全文获取类型
收费全文 | 6366篇 |
免费 | 496篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 47篇 |
综合类 | 3篇 |
化学工业 | 1298篇 |
金属工艺 | 77篇 |
机械仪表 | 100篇 |
建筑科学 | 183篇 |
矿业工程 | 8篇 |
能源动力 | 140篇 |
轻工业 | 1351篇 |
水利工程 | 84篇 |
石油天然气 | 32篇 |
无线电 | 290篇 |
一般工业技术 | 946篇 |
冶金工业 | 1265篇 |
原子能技术 | 32篇 |
自动化技术 | 1008篇 |
出版年
2024年 | 18篇 |
2023年 | 77篇 |
2022年 | 132篇 |
2021年 | 197篇 |
2020年 | 165篇 |
2019年 | 189篇 |
2018年 | 254篇 |
2017年 | 249篇 |
2016年 | 243篇 |
2015年 | 196篇 |
2014年 | 292篇 |
2013年 | 522篇 |
2012年 | 449篇 |
2011年 | 416篇 |
2010年 | 299篇 |
2009年 | 282篇 |
2008年 | 293篇 |
2007年 | 274篇 |
2006年 | 198篇 |
2005年 | 146篇 |
2004年 | 132篇 |
2003年 | 131篇 |
2002年 | 102篇 |
2001年 | 87篇 |
2000年 | 55篇 |
1999年 | 72篇 |
1998年 | 508篇 |
1997年 | 272篇 |
1996年 | 181篇 |
1995年 | 93篇 |
1994年 | 76篇 |
1993年 | 81篇 |
1992年 | 20篇 |
1991年 | 12篇 |
1990年 | 12篇 |
1989年 | 12篇 |
1988年 | 14篇 |
1987年 | 18篇 |
1986年 | 11篇 |
1985年 | 14篇 |
1984年 | 8篇 |
1983年 | 6篇 |
1981年 | 10篇 |
1980年 | 7篇 |
1978年 | 6篇 |
1977年 | 7篇 |
1976年 | 17篇 |
1973年 | 2篇 |
1971年 | 2篇 |
1960年 | 1篇 |
排序方式: 共有6864条查询结果,搜索用时 31 毫秒
1.
Claudia Paredes Francisco J. Martínez-Vázquez Hamada Elsayed Paolo Colombo Antonia Pajares Pedro Miranda 《Journal of the European Ceramic Society》2021,41(1):892-900
Bioactive ceramic scaffolds for bone regeneration consisting of a three-dimensional mesh of interpenetrating struts with square section were fabricated via Digital Light Processing (DLP). The ability of the technique to manufacture 3D porous structures from β-tricalcium phosphate (β-TCP) powders with different dimensions of struts and pores was evaluated, identifying the possibilities and limitations of the manufacturing process. Small pore sizes were found to seriously complicate the elimination of excess slurry from the scaffold’s innermost pores. The effect of the strut/pore size on the mechanical performance of the scaffolds under compressive stresses was also evaluated, but no significant influence was found. Under compressive stresses, the structures resulted weaker when tested perpendicularly to the printing plane due to interlayer shear failure. Interlayer superficial grooves are proposed as potential failure-controlling defects, which could also explain the lack of a Weibull size effect on the mechanical strength of the fabricated DLP scaffolds. 相似文献
2.
Romero-Garcés A. Salles De Freitas R. Marfil R. Vicente-Chicote C. Martínez J. Inglés-Romero J. F. Bandera A. 《Multimedia Tools and Applications》2022,81(3):3603-3628
Multimedia Tools and Applications - The design of robots capable of operating autonomously in changing and unstructured environments, requires using complex software architectures in which,... 相似文献
3.
Lissy Z. F. Gross Mariana Sacerdoti Prof. Albrecht Piiper Prof. Stefan Zeuzem Dr. Alejandro E. Leroux Dr. Ricardo M. Biondi 《ChemMedChem》2020,15(18):1682-1690
Angiotensin converting enzyme 2 (ACE2) is the human receptor that interacts with the spike protein of coronaviruses, including the one that produced the 2020 coronavirus pandemic (COVID-19). Thus, ACE2 is a potential target for drugs that disrupt the interaction of human cells with SARS-CoV-2 to abolish infection. There is also interest in drugs that inhibit or activate ACE2, that is, for cardiovascular disorders or colitis. Compounds binding at alternative sites could allosterically affect the interaction with the spike protein. Herein, we review biochemical, chemical biology, and structural information on ACE2, including the recent cryoEM structures of full-length ACE2. We conclude that ACE2 is very dynamic and that allosteric drugs could be developed to target ACE2. At the time of the 2020 pandemic, we suggest that available ACE2 inhibitors or activators in advanced development should be tested for their ability to allosterically displace the interaction between ACE2 and the spike protein. 相似文献
4.
