全文获取类型
收费全文 | 1859篇 |
免费 | 44篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 22篇 |
综合类 | 6篇 |
化学工业 | 312篇 |
金属工艺 | 37篇 |
机械仪表 | 30篇 |
建筑科学 | 183篇 |
矿业工程 | 12篇 |
能源动力 | 41篇 |
轻工业 | 155篇 |
水利工程 | 16篇 |
石油天然气 | 7篇 |
武器工业 | 1篇 |
无线电 | 225篇 |
一般工业技术 | 279篇 |
冶金工业 | 151篇 |
原子能技术 | 16篇 |
自动化技术 | 412篇 |
出版年
2023年 | 7篇 |
2022年 | 18篇 |
2021年 | 34篇 |
2020年 | 25篇 |
2019年 | 33篇 |
2018年 | 30篇 |
2017年 | 47篇 |
2016年 | 45篇 |
2015年 | 25篇 |
2014年 | 72篇 |
2013年 | 158篇 |
2012年 | 92篇 |
2011年 | 105篇 |
2010年 | 97篇 |
2009年 | 107篇 |
2008年 | 117篇 |
2007年 | 114篇 |
2006年 | 122篇 |
2005年 | 100篇 |
2004年 | 95篇 |
2003年 | 77篇 |
2002年 | 56篇 |
2001年 | 39篇 |
2000年 | 33篇 |
1999年 | 36篇 |
1998年 | 26篇 |
1997年 | 32篇 |
1996年 | 31篇 |
1995年 | 13篇 |
1994年 | 19篇 |
1993年 | 10篇 |
1992年 | 10篇 |
1991年 | 9篇 |
1990年 | 9篇 |
1989年 | 5篇 |
1988年 | 2篇 |
1987年 | 9篇 |
1985年 | 2篇 |
1984年 | 6篇 |
1983年 | 6篇 |
1982年 | 3篇 |
1981年 | 6篇 |
1980年 | 8篇 |
1979年 | 1篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1974年 | 1篇 |
1971年 | 2篇 |
1970年 | 1篇 |
1969年 | 2篇 |
排序方式: 共有1905条查询结果,搜索用时 15 毫秒
81.
Mike Woodward 《电子设计技术》2010,17(10)
(上篇)在无线系统设计过程中依靠基于部门划分的方法,往往会给开发流程带来麻烦。使用系统级模型不仅可以解决诸多此类问题,而且能够大大改进设计流程。各家公司都在使用基于模型的设计,以整合不同的开发团队(例如,模拟和数字)和各个设计阶段(例如,设计和验证),从而获得巨大收益。 相似文献
82.
This paper introduces a novel methodology based on disaggregate analysis of two-car crash data to estimate the partial effects of mass, through the velocity change, on absolute driver injury risk in each of the vehicles involved in the crash when absolute injury risk is defined as the probability of injury when the vehicle is involved in a two-car crash. The novel aspect of the introduced methodology is in providing a solution to the issue of lack of data on the speed of vehicles prior to the crash, which is required to calculate the velocity change, as well as a solution to the issue of lack of information on non-injury two-car crashes in national accident data. These issues have often led to focussing on relative measures of injury risk that are not independent of risk in the colliding cars. Furthermore, the introduced methodology is used to investigate whether there is any effect of vehicle size above and beyond that of mass ratio, and whether there are any effects associated with the gender and age of the drivers. The methodology was used to analyse two-car crashes to investigate the partial effects of vehicle mass and size on absolute driver injury risk. The results confirmed that in a two-car collision, vehicle mass has a protective effect on its own driver injury risk and an aggressive effect on the driver injury risk of the colliding vehicle. The results also confirmed that there is a protective effect of vehicle size above and beyond that of vehicle mass for frontal and front to side collisions. 相似文献
83.
Construction site layout planning (CSLP) is a dynamic multi-objective optimization (MOO) problem as there are different facilities employed in the different construction phases of a construction project. In this study, a new method using continuous dynamic searching scheme to guide the max-min ant system (MMAS) algorithm, which is one of the ant colony optimization (ACO) algorithms, to solve the dynamic CSLP problem under the two congruent objective functions of minimizing safety concerns and reducing construction cost is proposed. Using weighted sum method the MOO problem can be solved by the proposed MMAS method. An office building case was used to verify the capability of the proposed method to solve dynamic CSLP problem and the results are promising. The approach could be benchmarked by researchers using other advanced optimization algorithms to solve the same problem or expand the applications to other fields. 相似文献
84.
85.
