全文获取类型
收费全文 | 3118篇 |
免费 | 51篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 111篇 |
综合类 | 6篇 |
化学工业 | 528篇 |
金属工艺 | 159篇 |
机械仪表 | 53篇 |
建筑科学 | 36篇 |
矿业工程 | 5篇 |
能源动力 | 72篇 |
轻工业 | 146篇 |
水利工程 | 15篇 |
石油天然气 | 1篇 |
无线电 | 410篇 |
一般工业技术 | 519篇 |
冶金工业 | 854篇 |
原子能技术 | 63篇 |
自动化技术 | 199篇 |
出版年
2023年 | 9篇 |
2022年 | 20篇 |
2021年 | 36篇 |
2020年 | 14篇 |
2019年 | 27篇 |
2018年 | 26篇 |
2017年 | 23篇 |
2016年 | 29篇 |
2015年 | 23篇 |
2014年 | 47篇 |
2013年 | 123篇 |
2012年 | 87篇 |
2011年 | 132篇 |
2010年 | 102篇 |
2009年 | 122篇 |
2008年 | 131篇 |
2007年 | 103篇 |
2006年 | 83篇 |
2005年 | 77篇 |
2004年 | 83篇 |
2003年 | 86篇 |
2002年 | 90篇 |
2001年 | 67篇 |
2000年 | 53篇 |
1999年 | 62篇 |
1998年 | 332篇 |
1997年 | 180篇 |
1996年 | 169篇 |
1995年 | 95篇 |
1994年 | 89篇 |
1993年 | 91篇 |
1992年 | 44篇 |
1991年 | 38篇 |
1990年 | 33篇 |
1989年 | 44篇 |
1988年 | 47篇 |
1987年 | 40篇 |
1986年 | 30篇 |
1985年 | 33篇 |
1984年 | 29篇 |
1983年 | 28篇 |
1982年 | 28篇 |
1981年 | 26篇 |
1980年 | 35篇 |
1979年 | 16篇 |
1978年 | 15篇 |
1977年 | 19篇 |
1976年 | 33篇 |
1975年 | 8篇 |
1973年 | 4篇 |
排序方式: 共有3177条查询结果,搜索用时 666 毫秒
991.
Heat transfer coefficients were measured for the condensation of R410A and R22 inside internally grooved horizontal tubes. The experiment was performed for five different kinds of internally grooved tubes of about 8.00 mm o.d. the shapes of which were conventional helical grooved and herring-bone grooved ones. To measure the local heat transfer coefficients, the test section was subdivided into 10 small sections having 1 m working length. The ranges tested are as follows: the refrigerant mass velocity was from 130 to 400 kg/(m2/s) for R410A and R22, and the vapour pressure was 2.4l MPa for R410A and 1.53 MPa for R22. The obtained heat transfer data of R410A and R22 indicate that the values of the local heat transfer coefficients of the herring-bone grooved tube are about twice as large as those of helical one. All measured local heat transfer coefficients of condensation were compared with the predicted values from previous correlations proposed by other researchers, and were well correlated with the empirical equation using the frictional coefficients for each tube proposed by the author. 相似文献
992.
993.
By reducing an array matching problem to a string matching problem in a natural way, it is shown that efficient string matching algorithms may be applied to arrays. In this paper, based on the ideas due to Baker, an application of the two-dimensional on-line tessellation acceptor (2-dota) is presented for very rapid on-line detection of occurrences of a fixed set of keyarrays as embedded subarrays in a text array. The main part of the algorithm described in this paper consists of constructing two finite state pattern (string) matching machines from the keyarrays. By combining these two finite state pattern matching machines, we construct the 2-dota which, given an m × n text array, solves the two-dimensional pattern matching problem in m + n?1 steps. 相似文献
994.
New Brune-section simulation circuits using two operational amplifiers are proposed. A first-order allpass filter is constructed as an application using one of these simulation circuits. The measured response coincided closely with the calculated one in the frequency range less than about 10kHz. 相似文献
995.
The two extreme functionally equivalent possibilities of distributed or centralised crossbar function for realising a bank-based multiport memory are compared on the basis of required global signal and transistor numbers. With respect to both measures, the distributed crossbar function is found to be the better choice for practically relevant multiport-memory configurations. 相似文献
996.
Kumamoto Hiromitsu Tanaka Kazuo Inoue Koichi Henley Ernest J. 《Reliability, IEEE Transactions on》1980,(2):122-125
Reliability problems usually result in rare-event simulations, and hence direct Monte Carlo methods are extremely wasteful of computer time. This paper presents a new application of ``dagger-sampling', for calculating the system unavailability of a large complicated system represented by a coherent fault tree. Since a small number of uniform random numbers generate a number of trials, dagger-sampling appreciably reduces computation time, and hence a large number of trials become possible for the rare-event problems. Further, dagger-sampling decreases the variance of the Monte Carlo estimator because it generates negatively correlated samples. 相似文献
997.
998.
999.
Kajiya Fumihiko Kawagoe Kyoji Kodama Shinzo Hoki Noritake Inoue Michitoshi 《IEEE transactions on bio-medical engineering》1979,(7):422-428
This paper presents an approach to the problem of estimating the number of exponential functions and the pertinent parameters in the output of a radioactive tracer kinetic process. In particular, application of a criterion called an information theoretical criterion (AIC) for the estimation of the number of exponential functions is proposed; AIC was introduced by Akaike for the estimation of the order of linear dynamical systems and has been successfully applied for statistical model identification in a wide range of fields. Also, the maximum likelihood method was applied in order to evaluate AIC and to estimate decay constants and coefficients. 相似文献
1000.
The formation, stability and decomposition characteristics of the amorphous phase in binary titanium-silicon alloys rapidly quenched from the molten state have been investigated. Electron microscopy and diffraction coupled with X-ray diffraction techniques suggested that the amorphous phase could be obtained in alloys containing 15 to 20 at% silicon. The transformation of the amorphous phase to the equilibrium phases took place in two stages. A metastable b c c titanium solid solution, containing silicon in excess of the equilibrium value, formed initially, followed by the precipitation of the Ti5Si3 intermetallic compound. Microstructural features at various stages of decomposition have been described and interpreted in terms of the constitution of the alloys. Mechanical properties of the amorphous alloys have also been investigated. 相似文献