全文获取类型
收费全文 | 2007篇 |
免费 | 87篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 25篇 |
综合类 | 2篇 |
化学工业 | 489篇 |
金属工艺 | 57篇 |
机械仪表 | 38篇 |
建筑科学 | 58篇 |
矿业工程 | 9篇 |
能源动力 | 59篇 |
轻工业 | 173篇 |
水利工程 | 12篇 |
石油天然气 | 2篇 |
无线电 | 138篇 |
一般工业技术 | 374篇 |
冶金工业 | 311篇 |
原子能技术 | 18篇 |
自动化技术 | 332篇 |
出版年
2023年 | 15篇 |
2022年 | 26篇 |
2021年 | 36篇 |
2020年 | 29篇 |
2019年 | 45篇 |
2018年 | 64篇 |
2017年 | 62篇 |
2016年 | 73篇 |
2015年 | 58篇 |
2014年 | 78篇 |
2013年 | 126篇 |
2012年 | 107篇 |
2011年 | 146篇 |
2010年 | 105篇 |
2009年 | 110篇 |
2008年 | 111篇 |
2007年 | 87篇 |
2006年 | 56篇 |
2005年 | 69篇 |
2004年 | 44篇 |
2003年 | 52篇 |
2002年 | 41篇 |
2001年 | 23篇 |
2000年 | 31篇 |
1999年 | 22篇 |
1998年 | 64篇 |
1997年 | 47篇 |
1996年 | 63篇 |
1995年 | 18篇 |
1994年 | 29篇 |
1993年 | 34篇 |
1992年 | 16篇 |
1991年 | 9篇 |
1990年 | 11篇 |
1989年 | 10篇 |
1988年 | 7篇 |
1987年 | 16篇 |
1986年 | 10篇 |
1985年 | 9篇 |
1984年 | 12篇 |
1983年 | 6篇 |
1982年 | 19篇 |
1981年 | 9篇 |
1979年 | 10篇 |
1978年 | 4篇 |
1977年 | 18篇 |
1976年 | 25篇 |
1975年 | 7篇 |
1974年 | 4篇 |
1973年 | 8篇 |
排序方式: 共有2097条查询结果,搜索用时 15 毫秒
71.
Anne Toppinen Miska Sauru Satu Pätäri Katja Lähtinen Anni Tuppura 《Construction Management & Economics》2019,37(4):201-216
In transitioning to a renewable material-based bio economy, growing public and industry interest is apparent for using wooden multistory construction (WMC) as a sustainable urban housing solution in Europe, but its business implications are not well understood. In our study, we evaluate, which internal and external factors of competitiveness are shaping the future of WMC, especially in the context of Finland and Sweden. Based on a multi-level perspective of socio-technical transitions, we conducted a three-stage dissensus-based Delphi study. The identified internal and external factors affecting the future competitiveness of the WMC business emphasize the importance of skilled architects and builders and the role of standardized building systems. Based on our results, the key aspects influencing the future competitiveness of WMC in the region are related to the development of technical infrastructure and project-based business networks, while additional changes in regulatory framework are perceived as less important. We conclude that towards 2030, the strong cognitive rules founded in the concrete-based building culture in these countries is likely to inhibit the dynamics of the socio-technical regime level. A change is also needed in the WMC business culture towards more open cross-sectoral collaboration and new business networks between different-sized players. 相似文献
72.
Sergiu Cecoltan Izabela-Cristina Stancu Diana Maria Drăguşin Andrada Serafim Adriana Lungu Cătălin Ţucureanu Iuliana Caraş Vlad Constantin Tofan Aurora Sălăgeanu Eugeniu Vasile Romain Mallet Daniel Chappard Cristin Coman Mircea Istodorescu Horia Iovu 《Journal of materials science. Materials in medicine》2017,28(10):153
73.
Dana Petcu Silviu Panica Marc Frîncu Marian Neagul Daniela Zaharie Georgiana Macariu Dorian Gorgan Teodor Ştefănuţ 《Computer Standards & Interfaces》2012,34(6):493-508
Earth observation data processing and storing can be done nowadays only using distributed systems. Experiments dealing with a large amount of data are possible within the timeframe of a lesson and can give trainees the freedom to innovate. Following these trends and ideas, we have built a proof-of-the-concept platform, named GiSHEO, for Earth observation educational tasks. It uses Grid computing technologies to analyze and store remote sensing data, and combines them with eLearning facilities. This paper provides an overview of the GiSHEO's platform architecture and of its technical and innovative solutions. 相似文献
74.
