全文获取类型
收费全文 | 1113篇 |
免费 | 13篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 15篇 |
化学工业 | 237篇 |
金属工艺 | 38篇 |
机械仪表 | 17篇 |
建筑科学 | 42篇 |
矿业工程 | 7篇 |
能源动力 | 12篇 |
轻工业 | 130篇 |
水利工程 | 3篇 |
石油天然气 | 17篇 |
无线电 | 113篇 |
一般工业技术 | 152篇 |
冶金工业 | 173篇 |
原子能技术 | 8篇 |
自动化技术 | 165篇 |
出版年
2021年 | 11篇 |
2020年 | 12篇 |
2019年 | 19篇 |
2018年 | 34篇 |
2017年 | 10篇 |
2016年 | 19篇 |
2015年 | 15篇 |
2014年 | 16篇 |
2013年 | 56篇 |
2012年 | 19篇 |
2011年 | 59篇 |
2010年 | 51篇 |
2009年 | 38篇 |
2008年 | 52篇 |
2007年 | 38篇 |
2006年 | 26篇 |
2005年 | 46篇 |
2004年 | 28篇 |
2003年 | 27篇 |
2002年 | 28篇 |
2001年 | 18篇 |
2000年 | 12篇 |
1999年 | 14篇 |
1998年 | 38篇 |
1997年 | 29篇 |
1996年 | 24篇 |
1995年 | 17篇 |
1994年 | 15篇 |
1993年 | 21篇 |
1992年 | 28篇 |
1991年 | 16篇 |
1990年 | 18篇 |
1989年 | 18篇 |
1987年 | 8篇 |
1986年 | 11篇 |
1985年 | 16篇 |
1984年 | 10篇 |
1983年 | 8篇 |
1982年 | 9篇 |
1981年 | 10篇 |
1980年 | 8篇 |
1979年 | 13篇 |
1977年 | 10篇 |
1976年 | 17篇 |
1974年 | 8篇 |
1973年 | 8篇 |
1971年 | 9篇 |
1969年 | 7篇 |
1963年 | 8篇 |
1955年 | 11篇 |
排序方式: 共有1129条查询结果,搜索用时 15 毫秒
41.
Maurice Defo Graduate student Alain Cloutier Associate professor Yves Fortin Professor 《Drying Technology》2013,31(8):1737-1778
ABSTRACT A two-dimensional mathematical model for vacuum-contact drying of wood is presented. The moisture and heat equations are based on the water potential concept whereas the pressure equation is formulated considering unsteady state conservation equation of dry air. Most of the model parameters were determined during independent experiments. The set of equations is then solved in a coupled form using the finite element method. The validation of the model is performed using experimental results obtained during vacuum-contact drying of sugar maple sapwood. The experimental and calculated data are in good agreement. Nevertheless, some discrepancies are observed which can be attributed to the boundary conditions used and to the fact that heat transfer by convection was neglected. 相似文献
42.
J.Y. Cognard R. Créac'hcadec J. Maurice 《International Journal of Adhesion and Adhesives》2011,31(7):715-724
The single lap joint is the most used test in order to analyse the behaviour of an adhesive in an assembly as on one hand, the manufacturing of such specimens is quite easy, and on the other hand they require only a classic tensile testing machine. However, such specimens are associated with complex loading of the adhesive, i.e. non-uniform shear stress along the overlap length, quite large peel stress at the two ends of the overlap and significant edge effects associated with geometrical and material parameters. In addition, the stress concentrations can contribute to fracture initiation in the adhesive joints and thus can lead to an incorrect analysis of the adhesive behaviour. Therefore, understanding the stress distribution in an adhesive joint can lead to improvements in adhesively bonded assemblies. The first part of this paper presents the influence of edge effects on the stress concentrations in single lap joints under elastic assumption of the material and using a pressure-dependent elastic limit of the adhesive. In the second part, some usual geometries, proposed in the literature about stress limitation, are compared with respect to the maximum load transmitted by single lap joint. The last part presents some geometries, which significantly limit the influence of edge effects and are more appropriate for analysing the behaviour of the adhesive. 相似文献
43.
44.
