全文获取类型
收费全文 | 4416篇 |
免费 | 179篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 64篇 |
综合类 | 9篇 |
化学工业 | 590篇 |
金属工艺 | 87篇 |
机械仪表 | 83篇 |
建筑科学 | 320篇 |
矿业工程 | 17篇 |
能源动力 | 145篇 |
轻工业 | 433篇 |
水利工程 | 51篇 |
石油天然气 | 19篇 |
无线电 | 356篇 |
一般工业技术 | 753篇 |
冶金工业 | 639篇 |
原子能技术 | 24篇 |
自动化技术 | 1013篇 |
出版年
2023年 | 18篇 |
2022年 | 33篇 |
2021年 | 74篇 |
2020年 | 60篇 |
2019年 | 75篇 |
2018年 | 111篇 |
2017年 | 122篇 |
2016年 | 112篇 |
2015年 | 103篇 |
2014年 | 120篇 |
2013年 | 311篇 |
2012年 | 248篇 |
2011年 | 301篇 |
2010年 | 241篇 |
2009年 | 223篇 |
2008年 | 290篇 |
2007年 | 250篇 |
2006年 | 239篇 |
2005年 | 188篇 |
2004年 | 134篇 |
2003年 | 134篇 |
2002年 | 144篇 |
2001年 | 89篇 |
2000年 | 93篇 |
1999年 | 80篇 |
1998年 | 98篇 |
1997年 | 93篇 |
1996年 | 75篇 |
1995年 | 62篇 |
1994年 | 47篇 |
1993年 | 36篇 |
1992年 | 37篇 |
1991年 | 24篇 |
1990年 | 21篇 |
1989年 | 29篇 |
1988年 | 20篇 |
1987年 | 26篇 |
1986年 | 22篇 |
1985年 | 22篇 |
1984年 | 24篇 |
1983年 | 12篇 |
1982年 | 18篇 |
1981年 | 12篇 |
1980年 | 18篇 |
1979年 | 23篇 |
1978年 | 13篇 |
1977年 | 6篇 |
1976年 | 17篇 |
1975年 | 8篇 |
1972年 | 9篇 |
排序方式: 共有4603条查询结果,搜索用时 46 毫秒
11.
J Byrne S Kienzle D Johnson G Duke V Gannon B Selinger J Thomas 《Water science and technology》2006,53(10):327-334
Long-term trends in alpine and prairie snow pack accumulation and melt are affecting streamflow within the Oldman River Basin in southern Alberta, Canada. Unchecked rural and urban development also has contributed to changes in water quality, including enhanced microbial populations and increased waterborne pathogen occurrence. In this study we look at changing environment within the Oldman River Basin and its impact on water quality and quantity. The cumulative effects include a decline in net water supplies, and declining quality resulting in increased risk of disease. Our data indicates that decreases in the rate of flow of water can result in sedimentation of bacterial contaminants within the water column. Water for ecosystems, urban consumption, recreation and distribution through irrigation is often drawn from waterholding facilities such as dams and weirs, and concern must be expressed over the potential for contaminate build-up and disproportionate potential of these structures to pose a risk to human and animal health. With disruption of natural flow rates for water resulting from environmental change such as global warming and/or human intervention, increased attention needs to be paid to use of best management practices to protect source water supplies. 相似文献
12.
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
13.
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
14.
We present a two-sorted algebra, called aPeirce algebra, of relations and sets interacting with each other. In a Peirce algebra, sets can combine with each other as in a Boolean algebra, relations can combine with each other as in a relation algebra, and in addition we have both a set-forming operator on relations (the Peirce product of Boolean modules) and a relation-forming operator on sets (a cylindrification operation). Two applications of Peirce algebras are given. The first points out that Peirce algebras provide a natural algebraic framework for modelling certain programming constructs. The second shows that the so-calledterminological logics arising in knowledge representation have evolved a semantics best described as a calculus of relations interacting with sets. 相似文献
15.
R Byrne 《Canadian Metallurgical Quarterly》1998,69(7):24-6 contd; quiz 27
16.
17.
Chris Bergen 《电子测试》2005,(4):56-58
背板互连特性 背板是位于机架内的互连装置,它可能具备或不具备智能功能,通常其上可以有各种插卡和电路板插在插槽上.被动式背板电路可能需要使用电阻、处理器或一些控制驱动器电路.过去,背板互连一直是附加的物理端口如插头、插座或无线端口,如发射器、接收器等装置.大部分情况下,背板上都会为交换卡保留1~2个插槽作为背板的基础架构和逻辑层. 相似文献
18.
19.
Wenzhong Zhu John J. Hughes Nenad Bicanic Chris J. Pearce 《Materials Characterization》2007,58(11-12):1189
This paper reports a study to assess nanoindentation mapping of mechanical properties of cement paste and natural rocks. Initial work seems to show that mechanical property mapping by nanoindentation is feasible and can be related to microscopic information. Further work is however required on the effect of indent size and spacing. Such a testing technique can be very useful for materials with different phases to study the intrinsic properties of each component, and also the interaction and properties of the interfacial regions of different phases. The values of Young's modulus and hardness of the individual mineral phases were also determined by statistically analysing a large number of experimental data. 相似文献
20.
Cunningham William A.; Johnson Marcia K.; Gatenby J. Chris; Gore John C.; Banaji Mahzarin R. 《Canadian Metallurgical Quarterly》2003,85(4):639
Evaluative responses appear to involve 2 seemingly distinct sets of processes: those that are automatically activated and others that are more consciously controlled. Using functional magnetic resonance imaging, the authors investigated the brain systems associated with automatic and controlled evaluative processing. Participants made either evaluative (good-bad) or nonevaluative (past-present) judgments about famous names. Greater amygdala activity was observed for names rated as "bad" relative to those rated as "good," regardless of whether the task directly involved an evaluative judgment (good-bad) or not (past-present). Good-bad judgments resulted in greater medial and ventrolateral prefrontal cortex (PFC) activity than past-present judgments. Furthermore, there was greater ventrolateral PFC activity in good-bad judgments marked by greater ambivalence. Together, these findings indicate a neural distinction between processes engaged for automatic and controlled evaluation. Whereas automatic processes are sensitive to simple valence, controlled processes are sensitive to attitudinal complexity. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献