全文获取类型
| 收费全文 | 7628篇 |
| 免费 | 1139篇 |
| 国内免费 | 459篇 |
专业分类
| 电工技术 | 1157篇 |
| 综合类 | 670篇 |
| 化学工业 | 436篇 |
| 金属工艺 | 490篇 |
| 机械仪表 | 473篇 |
| 建筑科学 | 210篇 |
| 矿业工程 | 219篇 |
| 能源动力 | 204篇 |
| 轻工业 | 304篇 |
| 水利工程 | 77篇 |
| 石油天然气 | 289篇 |
| 武器工业 | 114篇 |
| 无线电 | 1407篇 |
| 一般工业技术 | 700篇 |
| 冶金工业 | 197篇 |
| 原子能技术 | 707篇 |
| 自动化技术 | 1572篇 |
出版年
| 2025年 | 73篇 |
| 2024年 | 228篇 |
| 2023年 | 240篇 |
| 2022年 | 242篇 |
| 2021年 | 327篇 |
| 2020年 | 313篇 |
| 2019年 | 288篇 |
| 2018年 | 273篇 |
| 2017年 | 299篇 |
| 2016年 | 362篇 |
| 2015年 | 308篇 |
| 2014年 | 479篇 |
| 2013年 | 663篇 |
| 2012年 | 536篇 |
| 2011年 | 517篇 |
| 2010年 | 408篇 |
| 2009年 | 390篇 |
| 2008年 | 404篇 |
| 2007年 | 467篇 |
| 2006年 | 458篇 |
| 2005年 | 316篇 |
| 2004年 | 290篇 |
| 2003年 | 251篇 |
| 2002年 | 180篇 |
| 2001年 | 180篇 |
| 2000年 | 142篇 |
| 1999年 | 110篇 |
| 1998年 | 73篇 |
| 1997年 | 63篇 |
| 1996年 | 64篇 |
| 1995年 | 45篇 |
| 1994年 | 50篇 |
| 1993年 | 34篇 |
| 1992年 | 26篇 |
| 1991年 | 21篇 |
| 1990年 | 16篇 |
| 1989年 | 15篇 |
| 1988年 | 8篇 |
| 1987年 | 3篇 |
| 1986年 | 7篇 |
| 1985年 | 7篇 |
| 1984年 | 11篇 |
| 1983年 | 10篇 |
| 1982年 | 1篇 |
| 1981年 | 5篇 |
| 1980年 | 5篇 |
| 1977年 | 1篇 |
| 1964年 | 1篇 |
| 1959年 | 16篇 |
排序方式： 共有9226条查询结果，搜索用时 15 毫秒
961.
962.
利用多层快速多极子方法(MLFMA)分析三维导体介质复合结构的电磁辐射与散射特性.根据等效原理,介质表面构造Poggio-Miller-Chang-Harrington-Wu(PMCHW)方程,导体表面建立电场积分方程(EFIE).分析了含介质目标MLFMA算法中远区组矩阵矢量相乘运算以及有耗媒质空间中格林函数的平面波展开.利用该方法研究了涂敷目标电磁散射特性以及天线罩对直线阵天线辐射特性的影响.MLFMA的应用降低了计算量和存储量,实现了对电大尺寸目标快速、准确的求解. 相似文献
963.
Ning Xie Yuanping Zhou Li Zhang Gongbin Qian Hui Wang Xia Li 《Wireless Communications and Mobile Computing》2009,9(2):239-249
Design of a nonlinear adaptive antenna array receiver is a challenging task in wireless communications due to the limited number of antenna elements and the presence of correlated signals, which directly affect the performance of an antenna array. More importantly, a conventional nonlinear array receiver is often associated with a high computational complexity that undermines its applicability in practice. In this paper, we present a new approach to adaptive beamforming receiver that provides superior performance in antenna array overloading and in the presence of correlated signals with a low complexity. In particular, the proposed receiver requires a small data‐record size to estimate the beamformer weights, which is beneficial in applications with fast fading channels. Simulation examples illustrate the performance improvement of the proposed array receiver when it is compared to the conventional beamformers. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
964.
Decision recommendations are a set of alternative options for clinical decisions (e.g., diagnosis, prognosis, treatment selection, follow-up, and prevention) that are provided to decision makers by knowledge-based Clinical Decision Support Systems (k-CDSS) as aids. We propose to follow a “reasoning over domain” approach for the generation of decision recommendations by gathering and inferring conclusions from production rules. In order to rationalize our approach, we present a specification that will sustain the logic models supported in the knowledge bases we use for persistence. We introduce first the underlying knowledge model and then the necessary extensions that will convey toward the solution of the reported needs. The starting point of our approach is the proposition of Reflexive Ontologies (RO). Here, we go a step further, proposing an extension of RO that includes the handling and reasoning that production rules provide. Our approach speeds up the recommendation generation process. 相似文献
965.
The fast multipole method (FMM) is a complex, multi‐stage algorithm over a distributed tree data structure, with multiple levels of parallelism and inherent data locality. X10 is a modern partitioned global address space language with support for asynchronous activities. The parallel tasks comprising FMM may be expressed in X10 by using a scalable pattern of activities. This paper demonstrates the use of X10 to implement FMM for simulation of electrostatic interactions between ions in a cyclotron resonance mass spectrometer. X10's task‐parallel model is used to express parallelism by using a pattern of activities mapping directly onto the tree. X10's work stealing runtime handles load balancing fine‐grained parallel activities, avoiding the need for explicit work sharing. The use of global references and active messages to create and synchronize parallel activities over a distributed tree structure is also demonstrated. In contrast to previous simulations of ion trajectories in cyclotron resonance mass spectrometers, our code enables both simulation of realistic particle numbers and guaranteed error bounds. Single‐node performance is comparable with the fastest published FMM implementations, and critical expansion operators are faster for high accuracy calculations. A comparison of parallel and sequential codes shows the overhead of activity management and work stealing in this application is low. Scalability is evaluated for 8k cores on a Blue Gene/Q system and 512 cores on a Nehalem/InfiniBand cluster. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
966.
