全文获取类型
收费全文 | 265858篇 |
免费 | 31803篇 |
国内免费 | 10881篇 |
专业分类
电工技术 | 15348篇 |
技术理论 | 17篇 |
综合类 | 15119篇 |
化学工业 | 52930篇 |
金属工艺 | 13278篇 |
机械仪表 | 15523篇 |
建筑科学 | 19289篇 |
矿业工程 | 7093篇 |
能源动力 | 7639篇 |
轻工业 | 22650篇 |
水利工程 | 4654篇 |
石油天然气 | 13350篇 |
武器工业 | 1925篇 |
无线电 | 33098篇 |
一般工业技术 | 37429篇 |
冶金工业 | 11685篇 |
原子能技术 | 2685篇 |
自动化技术 | 34830篇 |
出版年
2024年 | 1139篇 |
2023年 | 4265篇 |
2022年 | 7869篇 |
2021年 | 10817篇 |
2020年 | 9203篇 |
2019年 | 9123篇 |
2018年 | 9960篇 |
2017年 | 11087篇 |
2016年 | 10715篇 |
2015年 | 13232篇 |
2014年 | 15609篇 |
2013年 | 18965篇 |
2012年 | 18388篇 |
2011年 | 18916篇 |
2010年 | 16790篇 |
2009年 | 15902篇 |
2008年 | 14863篇 |
2007年 | 13760篇 |
2006年 | 13532篇 |
2005年 | 11533篇 |
2004年 | 8285篇 |
2003年 | 7285篇 |
2002年 | 6816篇 |
2001年 | 6103篇 |
2000年 | 5703篇 |
1999年 | 5663篇 |
1998年 | 4233篇 |
1997年 | 3573篇 |
1996年 | 3327篇 |
1995年 | 2721篇 |
1994年 | 2161篇 |
1993年 | 1607篇 |
1992年 | 1284篇 |
1991年 | 962篇 |
1990年 | 707篇 |
1989年 | 551篇 |
1988年 | 467篇 |
1987年 | 302篇 |
1986年 | 272篇 |
1985年 | 156篇 |
1984年 | 141篇 |
1983年 | 102篇 |
1982年 | 99篇 |
1981年 | 76篇 |
1980年 | 70篇 |
1979年 | 39篇 |
1978年 | 28篇 |
1977年 | 32篇 |
1976年 | 29篇 |
1975年 | 21篇 |
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
81.
Dong Zhang 《Korean Journal of Chemical Engineering》2008,25(5):1205-1207
Ceria-zirconia solid particles have been recognized as a key material of the automotive exhaust catalysts since they can release
and uptake oxygen owing to the rapid reversible oxidation states of cerium between Ce3+ and Ce4+. Several methods have recently been described to prepare the CeO2-ZrO2 solid particles used in the catalysts. In this paper, a new coprecipitation method is used to prepare the CeO2-ZrO2 solid particles. The Ce-Zr alcogel is dried and calcined in flowing N2 not in flowing air under atmospheric pressure. The results show that the ceria-zirconia sample calcined at 650 °C has high
surface area over 90 m2g−1, which drops to 40 m2g−1 following treatment at 900°C. 相似文献
82.
Y. L. Hao R. Yang M. Niinomi D. Kuroda Y. L. Zhou K. Fukunaga A. Suzuki 《Metallurgical and Materials Transactions A》2003,34(4):1007-1012
Alloys for implant devices require improved strength but a reduced Young’s modulus, in order to become mechanically more compatible
with adjacent bone tissues. In this study, a new metastable β-type titanium alloy, Ti-29Nb-13Ta-4.6Zr (wt pct), was subjected to aging treatment to produce different microstructures,
and the resulting mechanical properties, including the Young’s modulus, were measured. The Young’s modulus of this alloy is
found to be sensitive to microstructures generated by various heat treatments. For microstructures varying from (α + β) to (α + β + ω) and (β + ω), the Young’s modulus increases with an accompanying increase in tensile strength and hardness, but decreases in ductility.
The (β + ω) microstructure has a low strength, high modulus, and poor ductility and cannot be used for biomedical applications. For
an (α + β) microstructure, the volume fraction of the phases is shown to be the main factor that determines the mechanical properties. 相似文献
83.
84.
85.
Lie‐Fern Hsu 《Quality and Reliability Engineering International》2007,23(2):269-272
He and Grigoryan (Quality and Reliability Engineering International 2002; 18 :343–355) formulated the design of a double‐sampling (DS) s control chart as an optimization problem and solved it with a genetic algorithm. They concluded that the DS s control charts can be a more economically preferable alternative in detecting small shifts than traditional s control charts. We explain that, since they only considered the average sample size when the process is in control, their conclusion is questionable. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
86.
87.
Zhenghong Yang Yongjian Hu 《Automatic Control, IEEE Transactions on》2004,49(10):1783-1792
In this note, a generalized Bezoutian matrix with respect to a polynomial sequence of interpolatory type is introduced. The operator representation relative to a pair of dual bases and the generalized Barnett-type factorization formula are derived. An intertwining relation and a Bezoutian reduction to a block diagonal form by congruence via a generalized Vandermonde matrix are presented. Fujiwara-Hermite and Routh-Hurwitz criteria in terms of this generalized Bezout matrix are obtained. 相似文献
88.
Yanqing Ji Hao Ying John Yen Shizhuo Zhu Daniel C. Barth‐Jones Richard E. Miller R. Michael Massanari 《国际智能系统杂志》2007,22(8):827-845
Discovering unknown adverse drug reactions (ADRs) in postmarketing surveillance as early as possible is highly desirable. Nevertheless, current postmarketing surveillance methods largely rely on spontaneous reports that suffer from serious underreporting, latency, and inconsistent reporting. Thus these methods are not ideal for rapidly identifying rare ADRs. The multiagent systems paradigm is an emerging and effective approach to tackling distributed problems, especially when data sources and knowledge are geographically located in different places and coordination and collaboration are necessary for decision making. In this article, we propose an active, multiagent framework for early detection of ADRs by utilizing electronic patient data distributed across many different sources and locations. In this framework, intelligent agents assist a team of experts based on the well‐known human decision‐making model called Recognition‐Primed Decision (RPD). We generalize the RPD model to a fuzzy RPD model and utilize fuzzy logic technology to not only represent, interpret, and compute imprecise and subjective cues that are commonly encountered in the ADR problem but also to retrieve prior experiences by evaluating the extent of matching between the current situation and a past experience. We describe our preliminary multiagent system design and illustrate its potential benefits for assisting expert teams in early detection of previously unknown ADRs. © 2007 Wiley Periodicals, Inc. Int J Int Syst 22: 827–845, 2007. 相似文献
89.
90.