全文获取类型
收费全文 | 5411篇 |
免费 | 156篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 61篇 |
综合类 | 8篇 |
化学工业 | 906篇 |
金属工艺 | 118篇 |
机械仪表 | 98篇 |
建筑科学 | 223篇 |
矿业工程 | 38篇 |
能源动力 | 86篇 |
轻工业 | 591篇 |
水利工程 | 55篇 |
石油天然气 | 8篇 |
无线电 | 456篇 |
一般工业技术 | 884篇 |
冶金工业 | 1447篇 |
原子能技术 | 52篇 |
自动化技术 | 542篇 |
出版年
2023年 | 28篇 |
2021年 | 87篇 |
2020年 | 65篇 |
2019年 | 73篇 |
2018年 | 90篇 |
2017年 | 87篇 |
2016年 | 100篇 |
2015年 | 72篇 |
2014年 | 125篇 |
2013年 | 275篇 |
2012年 | 184篇 |
2011年 | 259篇 |
2010年 | 195篇 |
2009年 | 167篇 |
2008年 | 215篇 |
2007年 | 189篇 |
2006年 | 192篇 |
2005年 | 143篇 |
2004年 | 140篇 |
2003年 | 142篇 |
2002年 | 111篇 |
2001年 | 98篇 |
2000年 | 68篇 |
1999年 | 96篇 |
1998年 | 337篇 |
1997年 | 227篇 |
1996年 | 192篇 |
1995年 | 121篇 |
1994年 | 143篇 |
1993年 | 121篇 |
1992年 | 79篇 |
1991年 | 48篇 |
1990年 | 63篇 |
1989年 | 89篇 |
1988年 | 53篇 |
1987年 | 49篇 |
1986年 | 54篇 |
1985年 | 50篇 |
1984年 | 45篇 |
1983年 | 36篇 |
1982年 | 31篇 |
1981年 | 43篇 |
1980年 | 32篇 |
1979年 | 40篇 |
1978年 | 51篇 |
1977年 | 44篇 |
1976年 | 94篇 |
1975年 | 40篇 |
1974年 | 30篇 |
1970年 | 21篇 |
排序方式: 共有5573条查询结果,搜索用时 62 毫秒
1.
Nina Wurzler Jan D. Schutter Ralph Wagner Matthias Dimper Vasile-Dan Hodoroaba Dirk Lützenkirchen-Hecht Ozlem Ozcan 《工业材料与腐蚀》2021,72(6):983-994
Biofilm formation and microbially influenced corrosion of the iron-reducing microorganism Shewanella putrefaciens were investigated on stainless steel surfaces preconditioned in the absence and presence of flavin molecules by means of XANES (X-ray absorption near-edge structure) analysis and electrochemical methods. The results indicate that biofilm formation was promoted on samples preconditioned in electrolytes containing minute amounts of flavins. On the basis of the XANES results, the corrosion processes are controlled by the iron-rich outer layer of the passive film. Biofilm formation resulted in a cathodic shift of the open circuit potential and a protective effect in terms of pitting corrosion. The samples preconditioned in the absence of flavins have shown delayed pitting and the samples preconditioned in the presence of flavins did not show any pitting in a window of −0.3- to +0.0-V overpotential in the bacterial medium. The results indicate that changes in the passive film chemistry induced by the presence of minute amounts of flavins during a mild anodic polarization can change the susceptibility of stainless steel surfaces to microbially influenced corrosion. 相似文献
2.
Camila C. Lopes Wagner A. Pinheiro Daniel Navarro da Rocha José G. Neves Américo Bortolazzo Correr José R.M. Ferreira Rafael M. Barbosa Jefferson R.F. Soares Jheison L. Santos Marcelo H. Prado da Silva 《Ceramics International》2021,47(6):7653-7665
The repair of bone fractures is a clinical challenge for patients with impaired healing, such as osteoporosis. Currently, different strategies have been developed to design new biomaterials, enhancing their interactions with biological systems and conducting the cellular behavior in the desired direction to help fracture healing. In the present work, hydroxyapatite-graphene oxide (HA-GO) nanocomposites were produced and the morphological and physicochemical influences of the addition of 0.5 wt%, 1.0 wt% and 1.5 wt% of GO to HA were observed. FEG-SEM and TEM analyses of HA-GO nanocomposites showed HA nanoparticles adhered to the surface of the GO sheets, suggesting an effective method to form nanostructured graphene-based biomaterials. As confirmation, physicochemical analyses by Raman, FTIR and TGA demonstrated a strong affinity between HA and GO, according to the increase of concentration from 0.5 wt% to 1.5 wt% GO in the HA-GO nanocomposites. Also, in order to evaluate the HA-GO nanocomposites behavior under biological microenvironment, in vitro bioactivity and indirect cytotoxicity tests were performed. FEG-SEM analyses confirmed the positive results for the bioactivity properties of HA-GO nanocomposite and indirect cytotoxicity demonstrated that even with a decrease in the hDPSCs viability and proliferation, when increasing to 1.5 wt% of GO concentration, high level of cell viability was exhibited by HA-GO nanocomposites. These biological results suggested the 0.5 wt% HA-GO nanocomposite as a potential bioactive bone graft and a promising biomaterial for bone tissue regeneration, when compared to the pure HA. 相似文献
3.
