全文获取类型
收费全文 | 13935篇 |
免费 | 71篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 184篇 |
综合类 | 5篇 |
化学工业 | 1168篇 |
金属工艺 | 354篇 |
机械仪表 | 146篇 |
建筑科学 | 233篇 |
矿业工程 | 27篇 |
能源动力 | 129篇 |
轻工业 | 357篇 |
水利工程 | 66篇 |
石油天然气 | 15篇 |
无线电 | 557篇 |
一般工业技术 | 674篇 |
冶金工业 | 1628篇 |
原子能技术 | 130篇 |
自动化技术 | 8336篇 |
出版年
2019年 | 30篇 |
2018年 | 38篇 |
2016年 | 38篇 |
2015年 | 32篇 |
2014年 | 281篇 |
2013年 | 455篇 |
2012年 | 883篇 |
2011年 | 2423篇 |
2010年 | 1190篇 |
2009年 | 1046篇 |
2008年 | 802篇 |
2007年 | 725篇 |
2006年 | 570篇 |
2005年 | 720篇 |
2004年 | 639篇 |
2003年 | 697篇 |
2002年 | 404篇 |
2001年 | 75篇 |
2000年 | 79篇 |
1999年 | 72篇 |
1998年 | 95篇 |
1997年 | 89篇 |
1996年 | 82篇 |
1995年 | 93篇 |
1994年 | 66篇 |
1993年 | 105篇 |
1992年 | 93篇 |
1991年 | 50篇 |
1990年 | 97篇 |
1989年 | 83篇 |
1988年 | 84篇 |
1987年 | 91篇 |
1986年 | 77篇 |
1985年 | 112篇 |
1984年 | 115篇 |
1983年 | 101篇 |
1982年 | 99篇 |
1981年 | 88篇 |
1980年 | 59篇 |
1979年 | 106篇 |
1978年 | 74篇 |
1977年 | 101篇 |
1976年 | 81篇 |
1975年 | 103篇 |
1974年 | 66篇 |
1973年 | 81篇 |
1972年 | 48篇 |
1971年 | 38篇 |
1970年 | 35篇 |
1969年 | 33篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
Viara PopovaAuthor Vitae 《Data & Knowledge Engineering》2011,70(4):335-364
Every organisation exists or is created for the achievement of one or more goals. To ensure continued success, the organisation should monitor its performance with respect to the formulated goals. In practice the performance of an organisation is often evaluated by estimating its performance indicators. In most existing approaches for organisation modelling the relation between performance indicators and goals remains implicit. This paper proposes a formal framework for modelling goals based on performance indicators and defines mechanisms for establishing goal satisfaction, which enable evaluation of organisational performance. Methodological and analysis issues related to goals are also discussed in the paper. The described framework is a part of a general framework for organisation modelling and analysis. 相似文献
82.
J.A. DianesAuthor Vitae M. DíazAuthor VitaeB. RubioAuthor Vitae 《Computer Standards & Interfaces》2012,34(2):238-262
A pervasive application domain today is one in which independently developed real-time components participate in a dynamic and decentralized way from distributed environments. Several challenges arise from this domain, related with participant heterogeneity, transient behavior, scalability or quality of service. The use of standards is important here, where a multidiscipline approach is required. We propose ServiceDDS, a framework that combines different standard technologies to solve the problems related with the integration of components into the described environment. ServiceDDS is based on DDS to support dynamic distributed interactions, XMPP to provide Web access, and RTSJ for real-time performance. 相似文献
83.
The parallelism attained by the use of Field Programmable Gate Arrays (FPGAs) has shown remarkable potential for accelerating control systems applications. This comes at a time when well established methods based on inherited serial Central Processor Units (CPUs) cannot guarantee solutions for the increasing execution speed demands. However, the transition from serial to parallel architectures represents a tremendous challenge due to overwhelming numbers of unexplored options and conflicting factors. The work presented achieves a parallelisation characterisation for generic MIMO systems using stand-alone FPGA implementations. The main contribution is that a very fine subset of possible serial/parallel implementations is obtained. This is used to achieve a flexible trade-off between cost and performance. Automatic optimisation of latency, occupied FPGA area and execution speed is attained and justified in respect to most of the feasible scenarios. 相似文献
84.
Nguyen Quoc Dinh Author VitaeDong-Sung KimAuthor Vitae 《Computer Standards & Interfaces》2012,34(1):117-123
The International Society of Automation recently released ISA100.11a as an open standard for reliable wireless networks for industrial automation. ISA100.11a uses the TDMA scheme in the medium access layer to provide deterministic services. However, ISA100.11a adopts the CSMA-CA mechanism with priorities for retransmission from failure on dedicated links, sporadic data, and network configuration.This paper evaluates ISA100.11a CSMA-CA by simulation, considering the effects of backoff procedures and priority settings to probability of collision and successful use of slots. It's demonstrated that a high number of priority classes enable better network utilization resulting in less number of packets exceeding their lifetime. 相似文献
85.
