首页 | 官方网站   微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   352篇
  免费   35篇
工业技术   387篇
  2024年   3篇
  2023年   3篇
  2022年   11篇
  2021年   31篇
  2020年   19篇
  2019年   13篇
  2018年   22篇
  2017年   16篇
  2016年   19篇
  2015年   11篇
  2014年   11篇
  2013年   26篇
  2012年   25篇
  2011年   31篇
  2010年   24篇
  2009年   17篇
  2008年   11篇
  2007年   11篇
  2006年   9篇
  2005年   10篇
  2004年   8篇
  2003年   5篇
  2002年   6篇
  2001年   8篇
  2000年   3篇
  1999年   7篇
  1998年   8篇
  1997年   2篇
  1996年   4篇
  1995年   2篇
  1994年   1篇
  1993年   2篇
  1992年   3篇
  1990年   1篇
  1982年   1篇
  1976年   3篇
排序方式: 共有387条查询结果,搜索用时 15 毫秒
41.
Concurrent engineering (CE) involves a widely recognized revolution in the social organization of product development and a corresponding revolution in the underlying paradigm of design. We distinguish between two paradigms-point-based design and set-based design-and argue that effective, truly concurrent design requires shifting to a paradigm where design team members reason and communicate about sets of designs which we call “set-based concurrent engineering”. A survey of 92 Japanese and 119 US automotive parts suppliers who design their own products sought to quantify the pervasiveness and correlates of “set-based approaches”. The survey evidence indicates that set-based design communication is more prevalent among Japanese than among US parts suppliers, and is correlated with certain product development characteristics including years of experience with early involvement of suppliers in design, the degree of product-process design overlap, the degree to which subsystems are interdependent, and the use of quality function deployment (QFD)  相似文献   
42.
This paper presents a low cost test method for the static and dynamic characterization of analog-to-digital converters. The method is suitable for implementation in a SoC environment, as a built-in self test (BIST) solution. In the proposed approach, noise is used as the test signal. Theory of operation and practical results demonstrating the effectiveness of the method for INL, DNL, THD and SINAD characterization are presented. The BIST surface overhead caused by the noise generator is only 7.4% of the ADC total area. The reduced number of data samples required allows a reduction of about 7.5× in test time, in comparison to the histogram method.Maria da Gloria Cataldi Flores was born in Santa Maria, Brazil, in 1978. She received the electrical engineering degree in 2000 from Universidade Federal de Santa Maria (UFSM) and the M.S. degree engineering in 2003 from Universidade Federal do Rio Grande do Sul (UFRGS), Brazil. Since then, she has been working as a design engineer in an EAS Supply brazilian company. Her main research interests include mixed-signal and analog testing and digital signal processing.Marcelo Negreiros was born in Porto Alegre, Brazil, in 1969. He received the electrical engineering degree in 1992 and the M.S. degree engineering in 1994, both from Universidade Federal do Rio Grande do Sul (UFRGS), Brazil. Since then he was been working as an associate researcher in the Signal Processing Lab. (LaPSI) of the Electrical Engineering Department at UFRGS. Since 2000 he also works toward a Ph.D. in Computer Science from UFRGS. His main research interests include mixed-signal and analog testing and digital signal processing.Luigi Carro was born in Porto Alegre, Brazil, in 1962. He received the Electrical Engineering and the M.Sc. degrees from Universidade Federal do Rio Grande do Sul (UFRGS), Brazil, in 1985 and 1989, respectively. From 1989 to 1991 he worked at ST-Microelectronics, Agrate, Italy, in the R&D group. In 1996 he received the Ph.D. degree in the area of Computer Science from Universidade Federal do Rio Grande do Sul (UFRGS), Brazil. He is presently a lecturer at the Electrical Engineering Department of UFRGS, in charge of Digital Systems Design and Digital Signal processing disciplines at the graduate and undergraduate level. He is also a member of the Graduation Program in Computer Science of UFRGS, where he is responsible for courses in Embedded Systems, Digital Signal Processing, and VLSI Design. His primary research interests include mixed-signal design, digital signal processing, mixed-signal and analog testing, and fast system prototyping. He has published more than 90 technical papers in those topics and is the author of the book Digital Systems Design and Prototyping (in portuguese).Altamiro A Susin was born in Vacaria-RS, Brazil, in 1945. He received the Electrical Engineering and the MSc. degrees from Universidade Federal do Rio Grande do Sul (UFRGS), Brazil, in 1972 and 1977, respectively. Since 1968 he worked in the start up of Computer Centers of two local Universities. In 1981 he got his Dr. Eng degree from Institut National Polytechnique de Grenoble-France. He is