全文获取类型
收费全文 | 291278篇 |
免费 | 22976篇 |
国内免费 | 11161篇 |
专业分类
电工技术 | 18293篇 |
技术理论 | 62篇 |
综合类 | 26713篇 |
化学工业 | 22081篇 |
金属工艺 | 11983篇 |
机械仪表 | 23529篇 |
建筑科学 | 62484篇 |
矿业工程 | 11242篇 |
能源动力 | 6665篇 |
轻工业 | 14646篇 |
水利工程 | 6453篇 |
石油天然气 | 9074篇 |
武器工业 | 4226篇 |
无线电 | 25772篇 |
一般工业技术 | 24561篇 |
冶金工业 | 9343篇 |
原子能技术 | 1459篇 |
自动化技术 | 46829篇 |
出版年
2025年 | 23篇 |
2024年 | 3764篇 |
2023年 | 4113篇 |
2022年 | 6327篇 |
2021年 | 7901篇 |
2020年 | 8188篇 |
2019年 | 5455篇 |
2018年 | 5087篇 |
2017年 | 6865篇 |
2016年 | 8106篇 |
2015年 | 8981篇 |
2014年 | 21561篇 |
2013年 | 16445篇 |
2012年 | 21213篇 |
2011年 | 22197篇 |
2010年 | 18047篇 |
2009年 | 18545篇 |
2008年 | 16921篇 |
2007年 | 20492篇 |
2006年 | 17423篇 |
2005年 | 15285篇 |
2004年 | 12718篇 |
2003年 | 11465篇 |
2002年 | 9315篇 |
2001年 | 7892篇 |
2000年 | 6361篇 |
1999年 | 5054篇 |
1998年 | 3852篇 |
1997年 | 3117篇 |
1996年 | 2605篇 |
1995年 | 2120篇 |
1994年 | 1767篇 |
1993年 | 1257篇 |
1992年 | 1037篇 |
1991年 | 798篇 |
1990年 | 597篇 |
1989年 | 528篇 |
1988年 | 405篇 |
1987年 | 265篇 |
1986年 | 189篇 |
1985年 | 197篇 |
1984年 | 189篇 |
1983年 | 126篇 |
1982年 | 133篇 |
1981年 | 79篇 |
1980年 | 88篇 |
1979年 | 53篇 |
1978年 | 22篇 |
1977年 | 21篇 |
1959年 | 26篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
2.
Over the last five years, many activities have focused on the unexploited field of carrying out reactions on small scales. Due to the rapid development of new components, this paper deals with recent developments only in a compressed form. An important point is the analysis of possible plant concepts for microreactors and whether these are a sensible option. Due to the enormous difference in size between the microchannels and the fluid periphera of possible components this is not just a technical question. It touches on the microtechnology concept as a whole. The direction in which the field should be developed and which measures can be taken to influence its development are questions that are addressed here with respect to the big industrial interest in microreactors. 相似文献
3.
本文用计算机数字模拟方法研究了电活性分子多层Z型L-B膜修饰电极的循环伏安行为。计算了电极与修饰L-B膜分子第一层之间的电荷转移速度常数K_o,L-B膜分子层间的电荷转移速度常数k_i;对峰电位差△E_p及阳极峰面积Q的影响,以及在不同条件下各层分子的氧化态分数随扫描时间的变化。为研究和设计电活性分子修饰电极的实际体系提供了大量数据和信息。 相似文献
4.
Takeshi Nakajo 《Quality and Reliability Engineering International》1993,9(2):111-119
Work system improvements are implemented in various manufacturing processes to prevent problems caused by human errors. However, they are almost always applied to problems which have already occurred. This paper examines a method of identifying latent human errors existing within the work systems beforehand. A procedure for applying failure mode and effect analysis to this identification problem was defined based on over 1000 empirical errors: a work system decomposition criterion and fundamental error modes for listing latent human errors, and then applied to three practical manufacturing processes in order to evaluate its effectiveness. 相似文献
5.
6.
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
7.
Kyle A. Crawford
Osama K. Eyada PhD PE
《Computers & Industrial Engineering》1989,17(1-4):298-302The worldwide proliferation of fraudulent materials has brought about the need for a new approach to the control of purchased material quality. Nuclear power, defense, aerospace and many other industries are affected by the supply of poor quality clones that presume to be original replacement parts. Safety considerations abound as these highly defective materials are used in systems that are critical to the preservation of human lives. Commonly utilized quality assurance programs have not effectively stopped the influx of fraudulent materials. These programs fail to concentrate inspection efforts on materials and inspection attributes that would effectively prevent the acceptance of fraudulent materials. herein a solution is presented to this problem in the form of an expert system application. Information commonly available in industry is formulated into a knowledge based system wherein advisories are given to the user regarding key purchased material receipt inspection strategies. 相似文献
8.
9.
10.
A. Mclntyre 《Journal of Computer Assisted Learning》1993,9(4):262-267
Abstract This paper looks at some of the problems of existing courseware authoring systems, and advocates the use of knowledge-based techniques to resolve these problems and to form the basis of future authoring environments. The prototype knowledge-based representation language, GTE, is presented as an example of a knowledge-based language which might form the basis of such environments. The final part of the paper discusses some of the developments in GTE which must take place if it is to be used within a full and flexible authoring environment. The paper will focus particularly on the question of instructional strategies, but many of the observations can be taken as relevant to all the knowledge involved in a teaching interaction. 相似文献