全文获取类型
收费全文 | 1611篇 |
免费 | 83篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 5篇 |
综合类 | 16篇 |
化学工业 | 424篇 |
金属工艺 | 14篇 |
机械仪表 | 26篇 |
建筑科学 | 131篇 |
矿业工程 | 22篇 |
能源动力 | 21篇 |
轻工业 | 261篇 |
水利工程 | 7篇 |
石油天然气 | 3篇 |
武器工业 | 1篇 |
无线电 | 65篇 |
一般工业技术 | 225篇 |
冶金工业 | 284篇 |
自动化技术 | 192篇 |
出版年
2023年 | 11篇 |
2022年 | 36篇 |
2021年 | 35篇 |
2020年 | 35篇 |
2019年 | 47篇 |
2018年 | 34篇 |
2017年 | 38篇 |
2016年 | 44篇 |
2015年 | 40篇 |
2014年 | 54篇 |
2013年 | 134篇 |
2012年 | 75篇 |
2011年 | 118篇 |
2010年 | 63篇 |
2009年 | 65篇 |
2008年 | 62篇 |
2007年 | 71篇 |
2006年 | 60篇 |
2005年 | 58篇 |
2004年 | 63篇 |
2003年 | 42篇 |
2002年 | 50篇 |
2001年 | 21篇 |
2000年 | 27篇 |
1999年 | 43篇 |
1998年 | 21篇 |
1997年 | 17篇 |
1996年 | 32篇 |
1995年 | 24篇 |
1994年 | 17篇 |
1993年 | 19篇 |
1992年 | 15篇 |
1991年 | 8篇 |
1990年 | 20篇 |
1989年 | 15篇 |
1988年 | 8篇 |
1987年 | 8篇 |
1986年 | 11篇 |
1985年 | 7篇 |
1984年 | 11篇 |
1983年 | 10篇 |
1982年 | 8篇 |
1981年 | 8篇 |
1979年 | 9篇 |
1978年 | 8篇 |
1975年 | 8篇 |
1974年 | 9篇 |
1972年 | 6篇 |
1970年 | 6篇 |
1967年 | 6篇 |
排序方式: 共有1697条查询结果,搜索用时 15 毫秒
41.
The electricity industry is rapidly changing: costs are increasingly dominated by capital and technology is turning loads into resources. This is similar to the early days of the Internet. Building on rate-structures used in the communications industry, utilities of the future should offer customers a portfolio of service contract options that provide a signal to the utility regarding the type and amount of infrastructure that should be deployed. 相似文献
42.
43.
Lisa J. White Giles T.S. Kirby Helen C. Cox Roozbeh Qodratnama Omar Qutachi Felicity R.A.J. Rose Kevin M. Shakesheff 《Materials science & engineering. C, Materials for biological applications》2013,33(5):2578-2583
There is a need to control the spatio-temporal release kinetics of growth factors in order to mitigate current usage of high doses. A novel delivery system, capable of providing both structural support and controlled release kinetics, has been developed from PLGA microparticles. The inclusion of a hydrophilic PLGA–PEG–PLGA triblock copolymer altered release kinetics such that they were decoupled from polymer degradation. A quasi zero order release profile over four weeks was produced using 10% w/w PLGA–PEG–PLGA with 50:50 PLGA whereas complete and sustained release was achieved over ten days using 30% w/w PLGA–PEG–PLGA with 85:15 PLGA and over four days using 30% w/w PLGA–PEG–PLGA with 50:50 PLGA. These three formulations are promising candidates for delivery of growth factors such as BMP-2, PDGF and VEGF. Release profiles were also modified by mixing microparticles of two different formulations providing another route, not previously reported, for controlling release kinetics. This system provides customisable, localised and controlled delivery with adjustable release profiles, which will improve the efficacy and safety of recombinant growth factor delivery. 相似文献
44.
Elisandra Rigo Jorge Luiz Ninow Siu Mui Tsai Ademir Durrer Lillian Liva Foltran Daniela Remonatto Melania Sychoski Renata Vardanega Débora de Oliveira Helen Treichel Marco Di Luccio 《Food and Bioprocess Technology》2012,5(5):1592-1600
Current studies about lipase production involve the use of agro-industrial residues and newly isolated microorganisms aimed at increasing economic attractiveness of the process. Based on these aspects, the main objective of this work is to perform the partial characterization of enzymatic extracts produced by a newly isolated Penicillium crustosum in solid-state fermentation. Lipase extract presented optimal temperature and pH of 37?°C and 9?C10, respectively. The concentrated enzymatic extract showed more stability at 25?°C and pH?7. The enzymes kept 100% of their enzymatic activity until 60?days of storage at 4 and ?10?°C. The stability under calcium salts indicated that the hydrolytic activity presented decay with the increase of calcium concentration. The specificity under several substrates indicated good enzyme activities in triglycerides from C4 to C18. 相似文献
45.