Mulcahy and Call (2009) found that bonobos (Pan paniscus) and chimpanzees (Pan troglodytes) but not orangutans (Pongo pygmaeus) perform significantly better in a peripheral version of the object-choice task compared to the original central version. Orangutans may have failed because they avoided direct eye contact with the experimenter when the cue was given. We investigated this possibility by conducting peripheral and central object choice tasks with an obedient orangutan (Pongo abelii) whom the experimenter could elicit eye contact with in each trial. In contrast to Mulcahy and Call's findings, the subject only failed the object choice task when tested with the central and not the peripheral version. We investigated whether success was because of the greater distance the subject was required to move in order to make a choice in peripheral trials. Results show that this was an unlikely factor in the subject's success. We discuss our findings in relation to previous and future object-choice research. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
45.
Under the “Private Sector Participation in Micro-Hydro Development Project in Rwanda”, four newly registered Rwandan companies are each constructing a micro-hydro electricity plant (100–500 kW) and building a low-voltage distribution grid. These companies financed their plants through their own equity and debt with support from the PSP Hydro project. This support comprised a subsidy of 30–50% of investment costs, technical and business development assistance, project monitoring and financial controlling. The experiences gained so far have important implications for similar future micro-hydro energy sector development projects and this paper puts forward three key messages: (i) institutional arrangements rather than technical quality determine the success of such projects; (ii) truly sustainable rural electrification through micro-hydro development demands a high level of local participation at all levels and throughout all project phases, not just after plant commissioning; and (iii) real impact and sustainability can be obtained through close collaboration of local private and financial sector firms requiring only limited external funds. In short, micro-hydro projects can and will be taken up by local investors as a business if the conditions are right. Applying these messages could result in an accelerated uptake of viable micro-hydro activities in Rwanda, and in the opinion of the authors elsewhere too. 相似文献
46.
Mihai Cipu Isma?la Diouf Maurice Mignotte 《Applicable Algebra in Engineering, Communication and Computing》2011,22(4):289-300
Two methods to test whether a given polynomial has two distinct roots whose quotient is a root of unity are discussed. 相似文献
47.
MgO-Y2O3 nanostructured composite powder (volume ratio of 50:50) was synthesized by a sol-gel combustion process which generated crystal sizes in the 10-20 nm range. The MgO-Y2O3 nanopowder was plasma sprayed using a conventional, DC arc plasma spray system. X-ray diffraction analysis shows that the as-sprayed MgO-Y2O3 coating is composed of cubic MgO and Y2O3 phases and has ~95% density. Microstructure characterization by SEM reveals that the as-sprayed coating has fine grain sizes of 100-300 nm as a result of rapid solidification. The hardness of the coating, 7.5 ± 0.6 GPa, is higher than that of coarse-grained, dense MgO, and Y2O3 ceramics. This approach demonstrates the potential of plasma spray processes for making thick, dense MgO-Y2O3 nanocomposite performs for applications as durable, infrared windows. 相似文献
48.
Shunde Yin Maurice B. Dusseault Leo Rothenburg 《Journal of Petroleum Science and Engineering》2009,64(1-4):45-54
Field observations suggest that while pressure depletion is a local process that occurs dominantly in reservoirs being exploited, it triggers a redistribution of effective stress in a more extensive domain that involves not just the adjacent strata, but the entire overburden and surrounding rocks out to considerable distances. In an infinite or semi-infinite domain, a petroleum reservoir can be simulated as a displacement discontinuity, permitting use of an efficient displacement discontinuity boundary element method to calculate surrounding stress and displacement changes. A 3D poroelastic finite element method is used to account for the local reservoir model. By coupling the displacement discontinuity and finite element models, a 3D poroelastic reservoir in an infinite or semi-infinite domain is simulated. The numerical model has been verified and numerical examples are given. Results show that the relative deformation properties of surrounding strata have significant effects on pressure drawdown and reservoir deformation during production, and thus should be taken into account. 相似文献
49.
We present a correction to the paper, “Approximation algorithms for shop scheduling problems with minsum objective” (Journal of Scheduling 2002; 5:287–305) by Queyranne and Sviridenko. This correction provides a correct derivation of its 2eρ approximation result.
Wenhua Li and Jinjiang Yuan: Project supported by NNSFC (Grant 10371112) and NSFHN (Grant 0411011200).
Maurice Queyranne: Supported by research grants from NSERC, the Natural Sciences and Engineering Research Council of Canada. 相似文献
50.