全文获取类型
收费全文 | 1014篇 |
免费 | 43篇 |
专业分类
电工技术 | 13篇 |
综合类 | 3篇 |
化学工业 | 373篇 |
金属工艺 | 20篇 |
机械仪表 | 17篇 |
建筑科学 | 17篇 |
矿业工程 | 1篇 |
能源动力 | 20篇 |
轻工业 | 96篇 |
水利工程 | 7篇 |
石油天然气 | 2篇 |
无线电 | 56篇 |
一般工业技术 | 136篇 |
冶金工业 | 126篇 |
自动化技术 | 170篇 |
出版年
2023年 | 9篇 |
2022年 | 52篇 |
2021年 | 114篇 |
2020年 | 36篇 |
2019年 | 21篇 |
2018年 | 31篇 |
2017年 | 31篇 |
2016年 | 38篇 |
2015年 | 24篇 |
2014年 | 51篇 |
2013年 | 84篇 |
2012年 | 46篇 |
2011年 | 56篇 |
2010年 | 41篇 |
2009年 | 36篇 |
2008年 | 30篇 |
2007年 | 31篇 |
2006年 | 24篇 |
2005年 | 23篇 |
2004年 | 21篇 |
2003年 | 14篇 |
2002年 | 14篇 |
2001年 | 9篇 |
2000年 | 4篇 |
1999年 | 9篇 |
1998年 | 7篇 |
1996年 | 7篇 |
1995年 | 8篇 |
1994年 | 6篇 |
1993年 | 12篇 |
1992年 | 6篇 |
1991年 | 10篇 |
1990年 | 8篇 |
1989年 | 9篇 |
1988年 | 8篇 |
1986年 | 8篇 |
1985年 | 10篇 |
1984年 | 9篇 |
1983年 | 9篇 |
1982年 | 5篇 |
1981年 | 5篇 |
1980年 | 6篇 |
1976年 | 7篇 |
1975年 | 6篇 |
1973年 | 3篇 |
1970年 | 6篇 |
1969年 | 3篇 |
1967年 | 8篇 |
1966年 | 3篇 |
1923年 | 3篇 |
排序方式: 共有1057条查询结果,搜索用时 937 毫秒
101.
Gustav Lymer Jonas Ivarsson Oskar Lindwall 《International Journal of Computer-Supported Collaborative Learning》2009,4(4):423-444
This study investigates video recordings of design reviews in architectural education, focusing on how presentations and discussions
of designs are contingent on the specific tools employed. In the analyzed recordings, three different setups are utilized:
traditional posters, digital slide-show technologies, and combinations of the two. This range of different setups provides
a set of contrasts that make visible the role of technologies in shaping the ways in which the reviews are conducted. The
analysis is structured in three themes. First, we examine the sequential organization of digital presentations in relation
to the spatial structure of poster-based presentations. Second, the different ways in which shared attention is established
in digital, paper-based, and hybrid presentation practices are analyzed. Third, we address part-whole relations—how details
in presented materials are put in relation to the overarching project or the presentation as a whole. Taken together, the
analyses suggest that the detailed organization of the design review is transformed in subtle yet consequential ways through
the introduction of digital slide-show technologies. These transformations are consequential not only locally, for the design
review itself, but also for the instructive work that is accomplished through this practice. We conclude by discussing some
implications for design, arguing that an increased awareness of how the practice is influenced by the different setups might
be key for the proper adaptation of presentation technologies to particular purposes. 相似文献
102.
Experimental and theoretical analysis of the influence of the lubricant on the temperature distribution in the tool during forging is presented. Finite element solution of the general diffusion equation is used to calculate the heat transfer contact between the die and the hot workpiece and during the interpass times. The results of calculations are compared with the results of measurements carried out using thermocouples inserted in the die. Two ways of modelling heat transfer through the contact surface are considered. The first treats a lubricant as a separate layer with the relevant thermal properties. The second assumes a temperature discontinuity at the interface and introduces the heat transfer coefficient. Insulating properties of various lubricants are compared. White-water lubricant shows the best insulating properties. The values of the heat transfer coefficient obtained from the inverse analysis vary from 2600 (without lubrication) to 1500 W/m2K (white lubricant). 相似文献
103.