presently a lecturer at the Electrical Engineering Department of UFRGS, in charge of Digital Systems Design disciplines at the graduate and undergraduate level. He is also a member of the Graduation Program in Computer Science of UFRGS, where he is responsible by courses in VLSI Architecture and is also thesis director. His main research interests are Integrated Circuit Architecture, Embedded Systems, Signal Processing with more than 50 technical papers published in those domains. He is/was responsible for several R&D projects either funded with public and/or industry resources.Felipe Ricardo Clayton received the B.S. degree in Electrical Engineering from State University of Campinas (UNICAMP), Brazil, in 1986. He worked at CPqD (Brazilian PTT R&D Center) till 1996 designing analog and mixed signal circuits for telecom and automotive applications. From 1997 to the second half of 1998, he worked at Instituto Superior Técnico (IST), Lisbon, Portugal, under the guidance of Prof. Carlos Azeredo Leme on development of CMOS RF circuits. Since October 1998 he had worked for Motorola SPS. Now he is head of the Power Managment Group at Freescale.Cristiano Benevento received his B.S. degree in Electrical Engineering from Universidade Estadual de Campinas (Unicamp), Brazil, in 1997. He worked at Motorola Cellular Infrastructure Group until August 2000 as a Systems Engineer. He joined Motorola Semiconductor Product Sector in August 2000 as IC Designer for Power Management Group and is now at Freescale.  相似文献   
43.
The damage produced by implanting, at room temperature, 3 μm thick relaxed Si1−xGex layers with 2 MeV Si+ ions has been measured as a function of Ge content (x = 0.04, 0.13, 0.24 or 0.36) and Si dose in the dose range 1010–1015 cm−2. The accumulation of damage with increasing dose has been studied as a function of Ge content by Rutherford Backscattering Spectrometry, Optical Reflectivity Depth Profiling and Transmission Electron Microscopy and an increased damage efficiency in Si1−xGex with increasing x is observed. The characteristics of implantation-induced defects have been investigated by Electron Paramagnetic Resonance. The results are discussed in the context of a model of the damage process in SiGe.  相似文献   
44.
Scope: 2S albumins are the major allergens involved in severe food allergy to nuts, seeds, and legumes. We aimed to isolate, clone, and express 2S albumin from hazelnut and determine its allergenicity. Methods: 2S albumin from hazelnut extract was purified using size exclusion chromatography and RP‐HPLC. After N‐terminal sequencing, degenerated and poly‐d(T) primers were used to clone the 2S albumin sequence from hazelnut cDNA. After expression in Escherichia coli and affinity purification, IgE reactivity was evaluated by Immunoblot/ImmunoCAP (inhibition) analyses using sera of nut‐allergic patients. Results: N‐terminal sequencing of a ~10 kDa peak from size exclusion chromatography/RP‐HPLC gave two sequences highly homologous to pecan 2S albumin, an 11 amino acid (aa) N‐terminal and a 10aa internal peptide. The obtained clone (441 bp) encoded a 147aa hazelnut 2S albumin consisting of a putative signal peptide (22 aa), a linker peptide (20 aa), and the mature protein sequence (105 aa). The latter was successfully expressed in E. coli. Both recombinant and natural 2S albumin demonstrated similar IgE reactivity in Immunoblot/ImmunoCAP (inhibition) analyses. Conclusion: We confirmed the postulated role of hazelnut 2S albumin as an allergen. The availability of recombinant molecules will allow establishing the importance of hazelnut 2S albumin for hazelnut allergy.  相似文献   
45.
Compatibility of the new environmentally-friendly alternative of diesel engine fuels, biodiesel, with storage and engine part materials, is still an open issue. In this work, the interaction between three fuels (petroleum diesel and two types of biodiesel — soybean and sunflower) and two materials (carbon steel and high density polyethylene) used in storage and automotive tanks, is analyzed in detail. A wide set of characterization techniques was used to evaluate the changes in both solid and fluid materials, as weight change measurement, optical, scanning electron and atomic force (AFM) microscopies, Raman and FTIR spectroscopies, and differential scanning calorimetry. The AFM technique allowed detecting surface roughness and morphology changes in the metallic material following the trends in the weight losses. In the case of polymeric material, weight gain by fluid absorption occurred, being detected by the spectroscopic techniques. The biodiesel fuels underwent some ageing however this phenomenon did not affect the interaction between the biodiesel fuels and the substrates. The petrodiesel, which did not age, caused more significant degradation of the substrates.  相似文献   
46.
