全文获取类型
收费全文 | 88篇 |
免费 | 1篇 |
专业分类
化学工业 | 29篇 |
金属工艺 | 3篇 |
机械仪表 | 1篇 |
建筑科学 | 3篇 |
轻工业 | 1篇 |
无线电 | 5篇 |
一般工业技术 | 15篇 |
冶金工业 | 25篇 |
自动化技术 | 7篇 |
出版年
2023年 | 3篇 |
2022年 | 2篇 |
2021年 | 1篇 |
2017年 | 1篇 |
2016年 | 2篇 |
2014年 | 2篇 |
2013年 | 3篇 |
2012年 | 3篇 |
2011年 | 4篇 |
2010年 | 6篇 |
2009年 | 5篇 |
2008年 | 3篇 |
2007年 | 1篇 |
2006年 | 1篇 |
2005年 | 4篇 |
2004年 | 1篇 |
2003年 | 2篇 |
2002年 | 1篇 |
2001年 | 4篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 6篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 5篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1976年 | 3篇 |
1973年 | 2篇 |
排序方式: 共有89条查询结果,搜索用时 15 毫秒
1.
A. Bernasik J. Janowski W. Hirschwald F. Stolze J. Nowotny 《Journal of Materials Science》1991,26(9):2527-2532
Surface segregation of various impurities such as Mg, Si, Ca, Al and Cr were determined for the haematite phase (Fe2O3) annealed in two different gas compositions involving (1) air at 1173 K, and (2) a gas mixture containing sulphur at 773 K. The objective of work was to establish the effect of the gas-phase composition on segregation of lattice defects. The near-surface segregation profiles of the impurities were determined by secondary ion mass spectrometry. The depth profile analysis was made by sputtering using an Ar+ primary beam of energy 30 keV. The surface charge was neutralized by an electron gun. It was found that annealing Fe2O3 under a gas phase containing sulphur resulted in the formation of an Fe(SO4)3 surface layer. It was observed that the two surface treatment procedures applied (both with and without sulphur) result in Mg enrichment in the near-surface region of Fe2O3. Si and Ca exhibit an enrichment and impoverishment after the surface treatments 1 and 2, respectively. Finally, the near-surface layer is impoverished in Cr and Al after both types of surface treatment. Experimental results are discussed in terms of segregation driving forces of the respective elements and the possible effect of sulphur on the gas-solid heterogeneous kinetics. 相似文献
2.
Lucjan Janowski Piotr Kozłowski Remigiusz Baran Piotr Romaniak Andrzej Glowacz Tomasz Rusc 《Multimedia Tools and Applications》2014,68(1):23-40
Video transmission and analysis is often utilized in applications outside of the entertainment sector, and generally speaking this class of video is used to perform specific tasks. Examples of these applications include security and public safety. The Quality of Experience (QoE) concept for video content used for entertainment differs significantly from the QoE of surveillance video used for recognition tasks. This is because, in the latter case, the subjective satisfaction of the user depends on achieving a given functionality. Recognizing the growing importance of video in delivering a range of public safety services, we focused on developing critical quality thresholds in license plate recognition tasks based on videos streamed in constrained networking conditions. Since the number of surveillance cameras is still growing it is obvious that automatic systems will be used to do the tasks. Therefore, the presented research includes also analysis of automatic recognition algorithms. 相似文献
3.
The stereologic analysis of a solid grain has been applied for determination of its porosity. The investigations were carried out on a natural hematite grain reduced to magnetite at 723 K. Stereologic analysis enabled the porosity of this material to be determined on the basis of independently measured grain contours and volume fractions of grain components: hematite, magnetite and pores. A conformity criterion has been formulated, regarding determination of grain volume on the basis of known densities of components and their measured volume fractions in the grain, and on the basis of weight and apparent grain density measurements. The volume increase accompanying reduction of hematite to magnetite, determined from these independent measurements, was in the range 7–19%. By measuring Ferets diameter, the volume of the convex envelope of the grain increased as a result of phase transformation by about 11%. Simultaneously, the volume of the solid phase was found to decrease by 1.5%. The total porosity of the reduced grain, determined by stereologic analysis amounted to 17.5%; 7.7% of which was related to cracks and large pores, and 9.8% to small pores in the magnetite phase. The porosity value determined by the classical mercury method was approximately the same. 相似文献
4.
G. M. Janowski F. S. Biancaniello S. D. Ridder 《Metallurgical and Materials Transactions A》1992,23(12):3263-3272
Fully dense nitrogenated austenitic stainless steels were produced by gas atomization and HIP consolidation. The base alloy,
304L, contained about 0.15 wt pct nitrogen when melted under a nitrogen atmosphere, and a modified version of 304L with 23
wt pct Cr contained 0.21 wt pct nitrogen. A series of experiments using various combinations of N2 and Ar as the melt chamber backfill gas and atomizing gas demonstrated that the nitrogen content of the powder was largely
controlled by the backfill gas and that the fraction of hollow particles was determined by the atomization gas. The hollow
powder particles, which are common in inert-gas atomized materials, were virtually eliminated in the nitrogen atomized powders.
Additional atomizing experiments using copper and a nickel-base superalloy indicate that low gas solubility in the metal leads
to gas entrapment. Hardness and compression behavior (yield strength and flow stress) are substantially improved with the
addition of nitrogen. The results of this study suggest that the properties of nitrogenated stainless steels fabricated in
this manner are comparable to other high nitrogen austenitic alloys.
G.M. JANOWSKI, formerly NRC/NIST Postdoctoral Research Associate, National Institute of Standards and Technology. 相似文献
5.