This paper presents a dynamic compensation concept to grapple with the dynamic defects of a traditional robot arm, especially while performing high-speed endpoint regulations. The proposed high-speed dynamic compensation concept offers a new point of view for cooperating with a traditional manipulator to realize highly dexterous performance of manipulations. The concept is realized through adoption of a high-speed light-weight actuator as well as endpoint closed loop configured high-speed cameras. The dynamic compensation is analyzed experimentally with 1000 Hz visual feedback and a high-speed finger for a robot arm in the case of one degree of freedom. The advantage of the proposed approach is that the modeling for the robot system’s dynamics is not needed, whereas it is necessary and trivial in order to realize high-speed regulations by traditional approaches. Thus, the control issue becomes easier with the proposed approach. As an application for this concept, fast peg-and-hole alignment with large position and attitude uncertainty is studied. The alignment algorithm is based on a visual compliance strategy. Alignment experiments show that with the proposed concept of dynamic compensation as well as visual compliant motion control, robust and fast convergence was realized for most cases. 相似文献
967.
Abstract: In this study, ophthalmic arterial Doppler signals were obtained from 200 subjects, 100 of whom suffered from ocular Behcet disease while the rest were healthy subjects. An adaptive neuro-fuzzy inference system (ANFIS) was used to detect the presence of ocular Behcet disease. Spectral analysis of the ophthalmic arterial Doppler signals was performed by the fast Fourier transform method for determining the ANFIS inputs. The ANFIS was trained with a training set and tested with a testing set. All these data sets were obtained from ophthalmic arteries of healthy subjects and subjects suffering from ocular Behcet disease. Performance indicators and statistical measures were used for evaluating the ANFIS. The correct classification rate was 94% for healthy subjects and 90% for unhealthy subjects suffering from ocular Behcet disease. The classification results showed that the ANFIS was effective at detecting ophthalmic arterial Doppler signals from subjects with Behcet disease. 相似文献
968.
Very fast and accurate 3-D capacitance extraction is essential for interconnect optimization in VLSI ultra-deep sub-micron designs (UDSM). Parallel processing provides an approach to reducing the simulation turn-around time. This paper examines the parallelization of the well-known fast multipole-based 3-D capacitance extraction program FASTCAP, which employs new adaptive and preconditioning techniques. To account for the complicated data dependencies in the unstructured problems, we propose a novel generalized cost function model, which can be used to accurately measure the workload associated with each cube in the hierarchy. We then present two adaptive partitioning schemes, combined with efficient communication mechanisms with bounded buffer size, to reduce the parallel processing overhead. The overall load balance is achieved through balancing the load at each level of the multipole computation. We report detailed performance results on a variety of distributed memory parallel platforms, using standard benchmarks on 3-D capacitance extraction. 相似文献
969.
Suresh Kalichikadu Paramasivam;Senthil Kumar Ramu;Pazhanimuthu Cholamuthu; 《International Journal of Circuit Theory and Applications》2024,52(6):2889-2915
Fast battery charging units act as non-linear loads, which induce a more harmonic effect in the utility grid. Hence, maintaining the stable voltage, current ripple, and total harmonic distortions within the permissible IEEE std level during the charging time of grid to electric vehicle (G2V) has become an important task for researchers in the future. In order to mitigate power fluctuations during every charging cycle, it will enhance the battery life cycle in electric vehicles (EVs). Three phase–three level–three switch Vienna rectifier with fuzzy logic controller tuned PID controller is used here for AC/DC conversion with minimum switching loss. A fuzzy intelligent control strategy has been employed with the DC link voltage regulator in order to sustain the DC link voltage as constant and progress the voltage/current profile by injecting active power at the point of common coupling. Unit vector template (UVT)-based control strategy is employed here to identify the fundamental components from the load side and also estimate the reference phase current. This scheme enhances the performance and reduces the mathematical system complexity to diminish the harmonics in the distribution grid. The adaptability and feasibility of this proposed control method have been verified by the MATLAB simulation tool. To validate the response of the Vienna Rectifier with UVT controller are simulated with different unbalanced load conditions and also verified with 30 kW laboratory prototype experimental results using dsPIC30F4011 controller and the switch is IRFP260 with power diode RHRG30120. 相似文献
970.
Cheap control problems where a small parameter μ2 multiplies the control cost are considered. Due to the cheapness of control, a strong control action in the form of high-gain feedback forces the given system to have slow and fast, low and high amplitude variations. For a class of linear systems (uniform rank systems), a systematic procedure of amplitude scaling and time-scale decomposition which normalizes high and low amplitude variations and which separates slow and fast time scales is presented. The method permits the explicit characterization of all the limiting properties of the considered cheap control problem as μ → 0. Methods of calculating singular controls and how non-uniqueness can arise in them are discussed. Above all, several suboptimal composite control schemes are developed based on the decomposition of the given optimal design into two lower order subsystem designs. 相似文献