全文获取类型
收费全文 | 318142篇 |
免费 | 19498篇 |
国内免费 | 10206篇 |
专业分类
电工技术 | 14245篇 |
技术理论 | 17篇 |
综合类 | 16170篇 |
化学工业 | 51599篇 |
金属工艺 | 17024篇 |
机械仪表 | 17048篇 |
建筑科学 | 21049篇 |
矿业工程 | 6700篇 |
能源动力 | 7931篇 |
轻工业 | 18740篇 |
水利工程 | 5127篇 |
石油天然气 | 12816篇 |
武器工业 | 1618篇 |
无线电 | 37808篇 |
一般工业技术 | 45706篇 |
冶金工业 | 15077篇 |
原子能技术 | 2778篇 |
自动化技术 | 56393篇 |
出版年
2024年 | 1024篇 |
2023年 | 3757篇 |
2022年 | 6770篇 |
2021年 | 9245篇 |
2020年 | 6806篇 |
2019年 | 5856篇 |
2018年 | 19761篇 |
2017年 | 19763篇 |
2016年 | 15931篇 |
2015年 | 9179篇 |
2014年 | 11447篇 |
2013年 | 14507篇 |
2012年 | 17385篇 |
2011年 | 24995篇 |
2010年 | 21553篇 |
2009年 | 18613篇 |
2008年 | 19206篇 |
2007年 | 19702篇 |
2006年 | 12735篇 |
2005年 | 12318篇 |
2004年 | 8815篇 |
2003年 | 8298篇 |
2002年 | 7695篇 |
2001年 | 6497篇 |
2000年 | 6065篇 |
1999年 | 6490篇 |
1998年 | 5834篇 |
1997年 | 4790篇 |
1996年 | 4326篇 |
1995年 | 3635篇 |
1994年 | 3024篇 |
1993年 | 2350篇 |
1992年 | 1861篇 |
1991年 | 1431篇 |
1990年 | 1107篇 |
1989年 | 951篇 |
1988年 | 749篇 |
1987年 | 528篇 |
1986年 | 420篇 |
1985年 | 348篇 |
1984年 | 223篇 |
1983年 | 204篇 |
1982年 | 175篇 |
1981年 | 154篇 |
1980年 | 152篇 |
1979年 | 103篇 |
1978年 | 68篇 |
1977年 | 69篇 |
1976年 | 81篇 |
1954年 | 68篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Somsak Vanit-Anunchai Jonathan Billington Guy Edward Gallasch 《International Journal on Software Tools for Technology Transfer (STTT)》2008,10(1):29-56
State space explosion is a key problem in the analysis of finite state systems. The sweep-line method is a state exploration
method which uses a notion of progress to allow states to be deleted from memory when they are no longer required. This reduces
the peak number of states that need to be stored, while still exploring the full state space. The technique shows promise
but has never achieved reductions greater than about a factor of 10 in the number of states stored in memory for industrially
relevant examples. This paper discusses sweep-line analysis of the connection management procedures of a new Internet standard,
the Datagram Congestion Control Protocol (DCCP). As the intuitive approaches to sweep-line analysis are not effective, we
introduce new variables to track progress. This creates further state explosion. However, when used with the sweep-line, the
peak number of states is reduced by over two orders of magnitude compared with the original. Importantly, this allows DCCP
to be analysed for larger parameter values.
Somsak Vanit-Anunchai was partially supported by an Australian Research Council Discovery Grant (DP0559927) and Suranaree
University of Technology.
Guy Edward Gallasch was supported by an Australian Research Council Discovery Grant (DP0559927). 相似文献
72.
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
73.
磷矿中七种金属元素的光谱法测定 总被引:2,自引:0,他引:2
研究了磷矿样品中7种金属元素锰、钴、镍,锌、铬、钼及铋的分析方法,选择了灵敏度高干扰少的谱线,绘制出工作曲线,对样品进行了科学处理,不必进行化学分离即可对七种元素同时测定,经合成样分析、回收实验及样品测定,证明此方法精确可靠,其回收率在98%-102%之间。 相似文献
74.
该文介绍了Mall的产生条件和国内发展概况,并结合实例分析,着重论述建筑设计方面的有关问题。 相似文献
75.
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
76.
77.
Yi‐Hung Chen Ching‐Yuan Chang Wei‐Ling Su Chun‐Yu Chiu Yue‐Hwa Yu Pen‐Chi Chiang Chiung‐Fen Chang Je‐Lueng Shie Chyow‐San Chiou Sally IM Chiang 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2005,80(1):68-75
This study investigates the ozonation of CI Reactive Black 5 (RB5) by using the rotating packed bed (RPB) and completely stirred tank reactor (CSTR) as ozone contactors. The RPB, which provides high gravitational force by adjusting the rotational speed, was employed as a novel ozone contactor. The same ozone dosage was separately introduced into either the RPB or the CSTR for the investigation, while the experimental solution was continuously circulated within the apparatus consisting of the RPB and CSTR. The decolorization and mineralization efficiencies of RB5 in the course of ozonation are compared for these two methods. Moreover, the dissolved and off‐gas ozone concentrations were simultaneously monitored for the further analysis. As a result, the ozone mass transfer rate per unit volume of the RPB was significantly higher because of its higher mass transfer coefficient and gas–liquid concentration driving force. Furthermore, ozonation kinetics was found to be independent of the gravitational magnitude of an ozone gas–liquid contactor. Therefore, the results suggest employing RPBs as ozone‐contacting devices with the advantage of volume reduction. The experimental results, which can be used for further modeling of the ozonation process in the RPB, also show the requirement of correct design for the RPB. Consequently, the present study is useful for the understanding of practical application of RPBs. Copyright © 2004 Society of Chemical Industry 相似文献
78.
79.
80.