全文获取类型
收费全文 | 1933篇 |
免费 | 29篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 32篇 |
综合类 | 2篇 |
化学工业 | 751篇 |
金属工艺 | 64篇 |
机械仪表 | 52篇 |
建筑科学 | 59篇 |
矿业工程 | 12篇 |
能源动力 | 82篇 |
轻工业 | 103篇 |
水利工程 | 3篇 |
石油天然气 | 1篇 |
武器工业 | 3篇 |
无线电 | 143篇 |
一般工业技术 | 248篇 |
冶金工业 | 45篇 |
原子能技术 | 7篇 |
自动化技术 | 359篇 |
出版年
2024年 | 8篇 |
2023年 | 10篇 |
2022年 | 75篇 |
2021年 | 106篇 |
2020年 | 25篇 |
2019年 | 39篇 |
2018年 | 49篇 |
2017年 | 46篇 |
2016年 | 75篇 |
2015年 | 48篇 |
2014年 | 65篇 |
2013年 | 137篇 |
2012年 | 98篇 |
2011年 | 97篇 |
2010年 | 110篇 |
2009年 | 76篇 |
2008年 | 92篇 |
2007年 | 70篇 |
2006年 | 54篇 |
2005年 | 58篇 |
2004年 | 52篇 |
2003年 | 50篇 |
2002年 | 44篇 |
2001年 | 35篇 |
2000年 | 21篇 |
1999年 | 26篇 |
1998年 | 17篇 |
1997年 | 22篇 |
1996年 | 28篇 |
1995年 | 16篇 |
1994年 | 24篇 |
1993年 | 19篇 |
1992年 | 11篇 |
1991年 | 19篇 |
1990年 | 22篇 |
1989年 | 10篇 |
1988年 | 21篇 |
1987年 | 18篇 |
1986年 | 12篇 |
1985年 | 14篇 |
1984年 | 23篇 |
1983年 | 24篇 |
1982年 | 18篇 |
1981年 | 23篇 |
1980年 | 14篇 |
1979年 | 13篇 |
1978年 | 8篇 |
1977年 | 9篇 |
1975年 | 7篇 |
1974年 | 3篇 |
排序方式: 共有1966条查询结果,搜索用时 15 毫秒
101.
The architecture and performance of the face and eyes detection system based on the Haar cascade classifiers 总被引:1,自引:0,他引:1
The precise face and eyes detection is essential in many human–machine interface systems. Therefore, it is necessary to develop a reliable and efficient object detection method. In this paper we present the architecture of a hierarchical face and eyes detection system using the Haar cascade classifiers (HCC) augmented with some simple knowledge-based rules. The influence of the training procedure on the performance of the particular HCCs has been investigated. Additionally, we compared the efficiency of other authors’ face and eyes HCCs with the efficiency of those trained by us. By applying the proposed system to the set of 10,000 test images we were able to properly detect and precisely localize 94% of the eyes. 相似文献
102.
Beat-to-beat heart rate was measured for 50 normal and 60 diabetic subjects. Autonomic dysfunction in diabetic subject was assessed by the Ewing test. Next we employed two nonlinear measures of cardiac interbeat interval dynamics: entropy-like measure on AIP diagram, and parameter "forbidden words" for symbolic dynamics. We test their performance in detecting diabetic autonomic dysfunction and show that there is a very significant relationship between the measures and the Ewing score. 相似文献
103.
On-line Algorithm for Blind Signal Extraction of Arbitrarily Distributed,but Temporally Correlated Sources Using Second Order Statistics 总被引:4,自引:0,他引:4
Most of the algorithms for blind separation/extraction and independent component analysis (ICA) can not separate mixtures of sources with extremely low kurtosis or colored Gaussian sources. Moreover, to separate mixtures of super- and sub-Gaussian signals, it is necessary to use adaptive (time-variable) or switching nonlinearities which are controlled via computationally intensive measures, such as estimation of the sign of kurtosis of extracted signals. In this paper, we develop a very simple neural network model and an efficient on-line adaptive algorithm that sequentially extract temporally correlated sources with arbitrary distributions, including colored Gaussian sources and sources with extremely low values (or even zero) of kurtosis. The validity and performance of the algorithm have been confirmed by extensive computer simulation experiments. 相似文献
104.
105.
The effect of methanol, acetone, formalin and glucose on the nitrification process in the packed bed reactors has been investigated. For the utilized compounds the inhibition constant Ki was determined according to Dixon's method. The determined values were as follows: methanol Ki = 116.0 mg l?1; acetone Ki = 804.2 mg l?1; formalin Ki = 61.5 mg l?1. The value of Ki for glucose has not been determined because glucose in applied concentration up to 11,325 mg l?1 had no effect on the nitrification course. 相似文献
106.