This paper presents a novel global localization approach for mobile robots by exploring line-segment features in any structured environment. The main contribution of this paper is an effective data association approach, the Line-segment Relation Matching (LRM) technique, which is based on a generation and exploration of an Interpretation Tree (IT). A new representation of geometric patterns of line-segments is proposed for the first time, which is called as Relation Table. It contains relative geometric positions of every line-segment respect to the others (or itself) in a coordinate-frame independent sense. Based on that, a Relation-Table-constraint is applied to minimize the searching space of IT therefore greatly reducing the processing time of LRM. The Least Square algorithm is further applied to estimate the robot pose using matched line-segment pairs. Then a global localization system can be realized based on our LRM technique integrated with a hypothesis tracking framework which is able to handle pose ambiguity. Sufficient simulations were specially designed and carried out indicating both pluses and minuses of our system compared with former methods. We also presented the practical experiments illustrating that our approach has a high robustness against uncertainties from sensor occlusions and extraneous observation in a highly dynamic environment. Additionally our system was demonstrated to easily deal with initialization and have the ability of quick recovery from a localization failure. 相似文献
86.
K. VivekanandanAuthor Vitae D. RamyachitraAuthor Vitae 《Future Generation Computer Systems》2012,28(4):647-656
Scientific applications such as protein sequence analysis require a coordination of resources. This is due to hundreds and hundreds of protein sequences being deposited into data banks by the research community which results in an extensive database search when one wants to find a similar protein sequence. This search becomes easier and the time taken is reduced when it is conducted in a grid environment implemented using the Globus tool kit. This paper proposes the use of Bacteria Foraging Optimization (BFO) for finding similar protein sequences in the existing databases. Usage of BFO further reduces the time taken by a resource to execute the user’s requests. Also, the resources utilized in the proposed method are better balanced compared to the existing scheduling algorithms. Also, it is found that the number of tasks executed is more compared to the existing algorithms even though there is a fall in the execution of tasks as the number of resources increases which might be due to network failure etc. The proposed BFO has been compared with the existing First Come First Serve (FCFS) and Minimum Execution Time (MET) scheduling algorithms and it has been found that the proposed BFO performs well compared to the existing algorithms in terms of makespan, resource utilization and minimization in the case of non-execution of client requests. 相似文献
87.
Paul F. Mlakar Donald O. Dusenberry James R. Harris Gerald Haynes Long T. Phan Mete A. Sozen 《Canadian Metallurgical Quarterly》2005,19(3):197-205
On September 11, 2001, an airliner was intentionally crashed into the Pentagon. It struck at the first elevated slab on the west wall, and slid approximately 310?ft (94.5?m) diagonally into the building. The force of the collision demolished numerous columns and the fa?ade of the exterior wall, and induced damage to first-floor columns and the first elevated slab over an area approximately 90?ft (27.4?m) wide and 310?ft (94.5?m) long. None of the building collapsed immediately. The portion that remained standing, even after an intense fire, sustained substantial damage at the first-floor level. 相似文献
88.
Persky Irena; Spring Bonnie; Wal Jillon S. Vander; Pagoto Sherry; Hedeker Donald 《Canadian Metallurgical Quarterly》2005,24(2):153
The authors tested whether adherence to simultaneous health behavior changes was unitary or domain specific among 76 women who modified smoking, eating, and physical activity to accomplish smoking cessation plus weight control. Random-effects regression analyses showed that adherence to both smoking and diet plans declined linearly and covaried positively; their association tended to grow stronger over time. In contrast, physical activity plan adherence did not change over time and was unrelated to other domains. At the end of treatment, 65%, 30.5%, and 25% adhered well or excellently to smoking, diet, and activity treatments, respectively. Findings support both unitary and domain-specific aspects of adherence and suggest that among smokers, smoking and eating behaviors may have similarities unshared by physical activity. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
89.
90.
SATCHMORE was introduced as a mechanism to integrate relevancy testing with the model-generation theorem prover SATCHMO. This
made it possible to avoid invoking some clauses that appear in no refutation, which was a major drawback of the SATCHMO approach.
SATCHMORE relevancy, however, is driven by the entire set of negative clauses and no distinction is accorded to the query
negation. Under unfavorable circumstances, such as in the presence of large amounts of negative data, this can reduce the
efficiency of SATCHMORE. In this paper we introduce a further refinement of SATCHMO called SATCHMOREBID: SATCHMORE with BIDirectional
relevancy. SATCHMOREBID uses only the negation of the query for relevancy determination at the start. Other negative clauses
are introduced on demand and only if a refutation is not possible using the current set of negative clauses. The search for
the relevant negative clauses is performed in a forward chaining mode as opposed to relevancy propagation in SATCHMORE which
is based on backward chaining. SATCHMOREBID is shown to be refutationally sound and complete. Experiments on a prototype SATCHMOREBID
implementation point to its potential to enhance the efficiency of the query answering process in disjunctive databases.
Donald Loveland, Ph.D.: He is Emeritus Professor of Computer Science at Duke University. He received his Ph.D. in mathematics from New York University
and taught at NYU and CMU prior to joining Duke in 1973. His research in automated deduction includes defining the model elimination
proof procedure and the notion of linear resolution. He is author of one book and editor/co-editor of two other books on automated
theorem proving. He has done research in the areas of algorithms, complexity, expert systems and logic programming. He is
an AAAI Fellow, ACM Fellow and winner of the Herbrand Award in Automated Reasoning.
Adnan H. Yahya, Ph.D.: He is an associate professor at the Department of Electrical Engineering, Birzeit University, Palestine. He received his
Diploma and PhD degrees from St. Petersburg Electrotechnical University and Nothwestern University in 1979 and 1984 respectively.
His research interests are in Artificial Intelligence in general and in the areas of Deductive Databases, Logic Programming
and Nonmonotonic Reasoning in particular. He had several visiting appointments at universities and research labs in the US,
Germany, France and the UK. Adnan Yahya is a member of the ACM, IEEE and IEEE Computer Society. 相似文献