全文获取类型
收费全文 | 10835篇 |
免费 | 1897篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 582篇 |
综合类 | 652篇 |
化学工业 | 7322篇 |
金属工艺 | 125篇 |
机械仪表 | 51篇 |
建筑科学 | 357篇 |
矿业工程 | 42篇 |
能源动力 | 72篇 |
轻工业 | 406篇 |
水利工程 | 19篇 |
石油天然气 | 14篇 |
武器工业 | 3篇 |
无线电 | 132篇 |
一般工业技术 | 1861篇 |
冶金工业 | 86篇 |
原子能技术 | 11篇 |
自动化技术 | 1004篇 |
出版年
2023年 | 552篇 |
2022年 | 361篇 |
2021年 | 640篇 |
2020年 | 616篇 |
2019年 | 489篇 |
2018年 | 496篇 |
2017年 | 336篇 |
2016年 | 517篇 |
2015年 | 605篇 |
2014年 | 645篇 |
2013年 | 832篇 |
2012年 | 431篇 |
2011年 | 324篇 |
2010年 | 644篇 |
2009年 | 710篇 |
2008年 | 295篇 |
2007年 | 242篇 |
2006年 | 159篇 |
2005年 | 167篇 |
2004年 | 213篇 |
2003年 | 171篇 |
2002年 | 202篇 |
2001年 | 91篇 |
1999年 | 62篇 |
1998年 | 67篇 |
1996年 | 72篇 |
1995年 | 100篇 |
1994年 | 71篇 |
1993年 | 130篇 |
1992年 | 95篇 |
1991年 | 79篇 |
1990年 | 87篇 |
1989年 | 95篇 |
1988年 | 75篇 |
1987年 | 94篇 |
1986年 | 108篇 |
1985年 | 90篇 |
1984年 | 89篇 |
1983年 | 111篇 |
1982年 | 75篇 |
1981年 | 108篇 |
1980年 | 84篇 |
1979年 | 67篇 |
1977年 | 69篇 |
1976年 | 59篇 |
1975年 | 69篇 |
1974年 | 72篇 |
1973年 | 139篇 |
1972年 | 76篇 |
1971年 | 51篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Prof. Dr. S. M. Rump 《Computing》1989,42(2-3):225-238
A method is described which produces guaranteed bounds for a solution of the generalized complex eigenproblem. The method extends a similar approach for general systems of nonlinear equations to the special case of complex pencils, where under weaker assumptions stronger assertions can be proved. 相似文献
102.
Prof. em. M. Baruch 《Acta Mechanica》1998,131(1-2):89-101
Summary Changes in the mass matrix of a dynamic structure can be detected by using reduced measurements [1]. In the here proposed method the stiffness matrix is assumed to be correct. The missing measurements can be calculated by utilizing the connection between the measured and unmeasured quantities through the iterative process of identification of the tested structure. The missing measurements and to some extent the partial measurements obtained during the tests are treated as hidden functions of the mass parameters of the structure. This makes the Euclidean norm of the appropriate matrix to be minimized a nonlinear function of the parameters. This norm may have more than one minimum. The changes in the mass matrix must be identified by looking for the global mininum of the Euclidean norm. The global minimum can be found by changing the initial values of the mass parameters or by changing some special coefficients, or both.In order to identify the mass parameters of the structure the measured and the supplied missing quantities are forced to comply with the general laws for a linear structure. This compliance is achieved during any step of the iterative process. 相似文献
103.
Summary Stability of a twisted and axially compressed elastic rod is analysed using the Euler method of adjacent equilibrium configuration. The constitutive equations of the rod are assumed in the form that takes into account both shear of the cross-sections and compressibility of the rod axis. It is shown that bifurcation points of the non-linear system of equations describing equilibrium are determined from the linearized system of equations. The influence of shear and compressibility on the critical values of twisting couple and compressive force is obtained. Moreover, the bifurcation pattern is examined by using the Liapunov-Schmidt method. 相似文献
104.
Prof. Dr. rer. nat. Helmut F. Bauer 《Forschung im Ingenieurwesen》1985,51(5):133-140
The response due to time-fluctuating temperature distribution applied at the free surface of a viscoelastic cylindrical liquid
column with no axial dependency has been determined analytically. The amplitude of the radial- and angular velocity as well
as the free liquid surface elevation has been presented as a function of the “reduced” forcing frequency of the oscillatory
temperature and has numerically been evaluated for an angular temperature field proportional to sin 2φ. It was found, that
visco-elasticity as described by the Maxwell model has quite some influence upon the liquid behavior. It shows for larger
relaxation times besides the enlarged resonance peak additional peaks below and above resonance. This is particularly evident
inside the liquid column, indicating a more pronounced elastic behavior of the liquid. 相似文献
105.
Impacts of green roofs and rain water use on the water balance and groundwater levels in urban areas 总被引:1,自引:0,他引:1
Dr. P. Göbel Prof. Dr. W.G. Coldewey Dr.-Ing. C. Dierkes Dipl.-Math. H. Kories Dr. J. Meßer Dr.-Ing. E. Meißner 《Grundwasser》2007,12(3):189-200
Ohne Zusammenfassung
Impacts of green roofs and rain water use on the water balance and groundwater levels in urban areas
相似文献
106.
A consistent modelling scheme for digital images is presented, with the grey-level raster image as input and the list-oriented polygonal image as output. The output information consists of two parts: The metric of the polygonal object, represented by coordinates of marked positions, and the global topology, which takes the form of a two-dimensional topologic order. The central problem, which has to be solved, is to select a digital polygon, approximating a digital arc such that the essential feature of the arc is represented at a predefined precision level. The proposed algorithm uses simple incremental calculations of INTEGER quantities to solve the problem. 相似文献
107.
108.
A class of Generalized Approximate Inverse Matrix (GAIM) techniques, based on the concept of LU-sparse factorization procedures, is introduced for computing explicitly approximate inverses of large sparse unsymmetric matrices of irregular structure, without inverting the decomposition factors. Explicit preconditioned iterative methods, in conjunction with modified forms of the GAIM techniques, are presented for solving numerically initial/boundary value problems on multiprocessor systems. Application of the new methods on linear boundary-value problems is discussed and numerical results are given. 相似文献
109.
Prof. A. Guran 《Acta Mechanica》1993,97(1-2):91-100
Summary The nonlinear behaviour and static stability of a compressible elastic column whose flexural resistance changes as it is loaded is studied. A two-degree-of-freedom, compressible rod model of the column is analysed. Various types of load-stiffness relationships are considered. Post-buckling behaviour under static unidirectional loads is investigated. Singularities of the equilibrium paths of the column are classified according to the slenderness ratio of the column and the load-stiffness relationship of its support.On leave from Department of Mechanical Engineering, University of Toronto, 5 King's College Road Toronto, Ontario, Canada, M5S 1A4 相似文献
110.