Assume that a real-time programP
T consisting of a number of parallel processes is executed on a system having a setPr of processors which are shared between the processes by a real-time schedulerS
T. Assume that PT must meet some timing deadlines. We show that such an implementation ofP
T can be represented as a transformationL(P
T) and that the deadlines ofP
T will be met if they are satisfied by the timing properties of the transformed program. The condition for feasibility of a real-time program executed under a scheduler is formalized and rules are provided for verification. The schedulerS
T can be specifiedgenerically and applied to different programs, making it unnecessary to introduce low-level operations such as scheduling primitives into the programming language. Thus real-time program specification and Schedulability can be considered in the same framework and the timing properties of a program can be determined at the specification level. By separating the specification of the scheduler from that of the program, the feasibility of an implementation can be proved by considering a scheduling policy rather than its implementation details. 相似文献
6.
A mesoporous two-phase system, consisting of colloidal silica in the cavities of the main silica frame work of a macroporous glass, was investigated by use of Small-Angle X-ray scattering. The transformed correlation function T(r) was determined for this material for distances r<40 nm. The application of the intrinsic properties of T(r) yields estimations for two fundamental order distances L
1=11 nm and L
2=120 nm of the~porous glass possessing a clear geometric interpretation: L
1, a short-order-range, is the mean chord length of the mesopores plus the mean chord length in the secondary particles. L
2, a long-order-range, is an estimation of the mean diameter of a macropore plus the mean free distance in the silica framework which separates two nearly parallel segments of two adjacent macropores. 相似文献
7.
The paper discusses the problem of stress and strain concentration in the entry and exit planes during the drawing process. Earlier investigations carried out by Pierlin, Pawelski and Armstroff as well as Chen and Kobayashi's finite element analysis are reviewed. Authors’ calculations based on the rigid-plastic finite element approach are compared with experimental and theoretical results published by Pawelski and Armstroff. Solution for rigid-plastic material behaviour confirmed the die pressure increase in the entry and exit zones questioning Pierlin's suggestion that the elastic strains are responsible for pressure concentrations. Analysis of the strain rate distribution led to the presumption that pressure increase is due to the strain rate concentrations in the areas close to the entry and exit zones. 相似文献
8.
Lucjan Chmielarz Piotr Kutrowski Alicja Rafalska-asocha Roman Dziembaj 《Applied catalysis. B, Environmental》2005,58(3-4):235-244
The selective catalytic oxidation of ammonia to nitrogen (NH3-SCO) has been studied over hydrotalcite derived mixed metal oxides containing Cu, Co, Fe or Ni. XRD, BET, NH3-TPD and TPR techniques were used for catalysts characterization. Results of NH3-SCO were compared with those of selective catalytic reduction of NO with NH3 (NO-SCR). Reaction mechanism was studied by temperature-programmed surface reaction (TPSR) and activity tests with a various contact time. Catalytic performance of the studied samples depends on both kind and loading of transition metals in the mixed metal oxide system. The Cu-containing samples have been found to be the most active catalysts of the NH3-SCO process. Transition metal loading strongly influences distribution of ammonia oxidation products. The highest selectivity to N2 was measured for the catalysts with the lowest transition metal content. 相似文献
9.
A series of hybrid polyurethane-POSS materials have been synthesized on the basis of poly(tetramethylene glycol) (Terathane 1400®) as soft component, 4,4′-methylenebis(phenylisocyanate) (MDI) as hard component, and 1,4-butanediol as chain extender. POSS particles properly modified have been tethered on the main chain by substitution of the chain extender to weight fractions up to 10%. AFM measurements indicate the formation of POSS crystallites in the PU matrix, extended structures at low POSS content and more regular, smaller structures at higher POSS content. A detailed investigation of molecular mobility by means of Differential Scanning Calorimetry (DSC), Thermally Stimulated Depolarization Currents (TSDC) and, mainly, Broadband Dielectric Relaxation Spectroscopy (DRS) has been conducted in all samples of the series and in addition in neat Terathane, as reference. Four relaxations have been studied in detail: two secondary relaxations γ and β, the segmental α relaxation (dynamic glass transition) and an α′ relaxation slower than α associated with crystallinity in neat Terathane and with the presence of hard microdomains in the polyurethane and the hybrids. Secondary relaxations remain unaffected by POSS. The glass transition temperature rises by a few degrees and, in consistency with that, segmental dynamics slightly slows down with increasing POSS content. In addition, the dielectric strength of the segmental relaxation decreases with increasing POSS content, suggesting that a fraction of polymer is immobilized, making no contribution to the relaxation. These results are discussed in relation to morphology. 相似文献
10.
Mg-Al hydrotalcites intercalated with five different interlayer anions—CO32−, SO42−, Cl−, HPO42− or terephthalate—were synthesized by either the coprecipitation or ion-exchange method. The structure of the as-synthesized samples and the presence of intended anions in the interlayer gallery of hydrotalcites were determined by X-ray diffraction and FTIR spectroscopy. On calcination at 600 °C the materials were transformed into mixed metal oxides. The kind of the counterbalancing anions present in the parent hydrotalcite influences strongly textural parameters of the obtained Mg-Al oxides. Both temperature-programmed desorption of NH3 and CO2, and test reaction of 2-methyl-3-butyn-2-ol (MBOH) conversion were used to determine the acidity and basicity of the samples. The hydrotalcite derived mixed Mg-Al oxides showed the presence of Brønsted and Lewis acid and base sites. However, the strong basic character of the solids caused that acetone and acetylene were observed as the major products of MBOH conversion. 相似文献