全文获取类型
收费全文 | 173篇 |
免费 | 8篇 |
专业分类
化学工业 | 62篇 |
金属工艺 | 2篇 |
机械仪表 | 1篇 |
建筑科学 | 3篇 |
能源动力 | 2篇 |
轻工业 | 50篇 |
水利工程 | 1篇 |
无线电 | 4篇 |
一般工业技术 | 30篇 |
冶金工业 | 15篇 |
自动化技术 | 11篇 |
出版年
2023年 | 1篇 |
2022年 | 3篇 |
2021年 | 12篇 |
2020年 | 3篇 |
2019年 | 5篇 |
2018年 | 1篇 |
2017年 | 6篇 |
2016年 | 2篇 |
2015年 | 6篇 |
2014年 | 4篇 |
2013年 | 10篇 |
2012年 | 12篇 |
2011年 | 7篇 |
2010年 | 3篇 |
2009年 | 5篇 |
2008年 | 12篇 |
2007年 | 3篇 |
2006年 | 7篇 |
2005年 | 4篇 |
2004年 | 6篇 |
2003年 | 4篇 |
2002年 | 7篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1999年 | 4篇 |
1998年 | 8篇 |
1997年 | 8篇 |
1996年 | 3篇 |
1995年 | 1篇 |
1994年 | 4篇 |
1993年 | 5篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1990年 | 3篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1977年 | 1篇 |
1974年 | 1篇 |
1964年 | 1篇 |
排序方式: 共有181条查询结果,搜索用时 250 毫秒
141.
Tomasz Borowski Agnieszka Brojanowska Marcin Kost Halina Garbacz Tadeusz Wierzcho 《Vacuum》2009,83(12):1489-1493
The nickel alloys of the Inconel type (containing above 15wt% of chromium), used in many industrial applications including the manufacture of aircraft, chemistry, power generation, and material processing, have advantageous mechanical properties, high plasticity and good corrosion resistance, but their frictional wear resistance is poor. This drawback can be obviated by subjecting the alloys to various surface treatments.The paper describes the structure and properties of nitrided layers produced on the Inconel 625 nickel alloy (20wt%Cr, 10wt%Mo, 5wt%Fe, 1wt%Co, balance-Ni). It has been found that the diffusion-type chromium nitride layer produced on the alloy surface improves the hardness, frictional wear resistance, fatigue strength and corrosion resistance of the alloy. It was demonstrated that the nitriding process can be successfully used for prolonging the service life of the fiberizing disc intended for the fabrication of what is known as glass wool. 相似文献
142.
143.
The plastic deformation of monoclinic isotactic polypropylene is studied in compressive testing with particular attention to the effect of hydrostatic pressure up to 300 MPa, in the temperature range 20–60°C. The coefficients of the Coulomb criterion are fairly consistent with those assessed from the comparison of the tensile and compressive yield stresses at atmospheric pressure, in the same temperature range. The high friction coefficient of polypropylene is ascribed to a strain‐induced order‐to‐disorder transition from the monoclinic to the smectic form accompanied by an increase of specific volume. This local and transient phase change is assumed to result from the mobile conformational chain defects that govern the elementary mechanism of plasticity in the crystalline phase of polypropylene consisting of 3/1 helix chains. A comparative discussion is made with polyethylene that displays a much lower friction coefficient. The dislocation‐based approach that is proposed in relation to the viscoelastic relaxation processes provides a new insight into the molecular grounds of the elementary mechanism of plasticity of polypropylene. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 1241–1247, 1999 相似文献
144.
145.
The chromium content in selected convenience and fast foods was determined. Samples were wet digested with HNO3 (69%) in a microwave digestion system. Chromium was determined by graphite furnace atomic absorption spectroscopy (GF-AAS). The chromium content in convenience food ranged on average from 2.22 to 18.2 μg/100 g, in fast food from 3.76 to 28.6 μg/100 g, and in instant food from 0.34 to 4.75 μg/100 g. 相似文献
146.
Marzena Zaciera Jolanta Kurek Barbara Feist Halina Pyta 《Polycyclic Aromatic Compounds》2013,33(4):374-382
ABSTRACTPolycyclic aromatic hydrocarbons (PAHs) and their nitrated derivatives are responsible for mutagenic activation of ambient air. The aim of the study was the assessment of exposure for PAHs and nitro-PAHs in the urbanized region in Poland in comparison with the non-urbanized region and assessment of seasonal variation of PAHs and nitro-PAHs. Concentrations of 12 PAHs, 8 nitrated PAHs in total suspended particulate matter in air of urban and suburban (reference samples-mountain region) region in Poland during four seasons have been shown. The method of solvent extraction of particulate matter, fractionation organic extract and HPLC and GC/MS analysis were applied. The concentrations of PAHs and nitro-PAHs were 10–100 times lower in reference samples than concentrations of PAHs and nitro-PAHs in urban region in summer. The concentrations of PAHs and nitro-PAHs were highest in winter. The exposure profiles of PAHs and nitro-PAHs in four seasons have been shown. The correlation factor between concentrations of PAHs and nitro-PAHs was found. Important influence of ambient air temperature for PAHs and nitro-PAHs concentrations was shown. Obtained results suggest that the coal combustion in Polish households was the main source of PAHs and their nitro derivatives contaminations. Emission from transport sources is a secondary source of air pollution in urban areas. 相似文献
147.
Luger Karolin; Szadkowski Halina; Kirschner Kasper 《Protein engineering, design & selection : PEDS》1990,3(4):249-258
Protein sequences containing redundant segments of secondarystructure at both termini have the choice a priori of foldinginto several possible circularly permuted variants of the wild-typetertiary structure. To test this hypothesis the gene of phosphoribosylanthranilate isomerase from yeast, which is a single-domain8-fold ß barrel protein, was modified to produce a10-fold ß homologue in Escherichia coli. It containeda duplicate of the two C-terminal ß units of supersecondarystructure fused to its N-terminus. Most of the protein was recoveredfrom the insoluble fraction of disrupted cells by dissolutionin guanidinium chloride solutions and refolding. Pristine proteinwas purified from the soluble fraction. The purified (ß)10proteins were enzymically almost fully active. Absorbance, fluorescenceand circular dichroism spectra as well as the reversible unfoldingbehaviour of both proteins were also very similar to the propertiesof the original (ß)8 protein. Digestion with endopeptidasesconverted both the pristine and the refolded (ß)10variant to the same large fragment that had the N-terminal sequenceand mol. wt of the wild-type ß)8 protein. The datasuggest that the folding of the (ß)10 variant is controlledthermodynamically both in vivo and in vitro. 相似文献
148.
149.
150.