全文获取类型
收费全文 | 5537篇 |
免费 | 418篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 66篇 |
综合类 | 7篇 |
化学工业 | 1598篇 |
金属工艺 | 65篇 |
机械仪表 | 111篇 |
建筑科学 | 217篇 |
矿业工程 | 10篇 |
能源动力 | 219篇 |
轻工业 | 716篇 |
水利工程 | 45篇 |
石油天然气 | 7篇 |
无线电 | 390篇 |
一般工业技术 | 1050篇 |
冶金工业 | 462篇 |
原子能技术 | 31篇 |
自动化技术 | 966篇 |
出版年
2024年 | 12篇 |
2023年 | 81篇 |
2022年 | 241篇 |
2021年 | 408篇 |
2020年 | 188篇 |
2019年 | 190篇 |
2018年 | 222篇 |
2017年 | 196篇 |
2016年 | 269篇 |
2015年 | 198篇 |
2014年 | 294篇 |
2013年 | 370篇 |
2012年 | 363篇 |
2011年 | 471篇 |
2010年 | 308篇 |
2009年 | 261篇 |
2008年 | 312篇 |
2007年 | 246篇 |
2006年 | 171篇 |
2005年 | 155篇 |
2004年 | 138篇 |
2003年 | 127篇 |
2002年 | 90篇 |
2001年 | 64篇 |
2000年 | 54篇 |
1999年 | 55篇 |
1998年 | 65篇 |
1997年 | 50篇 |
1996年 | 50篇 |
1995年 | 31篇 |
1994年 | 35篇 |
1993年 | 35篇 |
1992年 | 28篇 |
1991年 | 22篇 |
1990年 | 16篇 |
1989年 | 16篇 |
1988年 | 13篇 |
1987年 | 18篇 |
1986年 | 10篇 |
1985年 | 13篇 |
1984年 | 15篇 |
1983年 | 13篇 |
1982年 | 14篇 |
1981年 | 6篇 |
1980年 | 5篇 |
1979年 | 10篇 |
1977年 | 2篇 |
1967年 | 2篇 |
1954年 | 1篇 |
1948年 | 1篇 |
排序方式: 共有5960条查询结果,搜索用时 359 毫秒
31.
Andrea Omicini Alessandro Ricci Mirko Viroli 《Electronic Notes in Theoretical Computer Science》2006,150(3):21-36
Human intelligence has evolved along with the use of more and more sophisticated tools, allowing Homo Faber (from Homo Habilis to Homo Sapiens Sapiens) to cope with environment changes, as well as to adapt the environment to his needs. Analogously, in this seminal paper we introduce the notion of Agens Faber, conveying the idea that agent intelligence should not be considered as separated by the agent ability to perceive and affect the environment—and so, that agent intelligence is strictly related to the artefacts that enable, mediate and govern any agent (intelligent) activity.
Along this line, we first discuss the notion of artefact for MAS in general, then we try to devise out the admissible / required / desirable features of an artefact for MAS. We elaborate on the many sorts of possible relations between agents and artefacts, focusing in particular on the issue of the rational exploitation of artefacts, and also rough out a possible taxonomy of artefacts for MAS. 相似文献
32.
Multiresidue method for pesticides in drinking water using a graphitized carbon black cartridge extraction and liquid chromatographic analysis 总被引:2,自引:0,他引:2
A general liquid-solid extraction procedure for the isolation of pesticides from groundwater and drinking water for high-performance liquid chromatography (HPLC) is presented. This simple and rapid procedure involved passing a 2-L sample through a 250-mg graphitized carbon black (Carbopack B) cartridge at a flow rate of 150-160 mL/min. By taking advantage of the presence of positively charged active centers on the Carbopack B surface, a stepwise elution system allowed the complete separation of base-neutral pesticides from acidic ones. After partial solvent removal, the components in the two fractions were separated and quantified by gradient elution, reversed-phase HPLC with ultraviolet (UV) detection. The performance of the Carbopack cartridge was compared with that of a 500-mg C-18 bonded silica cartridge. With the Carbopack cartridge, the grand mean measurement accuracy of the 35 pesticides considered was 95%. With the C-18 cartridge, the grand mean measurement accuracy of the analytes was 76%. Compared to the C-18 cartridge, additional advantages of using a Carbopack cartridge are that the extraction procedure is about 7 times shorter, no pH adjustment of the environmental sample is necessary for trapping acidic compounds, and one cartridge instead of two suffices to extract base-neutral and acidic pesticides, making the Carbopack cartridge more adaptable than the C-18 one for field use. The detection limits by this method of all the pesticides considered were between 0.003 and 0.07 micrograms/L. 相似文献
33.
