全文获取类型
收费全文 | 1938篇 |
免费 | 21篇 |
专业分类
电工技术 | 1篇 |
化学工业 | 37篇 |
金属工艺 | 2篇 |
机械仪表 | 2篇 |
建筑科学 | 3篇 |
轻工业 | 69篇 |
无线电 | 19篇 |
一般工业技术 | 37篇 |
冶金工业 | 1754篇 |
自动化技术 | 35篇 |
出版年
2023年 | 2篇 |
2021年 | 7篇 |
2020年 | 6篇 |
2019年 | 6篇 |
2018年 | 2篇 |
2017年 | 11篇 |
2016年 | 9篇 |
2015年 | 3篇 |
2014年 | 6篇 |
2013年 | 11篇 |
2012年 | 15篇 |
2011年 | 12篇 |
2010年 | 10篇 |
2009年 | 12篇 |
2008年 | 12篇 |
2007年 | 10篇 |
2006年 | 5篇 |
2005年 | 7篇 |
2004年 | 9篇 |
2003年 | 8篇 |
2002年 | 3篇 |
2001年 | 5篇 |
2000年 | 4篇 |
1999年 | 61篇 |
1998年 | 590篇 |
1997年 | 302篇 |
1996年 | 200篇 |
1995年 | 87篇 |
1994年 | 83篇 |
1993年 | 100篇 |
1992年 | 15篇 |
1991年 | 32篇 |
1990年 | 23篇 |
1989年 | 22篇 |
1988年 | 19篇 |
1987年 | 23篇 |
1986年 | 21篇 |
1985年 | 26篇 |
1984年 | 2篇 |
1983年 | 5篇 |
1982年 | 5篇 |
1981年 | 9篇 |
1980年 | 18篇 |
1979年 | 2篇 |
1978年 | 5篇 |
1977年 | 38篇 |
1976年 | 89篇 |
1975年 | 5篇 |
1962年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有1959条查询结果,搜索用时 31 毫秒
1.
In recent literature, a new chromatic adaptation transform, CAT16, has been published to improve upon the widely used CAT02 model. The CAT16 model is based on the form of the CAT02 transform adopted in CIECAM02, but uses a slightly different sensor space to fix some gamut problems plaguing CIECAM02 and adopts a two-step CAT to ensure symmetry and transitivity. CAT16 is included in CAM16 but is also being promoted as a stand-alone CAT, one that can be used outside of the CAM16 model. However, the use of CAT16 as a stand-alone model can cause inconsistencies in the calculated corresponding colors due to the presence of the relative luminance of the adapting white (Yw) in the von Kries-Ives gain control factors. Such inconsistencies are not present for the stand-alone version of the CAT02 model, which, unlike the version adopted in CIECAM02, does not include the Yw factors. CAT16 should therefore be modified by omitting the Yw factors. In this article, we will briefly discuss these issues in more detail and provide a consistent two-step CAT adopting the CAT16 sensor space. 相似文献
2.
Jared Freeman Drew Leins Conrad Bell IV The SD Research Consortium 《Theoretical Issues in Ergonomics Science》2019,20(1):27-38
AbstractOrganisations conducting research programs often focus the work of their scientists and technologists on challenge problems (CPs). These challenges are designed to ensure that progress is measurable and relevant to the goals of the program sponsor. Generating and selecting pertinent CPs is difficult, as is assessing their value. We describe a method of generating and selecting CPs and its application in a highly collaborative, multi-organisation research program. Thirty-eight biologists, chemists, mathematicians and computer scientists across academic, commercial and government organisations generated and ranked their top choices from among 12 richly described candidate challenge problems. A ranked-choice voting formula was applied. Five CPs were highly scored; the remaining seven were distributed across a lower range of scores. The program sponsor subsequently directed researchers to address six CPs, including the elected five. Analysis of the rationales that participants offered for their CP rankings revealed four domain-independent dimensions of value: capability, speed, impact and synergy. These dimensions of value can help managers of interdisciplinary research programs systematically select a portfolio of CPs that will efficiently apply utilise resources towards program goals and facilitate measurement of scientific progress. 相似文献
3.
Pieter Smet 《International Transactions in Operational Research》2021,28(1):91-118
Severe traffic congestion and growing ecological consciousness have led to the rise of alternative transportation systems. Ride sharing is one such alternative in which drivers and passengers with similar time schedules and travel plans are matched. For this service to be effective, a large number of users are required to increase the probability of finding suitable travel partners. The present paper proposes a late acceptance metaheuristic to decide which users act as drivers and to construct their routes. The underlying optimization model allows passengers to walk to/from alternative pickup/drop‐off locations so as to further exploit user flexibility. A computational study quantifies the impact of different types of participant flexibility on CO2 emissions. These insights can inform and support policymakers in organizing effective ride‐sharing systems. 相似文献
4.
5.
