全文获取类型
收费全文 | 9525篇 |
免费 | 451篇 |
国内免费 | 20篇 |
专业分类
电工技术 | 99篇 |
综合类 | 4篇 |
化学工业 | 1956篇 |
金属工艺 | 140篇 |
机械仪表 | 188篇 |
建筑科学 | 613篇 |
矿业工程 | 21篇 |
能源动力 | 317篇 |
轻工业 | 839篇 |
水利工程 | 108篇 |
石油天然气 | 28篇 |
无线电 | 697篇 |
一般工业技术 | 1938篇 |
冶金工业 | 1242篇 |
原子能技术 | 36篇 |
自动化技术 | 1770篇 |
出版年
2023年 | 70篇 |
2022年 | 135篇 |
2021年 | 215篇 |
2020年 | 175篇 |
2019年 | 210篇 |
2018年 | 232篇 |
2017年 | 231篇 |
2016年 | 254篇 |
2015年 | 226篇 |
2014年 | 334篇 |
2013年 | 657篇 |
2012年 | 554篇 |
2011年 | 785篇 |
2010年 | 501篇 |
2009年 | 472篇 |
2008年 | 586篇 |
2007年 | 509篇 |
2006年 | 433篇 |
2005年 | 386篇 |
2004年 | 328篇 |
2003年 | 306篇 |
2002年 | 276篇 |
2001年 | 146篇 |
2000年 | 155篇 |
1999年 | 133篇 |
1998年 | 133篇 |
1997年 | 143篇 |
1996年 | 130篇 |
1995年 | 113篇 |
1994年 | 88篇 |
1993年 | 85篇 |
1992年 | 80篇 |
1991年 | 61篇 |
1990年 | 75篇 |
1989年 | 61篇 |
1988年 | 42篇 |
1987年 | 59篇 |
1986年 | 52篇 |
1985年 | 56篇 |
1984年 | 52篇 |
1983年 | 67篇 |
1982年 | 49篇 |
1981年 | 40篇 |
1980年 | 36篇 |
1979年 | 38篇 |
1978年 | 29篇 |
1977年 | 26篇 |
1976年 | 23篇 |
1975年 | 22篇 |
1974年 | 14篇 |
排序方式: 共有9996条查询结果,搜索用时 0 毫秒
91.
Andrew B. Lambe Joaquim R. R. A. Martins 《Structural and Multidisciplinary Optimization》2016,53(3):589-603
In structural optimization subject to failure constraints, computing the gradients of a large number of functions with respect to a large number of design variables may not be computationally practical. Often, the number of constraints in these optimization problems is reduced using constraint aggregation at the expense of a higher mass of the optimal structural design. This work presents results of structural and coupled aerodynamic and structural design optimization of aircraft wings using a novel matrix-free augmented Lagrangian optimizer. By using a matrix-free optimizer, the computation of the full constraint Jacobian at each iteration is replaced by the computation of a small number of Jacobian-vector products. The low cost of the Jacobian-vector products allows optimization problems with thousands of failure constraints to be solved directly, mitigating the effects of constraint aggregation. The results indicate that the matrix-free optimizer reduces the computational work of solving the optimization problem by an order of magnitude compared to a traditional sequential quadratic programming optimizer. Furthermore, the use of a matrix-free optimizer makes the solution of large multidisciplinary design problems, in which gradient information must be obtained through iterative methods, computationally tractable. 相似文献
92.
Xiaoge Zhang Andrew Adamatzky Xin-She Yang Hai Yang Sankaran Mahadevan Yong Deng 《中国科学:信息科学(英文版)》2016,59(5):052203
A supply chain is a system which moves products from a supplier to customers, which plays a very important role in all economic activities. This paper proposes a novel algorithm for a supply chain network design inspired by biological principles of nutrients’ distribution in protoplasmic networks of slime mould Physarum polycephalum. The algorithm handles supply networks where capacity investments and product flows are decision variables, and the networks are required to satisfy product demands. Two features of the slime mould are adopted in our algorithm. The first is the continuity of flux during the iterative process, which is used in real-time updating of the costs associated with the supply links. The second feature is adaptivity. The supply chain can converge to an equilibrium state when costs are changed. Numerical examples are provided to illustrate the practicality and flexibility of the proposed method algorithm. 相似文献
93.
E-ARK (European Archiving of Records and Knowledge Preservation) is currently introducing standardization, new tools, and infrastructure into pan-European digital archival systems. The results of this pilot project can be applied to higher education where research data centers are required to preserve data for re-use in accordance with new open policies.We elucidate how the E-ARK best practice survey has informed the development of new information packages for ingest, preservation, and re-use, and show how these can be applied to the Arts, Humanities, and Social Sciences with practical exemplars such as census data. 相似文献
94.
Arun Lakhotia Andrew Walenstein Craig Miles Anshuman Singh 《Journal in Computer Virology》2013,9(3):109-123
VILO is a lazy learner system designed for malware classification and triage. It implements a nearest neighbor (NN) algorithm with similarities computed over Term Frequency $\times $ Inverse Document Frequency (TFIDF) weighted opcode mnemonic permutation features (N-perms). Being an NN-classifier, VILO makes minimal structural assumptions about class boundaries, and thus is well suited for the constantly changing malware population. This paper presents an extensive study of application of VILO in malware analysis. Our experiments demonstrate that (a) VILO is a rapid learner of malware families, i.e., VILO’s learning curve stabilizes at high accuracies quickly (training on less than 20 variants per family is sufficient); (b) similarity scores derived from TDIDF weighted features should primarily be treated as ordinal measurements; and (c) VILO with N-perm feature vectors outperforms traditional N-gram feature vectors when used to classify real-world malware into their respective families. 相似文献
95.
