全文获取类型
收费全文 | 2249篇 |
免费 | 62篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 22篇 |
综合类 | 2篇 |
化学工业 | 459篇 |
金属工艺 | 34篇 |
机械仪表 | 50篇 |
建筑科学 | 142篇 |
矿业工程 | 5篇 |
能源动力 | 75篇 |
轻工业 | 190篇 |
水利工程 | 17篇 |
石油天然气 | 12篇 |
无线电 | 174篇 |
一般工业技术 | 370篇 |
冶金工业 | 466篇 |
原子能技术 | 15篇 |
自动化技术 | 285篇 |
出版年
2022年 | 15篇 |
2021年 | 29篇 |
2020年 | 22篇 |
2019年 | 26篇 |
2018年 | 35篇 |
2017年 | 35篇 |
2016年 | 46篇 |
2015年 | 32篇 |
2014年 | 50篇 |
2013年 | 158篇 |
2012年 | 95篇 |
2011年 | 130篇 |
2010年 | 93篇 |
2009年 | 76篇 |
2008年 | 108篇 |
2007年 | 98篇 |
2006年 | 73篇 |
2005年 | 78篇 |
2004年 | 72篇 |
2003年 | 71篇 |
2002年 | 56篇 |
2001年 | 35篇 |
2000年 | 55篇 |
1999年 | 43篇 |
1998年 | 77篇 |
1997年 | 47篇 |
1996年 | 48篇 |
1995年 | 41篇 |
1994年 | 38篇 |
1993年 | 35篇 |
1992年 | 18篇 |
1991年 | 16篇 |
1990年 | 23篇 |
1989年 | 28篇 |
1988年 | 28篇 |
1987年 | 23篇 |
1986年 | 25篇 |
1985年 | 34篇 |
1984年 | 27篇 |
1983年 | 24篇 |
1982年 | 20篇 |
1981年 | 31篇 |
1980年 | 17篇 |
1979年 | 13篇 |
1978年 | 14篇 |
1977年 | 14篇 |
1976年 | 14篇 |
1975年 | 22篇 |
1974年 | 15篇 |
1973年 | 13篇 |
排序方式: 共有2318条查询结果,搜索用时 15 毫秒
31.
The objective of this research was to study the morphology and properties of PVC–polyurethane blends. Studies on blends of a segmented polyether polyurethane with PVC were carried out utilizing differential scanning calorimetry, Rheovibron, stress–strain, infrared peak position studies, and infrared dichroism experiments. This thermodynamically incompatible system was made kinetically compatible by precipitation from tetrahydrofuran (THF) solutions. THF–dioxane solution casting and melt processing produced an incompatible system. The compatible polyurethane–PVC system contains a well-mixed PVC–polyether matrix phase as evidenced by Tg shifts, orientation characteristics, and infrared peak position changes. The aromatic urethane segments which exhibit microphase separation in the pure polyurethane are not solubilized by blending with PVC by any of sample preparation methods used in this study. 相似文献
32.
Dan I. Enache Dean Barker Jennifer K. Edwards Stuart H. Taylor David W. Knight Albert F. Carley Graham J. Hutchings 《Catalysis Today》2007,122(3-4):407-411
The oxidation of benzyl alcohol with molecular oxygen under solvent-free conditions has been investigated using a range of titania-supported Au–Pd alloy catalysts to examine the effect of the Au–Pd ratio on the conversion and selectivity. The catalysts have been compared at high reaction temperature (160 °C) as well as at 100 °C, to determine the effect on selectivity since at lower reaction temperature the range of by-products that are formed are limited. Under these conditions the 2.5 wt.% Au–2.5 wt.% Pd/TiO2 was found to be the most active catalyst, whereas the Au/TiO2 catalyst demonstrated the highest selectivity to benzaldehyde. Toluene, formed via either a hydrogen transfer process or an oxygen transfer process, was observed as a major by-product under these forcing conditions. 相似文献
33.
Metallo-Supramolecular Polymerization: A Route to Easy-To-Process Organic/Inorganic Hybrid Materials
Mark Burnworth Daniel Knapton Stuart J. Rowan Christoph Weder 《Journal of Inorganic and Organometallic Polymers and Materials》2007,17(1):91-103
The self-assembly polymerization of ditopic macromolecules via metal–ligand binding is a facile route for the preparation
of metallo-supramolecular polymers (MSPs). We herein review our recent work focused on the synthesis and investigation of
metallo-supramolecular polymers based on 2,6-bis(1′-methylbenzimidazolyl)pyridine endcapped poly(p-phenylene ethynylene) and poly(p-xylene) macromonomers. These materials are readily solution-processable and display appreciable mechanical properties as
well as other attractive properties such as specific opto/electrical functions or high thermal stability. Our work illustrates
that metallosupramolecular polymerization offers an attractive approach to assemble high-molecular-weight macromolecules from
well-defined, easy to process precursors. Variation of the ditopic ligands and metal ions allows one to easily tailor the
desired properties.
This paper is dedicated to Professor Ian Manners and his scientific accomplishments. 相似文献
34.
