全文获取类型
收费全文 | 2350篇 |
免费 | 111篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 32篇 |
综合类 | 8篇 |
化学工业 | 668篇 |
金属工艺 | 41篇 |
机械仪表 | 47篇 |
建筑科学 | 120篇 |
矿业工程 | 8篇 |
能源动力 | 70篇 |
轻工业 | 204篇 |
水利工程 | 21篇 |
石油天然气 | 7篇 |
无线电 | 202篇 |
一般工业技术 | 397篇 |
冶金工业 | 244篇 |
原子能技术 | 22篇 |
自动化技术 | 375篇 |
出版年
2023年 | 27篇 |
2022年 | 35篇 |
2021年 | 45篇 |
2020年 | 37篇 |
2019年 | 46篇 |
2018年 | 55篇 |
2017年 | 54篇 |
2016年 | 73篇 |
2015年 | 69篇 |
2014年 | 87篇 |
2013年 | 127篇 |
2012年 | 104篇 |
2011年 | 150篇 |
2010年 | 110篇 |
2009年 | 98篇 |
2008年 | 119篇 |
2007年 | 106篇 |
2006年 | 82篇 |
2005年 | 85篇 |
2004年 | 59篇 |
2003年 | 70篇 |
2002年 | 51篇 |
2001年 | 38篇 |
2000年 | 36篇 |
1999年 | 40篇 |
1998年 | 81篇 |
1997年 | 47篇 |
1996年 | 44篇 |
1995年 | 40篇 |
1994年 | 36篇 |
1993年 | 39篇 |
1992年 | 25篇 |
1991年 | 23篇 |
1990年 | 27篇 |
1989年 | 22篇 |
1988年 | 11篇 |
1987年 | 15篇 |
1986年 | 21篇 |
1985年 | 23篇 |
1984年 | 19篇 |
1983年 | 12篇 |
1982年 | 10篇 |
1981年 | 13篇 |
1980年 | 13篇 |
1979年 | 12篇 |
1978年 | 17篇 |
1977年 | 11篇 |
1976年 | 19篇 |
1975年 | 11篇 |
1974年 | 12篇 |
排序方式: 共有2466条查询结果,搜索用时 15 毫秒
51.
Hao Fang Lihua DouJie Chen Roland LenainBenoit Thuilot Philippe Martinet 《Control Engineering Practice》2011,19(5):468-478
Path following control problem of autonomous vehicles is investigated, concerning both unmeasurable sliding effects and lateral disturbances which lead to some difficulties in designing autonomous control under complex environment. To deal with the sliding effects, sideslip angles are modeled and reconstructed by estimating the tire cornering stiffness, which plays important role in analyzing the sliding effects. To this end, a Luenberger-type observer is designed, which is able to identify the tire cornering stiffness adaptively even in presence of time-varying lateral disturbances. Furthermore, to guarantee high-precision guidance, a sliding mode controller is designed based on chained system theory, and this controller is shown to be robust to both the lateral disturbances and the inaccuracy of the sliding reconstruction. Simulations illustrate that the proposed methods can reconstruct the sliding angles and provide high-accuracy anti-sliding control even in presence of the time-varying lateral disturbances. 相似文献
52.
In an array of problem solving methods, one can traditionally distinguish two kinds of problems: one is a problem that has solutions in a search space and the other is a problem that does not have solutions in a given space. The later problem so called solutionless problem or inventive problem requires an inventive approach to reformulate the problem and dialectical thinking brings benefits in the process. The framework used to formulate problems in a dialectical approach is contradiction. Identification of contradictions plays an important role in distinguishing solutionless problems: a contradiction exists when no solution can be found, and a solution exists when no contradiction can be found. In this article, the inadequacy of existing frameworks in satisfying this requirement is demonstrated and a framework that fits this requirement is proposed. 相似文献
53.
