全文获取类型
收费全文 | 3796篇 |
免费 | 17篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 22篇 |
综合类 | 3篇 |
化学工业 | 103篇 |
金属工艺 | 6篇 |
机械仪表 | 4篇 |
建筑科学 | 33篇 |
矿业工程 | 1篇 |
能源动力 | 6篇 |
轻工业 | 31篇 |
石油天然气 | 1篇 |
武器工业 | 2篇 |
无线电 | 17篇 |
一般工业技术 | 71篇 |
冶金工业 | 3456篇 |
自动化技术 | 58篇 |
出版年
2022年 | 4篇 |
2021年 | 5篇 |
2020年 | 3篇 |
2019年 | 2篇 |
2018年 | 3篇 |
2017年 | 8篇 |
2016年 | 7篇 |
2015年 | 7篇 |
2014年 | 9篇 |
2013年 | 18篇 |
2012年 | 16篇 |
2011年 | 33篇 |
2010年 | 20篇 |
2009年 | 16篇 |
2008年 | 22篇 |
2007年 | 17篇 |
2006年 | 12篇 |
2005年 | 15篇 |
2004年 | 14篇 |
2003年 | 20篇 |
2002年 | 13篇 |
2001年 | 8篇 |
2000年 | 6篇 |
1999年 | 122篇 |
1998年 | 1148篇 |
1997年 | 666篇 |
1996年 | 406篇 |
1995年 | 205篇 |
1994年 | 188篇 |
1993年 | 236篇 |
1992年 | 15篇 |
1991年 | 31篇 |
1990年 | 33篇 |
1989年 | 46篇 |
1988年 | 33篇 |
1987年 | 39篇 |
1986年 | 19篇 |
1985年 | 26篇 |
1984年 | 4篇 |
1983年 | 10篇 |
1982年 | 20篇 |
1981年 | 14篇 |
1980年 | 29篇 |
1978年 | 14篇 |
1977年 | 80篇 |
1976年 | 139篇 |
1975年 | 3篇 |
1955年 | 3篇 |
1930年 | 1篇 |
1929年 | 1篇 |
排序方式: 共有3814条查询结果,搜索用时 15 毫秒
61.
在一次系统故障过程中。输电线路的两套高频保护装置CSL-101B型和LFP-901B型动作行为不一致。本文就此展开分析,以达到正确理解两种保护动作行为的目的。并对加强高频保护的现场管理提出意见。 相似文献
62.
本文中,Watts Humphrey谈到了自己担任IBM程序总监时的工作经历,生动形象,发人深省。 相似文献
63.
Crack growth measurements in InP crystals were conducted using an applied-moment, double cantilever beam (DCB) geometry. Controlled, smooth crack growth was observed in water; however, the crack growth velocities were not constant for constant applied stress intensity ( K I ). More importantly, there was no clear functional dependence of the crack growth rate (ν) on K I . 相似文献
64.
S. SIMARD M. DROGOWSKA H. ME´NARD L. BROSSARD 《Journal of Applied Electrochemistry》1997,27(3):317-324
The electrochemical behaviour of 1024 mild steel electrodes is investigated in the presence of 0.05–0.5 M sodium bicarbonate in aqueous solution at pH 8.9 and 25°C. Voltammograms are obtained with a rotating gold ring-mild steel electrode and the effect of the NaHCO3 concentration, the potential limits and the rotation speed of the disc electrode is considered. The voltammograms display an oxidation peak current at low potentials, a passivity region and a transpassive region at high potentials for the potential sweep in the anodic direction. The oxidation current in the passivity region is practically independent of the applied potential and the NaHCO3 concentration. The rate-determining step of the oxidation reaction in both the oxidation peak current region and the transpassive region is determined. 相似文献
65.
Fatoumata Ide Seyni Lawrence Barrett Steven Crossley Brian P. Grady 《Polymer Engineering and Science》2021,61(4):1186-1194
An asymmetric double cantilever beam test was used to determine the ability of carbon nanotubes with varying chemistry along their lengths, that is, diblock nanotubes, to compatibilize the polystyrene/poly(methyl methacrylate) (PS/PMMA) interface. PS molecules were grafted primarily to one of the blocks to cause that block to migrate to the PS phase since otherwise both blocks would prefer to reside in PMMA. Fracture toughnesses increased monotonically with increasing diblock carbon nanotube concentration and maximum values were like those for block copolymer-reinforced interfaces while single-chemistry nanotubes showed no reinforcing effect. However, the abrupt increase in fracture toughness with added compatibilizer indicative of a transition to crazing was not found consistent with nanotubes suppressing crazing in homopolymers. Scanning electron microscopy images of the fractured surfaces show agglomerates of carbon nanotubes present which are likely limiting the efficacy of carbon nanotubes at toughening the interface. 相似文献
66.
