rules without computing attribute reducts. The data completeness of missing attribute values is first presented. Positive and converse approximations in interval-valued fuzzy rough sets are then defined, and their important properties are discussed. Two algorithms based on positive and converse approximations, namely, mine rules based on the positive approximation (MRBPA) and mine rules based on the converse approximation (MRBCA), are proposed for rule extraction. The two algorithms are evaluated by several data sets from the UC Irvine Machine Learning Repository. The experimental results show that MRBPA and MRBCA achieve better classification performances than the method based on attribute reduction. 相似文献
970.
Meiling Liu Xiangnan Liu Menxin Wu Lufeng Li Lina Xiu 《Computers & Geosciences》2011,37(10):1642-1652
A generalized dynamic fuzzy neural network (GDFNN) was created to estimate heavy metal concentrations in rice by integrating spectral indices and environmental parameters. Hyperspectral data, environmental parameters, and heavy metal content were collected from field experiments with different levels of heavy metal pollution (Cu and Cd). Input variables used in the GDFNN model were derived from 10 variables acquired by gray relational analysis. The assessment models for Cd and Cu concentration employed five and six input variables, respectively. The results showed that the GDFNN for estimating Cu and Cd concentrations in rice performed well at prediction with a compact network structure using the training, validation, and testing sets (for Cu, fuzzy rules=9, R2 greater than 0.75, and RMSE less than 2.5; for Cd, fuzzy rules=9, R2 greater than 0.75, and RMSE less than 1.0). The final GDFNN model was then compared with a back-propagation (BP) neural network model, adaptive-network-based fuzzy interference systems (ANFIS), and a regression model. The accuracies of GDFNN model prediction were usually slightly better than those of the other three models. This demonstrates that the GDFNN model is more suitable for predicting heavy metal concentrations in rice. 相似文献