全文获取类型
收费全文 | 148639篇 |
免费 | 15088篇 |
国内免费 | 9523篇 |
专业分类
电工技术 | 14678篇 |
技术理论 | 2篇 |
综合类 | 18392篇 |
化学工业 | 16136篇 |
金属工艺 | 6446篇 |
机械仪表 | 10698篇 |
建筑科学 | 18303篇 |
矿业工程 | 6685篇 |
能源动力 | 5161篇 |
轻工业 | 7868篇 |
水利工程 | 6727篇 |
石油天然气 | 6318篇 |
武器工业 | 2045篇 |
无线电 | 10342篇 |
一般工业技术 | 18902篇 |
冶金工业 | 5726篇 |
原子能技术 | 2471篇 |
自动化技术 | 16350篇 |
出版年
2024年 | 629篇 |
2023年 | 1792篇 |
2022年 | 3421篇 |
2021年 | 4016篇 |
2020年 | 4549篇 |
2019年 | 3919篇 |
2018年 | 3788篇 |
2017年 | 4820篇 |
2016年 | 5307篇 |
2015年 | 5554篇 |
2014年 | 8996篇 |
2013年 | 8602篇 |
2012年 | 11361篇 |
2011年 | 11515篇 |
2010年 | 8896篇 |
2009年 | 9258篇 |
2008年 | 8540篇 |
2007年 | 10583篇 |
2006年 | 9333篇 |
2005年 | 7828篇 |
2004年 | 6417篇 |
2003年 | 5534篇 |
2002年 | 4623篇 |
2001年 | 3885篇 |
2000年 | 3452篇 |
1999年 | 2984篇 |
1998年 | 2330篇 |
1997年 | 2045篇 |
1996年 | 1744篇 |
1995年 | 1567篇 |
1994年 | 1305篇 |
1993年 | 961篇 |
1992年 | 854篇 |
1991年 | 591篇 |
1990年 | 496篇 |
1989年 | 501篇 |
1988年 | 360篇 |
1987年 | 205篇 |
1986年 | 166篇 |
1985年 | 77篇 |
1984年 | 71篇 |
1983年 | 41篇 |
1982年 | 43篇 |
1981年 | 58篇 |
1980年 | 32篇 |
1979年 | 36篇 |
1978年 | 18篇 |
1977年 | 14篇 |
1975年 | 16篇 |
1959年 | 33篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Using boundary element based three dimensional modelling for linear fracture mechanics, we present an analysis of cracking in a homogeneous medium subject to contact load. The proposed iterative solution procedure allows a simultaneous treatment of a reasonable number of partially closed cracks. It is shown that the most probable direction of propagation of a vertical internal crack is strongly dependent on its size compared to the contact radius and its location with respect to the axis of maximum normal load. 相似文献
32.
Sorin Manolache Petru Eles Zebo Peng 《International journal of parallel programming》2007,35(2):125-156
As feature sizes shrink, transient failures of on-chip network links become a critical problem. At the same time, many applications
require guarantees on both message arrival probability and response time. We address the problem of transient link failures
by means of temporally and spatially redundant transmission of messages, such that designer-imposed message arrival probabilities
are guaranteed. Response time minimisation is achieved by a heuristic that statically assigns multiple copies of each message
to network links, intelligently combining temporal and spatial redundancy. Concerns regarding energy consumption are addressed
in two ways. First, we reduce the total amount of transmitted messages, and, second, we minimise the application response
time such that the resulted time slack can be exploited for energy savings through voltage reduction. The advantages of the
proposed approach are guaranteed message arrival probability and guaranteed worst case application response time. 相似文献
33.
A. Yu. Luchka 《Cybernetics and Systems Analysis》2003,39(6):880-888
A modified variational-gradient method is proposed and substantiated for quasilinear operator equations in a Hilbert space. 相似文献
34.
Chuanju Xu 《Journal of scientific computing》2006,27(1-3):495-505
A stabilization method for the spectral element computation of incompressible flow problems is investigated. It is based on a filtering procedure which consists in filtering the velocity field by a spectral vanishing Helmholtz-type operator at each time step. Relationship between this filtering procedure and SVV-stabilization method, introduced recently in [JCP, 2004, 196(2), p680], is established. A number of numerical examples are presented to show the accuracy and stabilization capability of the method. 相似文献
35.
This paper studies a Kansas Department of Transportation welded plate girder bridge that developed fatigue cracks at small web gaps close to the girder top flange. Repair had been previously performed by softening the connection plate end with a slot retrofit, but cracks were recently found to have reinitiated at some of the repaired details and are again propagating. A comprehensive finite-element method study was performed to investigate the cracking behavior observed in the bridge and to recommend appropriate measures for future bridge retrofit. The analytical results show that stresses developed at the top flange web gaps could exceed yielding under the loading of an HS15 fatigue truck. The current slot repair used in the bridge was found to have introduced higher magnitude fatigue stresses in the web gap. To achieve a permanent repair of the bridge, it is recommended that a welded connection plate to flange attachment be used during future bridge retrofit. The web gap details should be able to withstand unlimited number of load cycles once this additional repair is performed. 相似文献
36.
Compared to other fields of engineering, in mechanical engineering, the Discrete Element Method (DEM) is not yet a well known
method. Nevertheless, there is a variety of simulation problems where the method has obvious advantages due to its meshless
nature. For problems where several free bodies can collide and break after having been largely deformed, the DEM is the method
of choice. Neighborhood search and collision detection between bodies as well as the separation of large solids into smaller
particles are naturally incorporated in the method. The main DEM algorithm consists of a relatively simple loop that basically
contains the three substeps contact detection, force computation and integration. However, there exists a large variety of
different algorithms to choose the substeps to compose the optimal method for a given problem. In this contribution, we describe
the dynamics of particle systems together with appropriate numerical integration schemes and give an overview over different
types of particle interactions that can be composed to adapt the method to fit to a given simulation problem. Surface triangulations
are used to model complicated, non-convex bodies in contact with particle systems. The capabilities of the method are finally
demonstrated by means of application examples.
Commemorative Contribution. 相似文献
37.
Recently, a demand for small-capacity generators has been increasing as electric sources in small ships and automobiles or as portable electric sources driven by engines. It is desired that the structure of small-capacity generators be simple and robust, and that the generators be highly reliable, easily maintained and controlled. This paper describes an analysis of the original brushless synchronous generator without exciter. The output voltage can be adjusted in the wide range by controlling the stator dc current. To analyze the characteristics of this generator, the finite element method is applied. It is found that the results of theoretical analysis agree well with the experimental results. 相似文献
38.
给出了滑移线场近似作图法的原理、证明以及近似滑移线场的特点,为进一步利用计算机求解应力分布和变形规律,尤其是为近似滑移线的计算机绘制奠定了基础. 相似文献
39.
参数三次B样条曲线的一种整体光顺方法 总被引:7,自引:0,他引:7
本文在能量法的基础上,提出了一种新的目标函数,给出了参数三次B样条曲线的一种新的整体光顺方法。利用这种方法得到的曲线不仅具有较小的应变能,而且曲率变化比较均匀,具有很好的光顺效果。该方法能推广到对曲面的光顺。 相似文献
40.