It has been shown that information collected from and about links between web pages and web sites can reflect real world phenomena
and relationships between the organizations they represent. Yet, government linking has not been extensively studied from
a webometric point of view. The aim of this study was to increase the knowledge of governmental interlinking and to shed some
light on the possible real world phenomena it may indicate. We show that interlinking between local government bodies in Finland
follows a strong geographic, or rather a geopolitical pattern and that governmental interlinking is mostly motivated by official
cooperation that geographic adjacency has made possible. 相似文献
87.
88.
Estimations of the effectiveness of remedial treatments in road safety analysis are frequently bedevilled by the problem of regression to the mean (RTM). The number of accidents x observed at a site in the “before” period is a “noisy” quantity: x is Poisson distributed about an (unknown) true mean m for that site, so that x = m + e. Sites selected for treatment tend to have a positive random error component e, which will on average be zero in the “after” period, even if no treatment is applied.Methods for estimating RTM usually require some assumption about the underlying (prior) between-site distribution of the true means f0(m): for example, in the empirical Bayes method, a gamma distribution is assumed. The paper considers the impact of different assumptions for this distribution and, indeed, whether any distributional form needs to be assumed. Using Markov Chain Monte Carlo methods, a variety of distributional forms are assumed for f0(m) and applied to each of a number of real data sets, including that from a major study on the effectiveness of speed cameras. It is shown that, in some cases, the size of the estimated RTM effect can be quite sensitive to the choice of distribution. 相似文献
89.
Sarah J. Wakes Tanja Maegli Katharine J. Dickinson Mike J. Hilton 《Environmental Modelling & Software》2010,25(2):237-247
Numerical modelling of wind flow over complex dune topography is an ambitious prospect. There is an increasing need to understand wind flow over complex topography for land planning purposes to enable prediction of sediment transport at a particular site. New surveying techniques permit the rapid development of digital terrain models, however a stumbling block is the ability of Computational Fluid Dynamics (CFD) to emulate the wind flow over such a landscape. To overcome these difficulties, it is important to establish the parameters within which such simulations can operate. This paper details an initial two-dimensional numerical model developed in order to test various modelling assumptions against experimental field wind data. Mason Bay, Stewart Island, New Zealand was chosen as an undisturbed but accessible experimental site with a prevalent on-shore wind perpendicular to a simple foredune and a complex down-wind parabolic dune system. A complex topographical two-dimensional model with vegetation represented as a roughness was compared against field data along a transect dissecting a dune system.This paper establishes that:
- * Replicating the roughness patterns at the surface is important
- * The inlet profile should be duplicated with care
- * Modelling only a portion of the domain can have an effect on the flow patterns due to outflow effects
- * There is a modelling decision to be made between the complexity of the topography and the sophistication of the turbulence model and degree to which vegetation and sand transportation are modelled.
90.
Bruce Moon Mike Berry Stephen Harris Ray Wyatt Kim Dovey Michelle Bennett 《Urban Policy and Research》2013,31(2):247-276
Australian Environmental Policy 2: Studies in Decline and Devolution Ken Walker and Kate Crowley (eds) UNSW Press, Sydney, 1999 ISBN 0868406732 (paperback) 323 pp.; bibliography and index RRP $35.00 Beyond Meltdown: The Global Battle for Sustained Growth. Peter Brain. Scribe, Melbourne, 1999 ISBN 0908011369 (paperback) 273 pp.; bibliography and index RRP $26.95 Cities Back from the Edge: New Life for Downtown Roberta Brandes Gratz with Norman Mintz John Wiley & Sons, New York, 1998 ISBN 0471144177 (hardback) 347 pp.; index RRP $59.95 Evaluation in Planning: Facing the Challenge of Complexity Nathaniel Lichfield, Angela Barbanente, Dino Bori, Abdul Khakee and Anna. Prat (eds). Kluwer, Dordrecht, 1998. ISBN 0792351770 (hardback). 383 pp.; index. RRP $254.00 Gritty Cities: Images of the Urban Lyaranette Finch and Chris McConville (eds). Pluto, Sydney, 1999. ISBN 1864030631 (paperback). 250 pp.; bibliography and index. RRP $24.95 Setting the Stage for Systainability: A Citizen's Handbook Chris Maser, Russ Beaton and Kevin Smith Lewis Publishers, Boca Raton, 1998 ISBN 1574441876 (hardback) 269 pp.; index RRP $47.50 The Australian Metropolis: A Planning History Stephen Hamnett and Robert Freestone (eds) Allen & Unwin, Sydney, 1999 ISBN 1865080535 (paperback) 229 pp.; index RRP $35.00 相似文献