Multimedia Tools and Applications - In this paper, we propose a hybrid fog and cloud-aware heuristic for the dynamic scheduling of multiple real-time Internet of Things (IoT) workflows in a... 相似文献
46.
47.
Protecting plant resources from harmful organisms that can spread internationally is a major challenge for plant protection organisations. Natural scientists and economists have methods that contribute to informing and supporting government decision makers in plant health authorities, who also need to account for stakeholders’ views when developing policy and regulations to mitigate plant pest risks. Increasingly plant protection authorities seek to develop integrated decision making through economists and scientists working within an interdisciplinary framework. In this special section of Food Security we introduce a series of papers presented at an international conference that brought together natural scientists, economists, industry representatives and plant health policy makers to report the state of the art and explore the direction and future research needs for such interdisciplinary working to deliver rational plant protection policy and improved food security for the 21st Century. The collection of papers combine contributions from leading academics and influential policy makers and provides cohesive international perspectives on the use of science and economics, as well as their integration, to progress the development of integrated multi-disciplinary plant health policy making around the world. Using a modified version of the world café method during a conference workshop activity, participants identified greater international co-operation as a key mechanism that would reduce international plant health risks. Specifically, co-operation over analysis among stakeholders and along supply chains were seen as key issues. 相似文献
48.
Distraction and inattention are considered to be very important and prevalent factors in the causation of road accidents. There have been many recent research studies which have attempted to understand the circumstances under which a driver becomes distracted or inattentive and how distraction/inattention can be prevented. Both factors are thought to have become more important in recent times partly due to the evolution of in-vehicle information and communication technology. This study describes a methodology that was developed to understand when factors such as distraction and inattention may have been contributors to crashes and also describes some of the consequences of distraction and inattention in terms of subsequent driver actions. 相似文献
49.
Hossein Agheshlui Helen Goldsworthy Emad Gad Saman Fernando 《Materials and Structures》2016,49(4):1511-1525
In this paper, the tensile behaviour of a new type of blind bolt, the anchored blind bolt, has been studied. This type of bolt consists of a conventional blind bolt with a headed stud extension that anchors it into the infill concrete. It has been developed for use in moment-resisting connections between I-beams and concrete-filled hollow section columns. The behaviour of these connections is highly dependent on the tensile behaviour of the anchored blind bolts. Hence, the fundamental mechanics of this behaviour has been studied here, both experimentally and in simulations using FE models. The complex interactions between the headed stud anchorage, the concrete infill, and the steel tube have been examined in detail. The experimental and numerical findings were used to understand the influence of important parameters in the tensile behaviour of the anchored blind bolts. It was found that the location of the bolt with respect to the side walls of the tube had a substantial influence on the behaviour of the anchored blind bolts. All the bolts located close to the side walls of the square hollow sections reached the ultimate tensile capacity of the equivalent structural bolts. This was due to the development of a concrete strut which transferred the load to the corner of the steel section. The bolt diameter also had a significant influence on the stiffness and strength of the anchored blind bolts. 相似文献
50.
Ronit Bitton Lesley W. Chow R. Helen Zha Yuri S. Velichko E. Thomas Pashuck Samuel I. Stupp 《Small (Weinheim an der Bergstrasse, Germany)》2014,10(3):500-505
Self‐assembling peptide amphiphiles (PAs) can form hierarchically ordered membranes when brought in contact with aqueous polyelectrolytes of the opposite charge by rapidly creating a diffusion barrier composed of filamentous nanostructures parallel to the plane of the incipient membrane. Following this event, osmotic forces and charge complexation template nanofiber growth perpendicular to the plane of the membrane in a dynamic self‐assembly process. In this work, we show that this hierarchical structure requires massive interfacial aggregation of PA molecules, suggesting the importance of rapid diffusion barrier formation. Strong PA aggregation is induced here through the use of heparin‐binding PAs with heparin and also with polyelectrolytes of varying charge density. Small angle X‐ray scattering shows that in the case of weak PA‐polyelectrolyte interaction, membranes formed display a cubic phase ordering on the nanoscale that likely results from clusters of PA nanostructures surrounded by polyelectrolyte chains. 相似文献