全文获取类型
收费全文 | 1459篇 |
免费 | 47篇 |
专业分类
电工技术 | 19篇 |
化学工业 | 142篇 |
金属工艺 | 29篇 |
机械仪表 | 17篇 |
建筑科学 | 61篇 |
矿业工程 | 27篇 |
能源动力 | 27篇 |
轻工业 | 127篇 |
水利工程 | 15篇 |
石油天然气 | 22篇 |
武器工业 | 1篇 |
无线电 | 209篇 |
一般工业技术 | 174篇 |
冶金工业 | 266篇 |
原子能技术 | 4篇 |
自动化技术 | 366篇 |
出版年
2023年 | 10篇 |
2022年 | 9篇 |
2021年 | 23篇 |
2020年 | 20篇 |
2019年 | 26篇 |
2018年 | 27篇 |
2017年 | 40篇 |
2016年 | 44篇 |
2015年 | 33篇 |
2014年 | 55篇 |
2013年 | 79篇 |
2012年 | 59篇 |
2011年 | 103篇 |
2010年 | 86篇 |
2009年 | 71篇 |
2008年 | 87篇 |
2007年 | 84篇 |
2006年 | 75篇 |
2005年 | 65篇 |
2004年 | 60篇 |
2003年 | 56篇 |
2002年 | 31篇 |
2001年 | 31篇 |
2000年 | 13篇 |
1999年 | 25篇 |
1998年 | 27篇 |
1997年 | 25篇 |
1996年 | 58篇 |
1995年 | 27篇 |
1994年 | 19篇 |
1993年 | 19篇 |
1992年 | 13篇 |
1991年 | 4篇 |
1990年 | 7篇 |
1989年 | 8篇 |
1988年 | 8篇 |
1987年 | 11篇 |
1986年 | 8篇 |
1985年 | 9篇 |
1984年 | 9篇 |
1983年 | 4篇 |
1982年 | 6篇 |
1981年 | 7篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1976年 | 8篇 |
1975年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有1506条查询结果,搜索用时 15 毫秒
71.
We develop a new method for estimating the discrepancy of tensors associated with multiparty communication problems in the “Number on the Forehead” model of Chandra, Furst, and Lipton. We define an analog of the Hadamard property of matrices for tensors in multiple dimensions and show that any k-party communication problem represented by a Hadamard tensor must have Ω(n/2 k ) multiparty communication complexity. We also exhibit constructions of Hadamard tensors. This allows us to obtain Ω(n/2 k ) lower bounds on multiparty communication complexity for a new class of explicitly defined Boolean functions. 相似文献
72.
Hike Gaynor 《电子设计应用》2009,(11):53-55,60
本文分析了目前无线产品设计面临的挑战,提出了一种只需少量电路,占用较少电路板面积的解决方案,即将功率放大器和前端模块RF装置集成到天线结构的蜂窝无线电天线模块中,针对天线负载条件使天线和RF电路实现最佳匹配。 相似文献
73.
74.
75.
76.
77.
Stice Eric; Rohde Paul; Seeley John R.; Gau Jeff M. 《Canadian Metallurgical Quarterly》2010,78(2):273
Objective: Evaluate a new 5-step method for testing mediators hypothesized to account for the effects of depression prevention programs. Method: In this indicated prevention trial, at-risk teens with elevated depressive symptoms were randomized to a group cognitive–behavioral (CB) intervention, group supportive expressive intervention, CB bibliotherapy, or assessment-only control condition. Results: The group CB intervention reduced depressive symptoms and negative cognitions and increased pleasant activities. Change in these mediators predicted change in depression, and intervention effects became weaker controlling for change in the mediators; yet, change in depression appeared typically to occur before change in the mediators. The supportive expressive intervention reduced depressive symptoms but affected only 1 of 2 mediators (emotional expression but not loneliness). Change in emotional expression did not correlate with change in depression, and change in depression usually occurred before change in the mediators. Bibliotherapy did not significantly affect depressive symptoms or the ostensive mediators (negative cognitions and pleasant activities), and change in depression usually occurred before change in the mediators. Conclusion: Results imply that this procedure provides a sensitive test of mediation but yielded limited support for the hypothesized mediators, suggesting that nonspecific factors may play an important mediational role. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
78.
Testing Web applications by modeling with FSMs 总被引:6,自引:0,他引:6
Anneliese A. Andrews Jeff Offutt Roger T. Alexander 《Software and Systems Modeling》2005,4(3):326-345
Researchers and practitioners are still trying to find effective ways to model and test Web applications. This paper proposes a system-level testing technique that combines test generation based on finite state machines with constraints. We use a hierarchical approach to model potentially large Web applications. The approach builds hierarchies of Finite State Machines (FSMs) that model subsystems of the Web applications, and then generates test requirements as subsequences of states in the FSMs. These subsequences are then combined and refined to form complete executable tests. The constraints are used to select a reduced set of inputs with the goal of reducing the state space explosion otherwise inherent in using FSMs. The paper illustrates the technique with a running example of a Web-based course student information system and introduces a prototype implementation to support the technique. 相似文献
79.
Hong-Kwang Jeff Kuo Yuqing Gao 《IEEE transactions on audio, speech, and language processing》2006,14(3):873-881
Traditional statistical models for speech recognition have mostly been based on a Bayesian framework using generative models such as hidden Markov models (HMMs). This paper focuses on a new framework for speech recognition using maximum entropy direct modeling, where the probability of a state or word sequence given an observation sequence is computed directly from the model. In contrast to HMMs, features can be asynchronous and overlapping. This model therefore allows for the potential combination of many different types of features, which need not be statistically independent of each other. In this paper, a specific kind of direct model, the maximum entropy Markov model (MEMM), is studied. Even with conventional acoustic features, the approach already shows promising results for phone level decoding. The MEMM significantly outperforms traditional HMMs in word error rate when used as stand-alone acoustic models. Preliminary results combining the MEMM scores with HMM and language model scores show modest improvements over the best HMM speech recognizer. 相似文献
80.
Although OWL is rather expressive, it has a very serious limitation on datatypes; i.e., it does not support customised datatypes. It has been pointed out that many potential users will not adopt OWL unless this limitation is overcome, and the W3C Semantic Web Best Practices and Development Working Group has set up a task force to address this issue. This paper makes the following two contributions: (i) it provides a brief summary of OWL-related datatype formalisms, and (ii) it provides a decidable extension of OWL DL, called OWL-Eu, that supports customised datatypes. A detailed proof of the decidability of OWL-Eu is presented. 相似文献