Jonas Stiller Daisy Nestler Husam Ahmad Erik Päßler Guntram Wagner Lothar Kroll 《International Journal of Applied Ceramic Technology》2021,18(2):280-288
The production of ceramic matrix composites (CMC) based on C/C-SiC is still very cost-intensive and therefore only economical for a few applications. The fabrication of the preforms involves many costs that need to be reduced. In this work, the shaping of the CFRP-preforms is realized by thermoset injection molding, which enables large-scale production. The polymeric matrix used is a multi-component matrix consisting of novolak resin, curing agent and lubricant. Six millimeter chopped carbon fiber with a proportion of 50 wt.% were used as a reinforcement. These ingredients are processed by an industrial equipment for compounding and injection molding in order to manufacture a CFRP demonstrator representing a brake disc. Test specimens are cut out of the demonstrator in different directions in order to investigate influences of flow direction and weld lines on microstructural and mechanical properties. Afterward, the CFRP samples were converted to C/C-SiC composites by the liquid silicon infiltration process. The article addresses the flow behavior of the compound during the injection molding and the building of the weld lines in the demonstrator. In addition, results of the directional dependence of the microstructural and mechanical properties within the fabricated disc in the different production steps are presented. 相似文献
4.
Carla C. B. Brasil Cristiano R. de Menezes Eduardo Jacob-Lopes Juliano Smanioto Barin Leila Queiroz Zepka Paulo Cezar Bastianello Campagnol Roger Wagner Alexandre José Cichoski 《International Journal of Food Science & Technology》2020,55(3):1136-1144
This study investigated the effect of the combination of basic electrolysed water (BEW) and slightly acid electrolysed water (SAEW) with ultrasound (US) for cleaning and sanitation of the knives used in slaughtering processes. The knives were sonicated in a US bath using two modes of operation (normal and sweep) in two steps: (i) 5 min with BEW and (ii) 10 min with SAEW at 35 °C. The microbiological counts and the possible changes in the physical structure of the knives were evaluated. The association BEW + SAEW + US, in the sweep mode, provided lower mesophilic, enterobacterial, Staphylococcus aureus and yeast counts when compared to the values recommended by the international legislation. In addition, these conditions removed all organic residues from the knife blades and promoted the highest migration rate of the residues to the US water bath (12.35 mg/L·min), without modifications in the knife blades. Thus, cleaning and sanitation of knives was feasible with the association of BEW + SAEW + US, which could be a useful alternative for the meat industry. 相似文献
5.
Dr. Santina Maiorana Prof. Roberta Ettari Dr. Santo Previti Dr. Giorgio Amendola Dr. Annika Wagner Prof. Sandro Cosconati Prof. Ute A. Hellmich Prof. Tanja Schirmeister Prof. Maria Zappalà 《ChemMedChem》2020,15(16):1552-1561
In this paper, we report the design, synthesis and biological investigation of a series of peptidyl vinyl ketones obtained by modifying the P2 fragment of previously reported highly potent inhibitors of rhodesain, the main cysteine protease of Trypanosoma brucei rhodesiense. Investigation of the structure–activity relationship led us to identify new rhodesain inhibitors endowed with an improved selectivity profile (a selectivity index of up to 22 000 towards the target enzyme), and/or an improved antitrypanosomal activity in the sub-micromolar range. 相似文献
6.