Cindy De Smet Jeroen BourgonjonBram De Wever Tammy SchellensMartin Valcke 《Computers & Education》2012,58(2):688-696
The aim of this large-scale study was to understand the technology acceptation of learning management systems (LMS) by secondary school teachers and to investigate the instructional use of LMS, distinguishing between informational use and communicational use. The predictive model further includes: perceived usefulness, perceived ease of use, subjective norm, personal innovativeness in the domain of information technology, experience and internal ICT support at school level. Data were collected from 505 Flemish secondary school teachers. After performing satisfactory reliability and validity checks, the study was able to support all relationships among the 9 variables. Informational use was found to be a precursor for communicational use, perceived ease of use of the LMS is the strongest predictor in LMS-acceptation. Internal ICT support has a direct effect on the informational use of the LMS and on subjective norm. Implications stress that secondary school managers in education should take into account the importance of a teachers’ efforts and performance perceptions and the direct and indirect impact of internal ICT support on LMS adoption. 相似文献
6.
Barbara Mendrek Łukasz Sieroń Marcin Libera Mario Smet Barbara Trzebicka Aleksander L. Sieroń Andrzej Dworak Agnieszka Kowalczuk 《Polymer》2014
Core-shell type stars synthesized via atom transfer radical polymerization were used for the delivery of nucleic acids. The interior of the stars consisted of hyperbranched poly(arylene oxindole), while the arms were composed of poly(N,N-dimethylaminoethyl methacrylate). The length of the star arms varied in degree of polymerization (DP) from 14 to 98. The hydrodynamic radius of the structures measured in water indicated the presence of small aggregates, while isolated stars ranging in size from 14 to 29 nm were seen in organic solvent. The phase transition temperatures of the stars in water, measured in basic conditions, were shifted to lower values with increasing DP of the arms. Stable polyplexes of stars with plasmid DNA were formed. Their size varied from 300 nm to 400 nm, depending upon the DP of arms. The zeta potential of the polyplexes was positive, which facilitated their cellular uptake. The DP of the arms influenced the transfection efficiency of HT-1080 cells, demonstrating that stars are promising candidates for synthetic gene vectors. 相似文献
7.
8.
Agnieszka Owczarek‐Fendor An Vermeulen Ilse Van Bree Markus Eriksson Stefaan Lescouhier Stefaan De Smet Bruno De Meulenaer Frank Devlieghere 《International Journal of Food Science & Technology》2014,49(4):1090-1098
The objective of this study was to evaluate the influence of two different vacuum ageing times (7 and 14 days) and the impact of the modified atmosphere packaging (MAP) configuration (gas/product ratios: 0.5 and 1 and gas composition: 70% O2 + 30% CO2 and 40% O2 + 30% CO2 + 30% N2) on the quality of fresh beef during subsequent storage at 4 °C. For this purpose, three separate experiments were performed. For each experiment, two different muscles (Longissimus dorsi and Biceps femoris) were sampled from four double‐muscled Belgian Blue beef carcasses. Next to colour, also the evolution in microbial load, pH, O2 and CO2 in the headspace and lipid oxidation at the meat surface were evaluated. A vacuum ageing for 14 days compared with 7 days resulted in a higher initial microbial load on the day of MAP packaging, which resulted finally in a significantly shorter shelf life. This ageing effect was less pronounced on the colour stability and lipid oxidation of the meat samples. No significant influence of the packaging configuration on any of the analysed parameters (colour, microbial load, pH and lipid oxidation at the meat surface) was observed. 相似文献
9.
Aykut Avci Jan De CockPeter Lambert Roel BeernaertJelle De Smet Lawrence BogaertYouri Meuret Hugo ThienpontHerbert De Smet 《Journal of Visual Communication and Image Representation》2012,23(2):287-292
An efficient disparity estimation algorithm for multi-view video sequences, recorded by a two-dimensional camera array in which the cameras are spaced equidistantly, is presented. Because of the strong geometrical relationship among views, the disparity vectors of a certain view can for most blocks be derived from the disparity vectors of other views. A frame constructed using that idea is called a D frame in this work. Three new prediction schemes which contain D frames are proposed for encoding 5 × 3 multi-view video sequences. The schemes are applied to several multi-view image sequences taken from a camera-array and they are compared in terms of quality, bit-rate and complexity. The experimental results show that the proposed prediction schemes significantly decrease the complexity of the encoder at a very low cost of quality and/or bit-rate. 相似文献
10.
Tony Wauters Joris Kinable Pieter Smet Wim Vancroonenburg Greet Vanden Berghe Jannes Verstichel 《Journal of Scheduling》2016,19(3):271-283
Scheduling projects is a difficult and time consuming process, and has far-reaching implications for any organization’s operations. By generalizing various aspects of project scheduling, decision makers are enabled to capture reality and act accordingly. In the context of the MISTA 2013 conference, the first MISTA challenge, organized by the authors, introduced such a general problem model: the Multi-Mode Resource-Constrained Multi-Project Scheduling Problem (MRCMPSP). The present paper reports on the competition and provides a discussion on its results. Furthermore, it provides an analysis of the submitted algorithms, and a study of their common elements. By making all benchmark datasets and results publicly available, further research on the MRCMPSP is stimulated. 相似文献