全文获取类型
收费全文 | 3448篇 |
免费 | 274篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 18篇 |
综合类 | 2篇 |
化学工业 | 1079篇 |
金属工艺 | 36篇 |
机械仪表 | 82篇 |
建筑科学 | 142篇 |
能源动力 | 72篇 |
轻工业 | 702篇 |
水利工程 | 41篇 |
石油天然气 | 11篇 |
无线电 | 209篇 |
一般工业技术 | 574篇 |
冶金工业 | 357篇 |
原子能技术 | 12篇 |
自动化技术 | 392篇 |
出版年
2024年 | 15篇 |
2023年 | 80篇 |
2022年 | 233篇 |
2021年 | 286篇 |
2020年 | 123篇 |
2019年 | 134篇 |
2018年 | 163篇 |
2017年 | 141篇 |
2016年 | 127篇 |
2015年 | 143篇 |
2014年 | 155篇 |
2013年 | 234篇 |
2012年 | 208篇 |
2011年 | 267篇 |
2010年 | 147篇 |
2009年 | 182篇 |
2008年 | 144篇 |
2007年 | 148篇 |
2006年 | 103篇 |
2005年 | 95篇 |
2004年 | 66篇 |
2003年 | 72篇 |
2002年 | 53篇 |
2001年 | 26篇 |
2000年 | 27篇 |
1999年 | 31篇 |
1998年 | 43篇 |
1997年 | 43篇 |
1996年 | 28篇 |
1995年 | 20篇 |
1994年 | 17篇 |
1993年 | 14篇 |
1992年 | 18篇 |
1990年 | 10篇 |
1989年 | 12篇 |
1988年 | 13篇 |
1987年 | 7篇 |
1986年 | 8篇 |
1985年 | 11篇 |
1984年 | 5篇 |
1983年 | 8篇 |
1982年 | 9篇 |
1981年 | 5篇 |
1979年 | 3篇 |
1977年 | 7篇 |
1976年 | 6篇 |
1975年 | 5篇 |
1973年 | 6篇 |
1972年 | 4篇 |
1964年 | 3篇 |
排序方式: 共有3729条查询结果,搜索用时 15 毫秒
61.
J. D. Santos P. L. Silva J. C. Knowles S. Talal F. J. Monteiro 《Journal of materials science. Materials in medicine》1996,7(3):187-189
Commercial hydroxyapatite was reinforced by adding small amounts (2 and 4 wt%) of P2O5-based glasses during its sintering process. The composites prepared had a chemical composition closely related to the mineral part of bone tissues in terms of trace elements usually detected, such as Na, K and Mg. X-ray diffraction analysis (XRD) showed that the glass reinforced-HA composites were composed of a HA matrix and variable amounts of tricalcium phosphate phase, depending on sintering temperature and glass composition. These composites were shown to have much higher biaxial bending strength than sintered HA, 107 MPa for Ha/2% of 35P2O5-35CaO-10Na2O-10K2O-10MgO glass composite and 28 MPa for sintered HA. The presence of -tricalcium phosphate in the microstructure of the composites is an important factor in the reinforcement process.This paper was accepted for publication after the 1995 Conference of the European Society of Biomaterials, Oporto. Portugal, 10–13 September. 相似文献
62.
63.
Krishnamurthy A McMains S Haller K 《IEEE transactions on visualization and computer graphics》2011,17(6):729-742
We present practical algorithms for accelerating distance queries on models made of trimmed NURBS surfaces using programmable Graphics Processing Units (GPUs). We provide a generalized framework for using GPUs as coprocessors in accelerating CAD operations. By supplementing surface data with a surface bounding-box hierarchy on the GPU, we answer distance queries such as finding the closest point on a curved NURBS surface given any point in space and evaluating the clearance between two solid models constructed using multiple NURBS surfaces. We simultaneously output the parameter values corresponding to the solution of these queries along with the model space values. Though our algorithms make use of the programmable fragment processor, the accuracy is based on the model space precision, unlike earlier graphics algorithms that were based only on image space precision. In addition, we provide theoretical bounds for both the computed minimum distance values as well as the location of the closest point. Our algorithms are at least an order of magnitude faster and about two orders of magnitude more accurate than the commercial solid modeling kernel ACIS. 相似文献
64.
We address the problem of control and synchronization of a class of uncertain chaotic systems. Our approach follows techniques of sliding mode control and adaptive estimation law. The adaptive algorithm is constructed based on the sliding mode control to ensure perfect tracking and synchronization in presence of system uncertainty and external disturbance. Stability of the closed-loop system is proved using Lyapunov stability theory. Our theoretical findings are supported by simulation results. 相似文献
65.
