全文获取类型
收费全文 | 14170篇 |
免费 | 1120篇 |
国内免费 | 872篇 |
专业分类
电工技术 | 3217篇 |
综合类 | 1397篇 |
化学工业 | 442篇 |
金属工艺 | 547篇 |
机械仪表 | 1822篇 |
建筑科学 | 229篇 |
矿业工程 | 406篇 |
能源动力 | 329篇 |
轻工业 | 226篇 |
水利工程 | 103篇 |
石油天然气 | 183篇 |
武器工业 | 184篇 |
无线电 | 1635篇 |
一般工业技术 | 400篇 |
冶金工业 | 332篇 |
原子能技术 | 106篇 |
自动化技术 | 4604篇 |
出版年
2024年 | 45篇 |
2023年 | 133篇 |
2022年 | 167篇 |
2021年 | 246篇 |
2020年 | 335篇 |
2019年 | 271篇 |
2018年 | 252篇 |
2017年 | 407篇 |
2016年 | 429篇 |
2015年 | 475篇 |
2014年 | 764篇 |
2013年 | 735篇 |
2012年 | 995篇 |
2011年 | 1106篇 |
2010年 | 818篇 |
2009年 | 795篇 |
2008年 | 901篇 |
2007年 | 1127篇 |
2006年 | 1038篇 |
2005年 | 963篇 |
2004年 | 768篇 |
2003年 | 648篇 |
2002年 | 570篇 |
2001年 | 422篇 |
2000年 | 380篇 |
1999年 | 321篇 |
1998年 | 238篇 |
1997年 | 169篇 |
1996年 | 145篇 |
1995年 | 121篇 |
1994年 | 106篇 |
1993年 | 56篇 |
1992年 | 70篇 |
1991年 | 38篇 |
1990年 | 32篇 |
1989年 | 24篇 |
1988年 | 16篇 |
1987年 | 7篇 |
1986年 | 7篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1977年 | 3篇 |
1971年 | 1篇 |
1966年 | 1篇 |
1959年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
951.
952.
Isha Gupta Sitender Singh Shri Bhagwan Devender Singh 《Ceramics International》2021,47(14):19282-19303
The evolution of luminescent materials has witnessed rapid advancement in research and development. Solid inorganic light-emitting materials or phosphors are the optoelectronic material of the 21st century because of their power-efficient potential over various illumination sources, eco-friendliness and resourceful display perspectives. The inorganic phosphors have been extensively explored to meet the demand of low voltage stimulated lighting sources owing to increased global energy consumption. Due to environmental friendliness, advantages long lifetime, lower energy consumption, reliability and high luminous efficiency, modern white light-emitting diodes (WLEDs) have replaced less effective incandescent and mercury-enclosing conventional fluorescent lighting sources. This review highlights the developments in preparation, luminescence and potential perceptions of rare-earth activated phosphors for solid-state lighting technologies. The role of RE ions as an activator as well as a sensitizer in doped materials and possible transitions within their energy levels are reviewed in detail. The paper reviews the substantial influence of host lattices such as aluminate, oxide, phosphate, silicate, sulfide, etc on the optical transitions of doped RE ions. Studies on the advancement into the design of novel phosphors are very crucial as they will provide an opportunity to boom prospects in the course of promising applications. The sustainable energy facilities include clean technologies providing a cheaper lighting source which can produce significant indirect economic benefits via limiting the deforestation and use of scrubbing technology to mitigate air pollution. 相似文献
953.
Under present widespread automatic generation control (AGC) centered on regional power grid, a large-capacity coal-fired supercritical (SC) power unit often operates under wide-range variable load conditions. Since a SC once-through boiler unit is represented by a typical multivariable system with large inertia and non-linear, slow time-variant and time-delay characteristics, it often makes the coordinated control quality deteriorate under wide-range loading conditions, and thus influences the unit load response speed and leads to heavy fluctuation of the main steam pressure. To improve the SC unit’s coordinated control quality with advanced intelligent control strategy, the neural-network (NN) based expanded-structure inverse system models of a 600 MW SC boiler unit were investigated. A feedforward neural network with time-delayed inputs and time-delayed output feedbacks was adopted to establish the inverse models for the load and the main steam pressure characteristics. Based on the model, a neural network inverse coordinated control scheme was designed and tested in a full-scope power plant simulator of the given SC power unit, which showed that the proposed coordinated control scheme can achieve better control results compared to the original PID coordinated control. 相似文献
954.
