全文获取类型
收费全文 | 5226篇 |
免费 | 33篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 14篇 |
综合类 | 1篇 |
化学工业 | 252篇 |
金属工艺 | 40篇 |
机械仪表 | 37篇 |
建筑科学 | 41篇 |
能源动力 | 28篇 |
轻工业 | 116篇 |
水利工程 | 17篇 |
石油天然气 | 5篇 |
无线电 | 114篇 |
一般工业技术 | 156篇 |
冶金工业 | 4308篇 |
原子能技术 | 11篇 |
自动化技术 | 120篇 |
出版年
2022年 | 9篇 |
2021年 | 11篇 |
2020年 | 14篇 |
2019年 | 8篇 |
2018年 | 11篇 |
2017年 | 14篇 |
2016年 | 14篇 |
2015年 | 11篇 |
2014年 | 29篇 |
2013年 | 72篇 |
2012年 | 38篇 |
2011年 | 60篇 |
2010年 | 55篇 |
2009年 | 40篇 |
2008年 | 43篇 |
2007年 | 48篇 |
2006年 | 40篇 |
2005年 | 40篇 |
2004年 | 28篇 |
2003年 | 42篇 |
2002年 | 28篇 |
2001年 | 27篇 |
2000年 | 27篇 |
1999年 | 177篇 |
1998年 | 1422篇 |
1997年 | 867篇 |
1996年 | 529篇 |
1995年 | 263篇 |
1994年 | 248篇 |
1993年 | 263篇 |
1992年 | 27篇 |
1991年 | 41篇 |
1990年 | 44篇 |
1989年 | 57篇 |
1988年 | 39篇 |
1987年 | 39篇 |
1986年 | 36篇 |
1985年 | 39篇 |
1984年 | 17篇 |
1983年 | 22篇 |
1982年 | 28篇 |
1981年 | 31篇 |
1980年 | 42篇 |
1979年 | 11篇 |
1978年 | 12篇 |
1977年 | 73篇 |
1976年 | 155篇 |
1975年 | 14篇 |
1973年 | 9篇 |
1970年 | 7篇 |
排序方式: 共有5260条查询结果,搜索用时 11 毫秒
81.
Frank C. Walsh 《金属精饰学会汇刊》2013,91(3):107-110
Important applications of electrode reactions in metal finishing are summarised. The characteristics of these reactions are considered; such heterogeneous, charge transfer processes are localised at the electrode/electrolyte interface and involve phase transformation. Electrode properties are seen to be important, particularly their high (electronic) conductivity in comparison to (ionically) conducting electrolytes. 相似文献
82.
Kexin Jiao Laurence J. Walsh Sao Ivanovski Pingping Han 《International journal of molecular sciences》2021,22(9)
Periodontitis is a chronic complex inflammatory disease associated with a destructive host immune response to microbial dysbiosis, leading to irreversible loss of tooth-supporting tissues. Regeneration of functional periodontal soft (periodontal ligament and gingiva) and hard tissue components (cementum and alveolar bone) to replace lost tissues is the ultimate goal of periodontal treatment, but clinically predictable treatments are lacking. Similarly, the identification of biomarkers that can be used to accurately diagnose periodontitis activity is lacking. A relatively novel category of molecules found in oral tissue, circular RNAs (circRNAs) are single-stranded endogenous, long, non-coding RNA molecules, with covalently circular-closed structures without a 5’ cap and a 3’ tail via non-classic backsplicing. Emerging research indicates that circRNAs are tissue and disease-specific expressed and have crucial regulatory functions in various diseases. CircRNAs can function as microRNA or RNA binding sites or can regulate mRNA. In this review, we explore the biogenesis and function of circRNAs in the context of the emerging role of circRNAs in periodontitis pathogenesis and the differentiation of periodontal cells. CircMAP3K11, circCDK8, circCDR1as, circ_0062491, and circ_0095812 are associated with pathological periodontitis tissues. Furthermore, circRNAs are expressed in periodontal cells in a cell-specific manner. They can function as microRNA sponges and can form circRNA–miRNA–mRNA networks during osteogenic differentiation for periodontal-tissue (or dental pulp)-derived progenitor cells. 相似文献
83.
84.
Marianne E. Walsh 《Journal of Energetic Materials》2013,31(1):76-91
Analytical methods are described for the analysis of post-detonation residues from insensitive munitions. Standard methods were verified or modified to obtain the mass of residues deposited per round. In addition, a rapid chromatographic separation was developed and used to measure the mass of NTO (3-nitro-1,2,4-triazol-5-one), NQ (nitroguanidine) and DNAN (2,4-dinitroanisole). The HILIC (hydrophilic-interaction chromatography) separation described here uses a trifunctionally-bonded amide phase to retain the polar analytes. The eluent is 75/25 v/v acetonitrile/water acidified with acetic acid, which is also suitable for LC/MS applications. Analytical runtime was three minutes. Solid phase extraction and LC/MS conditions are also described. 相似文献
85.