Haris Balta Janusz Bedkowski Shashank Govindaraj Karol Majek Pawel Musialik Daniel Serrano Kostas Alexis Roland Siegwart Geert De Cubber 《野外机器人技术杂志》2017,34(3):539-582
Search‐and‐rescue operations have recently been confronted with the introduction of robotic tools that assist the human search‐and‐rescue workers in their dangerous but life‐saving job of searching for human survivors after major catastrophes. However, the world of search and rescue is highly reliant on strict procedures for the transfer of messages, alarms, data, and command and control over the deployed assets. The introduction of robotic tools into this world causes an important structural change in this procedural toolchain. Moreover, the introduction of search‐and‐rescue robots acting as data gatherers could potentially lead to an information overload toward the human search‐and‐rescue workers, if the data acquired by these robotic tools are not managed in an intelligent way. With that in mind, we present in this paper an integrated data combination and data management architecture that is able to accommodate real‐time data gathered by a fleet of robotic vehicles on a crisis site, and we present and publish these data in a way that is easy to understand by end‐users. In the scope of this paper, a fleet of unmanned ground and aerial search‐and‐rescue vehicles is considered, developed within the scope of the European ICARUS project. As a first step toward the integrated data‐management methodology, the different robotic systems require an interoperable framework in order to pass data from one to another and toward the unified command and control station. As a second step, a data fusion methodology will be presented, combining the data acquired by the different heterogenic robotic systems. The computation needed for this process is done in a novel mobile data center and then (as a third step) published in a software as a service (SaaS) model. The SaaS model helps in providing access to robotic data over ubiquitous Ethernet connections. As a final step, we show how the presented data‐management architecture allows for reusing recorded exercises with real robots and rescue teams for training purposes and teaching search‐and‐rescue personnel how to handle the different robotic tools. The system was validated in two experiments. First, in the controlled environment of a military testing base, a fleet of unmanned ground and aerial vehicles was deployed in an earthquake‐response scenario. The data gathered by the different interoperable robotic systems were combined by a novel mobile data center and presented to the end‐user public. Second, an unmanned aerial system was deployed on an actual mission with an international relief team to help with the relief operations after major flooding in Bosnia in the spring of 2014. Due to the nature of the event (floods), no ground vehicles were deployed here, but all data acquired by the aerial system (mainly three‐dimensional maps) were stored in the ICARUS data center, where they were securely published for authorized personnel all over the world. This mission (which is, to our knowledge, the first recorded deployment of an unmanned aerial system by an official governmental international search‐and‐rescue team in another country) proved also the concept of the procedural integration of the ICARUS data management system into the existing procedural toolchain of the search and rescue workers, and this in an international context (deployment from Belgium to Bosnia). The feedback received from the search‐and‐rescue personnel on both validation exercises was highly positive, proving that the ICARUS data management system can efficiently increase the situational awareness of the search‐and‐rescue personnel. 相似文献
54.
Christoph Bosshard Roland Bouffanais Michel Deville Ralf Gruber Jonas Latt 《Computers & Fluids》2011,44(1):1-8
In this paper, a comprehensive performance review of an MPI-based high-order three-dimensional spectral element method C++ toolbox is presented. The focus is put on the performance evaluation of several aspects with a particular emphasis on the parallel efficiency. The performance evaluation is analyzed with the help of a time prediction model based on a parameterization of the application and the hardware resources. Two tailor-made benchmark cases in computational fluid dynamics (CFD) are introduced and used to carry out this review, stressing the particular interest for clusters with up to thousands of cores. Some problems in the parallel implementation have been detected and corrected. The theoretical complexities with respect to the number of elements, to the polynomial degree, and to communication needs are correctly reproduced. It is concluded that this type of code has a nearly perfect speedup on machines with thousands of cores, and is ready to make the step to next-generation petaFLOP machines. 相似文献
55.
Roland H. C. Yap 《Constraints》2001,6(2-3):157-172
Approximate matching techniques based on string alignment are important tools for investigating similarities between strings, such as those representing DNA and protein sequences. We propose a constraint based approach for parametric sequence alignment which allows for more general string alignment queries where the alignment cost can itself be parameterized as a query with some initial constraints. Thus, the costs need not be fixed in a parametric alignment query unlike the case in normal alignment. The basic dynamic programming string edit distance algorithm is generalized to a naive algorithm which uses inequalities to represent the alignment score. The naive algorithm is rather costly and the remainder of the paper develops an improvement which prunes alternatives where it can and approximates the alternatives otherwise. This reduces the number of inequalities significantly and strengthens the constraint representation with equalities. We present some preliminary results using parametric alignment on some general alignment queries. 相似文献
56.