P systems (PSs) are powerful computing models based on the structure of a biological cell and on the way chemicals interact in complex biochemical reactions which take place in various compartments (or membranes) of the cell. A lot of interest has been focused on developing various forms of PSs, from cell-like to tissue-like structures. Most of the research effort has been concentrated on symbolical PSs. Numerical P systems (NPSs) have been introduced in 2006 for possible applications in economics and business processes but no other structures and applications concerning this type of PSs have been provided since then. This paper proposes a new class of NPSs, in which enzyme-like variables allow the existence of more than one production function in each membrane, while keeping the deterministic nature of the system. The way this new type of deterministic NPSs works and a possible use of it for modeling mobile robot controllers are detailed. 相似文献
75.
Internal preference mapping (IPM) and Landscape Segmentation Analysis® (LSA) are two techniques broadly used to unfold consumers’ overall product liking ratings and create spatial maps that will provide further insights on consumers’ preferences. IPM is based on a vector model while LSA involves an ideal point model. Through a simulation and the analysis of 27 market research data sets, it is shown that IPM consistently creates a hedonic dimension that prevents the identification of satiety prone attributes (intensities higher or lower than a optimal level being disliked by the consumers) on that dimension. As a result, subsequent steps taken upon generating an IPM map such as the investigation of drivers of liking, population segmentation and the estimation of optimal product profiles have also a strong likelihood of resulting in distorted results, the level of distortion being dependent on the actual configuration of the underlying structure that IPM tried to uncover. It is also shown that a technique based on ideal points such as LSA does not exhibit this systematic artifact when unfolding liking data. Consequently, sensory scientists and market researchers should use caution when interpreting and using results issued from an internal preference mapping analysis. 相似文献
76.
Maikel León Lusine Mkrtchyan Benoît Depaire Da Ruan Koen Vanhoof 《Knowledge and Information Systems》2014,39(2):435-462
In modern society, more and more attention is given to the increase in public transportation or bike use. In this regard, one of the most important issues is to find and analyse the factors influencing car dependency and the attitudes of people in terms of preferred transport mode. Although the individuals’ transport behavioural modelling is a complex task, it has a notable social and economic impact. Thus, in this paper, fuzzy cognitive maps are explored to represent the behaviour and operation of such complex systems. This soft-computing technique allows modelling how the travellers make decisions based on their knowledge of different transport modes properties at different levels of abstraction. These levels correspond to the hierarchy perception including different scenarios of travelling, different benefits of choosing a specific travel mode, and different situations and attributes related to those benefits. We use learning and clustering of fuzzy cognitive maps to describe travellers’ behaviour and change trends in different abstraction levels. Cluster estimations are done before and after the learning of the maps, in order to compare people’s way of thinking if only considering an initial view of a transport mode decision for a daily activity, and when they really have a deeper reasoning process in view of benefits and consequences. The results of this study will help transportation policy decision makers in better understanding of people’s needs and consequently will help them actualizing different policy formulations and implementations. 相似文献
77.
A protective layers were prepared on a magnesium electrode by treatment in different solutions and times after modification
in 0.15 M HCl for 20 seconds. The corrosion of magnesium coated protective layer with different compounds was studied by using
potential-time, current-potential curves and AC impedance spectra. The coatings morphology depends on the treating bath compositions
and immersion times. The protective efficiencies of the surface layers were calculated by using corrosion rates obtained by
extrapolation of Tafel zones of current-potential curves to the corrosion potential and by using Stern-Geary equation with
polarization resistance from impedance spectra. 相似文献
78.
Ş. Aydoğan M. Sağlam A. Türüt Y. Onganer 《Materials science & engineering. C, Materials for biological applications》2009,29(4):1486-1490
The current–voltage (I–V) characteristics of Polypyrrole(PPy)/p-Si/Al structure have been investigated as a function of temperature. A modified Norde function combined with conventional forward I–V method has been used to extract the junction parameters including the ideality factor, barrier height and series resistance. Norde function has been compared with the Cheung functions and it has been seen that there is a good agreement with both method for the barrier height values. However, the values of series resistance have very different especially towards to the lower temperatures. This is attributed to non-ideal I–V characteristics of the Au/PPy/p-Si/Al structure and non-pure Thermionic emission theory due to the low temperature effects. 相似文献
79.
Data mining is sometimes treating data consisting of items representing measurements of a single property taken in different
time points. In this case data can be understood as a time series of one feature. It is no exception when the clue for evaluation
of such data is related to their development trends as observed in several successive time points. From the qualitative point
of view one can distinguish three basic types of behaviour between two neighbouring time points: the value of the feature
is stable (remains the same), it grows or it falls. This paper is concerned with identification of typical qualitative development
patterns as they appear in the windows of given length in the considered time-stamped data and their utilization for specification
of interesting subgroups. 相似文献
80.