全文获取类型
收费全文 | 6510篇 |
免费 | 315篇 |
国内免费 | 17篇 |
专业分类
电工技术 | 73篇 |
综合类 | 7篇 |
化学工业 | 1534篇 |
金属工艺 | 107篇 |
机械仪表 | 148篇 |
建筑科学 | 327篇 |
矿业工程 | 9篇 |
能源动力 | 226篇 |
轻工业 | 540篇 |
水利工程 | 61篇 |
石油天然气 | 26篇 |
武器工业 | 2篇 |
无线电 | 581篇 |
一般工业技术 | 1111篇 |
冶金工业 | 913篇 |
原子能技术 | 34篇 |
自动化技术 | 1143篇 |
出版年
2023年 | 67篇 |
2022年 | 108篇 |
2021年 | 173篇 |
2020年 | 123篇 |
2019年 | 125篇 |
2018年 | 175篇 |
2017年 | 157篇 |
2016年 | 192篇 |
2015年 | 160篇 |
2014年 | 223篇 |
2013年 | 406篇 |
2012年 | 366篇 |
2011年 | 428篇 |
2010年 | 325篇 |
2009年 | 369篇 |
2008年 | 356篇 |
2007年 | 367篇 |
2006年 | 262篇 |
2005年 | 253篇 |
2004年 | 204篇 |
2003年 | 183篇 |
2002年 | 157篇 |
2001年 | 105篇 |
2000年 | 111篇 |
1999年 | 107篇 |
1998年 | 103篇 |
1997年 | 111篇 |
1996年 | 80篇 |
1995年 | 100篇 |
1994年 | 87篇 |
1993年 | 63篇 |
1992年 | 64篇 |
1991年 | 31篇 |
1990年 | 46篇 |
1989年 | 65篇 |
1988年 | 49篇 |
1987年 | 37篇 |
1986年 | 51篇 |
1985年 | 57篇 |
1984年 | 44篇 |
1983年 | 54篇 |
1982年 | 35篇 |
1981年 | 35篇 |
1980年 | 32篇 |
1979年 | 26篇 |
1978年 | 19篇 |
1977年 | 17篇 |
1976年 | 24篇 |
1975年 | 29篇 |
1974年 | 22篇 |
排序方式: 共有6842条查询结果,搜索用时 15 毫秒
991.
Spinal Cord Scaffolds: 3D Printed Stem‐Cell Derived Neural Progenitors Generate Spinal Cord Scaffolds (Adv. Funct. Mater. 39/2018)
下载免费PDF全文
![点击此处可从《Advanced functional materials》网站下载免费的PDF全文](/ch/ext_images/free.gif)
992.
993.
Peter Schelkens Touradj Ebrahimi Antonin Gilles Patrick Gioia Kwan‐Jung Oh Fernando Pereira Cristian Perra Antonio M. G. Pinheiro 《ETRI Journal》2019,41(1):93-108
Guaranteeing interoperability between devices and applications is the core role of standards organizations. Since its first JPEG standard in 1992, the Joint Photographic Experts Group (JPEG) has published several image coding standards that have been successful in a plethora of imaging markets. Recently, these markets have become subject to potentially disruptive innovations owing to the rise of new imaging modalities such as light fields, point clouds, and holography. These so‐called plenoptic modalities hold the promise of facilitating a more efficient and complete representation of 3D scenes when compared to classic 2D modalities. However, due to the heterogeneity of plenoptic products that will hit the market, serious interoperability concerns have arisen. In this paper, we particularly focus on the holographic modality and outline how the JPEG committee has addressed these tremendous challenges. We discuss the main use cases and provide a preliminary list of requirements. In addition, based on the discussion of real‐valued and complex data representations, we elaborate on potential coding technologies that range from approaches utilizing classical 2D coding technologies to holographic content‐aware coding solutions. Finally, we address the problem of visual quality assessment of holographic data covering both visual quality metrics and subjective assessment methodologies. 相似文献
994.