An important area of Human Reliability Assessment in interactive systems is the ability to understand the causes of human
error and to model their occurrence. This paper investigates a new approach to analysis of task failures based on patterns
of operator behaviour, in contrast with more traditional event-based approaches. It considers, as a case study, a formal model
of an Air Traffic Control system operator’s task which incorporates a simple model of the high-level cognitive processes involved.
The cognitive model is formalised in the CSP process algebra. Various patterns of behaviour that could lead to task failure
are described using temporal logic. Then a model-checking technique is used to verify whether the set of selected behavioural
patterns is sound and complete with respect to the definition of task failure. The decomposition is shown to be incomplete
and a new behavioural pattern is identified, which appears to have been overlooked in the informal analysis of the problem.
This illustrates how formal analysis of operator models can yield fresh insights into how failures may arise in interactive
systems.
相似文献
Antonio Cerone (Corresponding author)Email: |
Simon ConnellyEmail: |
Peter LindsayEmail: |
57.
A positive and innovative organizational climate is of great importance in order to manage and adapt to change. Such a climate seldom evolves in organizations closely governed by rules and regulations. Because of ongoing organizational and technical changes within the Swedish Air Navigation Services Provider, a study concerning the organizational climate for changes and innovations was conducted to investigate the organization's capacity to cope with changes. Study locations were the two Swedish main air traffic control centers and parts of the civil aviation administration headquarters. In the study 390 subjects took part and the CCQ questionnaire was used to measure the organizational climate. The results show that the organizational climate is quite positive despite the rule-governed work. The results also show that administrative personnel assess the organizational climate as more positive than operative personnel. Comparisons between management positions did not result in any differences. 相似文献
58.
Pradeep K. Nalla Roland J. Weiss Prakash Peranandam Jürgen Ruf Thomas Kropf Wolfgang Rosenstiel 《Electronic Notes in Theoretical Computer Science》2006,135(2):47
In this paper we describe an algorithm for distributed, BDD-based bounded property checking and its implementation in the verification tool SymC. The distributed algorithm verifies larger models and returns results faster than the sequential version.The core algorithm distributes partitions of the state set to computation nodes after reaching a threshold size. The nodes proceed with image computation on the nodes asynchronously. The main scalability problem of this scheme is the overlap of state set partitions. We present static and dynamic overlap reduction techniques. 相似文献
59.
Roland Gerber 《电信纪事》1983,38(9-10):367-379
60.
Bernd Altmayer Klaus W. Eichhorn und Roland Plapp 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1982,175(3):172-174
Zusammenfassung Traubenmoste aus dem Weinanbaugebiet der Rheinpfalz wurden auf ihren Patulingehalt untersucht. Nach Extraktion und Reinigung wurde Patulin mit Hilfe der Hochleistungsflilssig- und Dünnschichtchromatographie bestimmt. Zur Extraktion des Patulins erwies sich die Verwendung von Extrelutsdulen als vorteilhaft. In 62% der untersuchten Proben (55) war kein Patulin nachweisbar, 22% enthielten weniger als 50 g, 16% mehr als 50 g Patulin pro Liter. Durch praxisübliche Mostschwefelung (100 mg Kaliumpyrosulîit/1) und Vergärung mit Hefen der GattungSaccharomyces konnte vorhandenes Patulin entfernt werden.
Analysis of patulin in grape juices and wine
Summary Grape juices from the wine-growing region of the palatinate Rheinpfalz were analysed for patulin. After extraction and purification patulin was determined by high performance liquid chromatography and thin layer chromatography. The use of Extrelut-columns for the extraction of patulin was found advantageous. 62% of the analysed samples (55) were free of patulin, 22% contained less than 50 g/l, 16% more than 50 g/l. By addition of sulfur dioxide to the must and fermentation withSaccharomyces sp. patulin could be removed from the samples.相似文献