全文获取类型
收费全文 | 15552篇 |
免费 | 3327篇 |
国内免费 | 757篇 |
专业分类
电工技术 | 4138篇 |
综合类 | 1572篇 |
化学工业 | 1853篇 |
金属工艺 | 330篇 |
机械仪表 | 970篇 |
建筑科学 | 609篇 |
矿业工程 | 317篇 |
能源动力 | 460篇 |
轻工业 | 1475篇 |
水利工程 | 164篇 |
石油天然气 | 450篇 |
武器工业 | 258篇 |
无线电 | 2166篇 |
一般工业技术 | 1625篇 |
冶金工业 | 251篇 |
原子能技术 | 88篇 |
自动化技术 | 2910篇 |
出版年
2025年 | 41篇 |
2024年 | 628篇 |
2023年 | 488篇 |
2022年 | 548篇 |
2021年 | 652篇 |
2020年 | 734篇 |
2019年 | 622篇 |
2018年 | 557篇 |
2017年 | 671篇 |
2016年 | 705篇 |
2015年 | 770篇 |
2014年 | 894篇 |
2013年 | 915篇 |
2012年 | 1069篇 |
2011年 | 1150篇 |
2010年 | 871篇 |
2009年 | 886篇 |
2008年 | 887篇 |
2007年 | 1133篇 |
2006年 | 969篇 |
2005年 | 769篇 |
2004年 | 671篇 |
2003年 | 587篇 |
2002年 | 449篇 |
2001年 | 395篇 |
2000年 | 352篇 |
1999年 | 268篇 |
1998年 | 206篇 |
1997年 | 164篇 |
1996年 | 144篇 |
1995年 | 93篇 |
1994年 | 84篇 |
1993年 | 60篇 |
1992年 | 59篇 |
1991年 | 27篇 |
1990年 | 29篇 |
1989年 | 20篇 |
1988年 | 7篇 |
1987年 | 15篇 |
1986年 | 7篇 |
1985年 | 10篇 |
1984年 | 6篇 |
1983年 | 7篇 |
1982年 | 7篇 |
1980年 | 4篇 |
1979年 | 1篇 |
1974年 | 2篇 |
1964年 | 1篇 |
1959年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
An effective system control method is presented for applying a three‐phase current‐source PWM converter with a deadbeat controller to active power filters (APFs). In the shunt‐type configuration, the APF is controlled such that the current drawn by the APF from the utility is equal to the current harmonics and reactive current required for the load. To attain the time‐optimal response of the APF supply current, a two‐dimensional deadbeat control scheme is applied to APF current control. Furthermore, in order to cancel both the delay in the two‐dimensional deadbeat control scheme and the delay in DSP control strategy, an Adaptive Line Enhancer (ALE) is introduced in order to predict the desired value three sampling periods ahead. ALE has another function of bringing robustness to the deadbeat control system. Due to the ALE, settling time is made short in a transient state. On the other hand, total harmonic distortion (THD) of source currents can be minimized compared to the case where ideal identification of the controlled system can be made. The experimental results obtained from the DSP‐based APF are also reported. The compensating ability of this APF is very high in accuracy and responsiveness although the modulation frequency is rather low. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 150(1): 50–61, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20014 相似文献
2.
T. RONALD A. MAGEE CAROLE P.D. WILKINSON 《International Journal of Food Science & Technology》1992,27(5):541-549
Investigation of the effects of varying air velocity, slice thickness, and pre-treatment with sodium chloride solutions and surface active agents on drying potato slices indicated that the drying occurred entirely in the falling rate period and was controlled by the mechanism of liquid diffusion. The rate of drying, and therefore the diffusion coefficients, increased with the addition of sodium chloride and surface active agents. Diffusion coefficients were also influenced by air velocity and slice thickness, suggesting that the rate of drying of potato slices is controlled by a combination of internal and external resistances. 相似文献
3.
新型城镇化背景下欠发达地区传统文化保护的关键取决于其能否在保护文化资本和环境资本的基础上,实现经济资本的提升、文化价值观念及生活方式的转变.通过对张家口市下花园区段家堡村传统文化的调查研究,提出转变观念,主动保护、挖掘和丰富欠发达地区传统文化特色,提升旅游开发优势,带动地区经济发展,实现新型城镇化的同时更好地保护传统文化. 相似文献
4.
建立了包括有源电力滤波器(APF)在内的公共连接点(PCC)的数学模型;针对实际控制器计算过程中的时间延迟,提出对负载电流值进行预测的两种算法,对逆变器的开关元件提出一种新型脉宽调制(PWM)控制方案,并采用电力电子仿真软件包进行了仿真验证。 相似文献
5.
在目标检测与提取中,传统的蛇模型和基于活动轮廓的局部区域检测方法受到初始条件或者自身的收敛性约束的影响,不仅时间花费多,而且不具备鲁棒性。本文提出一种基于C V模型的变分水平集的目标检测与提取方法,通过大量实验验证,在花费时间和鲁棒性上得到了显著的改善。 相似文献
6.
Chengkun Xu Richard Killmeyer McMahan L. Gray Shahed U.M. Khan 《Applied catalysis. B, Environmental》2006,64(3-4):312-317
The present research focused on wet process synthesis of visible light active carbon-modified (CM)-n-TiO2 nanoparticles and their photocatalytic activity. The CM-n-TiO2 was synthesized by hydrolysis of TiCl4 in the presence of tetrabutylammonium hydroxide and also in the presence of glucose and sodium hydroxide. UV–vis spectra, X-ray diffraction (XRD), and FT-IR were used to characterize these photocatalysts. It was found that the CM-n-TiO2 nanoparticles synthesized by hydrolysis with tetrabutylammonium hydroxide or with sodium hydroxide and glucose when subjected to extended aging and subsequent calcinations absorb well into the visible to near infrared region up to 800 nm and exhibit enhanced visible light photocatalytic activity on degradation of 4-chlorophenol. CM-n-TiO2 synthesized using glucose as the carbon source generated 13-fold increase in the initial rate of photodegradation of 4-chlorophenol compared to those by regular n-TiO2, whereas, it increased only eight-fold when tetrabutylammonium hydroxide was used as the carbon source. 相似文献
7.
《国际计算机数学杂志》2012,89(17):2374-2384
In this paper, we derive the piecewise linear system (PLS) associated with the bilateral obstacle problem and illustrate the equivalence between the linear system and finite-dimensional complementary problem. The existence and the uniqueness of the solution to the PLS are also demonstrated. Based on the PLS, a Picard iterative algorithm is proposed. The convergence analysis is given and examples are presented to verify the effectiveness of the method. 相似文献
8.
9.
10.
执行环境的结构组成直接影响主动节点对主动信包的处理性能,本文试图给出一种新型的执行环境实现方案.在分析了当前执行环境存在弊端的基础上,运用组件思想提出了一种一致性执行环境的框架模型.其核心思想是:使得接口与实现相分离,实现语言无关性以及利用组件构建执行环境和主动应用.该模型能够较好的克服当前执行环境EE存在的弊端,提高主动网络的整体性能. 相似文献