Polycyclic Aromatic Hydrocarbons (PAHs) are a major group of pollutants whose occurrence in the environment is mainly of anthropogenic origin. In this paper, we examine the effect of topographical slope exposure on PAH contamination and seasonal change in PAH concentrations in soils. We collected soil samples on three dates in 2007 (early May, end of July and beginning of November) from south- and north-facing aspects at 1900 m a.s.l. in the central Italian Alps. We found greater PAH contamination in soils from a north-facing slope than in those from a south-facing slope at all seasons. We calculated North-South Enrichment Factors as the ratio between the concentrations measured in soils from northern and southern aspects. These ratios ranged from 1.4 to 1.9 for lighter PAHs (from 2 to 4 rings). These values are consistent with theoretical calculations based on temperature-specific octanol-air partition coefficients (predicted North-South Enrichment Factors range from 1.6 to 2.0). For heavier PAHs (from 5 to 6 rings), smaller differences were observed between soils from northern and southern aspects, due to the gas/particle distribution of these compounds. We also found consistent differences in normalised PAH concentrations across the three sampling periods. The majority of compounds showed a significant decreasing trend from the beginning of May to the end of July, due to the annual cycles of physical processes (deposition vs. volatilisation) and biological processes (uptake and/or biotransformation). Only a few compounds showed different trends, presumably due to season-specific local emission sources.  相似文献   
47.
Hazelnuts have been shown to contain different allergenic proteins. Amongst these, major allergens Cor a 1 and Cor a 8 and the 2S albumin Cor a 14 were selected as targets to comparatively validate three Real-Time PCR protocols. We investigated both on the choice of the amplification target, and on the matrix effect on different sample foods. Applying statistics on the validation parameters obtained from the three protocols, we showed a significant difference in Ct values. This could turn critical when a high sensitivity method is required for the detection of hazelnut traces, confirming how fundamental the choice of the template during primer design phase is. Concluding, statistical approach represents a useful tool for the identification of the best performing primer pairs in Real-Time PCR. Cor a 8 gene permitted the identification of hazelnut based ingredients in complex foods, providing a significantly higher sensitivity in the PCR amplification, when compared to Cor a 1 and Cor a 14.  相似文献   
48.
In this work, Gd2Ge2O7 polymorphs were obtained by solid-state reactions at 1100–1300 °C. Structural and vibrational features were investigated by X-ray diffraction and Raman spectroscopy. For the triclinic (space group P1) polymorph, all the predicted phonons were discerned in perfect agreement with the group theory calculations, while for the tetragonal polymorph (space group P41212), 53 bands of the 81 predicted modes could be identified and characterized. The Gd3+ 4f-4f electronic transitions were investigated by diffuse reflectance spectroscopy in the range 200–340 nm. By applying the Kubelka-Munk function, it was possible to determine the bandgap values for all ceramics studied. The tetragonal polymorph exhibited higher bandgap values (5.88 eV) than the triclinic one (5.59 eV), which are both more energetic than other pyrochlore polymorphs reported in the literature. The results indicate that the presence of polymorphism in Gd2Ge2O7 ceramics can be used to produce tailor-made materials since their crystal structures have a strong influence on their optical properties. Consequently, these properties could be used to tuning the optical properties of Gd-containing materials to sensitize and transfer energy to other luminescent lanthanide ions, aiming for innovative applications.  相似文献   
49.
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   
50.
The catalytic hydrolysis of soybean oil was used as an alternative for the production of monoglycerides (MG) and diglycerides (DG). The reactions were conducted in a stainless-steel tubular reactor in the temperature range of 240–290 °C, on niobium phosphate (NBP) and niobium oxide (NBO) as catalysts. In the hydrolysis reactions at 270 °C, the maximum selectivities of the products of interest were obtained at 22 % MG and 48 % DG for the reaction with NBP, and 7 % MG and 33 % DG with NBO, for 59 % and 36 % of triglyceride conversion in 10 min, respectively. The proposed kinetic model presented a good fit of the theoretical model with the experimental data, showing that the previous hypotheses considered for the mechanism development are suitable for describing the kinetics of soybean oil hydrolysis.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司    京ICP备09084417号-23

京公网安备 11010802026262号