全文获取类型
收费全文 | 5564篇 |
免费 | 267篇 |
国内免费 | 54篇 |
专业分类
电工技术 | 105篇 |
综合类 | 85篇 |
化学工业 | 867篇 |
金属工艺 | 142篇 |
机械仪表 | 167篇 |
建筑科学 | 336篇 |
矿业工程 | 22篇 |
能源动力 | 250篇 |
轻工业 | 573篇 |
水利工程 | 54篇 |
石油天然气 | 60篇 |
武器工业 | 2篇 |
无线电 | 454篇 |
一般工业技术 | 938篇 |
冶金工业 | 593篇 |
原子能技术 | 30篇 |
自动化技术 | 1207篇 |
出版年
2024年 | 7篇 |
2023年 | 39篇 |
2022年 | 56篇 |
2021年 | 123篇 |
2020年 | 87篇 |
2019年 | 111篇 |
2018年 | 157篇 |
2017年 | 171篇 |
2016年 | 152篇 |
2015年 | 143篇 |
2014年 | 175篇 |
2013年 | 414篇 |
2012年 | 305篇 |
2011年 | 390篇 |
2010年 | 312篇 |
2009年 | 286篇 |
2008年 | 361篇 |
2007年 | 296篇 |
2006年 | 307篇 |
2005年 | 208篇 |
2004年 | 181篇 |
2003年 | 196篇 |
2002年 | 208篇 |
2001年 | 164篇 |
2000年 | 135篇 |
1999年 | 97篇 |
1998年 | 119篇 |
1997年 | 100篇 |
1996年 | 89篇 |
1995年 | 73篇 |
1994年 | 44篇 |
1993年 | 44篇 |
1992年 | 44篇 |
1991年 | 31篇 |
1990年 | 26篇 |
1989年 | 27篇 |
1988年 | 17篇 |
1987年 | 22篇 |
1986年 | 17篇 |
1985年 | 20篇 |
1984年 | 22篇 |
1983年 | 10篇 |
1982年 | 11篇 |
1981年 | 12篇 |
1980年 | 11篇 |
1979年 | 17篇 |
1978年 | 9篇 |
1977年 | 8篇 |
1976年 | 9篇 |
1975年 | 5篇 |
排序方式: 共有5885条查询结果,搜索用时 10 毫秒
1.
2.
Multifunctional 3D Patternable Drug‐Embedded Nanocarrier‐Based Interfaces to Enhance Signal Recording and Reduce Neuron Degeneration in Neural Implantation 下载免费PDF全文
3.
Chris Mathieu 《Creativity & Innovation Management》2006,15(3):242-249
Using a qualitative case study of the transformations of the infrastructure of the Danish film field by the Danish Film Institute and its CEO, three basic questions about entrepreneurial agency are raised. The first deals with the relationship between the institutional environment and the personal backgrounds of entrepreneurial actors. The study finds that certain actors can be seen as possessing extreme or unique levels of legitimacy resulting in being rewarded with tremendous resources and opportunities for strategic action. The second question has to do with how, and what sort of role transformations can take place from a structurally central, but static position in a field. Here ‘intermediary entrepreneurialism’ was used to penetrate and integrate the field in such a way as to turn a structurally fixed position from a weak to a strong nexus. The third question deals with how transformations can be effected by an organization that straddles three prominent institutional fields and logics – the state, market and artistic expression. Here, the key role of the term ‘professionalization’ is emphasized, arguing that this term proved evocative and compelling in each institutional field. The case also adds to our understanding of institutional and transformation processes in creative industries by focusing on two less‐studied contexts – the role and strategies of centrally placed actors in initiating and leading transformational activities, and the role that entrepreneurial ‘bureaucrats’ can play in transforming creative industries. 相似文献
4.
Marcia Cristina Kaezer Fran a Rosane Aguiar da Silva San Gil Jean-Guillaume Eon 《Catalysis Today》2003,78(1-4):105-115
γ-Al2O3 supported vanadium oxides were modified by tungsten and molybdenum oxides in order to improve dispersion and selectivity towards olefins in propane oxidative dehydrogenation (ODH). Both vanadium–tungsten and vanadium–molybdenum catalysts were obtained by adsorption of mixed isopolyanions (VW5O195−, V2W4O194−, VMo5O195− and V2Mo4O194−) from aqueous solutions. The isopolyanion solutions were characterized by UV-Vis and 51V NMR spectroscopy. Vanadium, vanadium–tungsten and vanadium–molybdenum precursors and catalysts were also characterized by UV-Vis (diffuse reflectance) and solid state 51V NMR spectroscopy. An improved selectivity to propene in the presence of tungsten and molybdenum in VOx/γ-Al2O3 was observed and attributed to dilution of vanadium by tungsten or molybdenum oxides on the γ-Al2O3 surface. 相似文献
5.
Chris Preist Kave Eshghi Bruno Bertolino 《Annals of Mathematics and Artificial Intelligence》1994,11(1-4):51-74
If realistic systems are to be successfully modelled and efficiently diagnosed using model-based techniques, a more expressive language than classical logic is required. In this paper, we present a definition of diagnosis which allows the use of a nonmonotonic construct, negation as failure, in the modelling language. This definition is based on thegeneralised stable model semantics of abduction. Furthermore, we argue that, if negation as failure is permitted in the modelling language, the distinction between abductive and consistency-based diagnosis is no longer clear. Our definition allows both forms of diagnosis to be expressed in a single framework. It also allows a single interference procedure to perform abductive or consistency-based diagnosis, as appropriate.This paper is an extended and revised version of ref. [29]. 相似文献
6.
