全文获取类型
收费全文 | 3146篇 |
免费 | 168篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 35篇 |
综合类 | 3篇 |
化学工业 | 805篇 |
金属工艺 | 58篇 |
机械仪表 | 80篇 |
建筑科学 | 98篇 |
矿业工程 | 35篇 |
能源动力 | 151篇 |
轻工业 | 390篇 |
水利工程 | 29篇 |
石油天然气 | 8篇 |
无线电 | 257篇 |
一般工业技术 | 436篇 |
冶金工业 | 360篇 |
原子能技术 | 31篇 |
自动化技术 | 542篇 |
出版年
2023年 | 37篇 |
2022年 | 73篇 |
2021年 | 149篇 |
2020年 | 98篇 |
2019年 | 82篇 |
2018年 | 102篇 |
2017年 | 91篇 |
2016年 | 108篇 |
2015年 | 79篇 |
2014年 | 148篇 |
2013年 | 213篇 |
2012年 | 208篇 |
2011年 | 212篇 |
2010年 | 167篇 |
2009年 | 130篇 |
2008年 | 163篇 |
2007年 | 133篇 |
2006年 | 93篇 |
2005年 | 84篇 |
2004年 | 63篇 |
2003年 | 46篇 |
2002年 | 52篇 |
2001年 | 45篇 |
2000年 | 41篇 |
1999年 | 37篇 |
1998年 | 65篇 |
1997年 | 44篇 |
1996年 | 46篇 |
1995年 | 45篇 |
1994年 | 30篇 |
1993年 | 39篇 |
1992年 | 20篇 |
1991年 | 26篇 |
1990年 | 14篇 |
1989年 | 14篇 |
1988年 | 15篇 |
1987年 | 15篇 |
1986年 | 13篇 |
1985年 | 18篇 |
1984年 | 16篇 |
1983年 | 13篇 |
1982年 | 21篇 |
1981年 | 14篇 |
1980年 | 11篇 |
1979年 | 11篇 |
1977年 | 15篇 |
1975年 | 9篇 |
1972年 | 11篇 |
1944年 | 10篇 |
1943年 | 21篇 |
排序方式: 共有3318条查询结果,搜索用时 328 毫秒
981.
982.
983.
Modification of a variety of fabric and fibrous surfaces was achieved by insolubilization thereon of crosslinked polythylene glycols (called POLYTHERM) to impart several useful properties: thermal storage and release, improved resiliency and resistance to oily soiling, static charge, pilling, wear life, and marked increases in hydrophilicity among them. Moreover, these improved properties were durable because up to 70% of the crosslinked polyol was retained after 50 launderings. Such modification was achieved by using average molecular weights of the polyols ranging from 600 to 20,000 by crosslinking with polyfunctional methylolamides (such as DMDHEU) in the presence of acid catalysts by a conventional pad-dry-cure textile finishing procedure. The role of crosslink density of the polyol in determining textile properties was determined by evaluation of films derived from crosslinking the polyols and comparison of selected properties. 相似文献
984.
Franck Schoefs & Xavier Aduriz &Olivier Bernard &Bruno Capra 《Computer-Aided Civil and Infrastructure Engineering》2009,24(7):492-508
Abstract: One of the uses of reinforced concrete pipes (RCPs) is the distribution of aggressive water in industrial systems, for example, in water-cooling systems of nuclear power plants. Some of them carry seawater and can deteriorate with time because of internal corrosion. Because of the low O2 content of aggressive water, slow corrosion is expected for such applications. If the RCPs are not periodically replaced, they will eventually fail. Replacement strategies for these pipes depend on (1) the risks associated with the failure of the water distribution network, and (2) the costs associated with replacing the pipes, including the removal of existing pipes, installation of new pipes, and associated production losses. Because of the lack of statistical data regarding RCP failure, the development of a risk-based replacement strategy is not an easy task. This article demonstrates how predictive models for the evolution of the failure of RCPs and the associated consequences of failure can be used to develop risk-based replacement strategies for RCPs. An application for the replacement strategies of a network modeled as a system consisting of 228 RCPs is presented as a case study. We focus on the assessment of the number of replaced components that governs the costs. The main objective of this article is to provide a theoretical approach for comparing replacement strategies, based on (1) the results of a reliability study, (2) the representation of the distributions of failed components (binomial distribution), and (3) the decision tree representation for replacement of RCPs. A focus on the scatter of the induced costs themselves is suggested to emphasize the financial risk. 相似文献
985.
986.
The ADIFOR 2.0 tool for Automatic Differentiation of Fortran programs has been used to generate analytic gradient code for all semiempirical SCF methods available in the MNDO97 program. The correctness and accuracy of the new code have been verified. Its performance has been compared with that of hand-coded analytic derivative routines and with numerical differentiation. From a quantum-chemical point of view, the major advance of this work is the development of previously unavailable analytic gradient code for the recently proposed OM1 and OM2 methods. 相似文献
987.
PD control with on-line gravity compensation for robots with elastic joints: Theory and experiments 总被引:1,自引:0,他引:1
A proportional-derivative (PD) control with on-line gravity compensation is proposed for regulation tasks of robot manipulators with elastic joints. The work extends a previous PD control with constant gravity compensation at the desired configuration. The control law requires measuring only position and velocity on the motor side of the elastic joints, while the on-line gravity compensation torque uses a biased measure of the motor position. It is proved via a Lyapunov argument that the control law globally asymptotically stabilizes the desired robot configuration. A simulation study on a two-joint arm reveals the better performance that can be obtained with the new scheme as compared to the case of constant gravity compensation. Moreover, the proposed controller is experimentally tested on an eight-joint cable-driven robot manipulator, in combination with a point-to-point interpolating trajectory, showing the practical advantages of the on-line compensation. 相似文献
988.
Bruno Gaujal Author Vitae Author Vitae 《Automatica》2004,40(9):1505-1516
In this paper, we consider a deterministic timed continuous Petri net model where conflicts at places are solved by using stationary routing parameters. We show how to compute the stationary firing rate for all transitions via linear programming, so as to determine the optimal routing parameters that maximize user-defined linear functions of the firing rates. Finally, we discuss the relations with discrete Petri nets. 相似文献
989.
F Helbling 《Canadian Metallurgical Quarterly》1998,87(43):1444-1448
990.
Laurence Likforman-Sulem Abderrazak Zahour Bruno Taconet 《International Journal on Document Analysis and Recognition》2007,9(2-4):123-138
There is a huge amount of historical documents in libraries and in various National Archives that have not been exploited
electronically. Although automatic reading of complete pages remains, in most cases, a long-term objective, tasks such as
word spotting, text/image alignment, authentication and extraction of specific fields are in use today. For all these tasks,
a major step is document segmentation into text lines. Because of the low quality and the complexity of these documents (background
noise, artifacts due to aging, interfering lines), automatic text line segmentation remains an open research field. The objective
of this paper is to present a survey of existing methods, developed during the last decade and dedicated to documents of historical
interest. 相似文献