5.
6.
7.
Iratxe Perez-Arnedo María J. Cantalejo Alba Martínez-Laorden Elena Gonzalez-Fandos 《International Journal of Food Science & Technology》2021,56(4):1855-1864
Microbiological contamination of chicken meat depends on the conditions under which the animals are reared, slaughtered and processed. The aim of this study was to determine the influence of farm origin and processing stages at slaughterhouse on the microbial safety and quality of chicken. Samples of chicken carcasses from three different farms were taken from a slaughterhouse. Mesophiles, Escherichia coli, coagulase positive Staphylococcci counts, presence of Listeria monocytogenes,Campylobacter and Salmonella were determined at five sampling points: after defeathering, after evisceration, after washing, after chilling and after cutting. Chilling reduced log numbers of mesophiles, coagulase positive Staphylococci and E. coli by 0.85, 1.52 and 2.2 log units, respectively. Salmonella was not detected after chilling. High prevalence of Campylobacter spp was observed at all the stages ranging between 84% and 100%. L. monocytogenes was not detected in chicken carcasses after defeathering. However, it was detected after evisceration and after washing and chilling. The most critical stage for L. monocytogenes contamination was the portioning operation, the prevalence in breast and legs being 88% and 84%, respectively. 相似文献
8.
D. Solís-Cortés E. Navarrete-Astorga J.L. Costa-Krämer J. Salguero-Fernandez R. Schrebler D. Leinen E.A. Dalchiele J.R. Ramos-Barrado F. Martín 《Ceramics International》2019,45(5):5577-5587
C-axis textured thin films of gallium-doped indium zinc oxide (GIZO) with a 2% ratio of Ga/Zn, were obtained via RF-magnetron sputtering with high transparency and electrical conductivity. A Box-Behnken response surface design was used to evaluate the effects of the deposition parameters (In2O3 target power, deposition time, and substrate temperature) on the chemical composition, optical, electrical, and structural properties of the GIZO films. The optical constants and the electrical properties were obtained using optical models. The GIZO stoichiometry, and therefore the In/Zn atomic ratio, affected the crystallinity, crystalline parameters, band gap, and charge carrier mobility of the GIZO films. The charge carrier density was related to the change in the crystalline parameters of the hexagonal structure and the In/Zn atomic ratio. The best electrical conductivity values (1.75?×?103 Ω?1 cm?1) were obtained for GIZO films with In/Zn ratio ≥?1. Several figures of merit (FOM) defined for the visible and solar regions were comparatively used to select the optimal In/Zn atomic ratio that provided the best balance between the conductivity and the transparency. The optimal In/Zn ratio was in a range of 0.85–0.90 for the GIZO films. 相似文献
9.
Roberto C. Dante Pablo Martín-Ramos Pedro Chamorro-Posada Dario Rutto José Vázquez-Cabo Denisse G. Dante 《Fullerenes, Nanotubes and Carbon Nanostructures》2020,28(7):533-540
AbstractIn this work, a new g-C3N4-based Z-scheme with γ-Fe2O3 and β-Ag2Se both n-type semiconductors, and graphite to favor electron exchange is presented. The composite material was studied by XRD, FTIR, UV-Vis, TEM, XPS, TGA, DSC and TOF-SIMS, and the ability of this photocatalytic system to act as a photo-reductant was assessed using crystal violet (CV+) dye. Solar light driven photo-reduction of CV+ in the presence of tri-sodium citrate evidenced a synergistic enhancement of the activity of the composite toward reduction, with ~20 times higher conversion rates per unit of surface area than those of g-C3N4. Photo-oxidation experiments under Xe lamp irradiation in the presence of H2O2 also showed that the AgFeCN composite featured a higher activity (~8×) than g-C3N4. This Z-scheme may deserve further study as a photo-reductant to obtain hydrogen or hydrogenated compounds. Moreover, the use of CV+ may represent a facile procedure that can aid in the selection of new photocatalysts to be used in hydrogen production. 相似文献
10.