Maureen G. Walsh Brian F. Lantry Brent Boscarino Kelly Bowen Jocelyn Gerlofsma Ted Schaner Richard Back Jennifer Questel A. Garry Smythe Roberta Cap Michael Goehle Bryan Young Marc Chalupnicki James H. Johnson James E. McKenna Jr. 《Journal of Great Lakes research》2010
Hemimysis anomala, a Ponto-Caspian littoral mysid, is an emerging Great Lakes invader that was discovered in Lakes Michigan and Ontario in 2006. Similar to the native mysid Mysis diluviana, Hemimysis exhibits a diel vertical migration pattern but generally inhabits shallower and warmer waters than M. diluviana. Because basic information on the distribution, habitat use, and biology of Hemimysis in the Great Lakes is scarce, the potential for food web disruption by Hemimysis cannot easily be predicted. Preliminary observations indicate widespread invasion of Hemimysis in Lake Ontario. In this study, we confirm the presence of Hemimysis at sites spanning the northern and southern shores of Lake Ontario and the presence of the individuals during winter months. In one horizontal tow in November 2007, over 26,000 individuals were collected with a length range of 4.4 to 9.0 mm and an average caloric density of 611 cal/g wet weight. The most effective methods for sampling Hemimysis were horizontal tows with either a zooplankton net in the water column or a benthic sled near the lake bottom. Although more quantitative data on the life history and distribution of this species is necessary, our preliminary observations support the prediction that the potential for Hemimysis to impact the nearshore food web in Lake Ontario appears high. 相似文献
86.
Derek Pletcher Hantao Zhou Gareth Kear C.T. John Low Frank C. Walsh Richard G.A. Wills 《Journal of power sources》2008
The structure of lead deposits (approximately 1 mm thick) formed in conditions likely to be met at the negative electrode during the charge/discharge cycling of a soluble lead-acid flow battery is examined. The quality of the lead deposit could be improved by appropriate additives and the preferred additive was shown to be the hexadecyltrimethylammonium cation, C16H33(CH3)3N+, at a concentration of 5 mM. In the presence of this additive, thick layers with acceptable uniformity could be formed over a range of current densities (20–80 mA cm−2) and solution compositions. While electrolyte compositions with lead(II) concentrations in the range 0.1–1.5 M and methanesulfonic acid concentrations in the range 0–2.4 M have been investigated, the best quality deposits are formed at lower concentrations of both species. Surprisingly, the acid concentration was more important than the lead(II) concentration; hence a possible initial electrolyte composition is 1.2 M Pb(II) + 5 mM C16H33(CH3)3N+ without added acid. 相似文献
87.
Textiles have emerged as a promising class of materials for developing wearable robots that move and feel like everyday clothing. Textiles represent a favorable material platform for wearable robots due to their flexibility, low weight, breathability, and soft hand-feel. Textiles also offer a unique level of programmability because of their inherent hierarchical nature, enabling researchers to modify and tune properties at several interdependent material scales. With these advantages and capabilities in mind, roboticists have begun to use textiles, not simply as substrates, but as functional components that program actuation and sensing. In parallel, materials scientists are developing new materials that respond to thermal, electrical, and hygroscopic stimuli by leveraging textile structures for function. Although textiles are one of humankind's oldest technologies, materials scientists and roboticists are just beginning to tap into their potential. This review provides a textile-centric survey of the current state of the art in wearable robotic garments and highlights metrics that will guide materials development. Recent advances in textile materials for robotic components (i.e., as sensors, actuators, and integration components) are described with a focus on how these materials and technologies set the stage for wearable robots programmed at the material level. 相似文献
88.
Anil Sawhney Kenneth D. Walsh Howard H. Bashford Sivakumar Palaniappan 《Canadian Metallurgical Quarterly》2009,135(4):319-329
This paper examines the production implications of quality control inspections conducted on the buffer between processes in a construction project by modeling the linkage between these processes. Inspection of partially completed work at the end of one activity but before the beginning of work by the next activity is fairly common. Work that is deemed to be of sufficient quality is then made available for the next activity. Work that is deemed insufficient requires rework, typically by the trade appropriate to the activity that fed into the buffer, to bring the work into compliance. This has implications for workload management for that trade, of course, as well as for the reliability of work flow to the successor or downstream processes. While such situations are common in all construction sectors, an example from the residential construction sector was examined via a simulation model augmented by field data collected from residential construction projects. The impacts of the work flow into the predecessor process, the inspection pass rate, and resource availability were examined. The inspection pass rate was found to dramatically affect the reliability of work flow, unless resources are unlimited. Furthermore, the inspection pass rate was found to be functionally related to the production parameters of the process. 相似文献
89.
M. P. Walsh S. L. Bryant R. S. Schechter L. W. Lake 《American Institute of Chemical Engineers》1984,30(2):317-328
A model is developed that calculates the chemical equilibrium that exists between a flowing electrolyte solution and mineral assemblages. The development computes the mineral and aqueous compositions as a function of time and position in a one-dimensional porous medium. The model considers the dissolution of solids as well as their precipitation. The application of the model to various problems has revealed that characteristic aqueous and solid phase concentration waves develop and propagate through the system in a chromatographic manner. Example calculations are presented that illustrate the widespread applicability of the model. Specifically, a calculation is presented that reproduces the genetic mineralization features that are found in sandstone-type uranium deposits. 相似文献
90.
C. J. Brown D. Pletcher F. C. Walsh J. K. Hammond D. Robinson 《Journal of Applied Electrochemistry》1993,23(1):38-43
Measurements of the mass transport limited current for the reduction of ferricyanide in 1M m potassium hydroxide and of copper(II) in 1.5 m sulphuric acid as a function of electrolyte flow rate are used to characterize the space-averaged mass transport properties of the FM01 laboratory electrolyser, with and without six types of polymer mesh turbulence promoters. In the absence of a promoter, the results followed the equation
For the cell with the preferred turbulence promoter, the corresponding equation is
Pressure drop data are also reported and it is confirmed that the presence of a turbulence promoter need not lead to a significant increase in the pressure drop over the reactor. 相似文献