Mnica Aguilera Valerio Rossini Ana Hickey Donjete Simnica Fiona Grady Valeria D. Felice Amy Moloney Lauren Pawley Aine Fanning Lorraine McCarthy Siobhan M. OMahony John F. Cryan Ken Nally Fergus Shanahan Silvia Melgar 《International journal of molecular sciences》2021,22(15)
Interactions between the intestinal microbiota, immune system and nervous system are essential for homeostasis in the gut. Inflammasomes contribute to innate immunity and brain–gut interactions, but their role in microbiota–neuro–immune interactions is not clear. Therefore, we investigated the effect of the inflammasome on visceral pain and local and systemic neuroimmune responses after antibiotic-induced changes to the microbiota. Wild-type (WT) and caspase-1/11 deficient (Casp1 KO) mice were orally treated for 2 weeks with an antibiotic cocktail (Abx, Bacitracin A and Neomycin), followed by quantification of representative fecal commensals (by qPCR), cecal short chain fatty acids (by HPLC), pathways implicated in the gut–neuro-immune axis (by RT-qPCR, immunofluorescence staining, and flow cytometry) in addition to capsaicin-induced visceral pain responses. Abx-treatment in WT-mice resulted in an increase in colonic macrophages, central neuro-immune interactions, colonic inflammasome and nociceptive receptor gene expression and a reduction in capsaicin-induced visceral pain. In contrast, these responses were attenuated in Abx-treated Casp1 KO mice. Collectively, the data indicate an important role for the inflammasome pathway in functional and inflammatory gastrointestinal conditions where pain and alterations in microbiota composition are prominent. 相似文献
67.
High‐Temperature Neutron Diffraction,Raman Spectroscopy,and First‐Principles Calculations of Ti3SnC2 and Ti2SnC 下载免费PDF全文
Grady W. Bentzel Michael Naguib Nina J. Lane Sven C. Vogel Volker Presser Sylvain Dubois Jun Lu Lars Hultman Michel W. Barsoum El'ad N. Caspi 《Journal of the American Ceramic Society》2016,99(7):2233-2242
Herein, we report—for the first time—on the additive‐free bulk synthesis of Ti3SnC2. A detailed experimental study of the structure of the latter together with a secondary phase, Ti2SnC, is presented through the use of X‐ray diffraction (XRD), and high‐resolution transmission microscopy (HRTEM). A previous sample of Ti3SnC2, made using Fe as an additive and Ti2SnC as a secondary phase, was studied by high‐temperature neutron diffraction (HTND) and XRD. The room‐temperature crystallographic parameters of the two MAX phases in the two samples are quite similar. Based on Rietveld analysis of the HTND data, the average linear thermal expansion coefficients of Ti3SnC2 in the a and c directions were found to be 8.5 (2)·10?6 K?1 and 8.9 (1)·10?6 K?1, respectively. The respective values for the Ti2SnC phase are 10.1 (3)·10?6 K?1 and 10.8 (6)·10?6 K?1. Unlike other MAX phases, the atomic displacement parameters of the Sn atoms in Ti3SnC2 are comparable to those of the Ti and C atoms. When the predictions of the atomic displacement parameters obtained from density functional theory are compared to the experimental results, good quantitative agreement is found for the Sn atoms. In the case of the Ti and C atoms, the agreement is more qualitative. We also used first principles to calculate the elastic properties of both Ti2SnC and Ti3SnC2 and their Raman active modes. The latter are compared to experiment and the agreement was found to be good. 相似文献
68.
Nutthakan Pongrakananon Nathaporn Somrang Worakanya Visitsart Pitt Supaphol Manit Nithitanakul Brian P. Grady 《应用聚合物科学杂志》2004,91(4):2216-2222
The effect of methyl acrylate content in ethylene–methyl acrylate–acrylic acid (E–MA–AA) terpolymers and acrylic acid content in ethylene–acrylic acid (E–AA) copolymers was investigated in blends of these two materials. The E–MA–AA terpolymer with 8 mol % methyl acrylate was not miscible with any E–AA material no matter what the AA content, whereas the terpolymer with only about 2 mol % methyl acrylate was miscible, at least to some extent, with the E–AA copolymer at high acrylic acid contents. Evidence supporting this conclusion derived from gloss, differential scanning calorimetry testing, and dynamic mechanical measurements. For the E–AA polymer material with the highest acid content, there was a synergistic effect for some properties at low added amounts of E–MA–AA copolymer; the tensile strength and hardness were 10% higher than values for the E–AA copolymer, even though the E–AA copolymer was much stiffer. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2216–2222, 2004 相似文献
69.
This paper describes a tool to aid the development of computer vision applications for pixel-level diagnosis. A conceptual framework for constructing pixel processors is described. The proposed tool is based on two domains: one deals with numerical images, named features, and the other deals with symbolic images, named classes. A reduced set of image and operator types is defined. Based on it, an object-oriented language is described. The main objects define features and classes and their associated operators, namely procedures, classifiers, and rules. All system control is goal oriented and is designed to provide symbolic images as results when a request is received from a higher level of the image understanding system. Some knowledge engineering concepts, such as certainty control and instances, are also included. 相似文献
70.
Neuroimaging experiments have shown that prefrontal regions of the brain, which have the most age-related volume loss, are also the regions most likely to be more active in older adults than in younger adults. In an attempt to solve this puzzle, P. M. Greenwood (see record 2007-15625-001) has proposed a cascade that flows from age-related atrophy in the brain to changed processing strategies that result in plastic changes in regions adjacent and contralateral to the atrophic areas, culminating in greater functional activity. This hypothesis should stimulate research into these mechanisms and hopefully will ultimately inform researchers' ability to rehabilitate cognitive disorders in the elderly. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献