全文获取类型
收费全文 | 12086篇 |
免费 | 595篇 |
国内免费 | 256篇 |
专业分类
电工技术 | 265篇 |
综合类 | 430篇 |
化学工业 | 2025篇 |
金属工艺 | 453篇 |
机械仪表 | 512篇 |
建筑科学 | 1227篇 |
矿业工程 | 186篇 |
能源动力 | 745篇 |
轻工业 | 695篇 |
水利工程 | 299篇 |
石油天然气 | 318篇 |
武器工业 | 33篇 |
无线电 | 549篇 |
一般工业技术 | 2092篇 |
冶金工业 | 250篇 |
原子能技术 | 84篇 |
自动化技术 | 2774篇 |
出版年
2024年 | 19篇 |
2023年 | 174篇 |
2022年 | 192篇 |
2021年 | 279篇 |
2020年 | 315篇 |
2019年 | 352篇 |
2018年 | 361篇 |
2017年 | 437篇 |
2016年 | 488篇 |
2015年 | 496篇 |
2014年 | 601篇 |
2013年 | 1176篇 |
2012年 | 530篇 |
2011年 | 674篇 |
2010年 | 481篇 |
2009年 | 613篇 |
2008年 | 554篇 |
2007年 | 535篇 |
2006年 | 504篇 |
2005年 | 450篇 |
2004年 | 396篇 |
2003年 | 384篇 |
2002年 | 332篇 |
2001年 | 239篇 |
2000年 | 265篇 |
1999年 | 253篇 |
1998年 | 274篇 |
1997年 | 210篇 |
1996年 | 260篇 |
1995年 | 181篇 |
1994年 | 164篇 |
1993年 | 117篇 |
1992年 | 115篇 |
1991年 | 94篇 |
1990年 | 51篇 |
1989年 | 52篇 |
1988年 | 46篇 |
1987年 | 42篇 |
1986年 | 25篇 |
1985年 | 41篇 |
1984年 | 38篇 |
1983年 | 43篇 |
1982年 | 23篇 |
1981年 | 13篇 |
1980年 | 22篇 |
1979年 | 8篇 |
1978年 | 11篇 |
1977年 | 5篇 |
1975年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
In this paper, a unified method is presented: (i) to model delaminated stiffened laminated composite shells; (ii) for synthesising
accurate multiple post-buckling solution paths under compressive loading; and (iii) for predicting delamination growth. A
multi-domain modelling technique is used for modelling the delaminated stiffened shell structures. Error-free geometrically
nonlinear element formulations — a 2-noded curved stiffener element (BEAM2) and a 3-noded shell element (SHELL3) — are used
for the finite element analysis. An accurate and simple automated solution strategy based on Newton type iterations is used
for predicting the general geometrically nonlinear and postbuckling behaviour of structures. A simple method derived from
the 3-dimensionalJ-integral is used for computing the pointwise energy release rate at the delamination front in the plate/shell models. Finally,
the influence of post-buckling structural behaviour and the delamination growth on each other has been demonstrated. 相似文献
62.
The GILDES computer model, incorporating Stumm's concept of proton- and ligand-promoted dissolution, has been used to simulate the exposure of copper at room temperature to 210 ppb sulfur dioxide and 80% relative humidity. The agreement is good between the calculations and laboratory exposures performed under these exposure conditions. Surface reactions are relatively more important at lower relative humidities and the dominant corrosion products formed are solid state Cu2SO3, CuSO3 and Cu2U. Free-radical redox processes are important participants and control the relative distribution of Cu(I)- and Cu(H)-containing corrosion products. 相似文献
63.
64.
65.
In this paper, dynamic model of a class of parallel systems, namely, the hexaslides, is proposed. The model developed is based on the concept the decoupled natural orthogonal complement (DeNOC) matrices, introduced elsewhere. The dynamic model of hexslides, though complex due to the existence of multi-loop kinematic chains, is required for actuator power estimation, computed-torque control, optimum tool trajectory generation, etc. The use of DeNOC offers many physical interpretations, recursive algorithms, and parallel computations. Using the proposed dynamic model, a parallel inverse dynamics algorithm has been presented to compute the actuator forces. This is useful to choose suitable motors for an application. An illustration is provided using an existing machine tool based on hexaslides, namely, the HexaM, while it is carrying out a circular contouring. Secondly, the effect of leg and slider inertias is also studied, which clearly suggests that neither of these can be neglected while finding the actuator forces. 相似文献
66.
Marcela Brugnach Andrew Tagg Florian Keil Wim J. de Lange 《Water Resources Management》2007,21(7):1075-1090
The use of computer models offers a general and flexible framework that can help to deal with some of the complexities and
difficulties associated with the development of water management plans as prescribed by the Water Framework Directive. However,
despite the advantages modelling presents, the integration of information derived from models into policy is far away from
being trivial or the norm. Part of the difficulties of this integration is rooted in the lack of confidence policy makers
have on the incorporation of modelling information into policy formulation. In this paper we examine the reasons for this
apparent lack of confidence and explore how some tools, presently in use, address this problem. We conclude that public confidence
in models is highly dependent on the way uncertainties are addressed and suggest possible directions of action to improve
the current situation. Four real case studies illustrate how computer models have been used in The Netherlands for carrying
out management plans at regional and national scale. We suggest that the solution to integrate modelling information into
policy formulation lies on both the modelling and the policy-making communities. 相似文献
67.
A framework is presented for examining the effectiveness of limiting and modelling arguments used in the analysis of fluid
flows. It consists of examining the consequences of the arguments on the flow problem as a whole and breaking down the limiting/modelling
process into a sequence of steps and associated sequence of flow problems, termed here as ‘lidels’. The notion of validity
of lidels is given. Several examples are given to explain the present approach.
Invited general lecture at 3rd ACFM, Tokyo, September 1986 相似文献
68.
69.
70.
This paper studies a system of partial differential equations modelling the behaviour of a reverse flow reactor. For the parameters appropriate for the oxidation of ammonia on a Pt/Al2O3 catalyst in a typical laboratory set-up, the reactor may be split into regions where approximate formulas that determine its behaviour are deduced. Numerical calculations are presented and can be used to compare with the analytical formulas. The physical insight gained from the asymptotic analysis suggests a new switching strategy which is the subject of numerical experiments. The switching strategy is found to be efficient at minimising the ammonia exiting the reactor after reversal. 相似文献