Shuaizhong Zhang Ye Wang Patrick R. Onck Jaap M. J. den Toonder 《Advanced functional materials》2019,29(6)
Biological cilia are versatile hair‐like organelles that are very efficient in manipulating particles for, e.g., feeding, antifouling, and cell transport. Inspired by the versatility of cilia, this paper experimentally demonstrates active particle‐removal by self‐cleaning surfaces that are fully or partially covered with micromolded magnetic artificial cilia (MAC). Actuated by a rotating magnet, the MAC can perform a tilted conical motion, which leads to the removal of spherical particles of different sizes in water, as well as irregular‐shaped sand grains both in water and in air. These findings can contribute to the development of novel particulate manipulation and self‐cleaning/antifouling surfaces, which can be applied, e.g., to prevent fouling of (bio)sensors in lab‐on‐a‐chip devices, and to prevent biofouling of submerged surfaces such as marine sensors and water quality analyzers. 相似文献
995.
Baiwei Wang Kiumars Aryana John T. Gaskins Patrick E. Hopkins Sanjay V. Khare Daniel Gall 《Advanced functional materials》2020,30(30)
Epitaxial (Ti1?xMgx)0.25Al0.75N(0001)/Al2O3(0001) layers are used as a model system to explore how Fermi‐level engineering facilitates structural stabilization of a host matrix despite the intentional introduction of local bonding instabilities that enhance the piezoelectric response. The destabilizing octahedral bonding preference of Ti dopants and the preferred 0.67 nitrogen‐to‐Mg ratio for Mg dopants deteriorate the wurtzite AlN matrix for both Ti‐rich (x < 0.2) and Mg‐rich (x ≥ 0.9) alloys. Conversely, x = 0.5 leads to a stability peak with a minimum in the lattice constant ratio c/a, which is caused by a Fermi‐level shift into the bandgap and a trend toward nondirectional ionic bonding, leading to a maximum in the expected piezoelectric stress constant e33. The refractive index and the subgap absorption decrease with x, the optical bandgap increases, and the elastic constant along the hexagonal axis C33 = 270 ± 14 GPa remains composition independent, leading to an expected piezoelectric constant d33 = 6.4 pC N?1 at x = 0.5, which is 50% larger than for the pure AlN matrix. Thus, contrary to the typical anticorrelation between stability and electromechanical coupling, the (Ti1?xMgx)0.25Al0.75N system exhibits simultaneous maxima in the structural stability and the piezoelectric response at x = 0.5. 相似文献
996.
J. Val Klump John Bratton Kevin Fermanich Patrick Forsythe Hallett J. Harris Robert W. Howe Jerry L. Kaster 《Journal of Great Lakes research》2018,44(5):825-828
Green Bay has sometimes been referred to as the largest freshwater “estuary” in the world. Its watershed, much of it in intensive agriculture, comprises one-third of the Lake Michigan basin and delivers one-third of the lake's total phosphorus load. At one time, the major tributary, the Fox River, was considered the most heavily industrialized river in North America, primarily from paper manufacturing. Deterioration in water quality and the loss of beneficial and ecological uses have been extensive and began well back into the last century. More recently, the bay has also become a test case for our resolve to remediate and restore ecosystems throughout the Great Lakes and elsewhere. Green Bay has stimulated a significant amount of widely relevant research on the fate and behavior of toxics, biogeochemistry, habitat, biodiversity, and ecological processes. The bay represents a true “proving ground” for adaptive restoration. Key findings of the recent summit on the Ecological and Socio-Economic Tradeoffs of Restoration in the Green Bay Ecosystem are summarized here. Foremost among recommendations of the workshop was the creation of a “Green Bay Ecosystem Simulation and Data Consortium” serving as a data clearing house, building upon the significant progress to date, and developing a modeling framework and visualization tools, furthering public outreach efforts, and ensuring a sustained growth in scientific expertise. Funding was estimated to be on the order of ~$15–20M over the next ~5?years – a modest investment relative to the value of the ecosystem and the long-term cost of inaction. 相似文献
997.