This paper presents the results of a study in the design of a neural network based adaptive robotic control scheme. The neural network used here is a two hidden layer feedforward network and the learning scheme is the well-known backpropagation algorithm. The neural network essentially provides the inverse of the plant and acts in conjunction with a standard PD controller in the feedback loop. The objective of the controller is to accurately control the end position of a single link manipulator in the presence of large payload variations, variations in the link length and also variations in the damping constant. Based on results of this study, guidelines are presented in selecting the number of neurons in the hidden layers and also the parameters for the learning scheme used for training the network. Results also indicate that increasing the number of neurons in the hidden layer will improve the convergence speed of learning scheme up to a certain limit beyond which the addition of neurons will cause oscillations and instability. Guidelines for selecting the proper learning rate, momentum and fast backpropagation constant that ensure stability and convergence are presented. Also, a relationship between the r.m.s. error and the number of iterations used in training the neural network is established. 相似文献
7.
(U,Gd)O2 sintered pellets are fabricated by different methods. The homogeneity characterisation of the Gd content seems to be necessary for a production control to qualify the process and the final product obtained. In this paper, we propose an analysis of the X-ray diffraction powder patterns through the Rietveld method, in which the differences between the experimental and the calculated data proposed from a crystalline structure model are evaluated. This result allows us to determine the cell parameters, that can be correlated with the Gd concentration, and the existence of other phases with different Gd contents. 相似文献
8.
Chris Harty 《Building Research & Information》2005,33(6):512-522
An alternative approach to understanding innovation is made using two intersecting ideas. The first is that successful innovation requires consideration of the social and organizational contexts in which it is located. The complex context of construction work is characterized by inter-organizational collaboration, a project-based approach and power distributed amongst collaborating organizations. The second is that innovations can be divided into two modes: 'bounded', where the implications of innovation are restricted within a single, coherent sphere of influence, and 'unbounded', where the effects of implementation spill over beyond this. Bounded innovations are adequately explained within the construction literature. However, less discussed are unbounded innovations, where many firms' collaboration is required for successful implementation, even though many innovations can be considered unbounded within construction's inter-organizational context. It is argued that unbounded innovations require an approach to understand and facilitate the interactions both within a range of actors and between the actors and technological artefacts. The insights from a sociology of technology approach can be applied to the multiplicity of negotiations and alignments that constitute the implementation of unbounded innovation. The utility of concepts from the sociology of technology, including 'system building' and 'heterogeneous engineering', is demonstrated by applying them to an empirical study of an unbounded innovation on a major construction project (the new terminal at Heathrow Airport, London, UK). This study suggests that 'system building' contains outcomes that are not only transformations of practices, processes and systems, but also the potential transformation of technologies themselves. 相似文献
9.
Georgios D. Styliaras Georgios K. Tsolis Chris M. Papaterpos 《International Journal on Digital Libraries》2007,8(1):61-78
In this paper, AssetCollector is presented, which is a system for managing collections of cultural assets. AssetCollector
covers the needs of collection curators towards defining, populating and searching a collection in a flexible way, while supporting
them in generating reports based on the collection’s assets and reusing them in order to build web sites and CD-ROMs. In order
to support the above functionality, the system provides the content structuring subsystem, the content input subsystem, the
search subsystem and the report subsystem. The use of the subsystems is straightforward and requires no technical skills from
the curators. AssetCollector has been successfully applied for organizing various collections of cultural assets in Greece,
such as archaeological sites, museums and published books. In the future, an evaluation procedure is planned in order to further
refine the use of the system according to the targeted users’ needs. Furthermore, more import and export facilities will be
provided, which will make the system compliant with widely accepted standards. 相似文献
10.
Yi‐Hung Chen Ching‐Yuan Chang Wei‐Ling Su Chun‐Yu Chiu Yue‐Hwa Yu Pen‐Chi Chiang Chiung‐Fen Chang Je‐Lueng Shie Chyow‐San Chiou Sally IM Chiang 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2005,80(1):68-75
This study investigates the ozonation of CI Reactive Black 5 (RB5) by using the rotating packed bed (RPB) and completely stirred tank reactor (CSTR) as ozone contactors. The RPB, which provides high gravitational force by adjusting the rotational speed, was employed as a novel ozone contactor. The same ozone dosage was separately introduced into either the RPB or the CSTR for the investigation, while the experimental solution was continuously circulated within the apparatus consisting of the RPB and CSTR. The decolorization and mineralization efficiencies of RB5 in the course of ozonation are compared for these two methods. Moreover, the dissolved and off‐gas ozone concentrations were simultaneously monitored for the further analysis. As a result, the ozone mass transfer rate per unit volume of the RPB was significantly higher because of its higher mass transfer coefficient and gas–liquid concentration driving force. Furthermore, ozonation kinetics was found to be independent of the gravitational magnitude of an ozone gas–liquid contactor. Therefore, the results suggest employing RPBs as ozone‐contacting devices with the advantage of volume reduction. The experimental results, which can be used for further modeling of the ozonation process in the RPB, also show the requirement of correct design for the RPB. Consequently, the present study is useful for the understanding of practical application of RPBs. Copyright © 2004 Society of Chemical Industry 相似文献