全文获取类型
收费全文 | 24461篇 |
免费 | 1430篇 |
国内免费 | 941篇 |
专业分类
电工技术 | 1397篇 |
综合类 | 1427篇 |
化学工业 | 2004篇 |
金属工艺 | 2764篇 |
机械仪表 | 1922篇 |
建筑科学 | 1915篇 |
矿业工程 | 502篇 |
能源动力 | 614篇 |
轻工业 | 1327篇 |
水利工程 | 233篇 |
石油天然气 | 1885篇 |
武器工业 | 263篇 |
无线电 | 2130篇 |
一般工业技术 | 3193篇 |
冶金工业 | 853篇 |
原子能技术 | 182篇 |
自动化技术 | 4221篇 |
出版年
2024年 | 71篇 |
2023年 | 221篇 |
2022年 | 335篇 |
2021年 | 483篇 |
2020年 | 492篇 |
2019年 | 427篇 |
2018年 | 436篇 |
2017年 | 616篇 |
2016年 | 708篇 |
2015年 | 927篇 |
2014年 | 1385篇 |
2013年 | 1332篇 |
2012年 | 1576篇 |
2011年 | 1849篇 |
2010年 | 1553篇 |
2009年 | 1535篇 |
2008年 | 1566篇 |
2007年 | 1683篇 |
2006年 | 1498篇 |
2005年 | 1298篇 |
2004年 | 1066篇 |
2003年 | 955篇 |
2002年 | 820篇 |
2001年 | 690篇 |
2000年 | 566篇 |
1999年 | 497篇 |
1998年 | 422篇 |
1997年 | 315篇 |
1996年 | 292篇 |
1995年 | 227篇 |
1994年 | 179篇 |
1993年 | 134篇 |
1992年 | 124篇 |
1991年 | 101篇 |
1990年 | 81篇 |
1989年 | 54篇 |
1988年 | 40篇 |
1987年 | 24篇 |
1986年 | 16篇 |
1985年 | 33篇 |
1984年 | 25篇 |
1983年 | 35篇 |
1982年 | 33篇 |
1981年 | 7篇 |
1979年 | 6篇 |
1978年 | 9篇 |
1965年 | 17篇 |
1962年 | 7篇 |
1957年 | 5篇 |
1955年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
Mauro Sassu 《Canadian Metallurgical Quarterly》2003,129(6):607-612
A plane elastic-plastic solid body presenting kinematic hardening is used to simulate a pair of dampers at the base of a rigid structure and determine the energy dissipation under conditions of assigned, homogeneous cyclic loading. The well-known von Mises theory of plasticity is applied with the aim of obtaining analytical solutions to the problem. Such solutions are arrived at by first calculating the Odqvist parameter, which yields dimensionless relations that depend on the external loads and mechanical properties of the material. The results, in terms of dissipated energy, are given for the case of a sinusoidal process, represented with the help of dimensionless parameters useful for engineering applications. 相似文献
73.
USB技术在飞机外场设备测试中的应用 总被引:3,自引:0,他引:3
李志伟 《计算机工程与设计》2003,24(1):72-74
通用串行总线(USB)是近年来流行的一种新的微机总线接口标准,它可以实现较传统方式更有效、更经济、更多点的数据采集,详细介绍了利用USB技术实现飞机外场快速测试的方法。 相似文献
74.
With youth participation in sports at an all-time high, youths have become more vulnerable to the silent epidemic of concussion. Psychologists should become aware of the alarming frequency of mild concussion and the subtle effects of concussion, which often go unnoticed or result in misdiagnosis. This article provides a basic survey of the research and literature on this topic, a simplified knowledge base for understanding updated assessment and management techniques, and a discussion of the important role psychologists can play in educating the public and their patients. Practitioners can become more aware of this developing practice opportunity. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
75.
Prediction of the effects on dynamic response due to distributed structural modification with additional degrees of freedom 总被引:1,自引:0,他引:1
Huajiang Hang Krishna Shankar Joseph C.S. Lai 《Mechanical Systems and Signal Processing》2008,22(8):1809-1825
The aim of this study is to investigate means of efficiently assessing the effects of distributed structural modification on the dynamic properties of a complex structure. The dynamic properties of the modified structure can be determined by experimental testing or numerical simulation, both of which are complex, expensive and time-consuming. Assuming that the original dynamic characteristics are already established and that the modification is a relatively simple attachment, the modified dynamic properties may be determined numerically without solving the equations of motion of the full-modified structure. The frequency response functions (FRFs) of the modified structure can be computed by coupling the original FRFs and a delta dynamic stiffness matrix for the modification introduced. The validity of this approach is investigated by applying it to a cantilever beam to which a smaller beam is attached as modification. The original FRFs were obtained experimentally as well as numerically. The delta dynamic stiffness matrix was determined numerically by modeling the attachment and part of the original structure including the attachment points. The FRFs of the modified beam were then computed. Good agreement is obtained by comparing the results to the FRFs of the modified beam determined experimentally as well as by numerical modeling of the complete modified structure. 相似文献
76.
77.
本文根据实地考察内容,结合宽带网络技术和业务重点及实施策略,全面介绍了日本关西宽带实验网发展背景,通信与广播电视综合应用实验和B-ISDN实用化实验的进展以及NTT所起作用。文章最后就关西宽带实验网的借鉴意义提出了几方面意见。 相似文献
78.
A test chamber has been developed in order to provide a small and simple emission testing facility capable of testing construction products in a climate where the important climatic parameters such as temperature, ventilation rate and air velocity can be varied independently around typical indoor values. The test chamber CLIMPAQ is made of panes of window glass. Other main surface materials are stainless steel and eloxated aluminium. The chamber has a volume of 50.9 litres and is designed to meet the requirements for quantifying air pollution. In this investigation human subjects acted as air pollution judges, and chemical characterization of the air pollution was carried out. Carpet, linoleum, wall paint and seal- ant were tested simultaneously in the CLIMPAQ and in four other chambers ranging from a full-scale chamber of 28 m3 to a field and laboratory emission cell of 3.5· 10?5m3. Product ranking is the same in all chambers for the sensory measurements. Emission rates based on sensory measurements differ for all products less than 100 % except for tests in a 3-litre chamber where emission rates were higher. Chemical measurements differ up to approximately 10 times for the same product in different chambers. Deviations appear to be the result of different environmental parameters in the various chambers. Low air concentrations or high specific ventilation rates seem to increase emissions, while differences in air velocities and sink properties may also be the cause of differences in emission rates. 相似文献
79.
80.
V. Székely M. Rencz J.M. Karam M. Lubaszewski B. Courtois 《Journal of Electronic Testing》1998,12(1-2):81-92
With the increasing power density in integrated systems resulting from scaling down, the occurrence of field failures due to overheating has considerably increased. Faulty operation can be prevented by on-line temperature monitoring. This paper deals with questions of on-line temperature monitoring in safety-critical systems. First the possible temperature sensors are reviewed and basic principles of self-checking systems including such sensors are detailed, then a new temperature sensor cell with extremely good parameters designed especially for DfTT applications is presented. The basic questions of integrating thermal sensors into self-checking systems are also discussed. 相似文献