Richard H. Harris Vicki J. Boyd Graham J. Hutchings Stuart H. Taylor 《Catalysis Letters》2002,78(1-4):369-372
The effect of water addition on the complete oxidation of benzene and propane VOCs by uranium oxide catalysts has been investigated. Benzene oxidation was studied using a silica supported U3O8 catalyst. Complete oxidation is promoted by the addition of 2.6% water compared with the reactivity when no water is added to the reactant feed. Increasing the water concentration to 12.1% resulted in a suppression of oxidation activity. Investigation of propane oxidation using U3O8 shows a dramatic promotion of activity. Propane conversion was ca. 50% at 600 °C without added water, whilst it increased to 100% at 400 °C with the addition of 2.6% water. A comparison of oxidation activity has been made with Mn2O3, an oxide recognised for complete oxidation. In contrast to the U3O8 catalysts the addition of 2.6% water suppresses the activity of Mn2O3. In situ powder X-ray diffraction studies showed that the bulk U3O8 structure was stable under all the reaction conditions. The origin of the increased activity is not clear but may be due to modification of the catalyst surface and the contribution from new reaction pathways such as steam reforming. 相似文献
35.
Rogers Jeffrey M. Jensen Jenny Valderrama Joaquin T. Johnstone Stuart J. Wilson Peter H. 《Virtual Reality》2021,25(2):357-366
Virtual Reality - Stroke rehabilitation suffers from low levels of patient engagement, impeding recovery. Virtual rehabilitation (VR) approaches can improve patient outcomes; however, there is... 相似文献
36.
Stuart Moran Nils Jäger Holger Schnädelbach Kevin Glover 《Personal and Ubiquitous Computing》2016,20(2):261-275
Both breathing and internal self-awareness are an integral part of any yoga practice. We describe and discuss the development of ExoPranayama, an actuated environment that physically manifests users’ breathing in yoga. Through a series of trials with yoga practitioners and expert teachers, we explore its role in the practice of yoga. Our interview results reveal that biofeedback through the environment supported teaching and improved self-awareness, but it impacted group cohesion. Two practical uses of the technology emerged for supporting breath control in yoga: (1) biofeedback can provide new information about users’ current internal states; (2) machine-driven feedback provides users with a future state or goal and leads to improved cohesiveness. 相似文献
37.
Abstract While rich support for a wide variety of media such as text, video and image is common among contemporary hypermedia systems, so too is the inadequate support for audio. The primary reason that audio has not attracted as much attention as other media can be attributed to its obvious lack of visual identity. The main focus of this work was to identify a generic and meaningful visual representation of audio within a hypermedia context, and significantly promote hypermedia support for audio through the provision of a sound viewer. This paper describes the inherent difficulties in providing a consistent interface to audio, and discusses in some depth the issues raised during the development process. The sound viewer is then introduced and the associated concepts described. The creation and traversal of links to and from audio are facilitated by the sound viewer across formats including WAV (proprietary digital sound file format from Microsoft), CD (Compact Disc) Audio and MIDI (Musical Instrument Digital Interface). The resultant viewer provides a unified and extensible framework for interacting with audio from within an open hypermedia environment. The open hypermedia system Microcosm was used as the development platform for this work. Microcosm can be augmented to supply a hypermedia link service to additional media with minimal overhead. 相似文献
38.
Stuart Nolan 《Digital Creativity》2013,24(3):185-192
Abstract This paper reports on 12 participatory design workshops involving 216 young people, aged 9 to 16. It discusses responses to existing and proposed locative and pervasive media technologies in gaming, mapping, gifting, game design, bodystorming, and collaborative storytelling activities. Issues of the technomagical in scenario planning are discussed. 相似文献
39.
Understanding, monitoring and modelling attributes of seagrass biodiversity, such as species composition, richness, abundance, spatial patterns, and disturbance dynamics, requires spatial information. This work assessed the accuracy of commonly available airborne hyper-spectral and satellite multi-spectral image data sets for mapping seagrass species composition, horizontal horizontal-projected foliage cover and above-ground dry-weight biomass. The work was carried out on the Eastern Banks in Moreton Bay, Australia, an area of shallow and clear coastal waters, containing a range of seagrass species, cover and biomass levels. Two types of satellite image data were used: Quickbird-2 multi-spectral and Landsat-5 Thematic Mapper multi-spectral. Airborne hyper-spectral image data were acquired from a CASI-2 sensor using a pixel size of 4.0 m. The mapping was constrained to depths shallower than 3.0 m, based on past modelling of the separability of seagrass reflectance signatures at increasing water depths. Our results demonstrated that mapping of seagrass cover, species and biomass to high accuracy levels (> 80%) was not possible across all image types. For each parameter mapped, airborne hyper-spectral data produced the highest overall accuracies (46%), followed by Quickbird-2 and then Landsat-5 Thematic Mapper. The low accuracy levels were attributed to the mapping methods and difficulties in matching locations on image and field data sets. Accurate mapping of seagrass cover, species composition and biomass, using simple approaches, requires further work using high-spatial resolution (< 5 m) and/or hyper-spectral image data. Further work is required to determine if and how the seagrass maps produced in this work are suitable for measuring attributes of seagrass biodiversity, and using these data for modelling floral and fauna biodiversity properties of seagrass environments, and for scaling-up seagrass ecosystem models. 相似文献
40.
We examine the effect of information sharing within small world networks. Agents receive a signal correlated with the state
of the world (SoW) which is adjusted following discussions with neighbours. If one agent in the network, referred to as an
expert, does not engage in social learning (that is they always follow their own signal) then all agents learn the SoW. It
is found that volatility in the mean level of expectations varies with changes in the number of experts and the network structure.
A trade-off emerges between the level of volatility and the speed at which agents learn of changes to the SoW. A second finding
is that certain network structures lead to information cascades.
相似文献