全文获取类型
收费全文 | 229992篇 |
免费 | 18867篇 |
国内免费 | 13430篇 |
专业分类
电工技术 | 34791篇 |
技术理论 | 22篇 |
综合类 | 25922篇 |
化学工业 | 12361篇 |
金属工艺 | 7677篇 |
机械仪表 | 18830篇 |
建筑科学 | 19152篇 |
矿业工程 | 8984篇 |
能源动力 | 8286篇 |
轻工业 | 7476篇 |
水利工程 | 6474篇 |
石油天然气 | 6718篇 |
武器工业 | 3850篇 |
无线电 | 23161篇 |
一般工业技术 | 12528篇 |
冶金工业 | 7161篇 |
原子能技术 | 2305篇 |
自动化技术 | 56591篇 |
出版年
2024年 | 784篇 |
2023年 | 2079篇 |
2022年 | 4141篇 |
2021年 | 5231篇 |
2020年 | 5757篇 |
2019年 | 4210篇 |
2018年 | 3851篇 |
2017年 | 5454篇 |
2016年 | 6409篇 |
2015年 | 7556篇 |
2014年 | 14375篇 |
2013年 | 12293篇 |
2012年 | 16956篇 |
2011年 | 17961篇 |
2010年 | 13782篇 |
2009年 | 13821篇 |
2008年 | 14076篇 |
2007年 | 18013篇 |
2006年 | 16125篇 |
2005年 | 14405篇 |
2004年 | 11778篇 |
2003年 | 10612篇 |
2002年 | 8064篇 |
2001年 | 6747篇 |
2000年 | 5571篇 |
1999年 | 4513篇 |
1998年 | 3377篇 |
1997年 | 2763篇 |
1996年 | 2456篇 |
1995年 | 2075篇 |
1994年 | 1727篇 |
1993年 | 1175篇 |
1992年 | 987篇 |
1991年 | 698篇 |
1990年 | 567篇 |
1989年 | 467篇 |
1988年 | 330篇 |
1987年 | 190篇 |
1986年 | 117篇 |
1985年 | 131篇 |
1984年 | 105篇 |
1983年 | 91篇 |
1982年 | 72篇 |
1981年 | 64篇 |
1980年 | 52篇 |
1979年 | 47篇 |
1978年 | 36篇 |
1977年 | 28篇 |
1976年 | 24篇 |
1959年 | 22篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
The problem of tracking a periodic trajectory of the well-known cart-pendulum system is solved. After a change of coordinates and a change of feedback, the equations of this system are nonlinear but feedforward. This property is extensively used to carry out for this system the design of uniformly asymptotically stabilizing time-varying state feedbacks by using the forwarding approach. 相似文献
82.
油田勘探数据中心及辅助支持系统研究 总被引:2,自引:1,他引:1
周霞 《计算机工程与应用》2003,39(24):202-204
文章简要介绍胜利油田近年来致力于勘探数据中心建设及辅助支持系统研究的背景、主要研究内容及进展情况,探讨了石油勘探行业在信息化时代利用先进的数据管理理念和技术对勘探工作提供数据支持和应用支持的尝试,对于其它油田勘探行业具有一定的借鉴意义。 相似文献
83.
Stephen Dain 《Color research and application》2007,32(6):428-432
There are anecdotal reports of color vision deficient medical practitioners (particularly deuteranopes) having difficulty in recognizing cyanosis. An understanding of the color changes in oxygenated blood has led to a better understanding of the lighting needs for hospitals. Using the same database, this article investigates the propensity for color vision deficient observers to make mistakes with cyanotic patients. The possibilities for helping the observer with appropriate color of lighting are considered. The spectral reflectances of blood at varying oxygenation levels previously reported were used 7 ; 8 to calculate chromaticity and lightness. The direction of the chromaticity change was compared with the protanopic and deuteranopic confusion lines. An attempt was made to identify sources that enhanced color changes for the color deficient. The color change of blood oxygenation is closely aligned with the confusion lines of congenital dichromats (particularly protanopia) showing the potential for difficulty in making this decision. No source could be demonstrated to solve the problem or even reduce it significantly. © 2007 Wiley Periodicals, Inc. Col Res Appl, 32, 428–432, 2007 相似文献
84.
Ken Smith 《Color research and application》2007,32(4):249-255
This study describes a process of relating the perceptual analysis of the colors of the terrestrial atmosphere to currently available pigments used in artists' painting systems. This process sought to discover how the colors of the sky could be defined and simulated by these pigments. The author also describes how confusion over the bewildering choice of suitable pigments on offer in the market place can be clarified. © 2006 Wiley Periodicals, Inc. Col Res Appl, 32, 249–255, 2007 相似文献
85.
Ralph W. Pridmore 《Color research and application》2007,32(3):208-222
A color stimulus may be characterized by three psychophysical dimensions (luminance, dominant wavelength, and purity), whose corresponding color attributes are lightness, hue, and chroma/colorfulness. The 3 × 3 matrix gives nine basic effects of the psychophysical dimensions on the color attributes (e.g. the effect of luminance on hue), but there are 49 possible combinations as more complex effects (e.g. the effect of luminance on hue and chroma, i.e. on chromaticity). Researching and quantifying such effects enables modelling of the underlying neural mechanisms and of color appearance. Using a simple nomenclature to identify the effects (e.g. Ph denotes the effect of Purity on hue), this paper briefly reviews and interrelates 15 of the commonest effects, giving new data or new graphical perspectives to clarify or fill gaps in the literature. Contrast and no‐contrast effects (stimuli viewed simultaneously or singly, respectively) are differentiated. © 2007 Wiley Periodicals, Inc. Col Res Appl, 32, 208–222, 2007 相似文献
86.
87.
Katsuhiko Fuwa Tatsuo Narikiyo Yasuyuki Funahashi 《Electrical Engineering in Japan》2002,138(4):50-60
A well‐known control system which can reduce the adverse effects of disturbances is a disturbance observer. However, in many cases of mechanical systems, system disturbances which do not satisfy the matching condition may be imposed. Therefore, it may be difficult to reduce the adverse effects of the disturbances by the traditional disturbance observer. In this paper, a method of control system synthesis for disturbance rejection using a dual observer is proposed. This method is based on the zeroing induced by the disturbance localization problem. This problem may be solved by dividing the state space into observable subspace and unobservable subspace. As compared with an H∞ controller based on perfect observation, the usefulness of the proposed control system for disturbance rejection is demonstrated by numerical simulations for a two‐mass spring system. © 2002 Scripta Technica, Electr Eng Jpn, 138(4): 50–60, 2002; DOI 10.1002/eej.1138 相似文献
88.
89.
90.
Masahide Hojo Yasunori Mitani Toshifumi Ise Kiichiro Tsuji 《Electrical Engineering in Japan》2002,138(3):43-51
The advancement of power electronics technologies has significantly developed the power system stabilizing controllers. Quantitative as well as qualitative evaluation of their effectiveness in power systems is a matter of great importance for the feasibility investigation of these apparatus. In this paper, the possible control region of FACTS controllers with series and/or shunt configuration in a single machine to infinite bus system is formulated in the powerangle curve with a set of algebraic equations. The effectiveness of TCPST (Thyristor‐Controlled Phase Shifting Transformer), SSSC (Static Synchronous Series Compensator), and TCSC (Thyristor‐Controlled Series Compensator) for the improvement of the transient stability is evaluated quantitatively as a numerical example. The correctness of the proposed method has been confirmed by analysis based on the electromagnetic transients simulation with a detailed system model. © 2001 Scripta Technica, Electr Eng Jpn, 138(3): 43–51, 2002 相似文献