Shana Wagner Megan Waldman Simran Arora Sinan Wang Valerie Scott Dr. Kabirul Islam 《Chembiochem : a European journal of chemical biology》2019,20(9):1133-1138
Histone demethylases play a critical role in mammalian gene expression by removing methyl groups from lysine residues in degree- and site-specific manner. To specifically interrogate members and isoforms of this class of enzymes, we have developed demethylase variants with an expanded active site. The mutant enzymes are capable of performing lysine demethylation with wild-type proficiency, but are sensitive to inhibition by cofactor-competitive molecules embellished with a complementary steric “bump”. The selected inhibitors show more than 20-fold selectivity over the wild-type demethylase, thus overcoming issues typical to pharmacological and genetic approaches. The mutant–inhibitor pairs are shown to act on a physiologically relevant full-length substrate. By engineering a conserved amino acid to achieve member-specific perturbation, this study provides a general approach for studying histone demethylases in diverse cellular processes. 相似文献
7.
Khaldoon O. Al-Nosairy Marc Horbrügger Sven Schippling Markus Wagner Aiden Haghikia Marc Pawlitzki Michael B. Hoffmann 《International journal of molecular sciences》2021,22(7)
The retinal ganglion cells (RGC) may be considered an easily accessible pathophysiological site of degenerative processes in neurological diseases, such as the RGC damage detectable in multiple sclerosis (MS) patients with (HON) and without a history of optic neuritis (NON). We aimed to assess and interrelate RGC functional and structural damage in different retinal layers and retinal sites. We included 12 NON patients, 11 HON patients and 14 healthy controls for cross-sectional multifocal pattern electroretinography (mfPERG) and optical coherence tomography (OCT) measurements. Amplitude and peak times of the mfPERG were assessed. Macula and disc OCT scans were acquired to determine macular retinal layer and peripapillary retinal nerve fiber layer (pRNFL) thickness. In both HON and NON patients the foveal N2 amplitude of the mfPERG was reduced compared to controls. The parafoveal P1 peak time was significantly reduced in HON only. For OCT, parafoveal (pfGCL) and perifoveal (pGCL) ganglion cell layer thicknesses were decreased in HON vs. controls, while pRNFL in the papillomacular bundle sector (PMB) showed reductions in both NON and HON. As the mfPERG derived N2 originates from RGC axons, these findings suggest foveal axonal dysfunction not only in HON, but also in NON patients. 相似文献
8.
Journal of Applied Electrochemistry - Large area MoS2 ultra-thin film deposition is one of the big challenges in the recent years. Electrodeposition provides an opportunity to grow such ultra-thin... 相似文献
9.
Roberta Bastos Vasques Marjory Moreira Levy Matheus Souza Rodrigues Francisco Wagner de Queiroz Almeida Neto Leonardo Paes da Silva Gustavo Leitão Vaz Álvaro Augusto Oliveira Magalhães Pedro de Lima-Neto Walney Silva Araújo 《工业材料与腐蚀》2021,72(8):1417-1432
Phosphate ester was investigated as a corrosion inhibitor for AISI 1018 carbon steel in carbon dioxide-saturated chloride solutions at different temperatures and pressures. The corrosion tests were realized by electrochemical techniques, weight loss measurements, bubble tests, and a high-pressure/high-temperature autoclave system. The corrosion tests demonstrated that the investigated molecule is an excellent corrosion inhibitor. The inhibiting effect is even bigger at high pressure and temperature than at atmospheric pressure and room temperature. The thermodynamic parameters were calculated and determined to obey the Langmuir isotherm. Polarization studies revealed that the evaluated inhibitor is a mixed type. 相似文献
10.
Moritz Raab Simon Maier Ralph-Uwe Dietrich 《International Journal of Hydrogen Energy》2021,46(21):11956-11968
A large-scale point to point hydrogen transport is one strategy for a prospective energy import scenario for certain countries. The case for a hydrogen transport from Australia to Japan has been addressed in several studies. However, most studies lack transparency and detailed insights into the made assumptions thus a fair evaluation of different transport pathways is challenging. To address this issue, we developed a model where a large-scale point to point hydrogen transport of liquid hydrogen is compared with the transport via liquid organic hydrogen carrier (LOHC), namely via methyl cyclohexane and hydrogenated dibenzyl toluene. We analyzed, where energy is required along the different pathways, where hydrogen losses do occur and how the costs are put together. Furthermore, the influence of hydrogen feed costs is also considered. For hydrogen production costs of 5 €2018/kgH2 the total delivery costs are in the range of 6.40– 8.10 €2018/kgH2. 相似文献