Leonardo Badia Andrea Baiocchi Alfredo Todini Simone Merlin Silvano Pupolin Andrea Zanella Michele Zorzi 《Wireless Communications, IEEE》2007,14(1):36-43
Multicellular networks based on the IEEE 802.16 standard appear to be very promising candidates to provide end users with broadband wireless access. However, they also pose interesting challenges in terms of radio resource management, where several design choices are not specified in the standard, intentionally left open to implementors. For this reason, we focus in this article on scheduling and resource allocation, and investigate how they could operate in a cross-layer fashion. In particular, we describe the principles of joint scheduling and resource allocation for IEEE 802.16 operating in AMC mode, and discuss the critical role played by physical layer considerations, especially intercell interference estimation and channel state awareness, in the obtained performance. This leads to identifying key open issues and possible general solutions 相似文献
34.
M Andrea 《Canadian Metallurgical Quarterly》1993,103(10):1177-1178
35.
The usual laser rate equations have been applied to fit energy and shape of pulsed emissions of RF CO2 single mode lasers starting from the discharge and cavity parameters. The model well reproduce the laser behaviour, if to fit the turn-off normally observed in these lasers we introduce a phase laser gain correction related to the frequency chirp. 相似文献
36.
Laurent Busé Carlos D’Andrea 《Applicable Algebra in Engineering, Communication and Computing》2006,17(6):393-407
We present a matrix-based approach for deciding if the parameterization of an algebraic space surface is invertible or not, and for computing the inverse of the parametrization if it exists. 相似文献
37.
Environment as a first class abstraction in multiagent systems 总被引:2,自引:1,他引:1
The current practice in multiagent systems typically associates the environment with resources that are external to agents and their communication infrastructure. Advanced uses of the environment include infrastructures for indirect coordination, such as digital pheromones, or support for governed interaction in electronic institutions. Yet, in general, the notion of environment is not well defined. Functionalities of the environment are often dealt with implicitly or in an ad hoc manner. This is not only poor engineering practice, it also hinders engineers to exploit the full potential of the environment in multiagent systems. In this paper, we put forward the environment as an explicit part of multiagent systems.We give a definition stating that the environment in a multiagent system is a first-class abstraction with dual roles: (1) the environment provides the surrounding conditions for agents to exist, which implies that the environment is an essential part of every multiagent system, and (2) the environment provides an exploitable design abstraction for building multiagent system applications. We discuss the responsibilities of such an environment in multiagent systems and we present a reference model for the environment that can serve as a basis for environment engineering. To illustrate the power of the environment as a design abstraction, we show how the environment is successfully exploited in a real world application. Considering the environment as a first-class abstraction in multiagent systems opens up new horizons for research and development in multiagent systems. 相似文献
38.
Chronis Andrea M.; Lahey Benjamin B.; Pelham William E. Jr.; Williams Stephanie Hall; Baumann Barbara L.; Kipp Heidi; Jones Heather A.; Rathouz Paul J. 《Canadian Metallurgical Quarterly》2007,43(1):70
Children with attention-deficit/hyperactivity disorder (ADHD) are at risk for adverse outcomes such as substance abuse and criminality, particularly if they develop conduct problems. Little is known about early predictors of the developmental course of conduct problems among children with ADHD, however. Parental psychopathology and parenting were assessed in 108 children who first met Diagnostic and Statistical Manual of Mental Disorders (4th ed.) criteria for ADHD at 4-7 years old. When demographic variables and baseline ADHD and conduct problems were controlled, maternal depression predicted conduct problems 2-8 years following the initial assessment, whereas positive parenting during the structured parent- child interaction task predicted fewer future conduct problems. These findings suggest that maternal depression is a risk factor, whereas early positive parenting is a protective factor, for the developmental course of conduct problems among children with ADHD. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
39.
Andrea Bacciotti Author Vitae Author Vitae 《Automatica》2006,42(3):453-458
Differential equations with discontinuous right-hand side and solutions intended in Carathéodory sense are considered. For these equations, sufficient conditions which guarantee both Lyapunov stability and asymptotic stability in terms of nonsmooth Lyapunov functions are given. An invariance principle is also proven. 相似文献
40.
In this paper an extension of the method of the Fourier series expansion to the fire analysis of composite beams is presented. In particular the extension concerns the introduction of the temperature dependent interaction of all the components: steel beams, concrete slab and steel connectors. These last are considered of finite stiffness, and a proper account is given to the combined effect of thermal degradation of the properties, and stress amplification caused by the differential thermal expansion across the interface.The proposed method compares very well with some experimental fire tests of simply supported and framed composite beams. Due to its relative simplicity and speed, it can be used for design purposes in evaluating the critical temperature in terms of critical deflection. Finally we recall that the method is capable of dealing with every type of fastening distribution, such as discontinuous or variable length. 相似文献