全文获取类型
收费全文 | 145876篇 |
免费 | 7581篇 |
国内免费 | 4607篇 |
专业分类
电工技术 | 6286篇 |
技术理论 | 3篇 |
综合类 | 7606篇 |
化学工业 | 20177篇 |
金属工艺 | 8509篇 |
机械仪表 | 7199篇 |
建筑科学 | 7520篇 |
矿业工程 | 2271篇 |
能源动力 | 2906篇 |
轻工业 | 8372篇 |
水利工程 | 2767篇 |
石油天然气 | 3048篇 |
武器工业 | 702篇 |
无线电 | 16964篇 |
一般工业技术 | 23034篇 |
冶金工业 | 4824篇 |
原子能技术 | 1080篇 |
自动化技术 | 34796篇 |
出版年
2024年 | 399篇 |
2023年 | 1120篇 |
2022年 | 2187篇 |
2021年 | 3007篇 |
2020年 | 2289篇 |
2019年 | 1758篇 |
2018年 | 16102篇 |
2017年 | 15353篇 |
2016年 | 11802篇 |
2015年 | 3314篇 |
2014年 | 3576篇 |
2013年 | 4140篇 |
2012年 | 7831篇 |
2011年 | 14219篇 |
2010年 | 12613篇 |
2009年 | 9842篇 |
2008年 | 11119篇 |
2007年 | 11654篇 |
2006年 | 3844篇 |
2005年 | 4185篇 |
2004年 | 3266篇 |
2003年 | 3042篇 |
2002年 | 2729篇 |
2001年 | 2021篇 |
2000年 | 1616篇 |
1999年 | 1082篇 |
1998年 | 702篇 |
1997年 | 573篇 |
1996年 | 487篇 |
1995年 | 370篇 |
1994年 | 289篇 |
1993年 | 205篇 |
1992年 | 186篇 |
1991年 | 146篇 |
1990年 | 85篇 |
1989年 | 81篇 |
1988年 | 66篇 |
1987年 | 43篇 |
1968年 | 43篇 |
1967年 | 33篇 |
1966年 | 42篇 |
1965年 | 44篇 |
1963年 | 28篇 |
1960年 | 30篇 |
1959年 | 40篇 |
1958年 | 37篇 |
1957年 | 36篇 |
1956年 | 34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
31.
32.
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
33.
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
34.
The multi-homogeneous Bezout number is a bound for the number of solutions of a system of multi-homogeneous polynomial equations,
in a suitable product of projective spaces. Given an arbitrary, not necessarily multi-homogeneous, system, one can ask for
the optimal multi-homogenization that would minimize the Bezout number. In this paper it is proved that the problem of computing,
or even estimating, the optimal multi-homogeneous Bezout number is actually NP-hard. In terms of approximation theory for
combinatorial optimization, the problem of computing the best multi-homogeneous structure does not belong to APX, unless P
= NP. Moreover, polynomial-time algorithms for estimating the minimal multi-homogeneous Bezout number up to a fixed factor
cannot exist even in a randomized setting, unless BPP ⫆ NP. 相似文献
35.
36.
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
37.
38.
39.
40.
本文介绍了以微处理器与IBM-PC上的彩色/图形适配器相结合构成的一种智能显示系统。本系统主要解决数控系统中主CPU与6845CRTC争夺显示缓存的矛盾。保证了6845CRTC对显示缓存操作的时间要求;并且保证了数控系统中主CPU对显示缓存操作的随意性。 相似文献