Lucyna Iberhan Maciej Winiewski 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2003,78(6):659-665
Extraction of arsenic(III) and arsenic(V) from sulfuric acid solution was studied. Cyanex® 923, Cyanex® 925, dialkyldithiophosphinic acids (Cyanex® 301), hydrophobic glycol (2‐ethylhexane‐1,3‐diol), and hydroxamic acids were used as extractants. The efficiency of extraction depended on extractant, diluent, valency of arsenic, and sulfuric acid concentration. Acidic reagents extracted As(III) better than As(V), while the opposite order of extraction efficiency was observed for the solvating extractants. The use of an aromatic diluent (toluene) was preferred. Toluene was found to be a better diluent for the Cyanex® 923 and Cyanex® 925 than Exxsol D 220/230 and octane. In the case of neo‐decanohydroxamic acids, the type of diluent had no significant effect on extraction of arsenic. The extraction of both As(III) and As(V) increased when the concentration of the sulfuric acid in the feed increased. The co‐extraction of sulfuric acid was observed. The extraction with hydroxamic acids was significantly slower in comparison to the extraction with other reagents. Extractant: arsenic species: sulfuric acid molar ratios were determined and they confirmed the composition of extracted species. Copyright © 2003 Society of Chemical Industry 相似文献
104.
Summary Living cationic polymerization of isobutul vinyl ether (IBVE), initiated by1-iodo-1-(2-methyl propyloxy)-ethane (1) and tetraalkylammonium perchlorate yields polymers of well defined molar masses and end groups. The controlled introduction of end groups was confirmed by a model reaction and was then applied to introduce and azo initiator function. The resulting polymeric initiator was used for the synthesis of a blockcopolymer. 相似文献
105.
106.
Maciej Giedyk Dr. Keith ó Proinsias Sylwester Kurcoń Dr. Iraida Sharina Dr. Emil Martin Prof. Dorota Gryko 《ChemMedChem》2014,9(10):2344-2350
Specially designed B‐ring‐modified cobalamin derivatives were synthesized and tested as potential activators of soluble guanylyl cyclase (sGC). Herein, we disclose the influence of substituents at the c‐ and d‐positions in hydrophilic and hydrophobic cobyrinic acid derivatives on their capacities to activate sGC. The presence of the amide group at c‐/d‐position in cobyrinic acid derivatives strongly influence the level of sGC activation. Removal of the d‐position altogether has a profound effect for hydrophobic compounds. In contrast, little differences were observed in hydrophilic ones. 相似文献
107.
In this paper a numerically efficient method for designing a nearly optimal variable fractional delay (VFD) filter based on a simple and well-known window method is presented. In the proposed method a single window extracted from the optimal filter with fixed fractional delay (FD) is divided into even and odd part. Subsequently, the odd part is discarded and symmetric even part of the extracted window is used to design a family of nearly optimal filters with varying FD. In addition to window extraction, the proposed approach requires filter gain correction which is dependent on the desired FD. Optimum values of the gain correction factor as well as the extracted window can be computed beforehand, which allows us to design a nearly optimal FD filter with arbitrary FD at low numerical costs during runtime. On the basis of the proposed filter design method, the universal structure of VFD filter allowing for change of filter type and length has been proposed. In the paper, three FD filter optimality criteria are considered, which are maximal flatness, Chebyshev (minimax), and least squares. 相似文献
108.
109.
Maciej RadzieńskiMarek Krawczuk Magdalena Palacz 《Mechanical Systems and Signal Processing》2011,25(6):2169-2190
The objective of this paper is to introduce a new method for structural damage detection based on experimentally obtained modal parameters. The new method is suitable for detection of fatigue damage occurring in an aluminium cantilever beam. The damage has been practically realised as saw cuts of different sizes and at different locations. The first step of analysis included an attempt of damage identification with the most often used damage indicators based on measured modal parameters. For that purpose special signal processing technique has been proposed improving the effectiveness of indicators tested. However the results obtained have not been satisfactory. That was the motivation for defining new damage indicators (frequency change based damage indicator, Hybrid Damage Detection method), utilising the change of natural frequencies and any mode shape (measured or modelled) as the measurement of frequencies is much less time consuming in comparison to total mode shape measurement. It has been shown that the proposed technique is suitable for damage localisation in beam-like structures. 相似文献
110.