全文获取类型
收费全文 | 1049篇 |
免费 | 30篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 13篇 |
综合类 | 1篇 |
化学工业 | 176篇 |
金属工艺 | 17篇 |
机械仪表 | 52篇 |
建筑科学 | 60篇 |
矿业工程 | 3篇 |
能源动力 | 16篇 |
轻工业 | 66篇 |
水利工程 | 14篇 |
石油天然气 | 11篇 |
武器工业 | 1篇 |
无线电 | 65篇 |
一般工业技术 | 184篇 |
冶金工业 | 190篇 |
原子能技术 | 4篇 |
自动化技术 | 212篇 |
出版年
2023年 | 8篇 |
2022年 | 7篇 |
2021年 | 11篇 |
2019年 | 16篇 |
2018年 | 18篇 |
2017年 | 17篇 |
2016年 | 22篇 |
2015年 | 11篇 |
2014年 | 19篇 |
2013年 | 88篇 |
2012年 | 29篇 |
2011年 | 51篇 |
2010年 | 32篇 |
2009年 | 28篇 |
2008年 | 42篇 |
2007年 | 40篇 |
2006年 | 39篇 |
2005年 | 42篇 |
2004年 | 34篇 |
2003年 | 37篇 |
2002年 | 33篇 |
2001年 | 22篇 |
2000年 | 15篇 |
1999年 | 21篇 |
1998年 | 49篇 |
1997年 | 23篇 |
1996年 | 19篇 |
1995年 | 20篇 |
1994年 | 28篇 |
1993年 | 16篇 |
1992年 | 15篇 |
1991年 | 11篇 |
1990年 | 14篇 |
1988年 | 14篇 |
1987年 | 16篇 |
1986年 | 12篇 |
1985年 | 14篇 |
1984年 | 15篇 |
1983年 | 7篇 |
1982年 | 10篇 |
1981年 | 10篇 |
1980年 | 10篇 |
1979年 | 9篇 |
1978年 | 9篇 |
1976年 | 10篇 |
1975年 | 11篇 |
1973年 | 7篇 |
1971年 | 6篇 |
1970年 | 7篇 |
1968年 | 6篇 |
排序方式: 共有1085条查询结果,搜索用时 833 毫秒
11.
12.
13.
The current study examined psychological and physical health outcomes of the written disclosure paradigm and the hypothesis that the principles of therapeutic exposure account for the beneficial effects of the paradigm. Participants were randomly assigned to either a written disclosure condition or a control condition. Reactivity to the writing sessions was examined using both subjective and physiological measures. Measures of psychological and physical health were completed before and 1 month after the sessions. Participants assigned to the disclosure condition reported fewer psychological and physical symptoms at follow-up compared with control participants, though reductions were clinically significant for only 1 outcome measure. Physiological activation to the 1st disclosure session was associated with reduced psychological symptoms at follow-up for disclosure participants. Subjective reports of emotional responding corresponded with physiological reactivity. Implications of these findings are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
14.
15.
Early trials and analysis of a new adhesion test are discussed. The test is designed for measuring the adhesion of paint to
deformable steel sheets as used in building, automotive, and other cladding applications, and does not require detailed knowledge
of the paint mechanical properties. A stiff overlay, such as an epoxy resin, is applied to the coating, and the steel substrate
is peeled away using a roll of well-defined radius to which the steel substrate is constrained. The propagation of a crack
within the paint or at some interface in the paint/metal system depends mostly on the mechanical properties and thickness
of the overlay and the radius of the constraining roll. The test is shown to discriminate better than existing practical adhesion
tests between paints of expected differing adhesion/cohesion, but also presents some inconsistencies that require further
work to resolve.
BHP Institute of Steel Processing and Products, Wollongong NSW 2522, Australia. 相似文献
16.
S. W. Sloan J. R. Booker 《International journal for numerical methods in engineering》1992,33(1):163-196
This paper considers the problem of integrating the constitutive relations for Tresca and Mohr–Coulomb materials under conditions of plane strain. In the case of a Tresca material, we show that the constitutive law may be integrated exactly by assuming the strain rates d?/dλ to be constant. We also derive a semi-analytic method for integrating both types of constitutive law which assumes that the quantities d?/dλ are constant. This approach is motivated by the fact that the exact variation of the strains during a time interval is unknown and leads to a single non-linear equation in λ which can be solved efficiently to yield the unknown stresses. Finally, we compare the results from the analytic and semi-analytic methods with those from a variety of numerical integration schemes. 相似文献
17.
A series of novel pi (π) conjugated polymers, originating from the archetypical Polyphenylene vinylene, in which the phenyl units are successively replaced by the larger naphthyl and anthryl acene units, were previously found to have a well-defined relationship between their relative fluorescence yields and their vibrational characteristics, as determined by Raman spectroscopy. In this study the Strickler-Berg equation is used to probe the influence of continual substitution of higher order acene units into the conjugated backbone in terms of the variation of the radiative and non-radiative rates. The deconvolution of the radiative and non-radiative rates enables the correlation of the reduction of the Raman intensity and concomitant increase in the fluorescence yield with the reduction of the non-radiative rate. This confirms that the reduction of the non-radiative rate is the dominant process introduced by the vibrational confinement originating from systematic substitution of higher order acene units into the polymer backbone. 相似文献
18.
19.
Trajectory planning is an essential part of systems controlling autonomous entities such as vehicles or robots. It requires not only finding spatial curves but also that dynamic properties of the vehicles (such as speed limits for certain maneuvers) must be followed. In this paper, we present an approach for augmenting existing path planning methods to support basic dynamic constraints, concretely speed limit constraints. We apply this approach to the well known A* and state-of-the-art Theta* and Lazy Theta* path planning algorithms. We use a concept of trajectory planning based on a modular architecture in which spatial and dynamic parts can be easily implemented. This concept allows dynamic aspects to be processed during planning. Existing systems based on a similar concept usually add dynamics (velocity) into spatial curves in a post-processing step which might be inappropriate when the curves do not follow the dynamics. Many existing trajectory planning approaches, especially in mobile robotics, encode dynamic aspects directly in the representation (e.g. in the form of regular lattices) which requires a precise knowledge of the environmental and dynamic properties of particular autonomous entities making designing and implementing such trajectory planning approaches quite difficult. The concept of trajectory planning we implemented might not be as precise but the modular architecture makes the design and implementation easier because we can use (modified) well known path planning methods and define models of dynamics of autonomous entities separately. This seems to be appropriate for simulations used in feasibility studies for some complex autonomous systems or in computer games etc. Our basic implementation of the augmented A*, Theta* and Lazy Theta* algorithms is also experimentally evaluated. We compare (i) the augmented and basic A*, Theta* and Lazy Theta* algorithms and (ii) optimizing of augmented Theta* and Lazy Theta* for distance (the trajectory length) and duration (time needed to move through the trajectory). 相似文献
20.
Kyeising Kwong Art Petty James Bennett Rick Krabbe Hugh Thomas 《International Journal of Applied Ceramic Technology》2007,4(6):503-513
The hot-face refractory lining is a key component of gasification systems. The refractory liner protects the gasification system from the high-temperature corrosive gaseous and from the molten slag environment associated with the conversion of carbon feedstocks. This paper will discuss the effect of gasifier operating conditions and carbon feedstock slag/ash chemistry on the refractory service life. Particular attention is focused on the wear mechanism of chromia refractories, determined through postmortem analysis of spent refractory bricks from service in gasifiers. Also presented is the behavior of a phosphate-containing chromia refractory with improved resistance to structural spalling. 相似文献