Clarke DT Botchway SW Coles BC Needham SR Roberts SK Rolfe DJ Tynan CJ Ward AD Webb SE Yadav R Zanetti-Domingues L Martin-Fernandez ML 《The Review of scientific instruments》2011,82(9):093705
Optics clustered to output unique solutions (OCTOPUS) is a microscopy platform that combines single molecule and ensemble imaging methodologies. A novel aspect of OCTOPUS is its laser excitation system, which consists of a central core of interlocked continuous wave and pulsed laser sources, launched into optical fibres and linked via laser combiners. Fibres are plugged into wall-mounted patch panels that reach microscopy end-stations in adjacent rooms. This allows multiple tailor-made combinations of laser colours and time characteristics to be shared by different end-stations minimising the need for laser duplications. This setup brings significant benefits in terms of cost effectiveness, ease of operation, and user safety. The modular nature of OCTOPUS also facilitates the addition of new techniques as required, allowing the use of existing lasers in new microscopes while retaining the ability to run the established parts of the facility. To date, techniques interlinked are multi-photon/multicolour confocal fluorescence lifetime imaging for several modalities of fluorescence resonance energy transfer (FRET) and time-resolved anisotropy, total internal reflection fluorescence, single molecule imaging of single pair FRET, single molecule fluorescence polarisation, particle tracking, and optical tweezers. Here, we use a well-studied system, the epidermal growth factor receptor network, to illustrate how OCTOPUS can aid in the investigation of complex biological phenomena. 相似文献
96.
Andrew Morrison Geska Helena Andersson Robert Brečević Synne Skjulstad 《Digital Creativity》2013,24(1-2):3-20
The metaphor of plasma is taken up to present and discuss movement and engagement by participants in mixed reality installation arts. Two works involving full body video portraits exhibited through large plasma screens in a variety of public settings are covered. Machinic mediations of video realism are considered in terms of embodied interaction in which viewer-participants contribute to the ‘disquiet’ of gendered figuring. Processural, proximal and personal aspects of responsive engagement are discussed. This is extended to performativity that may lead us to critical reflection of our own actions and responses in mixed reality arts. 相似文献
97.
Advanced cloth simulation plug-in tools are increasingly being used by designers in movies, television, advertising and computer games, to take the strain out of creating and simulating realistic cloth effects for dressing virtual characters. This paper describes experiments into designing textiles and clothing using 3D graphics software and a digital cloth dynamics plug-in, which are an integral part of PhD research in progress. The methods used in testing the 3D software and the cloth dynamics plug-in illustrate the experiences of a designer/learner. The results identify designer/learner needs and expectations for the further educational development of the research and use of cloth simulation tools in textiles/fashion design in the near future. 相似文献
98.
This article investigates how transdisciplinary approaches to curriculum design on a taught masters programme in creative technologies enhance digital creativity in students. Drawing on the experience of developing and running the Masters in Creative Technologies (MA/MSc) at the Institute of Creative Technologies at De Montfort University, Leicester, we explore a number of areas relating to transdisciplinary teaching and learning in higher education, including: how digital technologies enable students to work in a transdisciplinary manner; how working creatively with technology enables transdisciplinary modes of working; and the ways in which transdisciplinarity, enabled by digital technologies, has affected the creative practice of learners. The article discusses how the programme has developed a climate for creativity, and outlines how the knowledge and skills gained during a creative technologies-related transdisciplinary programme meet the needs of a changing workplace. 相似文献
99.
We introduce the idea of a new kind of web search tool that uses the literary and philosophical idea of pataphysics as a conceptual framework in order to return creative results. Pataphysics, the science of exceptions and imaginary solutions, can be directly linked to creativity and is therefore very suitable to guide the transformation from relevant into creative search results. To enable pataphysical algorithms within our system we propose the need for a new type of system architecture. We discuss a component-based software architecture that would allow the flexible integration of the new algorithms at any stage or location and the need for an index suitable to handle patadata, data which have been transformed pataphysically. This tool aims to generate surprising, novel and provocative search results rather than relevant ones, in order to inspire a more creative interaction that has applications in both creative work and learning contexts. 相似文献
100.
Friday Njaya Katherine A. Snyder Daniel Jamu John Wilson Clive Howard-Williams Edward H. Allison Neil L. Andrew 《Journal of Great Lakes research》2011
Lake Chilwa produces between zero and 24,000 metric tons of fish per year, making it one of the most productive but variable lakes in Africa. The size of the lake varies seasonally and among years, sometimes drying completely. Its surrounding wetland and floodplain provide habitat for a diversity of birds and economically valuable grasses and reeds. When the lake has water, there is considerable activity on its shores and temporary fishing villages spring up. People move in and out of the lake basin in concert with these seasonal and longer term changes. This paper examines the environmental dynamics of Lake Chilwa and its surrounding wetlands, presents an overview of the socio-economic context of the area and discusses threats to this resilient system that might occur as a result of climate change. We conclude that management of Lake Chilwa must place the lake in the wider economic and ecological system in which it is situated. Ultimately, land-use practices within the basin present more of a threat to the resilience of the fishery and people's livelihoods than overfishing or a strict focus on the lake's resources. These perspectives present significant challenges to conventional fisheries governance. 相似文献