全文获取类型
收费全文 | 184687篇 |
免费 | 23275篇 |
国内免费 | 16944篇 |
专业分类
电工技术 | 14634篇 |
技术理论 | 9篇 |
综合类 | 24168篇 |
化学工业 | 13868篇 |
金属工艺 | 8624篇 |
机械仪表 | 16789篇 |
建筑科学 | 20224篇 |
矿业工程 | 6178篇 |
能源动力 | 7640篇 |
轻工业 | 5471篇 |
水利工程 | 10459篇 |
石油天然气 | 8866篇 |
武器工业 | 2704篇 |
无线电 | 13500篇 |
一般工业技术 | 22073篇 |
冶金工业 | 6852篇 |
原子能技术 | 1870篇 |
自动化技术 | 40977篇 |
出版年
2024年 | 913篇 |
2023年 | 2644篇 |
2022年 | 5063篇 |
2021年 | 5857篇 |
2020年 | 6375篇 |
2019年 | 5578篇 |
2018年 | 5403篇 |
2017年 | 6761篇 |
2016年 | 7707篇 |
2015年 | 8200篇 |
2014年 | 11131篇 |
2013年 | 11814篇 |
2012年 | 13658篇 |
2011年 | 14641篇 |
2010年 | 11398篇 |
2009年 | 11905篇 |
2008年 | 11715篇 |
2007年 | 13495篇 |
2006年 | 11796篇 |
2005年 | 10122篇 |
2004年 | 8253篇 |
2003年 | 7126篇 |
2002年 | 5685篇 |
2001年 | 4709篇 |
2000年 | 4178篇 |
1999年 | 3275篇 |
1998年 | 2711篇 |
1997年 | 2328篇 |
1996年 | 2150篇 |
1995年 | 1842篇 |
1994年 | 1499篇 |
1993年 | 1068篇 |
1992年 | 888篇 |
1991年 | 683篇 |
1990年 | 567篇 |
1989年 | 457篇 |
1988年 | 305篇 |
1987年 | 195篇 |
1986年 | 140篇 |
1985年 | 123篇 |
1984年 | 127篇 |
1983年 | 54篇 |
1982年 | 84篇 |
1981年 | 53篇 |
1980年 | 62篇 |
1979年 | 58篇 |
1978年 | 18篇 |
1974年 | 10篇 |
1959年 | 19篇 |
1951年 | 12篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
NUMERICALSIMULATIONSOFWHOLEFIELDBEHAVIORFORROUNDBUOYANTJETLiWei,HuaiWen-xin(WuhanUniversityofHydraulicandElectricEngineering,... 相似文献
92.
K. Y. Sze W. K. Chan T. H. H. Pian 《International journal for numerical methods in engineering》2002,55(7):853-878
This paper presents eight‐node solid‐shell elements for geometric non‐linear analysis of elastic shells. To subdue shear, trapezoidal and thickness locking, the assumed natural strain method and an ad hoc modified generalized laminate stiffness matrix are employed. A selectively reduced integrated element is formulated with its membrane and bending shear strain components taken to be constant and equal to the ones evaluated at the element centroid. With the generalized stresses arising from the modified generalized laminate stiffness matrix assumed to be independent from the ones obtained from the displacement, an extended Hellinger–Reissner functional can be derived. By choosing the assumed generalized stresses similar to the assumed stresses of a previous solid element, a hybrid‐stress solid‐shell element is formulated. Commonly employed geometric non‐linear homogeneous and laminated shell problems are attempted and our results are close to those of other state‐of‐the‐art elements. Moreover, the hybrid‐stress element converges more readily than the selectively reduced integrated element in all benchmark problems. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
93.