María Bermúdez Victor Ntegeka Vincent Wolfs Patrick Willems 《Water Resources Management》2018,32(8):2801-2815
Detailed full hydrodynamic 1D-2D dual drainage models are a well-established approach to simulate urban pluvial floods. However, despite modelling advances and increasing computational power, this approach remains unsuitable for many real time applications. We propose and test two computationally efficient surrogate models. The first approach links a detailed 1D sewer model to a GIS-based overland flood network. For the second approach, we developed a conceptual sewer and flood model using data-driven and physically based structures, and coupled the model to pre-simulated flood maps. The city of Ghent (Belgium) is used as a test case. Both surrogate models can provide comparable results to the original model in terms of peak surface flood volumes and maximum flood extent and depth maps, with a significant reduction in computing time. 相似文献
998.
In his 1993 IEA keynote address, Neville Moray urged the ergonomics discipline to face up to the global problems facing humanity and consider how ergonomics might help find some of the solutions. In this State of Science article we critically evaluate what the ergonomics discipline has achieved in the last two and a half decades to help create a secure future for humanity. Moray’s challenges for ergonomics included deriving a value structure that moves us beyond a Westernised view of worker-organisation-technology fit, taking a multidisciplinary approach which engages with other social and biological sciences, considering the gross cross-cultural factors that determine how different societies function, paying more attention to mindful consumption, and embracing the complexity of our interconnected world. This article takes a socio-historical approach by considering the factors that influence what has been achieved since Moray’s keynote address. We conclude with our own set of predictions for the future and priorities for addressing the challenges that we are likely to face.
Practitioner Summary: We critically reflect on what has been achieved by the ergonomics profession in addressing the global challenges raised by Moray's 1993 keynote address to the International Ergonomics Association. Apart from healthcare, the response has largely been weak and disorganised. We make suggestions for priority research and practice that is required to facilitate a sustainable future for humanity. 相似文献
999.
Lu Chen Jianan Li Yuhe Tang Yun‐Yi Pai Yunzhong Chen Nini Pryds Patrick Irvin Jeremy Levy 《Advanced materials (Deerfield Beach, Fla.)》2018,30(33)
Complex oxide heterostructures have fascinating emergent properties that originate from the properties of the bulk constituents as well as from dimensional confinement. The conductive behavior of the polar/nonpolar LaAlO3/SrTiO3 interface can be reversibly switched using conductive atomic force microscopy (c‐AFM) lithography, enabling a wide range of devices and physics to be explored. Here, extreme nanoscale control over the CaZrO3/SrTiO3 (CZO/STO) interface, which is formed from two materials that are both nonpolar, is reported. Nanowires with measured widths as narrow as 1.2 nm are realized at the CZO/STO interface at room temperature by c‐AFM lithography. These ultrathin nanostructures have spatial dimensions at room temperature that are comparable to single‐walled carbon nanotubes, and hold great promise for alternative oxide‐based nanoelectronics, as well as offer new opportunities to investigate the electronic structure of the complex oxide interfaces. The cryogenic properties of devices constructed from quasi‐1D channels, tunnel barriers, and planar gates exhibit gate‐tunable superconductivity, quantum oscillations, electron pairing outside of the superconducting regime, and quasi‐ballistic transport. This newly demonstrated ability to control the metal–insulator transition at nonpolar oxide interface greatly expands the class of materials whose behavior can be patterned and reconfigured at extreme nanoscale dimensions. 相似文献
1000.
Ilya Simanovskii Antonio Viviani Frank Dubois Patrick Queeckers 《Microgravity science and technology》2018,30(3):243-256
Nonlinear convective flows developed under the joint action of buoyant and thermocapillary effects in a laterally heated two-layer system filling the closed cavity, have been investigated. The influence of a temperature-dependent interfacial heat release/consumption on nonlinear steady and oscillatory regimes, has been studied. It is shown that sufficiently strong temperature dependence of interfacial heat sinks and heat sources can change the sequence of bifurcations and lead to the development of specific oscillatory regimes in the system. 相似文献