全文获取类型
收费全文 | 434214篇 |
免费 | 28700篇 |
国内免费 | 16060篇 |
专业分类
电工技术 | 21654篇 |
技术理论 | 45篇 |
综合类 | 27140篇 |
化学工业 | 70080篇 |
金属工艺 | 25095篇 |
机械仪表 | 25214篇 |
建筑科学 | 29674篇 |
矿业工程 | 12159篇 |
能源动力 | 10719篇 |
轻工业 | 27328篇 |
水利工程 | 7947篇 |
石油天然气 | 23711篇 |
武器工业 | 2805篇 |
无线电 | 47298篇 |
一般工业技术 | 54215篇 |
冶金工业 | 20945篇 |
原子能技术 | 3864篇 |
自动化技术 | 69081篇 |
出版年
2024年 | 1458篇 |
2023年 | 5565篇 |
2022年 | 9875篇 |
2021年 | 13885篇 |
2020年 | 10449篇 |
2019年 | 8553篇 |
2018年 | 22767篇 |
2017年 | 23110篇 |
2016年 | 19160篇 |
2015年 | 14419篇 |
2014年 | 17672篇 |
2013年 | 21088篇 |
2012年 | 25604篇 |
2011年 | 33896篇 |
2010年 | 29866篇 |
2009年 | 26124篇 |
2008年 | 26940篇 |
2007年 | 27058篇 |
2006年 | 20171篇 |
2005年 | 18777篇 |
2004年 | 13025篇 |
2003年 | 11803篇 |
2002年 | 10426篇 |
2001年 | 8914篇 |
2000年 | 8931篇 |
1999年 | 9451篇 |
1998年 | 7234篇 |
1997年 | 6166篇 |
1996年 | 5861篇 |
1995年 | 4795篇 |
1994年 | 3907篇 |
1993年 | 2633篇 |
1992年 | 2084篇 |
1991年 | 1591篇 |
1990年 | 1234篇 |
1989年 | 995篇 |
1988年 | 839篇 |
1987年 | 524篇 |
1986年 | 410篇 |
1985年 | 258篇 |
1984年 | 206篇 |
1983年 | 165篇 |
1982年 | 128篇 |
1981年 | 76篇 |
1980年 | 96篇 |
1968年 | 46篇 |
1966年 | 45篇 |
1965年 | 45篇 |
1955年 | 63篇 |
1954年 | 68篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
Takeshi Shiofuku Norihiro Abe Yoshihiro Tabuchi Hirokazu Taki Shoujie He 《Artificial Life and Robotics》2008,13(1):290-293
This paper presents an approach of measuring in real-time the vector of finger that is pointing to an object. DSP is used
in the operation processing unit in order to do the real-time processing. The steps include the extraction of flesh-colored
regions from an image, the labeling of the flesh-colored regions, and the detection of two characteristic positions on the
finger so that the direction that the finger is pointing at will be calculated. The entire process takes about 29 msec, which
makes it possible to have the frame rate of 34 fps. With this frame rate, this measurement approach is considered real-time
and promising to be merged into other application systems.
This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January
31–February 2, 2008 相似文献
42.
43.
Yung Ting Liang-Chiang Chen Chun-Chung Li Jeng-Lin Huang 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2007,54(4):847-853
A new type of piezoelectric linear motor incorporating a traveling wave has been developed. The linear motor is comprised of a stator and a carriage. The stator design, which consists of a meander-line structure and gear teeth mounted on the meander-line structure, is the focus of this article. The meander-line structure is constructed with bimorph actuators arranged in a line. These actuators are driven by two phased sets of alternating current (ac) in order to generate a traveling wave. The traveling wave is transferred to the gear teeth, by which the carriage is driven. Modeling of the stator is derived by use of a strain energy method. The performance of various materials is evaluated by analytical and experimental methods. The analytical and the experimental results are quite approximate. Modal analysis is investigated using ANSYS. Appropriate modes associated with ultrasonic levels of resonant frequency are selected to obtain desired motion and to enhance the output performance. Surface speed for various applied input voltage are studied and indicate a nearly linear relationship. The stator in combination with the carriage makes up the linear motor. 相似文献
44.
45.
Qing Li 《Computer Standards & Interfaces》1991,13(1-3):99-103
The term ‘object-oriented database’ has been used to refer to different characteristics and mechanisms supported by semantic databases and (behaviorally) object-oriented ones. While this indicates the current confusion due to the lack of a common model, it also suggests the potential desirability of combining these two kinds of modeling facilities into the same nutshell. This paper summarizes from these two paradigms the features common to both, the features influenced/adopted by each other, and the features which are presented in one paradigm but missing from the other. After a brief analysis and discussion of these features, we conclude this paper by proposing our major theme: a complete object data model should take the union of the facilities offered by these two kinds of models. 相似文献
46.
47.
48.
49.
50.
报道了4,4′-硫代双[2-(1,1-二甲基乙基)-5一甲基苯酚]的合成方法及结构鉴定。 相似文献