Michael Anthony Puso Tod A. Laursen 《International journal for numerical methods in engineering》2002,54(8):1161-1194
In this work, a method is developed for smoothing three‐dimensional contact surfaces. The method can be applied to both regular and irregular meshes. The algorithm employs Gregory patches to interpolate finite element nodes and provide tangent plane continuity between adjacent patches. The resulting surface interpolation is used to calculate gaps and contact forces, in a variationally consistent way, such that contact forces due to normal and frictional contact vary smoothly as slave nodes transition from one patch to the next. This eliminates the ‘chatter’ which typically occurs in a standard contact algorithm when a slave node is situated near a master facet edge. The elimination of this chatter provides a significant improvement in convergence behaviour, which is illustrated by a number of numerical examples. Furthermore, smoothed surfaces also provide a more accurate representation of the actual surface, such that resulting stresses and forces can be more accurately computed with coarse meshes in many problems. This fact is also demonstrated by the numerical examples. Published in 2002 by John Wiley & Sons, Ltd. 相似文献
94.
压电类智能层合结构的力学和计算模型综述 总被引:2,自引:0,他引:2
综述了压电类智能层合结构的力学和计算模型。基于大量国内外有关压电类智能层合结构的文献 ,根据各自采用的运动学假设、场变量的近似、压电层的表达法以及曲率和温度的影响 ,对压电层合结构的力学和计算模型进行了分类 ,阐述了各种理论的特点及一般形式。 相似文献
95.
96.
V. P. Naumenko 《Strength of Materials》1996,28(1):10-18
The adoption of unified fracture mechanics terminology (UFMT) will promote efficient communication between specialists in different fields of fracture research, harmonization of national and international standards relating to fracture mechanics, and last but not least improvement of the existing methodology for teaching and education in fatigue and fracture. In this paper the definitions of some basic and related terms included in different standards on fracture mechanics terminology are confronted with one another. Alternative definitions of the same terms are offered. By this strategy the author tries to show that the definitions of basic and related terms appropriate for the UFMT should emerge as a consequence of harmonizing a crack model with an actual crack and then both taken together with a fracture model, laboratory test methods, and failure assessment codes.Published in Problemy Prochonsti, No. 1, pp. 17–29, January, 1996.This paper is published as a matter of discussion. 相似文献
97.
The effect of particle distribution on damage formation in particulate reinforced metal matrix composites deformed in compression 总被引:1,自引:0,他引:1
P.B. Prangnell S.J. Barnes S.M. Roberts P.J. Withers 《Materials Science and Engineering: A》1996,220(1-2):41-56
Image analysis results are reported on the generation of damage in particulate reinforced metal matrix composites during compressive deformation. The technique allows the automated collection of data on the incidence of particle fracture and void formation in the matrix as a function of important microstructural parameters such as local particle volume fraction and particle size. There is a strong relationship between damage and the local volume fraction of the reinforcement proving that damage formation is accentuated in regions of particle clustering. With the SiC reinforced materials examined, there was observed to be a change in dominance of damage mechanism from particle fracture at low local volume fractions to void formation in the matrix within strongly clustered regions. The results are compared with finite element (FE) modelling of the compressive deformation of clustered particles using a simple cluster of equi-spaced particles. The FE results suggest that plastic flow is generally inhibited in clustered regions. In certain highly clustered configurations shielding is such that flow does not occur in the heart of the cluster even at high levels of average plastic strain. The modelling suggests that the change in dominance of damage mechanism is related to the dramatic increase in tensile hydrostatic stresses in the matrix with higher levels of particle clustering. 相似文献
98.
本文介绍了一种实用的数据库设计方法,它以实体分析法为理论基础,通过对我们日常使用的表进行聚集和归类,完成数据库的逻辑设计,所设计的数据库满足BNOF范式。同时该方法可操作性较强,本文还介绍了自行设计的ERCM数据库辅助设计工具。 相似文献
99.
100.
A general numerical model is described for the dissolution kinetics of spherical particles in binary systems for any combination of first order reactions at the particle-matrix interface and long distance diffusion within the matrix. The model is applicable to both finite and infinite media and handles both complete and partial particle dissolution. It is shown that interfacial reactions can have a strong effect on the dissolution kinetics, the solute concentration at the particle-matrix interface and the solute concentration profile in the matrix. 相似文献