The objective of this paper is to compare the reliability level of prestressed concrete bridge girders designed using three codes: Spanish Norma IAP-98 (1998), ENV 1991-3 Eurocode 1 (1994), and AASHTO LRFD (1998). Typical precast girders used in Spain are considered. Load and resistance parameters are treated as random variables. The statistical parameters are based on the available literature, test data and load surveys. Reliability indices are calculated by iterations. The results indicate that Eurocode is more conservative than the other two codes, and AASHTO LRFD is the most permissive code. 相似文献
107.
The design of thin structures must take into account the overall instability and the instability of component plates in the form of local buckling. This investigation is concerned with the interactive buckling of thin-walled structures with central intermediate stiffeners under axial compression and/or a constant bending moment. The structures are assumed to be simply supported at the ends. The lower bound estimation of load-carrying capacity on the basis of the post-buckling behaviour of thin-walled structures with imperfections is studied when the distortional deformations are taken into account. The asymptotic expansion established by Byskov and Hutchinson (AIAA J. 15 (1977) 941) is employed in the numerical calculations performed using the transition matrix method. The present paper is a continuation of previous work by the authors (Int. J. Solids Struct. 32 (1995) 1501; 33 (1996) 315; 37 (2000) 3323), where the interactive buckling of thin-walled beam-columns with central intermediate stiffeners in the first- and the second-order approximation were considered. In the solution obtained, the transformation of buckling modes with an increase in the load up to the ultimate load, the effect of cross-sectional distortions and the shear lag phenomenon are included. The results obtained are compared with data reported by other authors. 相似文献
108.
Nowak Andrzej; Vallacher Robin R.; Tesser Abraham; Borkowski Wojciech 《Canadian Metallurgical Quarterly》2000,107(1):39
Using cellular automata, the authors show how mutual influences among elements of self-relevant information give rise to dynamism, differentiation, and global evaluation in self-concept. The model assumes a press for integration that promotes internally generated dynamics and enables the self-structure to operate as a self-organizing dynamical system. When this press is set at high values, the self can resist inconsistent information and reestablish equilibrium after being perturbed by such information. A weak press for integration, on the other hand, impairs self-organization tendencies, making the system vulnerable to external information. Paradoxically, external information of a random nature may enhance the emergence of a stable self-structure in an initially disordered system. The simulation results suggest that important global properties of the self reflect the operation of integration processes that are generic in complex systems. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
109.
Łukasz Ciupiński Grzegorz Krzesiński Krzysztof Kurzydłowski Piotr Marek Tomasz Zagrajek Victor Bykov Paweł Czarkowski Wolfgang Daenner Andrzej Dudek Felix Schauer 《Fusion Engineering and Design》2009,84(2-6):613-617
The stellarator Wendelstein 7-X is under construction at the Max-Planck-Institut für Plasmaphysik in Greifswald. Its superconducting coil system is fixed by a massive structure. During machine operation the coils exert high forces and moments against each other and the central support structure (CSS). Therefore, the detailed analysis of the coil to CSS connections, the so-called central support elements (CSE), is a critical item. The major details of the design have been frozen; nevertheless, there is still need for detailed analysis of the CSEs due to assembly issues, and later on for exploring operational limits of the machine. These analyses have to be performed quickly, reliably, and shall provide results in a standardized form to enable timely responses to the assembly team. Special numerical tools – finite element (FE) parametric models of CSEs – have been developed for the purpose of such analyses. In the models, the geometry, material properties, contact conditions, loads as well as results presentation are defined in a parametric way. The use of the developed models for the definition of the final weld parameters, bolt preloads, assessment of acceptable tolerances, and optimal positions of the CSE-wedges before welding is also discussed. 相似文献
110.
Jorge?OyarzúnEmail author Hugo?Maturana Andrzej?Paulo Anna?Pasieczna 《Mine Water and the Environment》2003,22(3):155-161
Abstract.
Active sediments from the Elqui River in Chile were
sampled 4 times at 10 sites during 2000. Concentrations of Ag,
Ba, Cd, Co, Cr, Hg, Mn, Mo, Ni, Pb, Sr, Ti, V, Al, Ca, Fe, K,
Mg, Na, P, and S were normal. Zinc levels were clearly high, and
those of Cu (hundred to thousands ppm) and As (tens to hundreds
ppm) were highly anomalous. Dissolved Cu (0.1-12.7 ppm) and Zn
(0.2-2.2 ppm) levels were also very high. The anomalies of the
upper tributaries are due to the El Indio–Tambo Au-Cu-As
district and large hydrothermal alteration zones at altitudes
between 3500–4500 m. Lower on the river, old and active tailing
waste deposits and on-going mining operations in the Talcuna Cu
(Pb) district are responsible. Partially eroded tailing deposits
in the alluvial plain of the Elqui River and its tributaries,
and especially in the El Indio-Tambo district, after mine
closure in 2000, warrant special attention. 相似文献