Low‐income Hispanics are the most digitally underserved population in the U.S. This article examines the potential of community‐based participatory research approach to e‐health to decrease the disparities in access to technology and health information in low‐income Hispanic communities. To demonstrate this framework, we describe the process of designing a community‐based e‐health intervention to increase knowledge and parental self‐efficacy in coping with young children's mental health problems including mental health service utilization. Our model incorporates utilizing promotoras de salud (lay community health educators) and community media principles to create the content of e‐health interventions and train community members in using the technology. This case study illustrates the processes involved in using this approach, barriers for participatory e‐health interventions in bridging the Digital Divide, and lessons learned. 相似文献
66.
Beatriz C. BarjaAuthor Vitae Sara E. BariAuthor VitaeM. Claudia MarchiAuthor Vitae Fabricio L. IglesiasAuthor VitaeMilagros BernardiAuthor Vitae 《Sensors and actuators. B, Chemical》2011,158(1):214-222
In this work we used the sol-gel technique to develop luminescent Eu(III) transparent films deposited on glass slides to build for sensor devices capable of monitoring transition metal ions in aqueous solutions. The films were obtained from a bis(trialkoxysilyl) organic precursor synthesized from the amide of the 2,6-pyridinedicarboxylic acid (DPA) with aminopropyltriethoxysilane (APTES) in the presence or absence of cetyl trimethyl ammonium bromide (CTAB) surfactant as templating agent and triethylethoxysilane (TEOS) as crosslinker. These sensor devices were used to perform in situ quenching experiments by Cu(II), Fe(III), Co(II) and Ni(II) ions. The results indicate that the templated films allow the detection and quantification of these metals down to ppb levels by means of the values of the Stern-Volmer constants. In particular, it was shown that Cu(II) acts as an extremely efficient quencher (KSV = 3.5 × 105 M−1) when compared with the results obtained for the other metals, opening the possibility to use these devices as potential Cu(II) sensors for actual applications in aqueous media. 相似文献
67.
Fotis Liarokapis Louis Macan Gary Malone Genaro Rebolledo-Mendez Sara de Freitas 《The Visual computer》2009,25(12):1109-1120
This paper presents tangible augmented reality gaming environment that can be used to enhance entertainment using a multimodal
tracking interface. Players can interact using different combinations between a pinch glove, a Wiimote, a six-degrees-of-freedom
tracker, through tangible ways as well as through I/O controls. Two tabletop augmented reality games have been designed and
implemented including a racing game and a pile game. The goal of the augmented reality racing game is to start the car and
move around the track without colliding with either the wall or the objects that exist in the gaming arena. Initial evaluation
results showed that multimodal-based interaction games can be beneficial in gaming. Based on these results, an augmented reality
pile game was implemented with goal of completing a circuit of pipes (from a starting point to an end point on a grid). Initial
evaluation showed that tangible interaction is preferred to keyboard interaction and that tangible games are much more enjoyable. 相似文献
68.
User interfaces are becoming more intuitive following the requirements of the individual learner and reinforcing the drive towards more personalised learning and greater learner autonomy. There are clearly a new set of challenges emerging for teaching practitioners that will have implications upon not just what is learned but importantly upon lesson planning. This paper explores these changes to teaching through a consideration of an exploratory learning model which allows practitioners to rethink how they teach in 3D and immersive spaces where learning sequences and experiences are choreographed to support peer interactions and exchanges. The ELM extends from Kolb’s experiential learning model to adapt the use of 3D applications, and provides examples from research and development projects to exemplify how the model works in practice. Teaching in these contexts provides less emphasis upon curriculum and more emphasis upon sequencing learning experiences, meta-reflection, peer assessment and group work. 相似文献
69.
Teachers’ knowledge of computer-related ergonomics in education will have an effect on the learning process and the work practices of their students. However little is known about teacher education in this area. The study aimed to investigate the sources and nature of secondary school teachers’ education about computer-related ergonomics. It also investigated the use of computers by secondary school children. The study included all secondary schools in the Republic of Ireland. The findings suggest that computers are widely available and are used frequently by students and teachers. However, there is evidence that teachers are not receiving information on computer-related ergonomics. Teachers were generally dissatisfied with this and would welcome information on the subject. The study discusses the implications of the findings and makes recommendations to meet the needs of the teachers. 相似文献
70.
We propose FMJ (Featherweight Multi Java), an extension of Featherweight Java with encapsulated multi-methods thus providing dynamic overloading. Multi-methods (collections of overloaded methods associated to the same message, whose selection takes place dynamically instead of statically as in standard overloading) are a useful and flexible mechanism which enhances re-usability and separation of responsibilities. However, many mainstream languages, such as, e.g., Java, do not provide it, resorting to only static overloading.The proposed extension is conservative and type safe: both “message-not-understood” and “message-ambiguous” are statically ruled out. Possible ambiguities are checked during type checking only on method invocation expressions, without requiring to inspect all the classes of a program. A static annotation with type information guarantees that in a well-typed program no ambiguity can arise at run-time. This annotation mechanism also permits modeling static overloading in a smooth way.Our core language can be used as the formal basis for an actual implementation of dynamic (and static) overloading in Java-like languages. 相似文献