全文获取类型
收费全文 | 209289篇 |
免费 | 20541篇 |
国内免费 | 11595篇 |
专业分类
电工技术 | 17171篇 |
技术理论 | 13篇 |
综合类 | 21246篇 |
化学工业 | 22023篇 |
金属工艺 | 9131篇 |
机械仪表 | 17766篇 |
建筑科学 | 24149篇 |
矿业工程 | 8178篇 |
能源动力 | 9091篇 |
轻工业 | 15370篇 |
水利工程 | 8943篇 |
石油天然气 | 10957篇 |
武器工业 | 2689篇 |
无线电 | 12355篇 |
一般工业技术 | 21695篇 |
冶金工业 | 8631篇 |
原子能技术 | 3255篇 |
自动化技术 | 28762篇 |
出版年
2024年 | 858篇 |
2023年 | 2630篇 |
2022年 | 5469篇 |
2021年 | 6425篇 |
2020年 | 6599篇 |
2019年 | 5380篇 |
2018年 | 5395篇 |
2017年 | 6561篇 |
2016年 | 7891篇 |
2015年 | 8300篇 |
2014年 | 13372篇 |
2013年 | 13696篇 |
2012年 | 15435篇 |
2011年 | 17104篇 |
2010年 | 12339篇 |
2009年 | 12545篇 |
2008年 | 11773篇 |
2007年 | 14055篇 |
2006年 | 12270篇 |
2005年 | 10329篇 |
2004年 | 8683篇 |
2003年 | 7406篇 |
2002年 | 6083篇 |
2001年 | 5034篇 |
2000年 | 4266篇 |
1999年 | 3588篇 |
1998年 | 3048篇 |
1997年 | 2528篇 |
1996年 | 2128篇 |
1995年 | 1757篇 |
1994年 | 1577篇 |
1993年 | 1134篇 |
1992年 | 1032篇 |
1991年 | 764篇 |
1990年 | 670篇 |
1989年 | 560篇 |
1988年 | 490篇 |
1987年 | 310篇 |
1986年 | 255篇 |
1985年 | 237篇 |
1984年 | 281篇 |
1983年 | 248篇 |
1982年 | 210篇 |
1981年 | 105篇 |
1980年 | 107篇 |
1979年 | 70篇 |
1978年 | 54篇 |
1977年 | 50篇 |
1976年 | 44篇 |
1959年 | 35篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
161.
162.
163.
Using an integrated process of data and modeling in HRA 总被引:1,自引:0,他引:1
John Wreathall Dennis Bley Emilie Roth Jordan Multer Thomas Raslear 《Reliability Engineering & System Safety》2004,83(2):221
The paper describes an approach taken to estimate the probabilities of failure associated with various railroad tasks to prevent accidents (principally collisions and derailments). These probabilities were estimated using an expert elicitation process that used partially relevant data available from a variety of databases and that were filtered and scaled to make them more directly relevant to the analyses being performed. Extensive qualitative studies were performed prior to the elicitation process to identify relevant contexts under which the tasks can be performed. 相似文献
164.
165.
166.
In this paper, the moving least-squares differential quadrature (MLSDQ) method is employed for free vibration of thick antisymmetric laminates based on the first-order shear deformation theory. The generalized displacements of the laminates are independently approximated with the centered moving least-squares (MLS) technique within each domain of influence. The MLS nodal shape functions and their partial derivatives are computed quickly through back-substitutions after only one LU decomposition. Subsequently, the weighting coefficients in the MLSDQ discretization are determined with the nodal partial derivatives of the MLS shape functions. The MLSDQ method combines the merits of both the differential quadrature and meshless methods which can be conveniently applied to complex domains and irregular discretizations without loss of implementation efficiency and numerical accuracy. The natural frequencies of the laminates with various edge conditions, ply angles, and shapes are calculated and compared with the existing solutions to study the numerical accuracy and stability of the MLSDQ method. Effects of support size, order of completeness of basis functions, and node irregularity on the numerical accuracy are investigated in detail. 相似文献
168.
169.
The Two-Dimensional Clifford-Fourier Transform 总被引:1,自引:0,他引:1
Fred Brackx Nele De Schepper Frank Sommen 《Journal of Mathematical Imaging and Vision》2006,26(1-2):5-18
Recently several generalizations to higher dimension of the Fourier transform using Clifford algebra have been introduced,
including the Clifford-Fourier transform by the authors, defined as an operator exponential with a Clifford algebra-valued
kernel.
In this paper an overview is given of all these generalizations and an in depth study of the two-dimensional Clifford-Fourier
transform of the authors is presented. In this special two-dimensional case a closed form for the integral kernel may be obtained,
leading to further properties, both in the L
1 and in the L
2 context. Furthermore, based on this Clifford-Fourier transform Clifford-Gabor filters are introduced.
AMS subject classification numbers: 42B10, 30G35
Fred Brackx received a diploma degree in mathematics from Ghent University, Belgium, in 1970 and a Ph.D. degree in mathematics from the
same university in 1973. Since 1984 he is professor for mathematical analysis at Ghent University and currently he is leading
the Clifford Research Group. His main interests are function theory and functional analysis for functions with values in quaternion
and Clifford algebras. The research covers Clifford distributions, generalized Fourier, Radon and Hilbert transforms, orthogonal
polynomials and multi-dimensional wavelets.
Nele De Schepper received a diploma degree in mathematics from Ghent University, Belgium, in 2001. Since then she holds an assistantship at
the Department of Mathematical Analysis of Ghent University and is a member of the Clifford Research Group. Her main interests
are function theory and functional analysis for functions with values in Clifford algebras. The research covers generalized
Fourier transforms, orthogonal polynomials and multi-dimensional wavelets.
Frank Sommen received a diploma degree in mathematics from Ghent University, Belgium, in 1978, a Ph.D. degree in mathematics from the
same university in 1980, and a habilitation degree in mathematical analysis in 1984. From 1978 until 1999 he was at the National
Fund for Scientific Research (Flanders). Since 2000 he holds a Research professorship at Ghent University. His main interests
are function theory and functional analysis for functions with values in quaternion and Clifford algebras. The research covers
Clifford distributions, generalized Fourier, Radon and Hilbert transforms, orthogonal polynomials and multi-dimensional wavelets,
algebraic analysis, hyperfunctions and radial algebra. 相似文献
170.
结合国内外对碳钢CO2腐蚀影响因素的研究成果,采用模糊层次分析法对影响输油管道 CO2腐蚀的因素进行定量分析,明确界定出这些因素对二氧化碳腐蚀影响的相对重要性(权重),为后续制定经济有效的管道内腐蚀防护措施提供了客观依据。 相似文献