Most research of run-to-run process control has been based on single-input and single-output processes with static input–output relationships. In practice, many complicated semiconductor manufacturing processes have multiple-input and multiple-output (MIMO) variables. In addition, the effects of previous process input recipes and output responses on the current outputs might be carried over for several process periods. Under these circumstances, using conventional controllers usually results in unsatisfactory performance. To overcome this, a complicated process could be viewed as dynamic MIMO systems with added general process disturbance and this article proposes a dynamic-process multivariate exponentially weighted moving average (MEWMA) controller to adjust those processes. The long-term stability conditions of the proposed controller are derived analytically. Furthermore, by minimizing the total mean square error (TMSE) of the process outputs, the optimal discount matrix of the proposed controller under vector IMA(1,?1) disturbance is derived. Finally, to highlight the contribution of the proposed controller, we also conduct a comprehensive simulation study to compare the control performance of the proposed controller with that of the single MEWMA and self-tuning controllers. On average, the results demonstrate that the proposed controller outperforms the other two controllers with a TMSE reduction about 32% and 43%, respectively. 相似文献
955.
设计的基于嵌入式微处理器、可组态的工业通用控制器支持以控制系统图形化编程为基础的过程控制。在论述控制器硬件整体架构的基础上,详细分析了软件设计中,组态序列解析方法、多任务之间的同步及通信协议状态转换等影响系统实时性和鲁棒性的因素,并提出有效的解决方法。 相似文献
956.
针对高速率通信网络和Round-Robin(RR)协议影响下网络化时变系统的有限时域[H∞]控制问题,考虑到系统中存在乘性噪声、随机时滞和量化效应,提出了一种基于观测器的有限时域[H∞]控制器的设计方法。利用李雅普诺夫稳定性理论和线性矩阵不等式(Linear Matrix Inequality,LMI)技术得到有限时域[H∞]控制器存在的充分条件。基于锥补线性化(Cone Complementarity Linearization,CCL)方法通过求解一组递归矩阵不等式得到观测器和控制器参数。所设计的控制器保证闭环网络化时变系统在给定的时域内稳定,且满足预定的[H∞]性能指标。数值仿真验证了所提方法的有效性。 相似文献
957.
This paper introduces a new, adaptive-filter-based controller that shows advantageous properties from the viewpoint of its communication requirement. The algorithm is called signed-error filtered-x LMS (SE-FxLMS). Its novelty is characterized by the fact that it makes possible data compression in the feedback path of adaptive-filter-based control loops in a very simple way. This feature is especially useful in such closed-loop systems where the feedback signals are transmitted over a low-bandwidth communication channel. This is a typical case in so-called networked control systems (NCS), where the communication is carried out over a shared communication channel, e.g., using a wireless sensor network. The paper introduces an analysis of the algorithm as well. 相似文献
958.
959.
This work describes a new control strategy for active energy flow in a hybrid photovoltaic (PV) system. The method introduces an online energy management by a hierarchical fuzzy controller between energy sources that consist of a photovoltaic panel (PVP), the battery and the load. The fuzzy logic controller has been developed for power splitting between PVP and battery, and it makes decision to choose the switching chain rules and corresponding controller. Simulation test results illustrate improvement in the operation's efficiency of online state of the switches and the battery's state of charge (SOC) has been maintained at a reasonable level. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
960.
《Displays》2017
An automatic optical inspection system to evaluate functional defects of sub-pixel elements in image displays is proposed, which is based on a single full-field imaging sensor. In order to circumvent sampling aliasing, the display is addressed with a set of grid patterns whose defocused optical images imitate a lower resolution display. The cross-talk between the sensor and the display primary colors is corrected by means of a linear transformation between their color-spaces. Dark and bright dots are located and quantified by applying a notch multi-band Fourier filter to the sensor images. The technique is simple, robust, and easily scalable, since only one image sensor is required, no moving parts are used, and the sensor can be reused to analyze increasing resolution displays. 相似文献