全文获取类型
收费全文 | 12005篇 |
免费 | 1075篇 |
国内免费 | 618篇 |
专业分类
电工技术 | 672篇 |
综合类 | 1079篇 |
化学工业 | 2135篇 |
金属工艺 | 888篇 |
机械仪表 | 594篇 |
建筑科学 | 2067篇 |
矿业工程 | 339篇 |
能源动力 | 427篇 |
轻工业 | 250篇 |
水利工程 | 421篇 |
石油天然气 | 496篇 |
武器工业 | 108篇 |
无线电 | 745篇 |
一般工业技术 | 1985篇 |
冶金工业 | 314篇 |
原子能技术 | 129篇 |
自动化技术 | 1049篇 |
出版年
2024年 | 30篇 |
2023年 | 182篇 |
2022年 | 274篇 |
2021年 | 341篇 |
2020年 | 346篇 |
2019年 | 311篇 |
2018年 | 295篇 |
2017年 | 395篇 |
2016年 | 422篇 |
2015年 | 464篇 |
2014年 | 662篇 |
2013年 | 856篇 |
2012年 | 849篇 |
2011年 | 878篇 |
2010年 | 711篇 |
2009年 | 704篇 |
2008年 | 601篇 |
2007年 | 756篇 |
2006年 | 652篇 |
2005年 | 562篇 |
2004年 | 504篇 |
2003年 | 460篇 |
2002年 | 374篇 |
2001年 | 348篇 |
2000年 | 252篇 |
1999年 | 217篇 |
1998年 | 194篇 |
1997年 | 171篇 |
1996年 | 154篇 |
1995年 | 101篇 |
1994年 | 101篇 |
1993年 | 68篇 |
1992年 | 62篇 |
1991年 | 80篇 |
1990年 | 62篇 |
1989年 | 44篇 |
1988年 | 38篇 |
1987年 | 34篇 |
1986年 | 20篇 |
1985年 | 34篇 |
1984年 | 29篇 |
1983年 | 16篇 |
1982年 | 24篇 |
1981年 | 7篇 |
1980年 | 2篇 |
1979年 | 4篇 |
1976年 | 2篇 |
1959年 | 1篇 |
1955年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 812 毫秒
61.
62.
63.
并购是手段,效益是目的,整合是保障--对中国啤酒工业规模扩张潮的思考 总被引:1,自引:0,他引:1
近年来啤酒工业掀起并购扩张高潮,虽然规模扩张,但是却没有带来经济效益的同步增长。其主要原因是:扩张后生产能力未能充分发挥;价格战的扼制;没有充分的资金、人力对并购企业进行内部整合。而内部整合重于规模扩张建设,扩张的目的不是简单做大,而是要做强。有效的整合应做到:(1)具备充足的整合能力。(2)被并购企业积极支持内部整合。(3)加强企业文化整合,使两种企业文化完美融合,并形成一种新的文化。(君健) 相似文献
64.
65.
AN EXTENDED MODELING OF TIDE-WAVE MOTION 总被引:1,自引:1,他引:0
Zhang Qing hua Xu Hao Qu Yuan yuan First Institute of Oceanography State Oceanic Administration Qingdao China Key Laboratory of Marine Science Numerical Modeling State Oceanic Administration Qingdao China 《水动力学研究与进展(B辑)》2001,(3)
1 . INTRODUCTIONTostudythemotionofthetide waves,theshallowwaterequations ,i.e .theverticalintergra tionofthecontinuityequationandmomentumequa tion ,isconsideredasthegoverningequations.Byaboveequationstwoequationsrelatedtothehorizon talfluxofthetide currentsa… 相似文献
66.
转子系统热膨胀状态下固有横振频率 总被引:8,自引:3,他引:5
把转子的惯性力看成作用在轴上的外力,采用新的非线性渐近法研究热膨胀对转子系统固有横振频率的影响. 相似文献
67.
This paper presents observations regarding the cracking behavior of tensile-loaded structural adhesive joints. Experiments showed that fracture occurred by the development and propagation of a damage zone, rather than a single, sharp crack, and that the presence of the adhesive spew fillet did not affect the fracture load of the adhesive joints studied. For joints bonded with the mineral-filled epoxy Cybond 4523GB (American Cyanamid), there was approximately 5 mm of subcritical crack propagation prior to final fracture. Fracture-load predictions based on the initial uncracked geometry made in previous papers were unaffected by this small change in geometry. For joints bonded with the rubber-toughened epoxy Permabond ESP 310, approximately 50 mm of subcritical crack propagation was observed. It was again found that predictions made in previous papers on the basis of the initial geometry gave a good estimate of the final fracture load even though this subcritical crack propagation significantly altered the geometry, and thus the applied energy release rates. The effect of shear deformations of the adherends was also investigated, and it was found that shear deformations could be neglected in engineering calculations for joints subject to remote tensile loading. 相似文献
68.
On the mechanical behavior of aluminum alloys reinforced by long or short alumina fibers or SiC whiskers 总被引:2,自引:0,他引:2
This study was initiated to examine the dispersion of longitudinal and transverse waves in metal matrix composites in order to obtain the dynamic elastic modulus and to evaluate various models for predicting the composite's macroscopic elastic constants from the properties of its constituents. The materials chosen for this investigation were alumina continuous fibers on the one hand and alumina and SiC short fibers on the other hand, all embedded in an aluminum alloy matrix. In addition, some indications have been obtained experimentally for the acoustoelastic effect in the composite. 相似文献
69.
We look at the task of computing the time-evolution of a non-linear system for a long time, in our case under random external
influences. Our specific example is the fatigue evaluation of a wind turbine. To facilitate such a computation, we look at
a reduction of the computational effort by projecting everything on a low-dimensional basis. In this case we take the Karhunen-Loève
basis generated from running the model a little while under the random loading. It is important that the error which is caused
by this reduction process can be controlled. We estimate the error by dual or adjoint methods. This in turn allows the process
of model reduction to be performed adaptively.
Dedicated to the memory of Prof. Mike Crisfield, for his cheerfulness and cooperation as a colleague and friend over many
years. 相似文献
70.
T. MANN B. W. TVEITEN G. HÄRKEGÅRD 《Fatigue & Fracture of Engineering Materials & Structures》2006,29(2):113-122
The fatigue life of a welded aluminium T‐joint made from beams with rectangular hollow section (RHS) has been predicted using a crack propagation analysis and compared with experimental results from joints with different residual stress levels. To include the effect of the residual stresses, the stress ratio was calculated at the weld toe and, via Walker's equation, introduced into the analysis. How to obtain the Walker exponent has been discussed in detail. The introduction of a stress ratio at the weld toe provides good agreement between the experimentally and analytically found S–N curves. The effect of the residual stress was successfully included in the analysis. 相似文献