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41.
J. Gregor 《International Journal of Circuit Theory and Applications》1984,12(2):111-122
The interpolation problem for n-dimensional positive real functions is formulated in two different settings: with interpolation knots either contained on the distinguished boundary of the Cartesian product of open right half planes or in this n-dimensional ‘open right half plane’. A complete solution of the first problem is given. Necessary conditions of existence of a solution of the second problem are proved and the well known Nevanlinna-Pick algorithm is generalized so that construction of interpolating n-dimensional positive real functions becomes possible at least in case when the interpolation knots are real vectors. Examples illustrate the suggested methods, show the complexity and significance of the problem and methods under discussion. Interpolation in special classes of functions has for some time been an important problem in mathematics. General schemes of solution in linear functional spaces with orthogonality are well known. For classes of functions which do not satisfy the axioms of a linear space special methods have been studied in detail, because they are closely connected to other important parts of mathematics such as approximation theory, numerical analysis and the theory of moments. Considerable efforts have been put into interpolation in the complex domain with functions analytic in the unit disc and with positive real functions. the significance of interpolation procedures in the class of one-variable positive real functions in network theory, e.g. in broadband matching and approximation problems has been recognized in References 1-3. an excellent survey paper has recently been devoted to these problems;4 in this paper some new ideas for the use of interpolation in system theory were outlined. the growing interest in multivariable network theory calls for generalizations of interpolation procedures to multivariable cases. Many of the one-variable applications can easily be extended to the multivariable case and it is hoped that in passive network theory and in problems of n-dimensional digital systems the solution of the interpolation problem will contribute to the difficult synthesis problems in the multivariable theory. In this paper conditions for the existence of multivariable positive real interpolating functions will be investigated and some procedures for the construction of such functions will be described. 相似文献
42.
Gregor Gary L.; Smith Richard F.; Simons Lynn S.; Parker Howard B. 《Canadian Metallurgical Quarterly》1972,79(3):488
Hypothesized that, when the degree of crowding is manipulated by varying group size in cages of equal size, it is probable that crowded animals will engage in more contact than uncrowded animals. Home-cage observation of 24 male and 24 female deer mice indicates that crowded Ss do, in fact, engage in more contact behavior. Both home-cage observation and testing in pairs for pain-elicited aggression reveal that (a) crowded Ss display more agonistic behavior than uncrowded Ss, and (b) agonistic behavior increases with prolonged crowding. Support is obtained for the theory that the effect of crowding derives from contact with conspecifics. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
43.
Two phenolic acids were identified in the collembolan Ceratophysella denticulata: 3-hydroxy-4,5 dimethoxy benzoic acid and 4-hydroxy-3,5-dimethoxybenzoic acid (syringic acid). These are localized on or in the integument of the springtail, in field-collected animals, in a ratio of 47:100 (v/v). Springtails kept under different temperature regimes showed differences in production and ratio of the benzoic acid derivatives. At 20 degrees C, C. denticulata produced only syringic acid, whereas at 10 degrees C both isomers in a ratio of 100:61 (v/v) were detected. Bioassays with C. denticulata as well as with the specialized collembolan predator Stenus comma (Staphylinidae) were carried out. Staphylinid beetles topically treated with the acids try to clean their mouthparts by rubbing them on the ground significantly more often than do control beetles. Both compounds individually and as a natural mixture have deterrent effects towards the predator S. comma. 相似文献
44.
Development of a computer-based interviewing tool to enhance the requirements gathering process 总被引:1,自引:1,他引:0
Katrina?HandsEmail author D.?Ramanee?Peiris Peter?Gregor 《Requirements Engineering》2004,9(3):204-216
Software design is an area where it is most important to elicit an accurate and complete set of requirements. Determining the users requirements and their qualitative satisfaction with a developing product are two major problems which arise, often due to the different backgrounds and perspectives of the different stakeholders, including the software engineer, the domain expert and the end-user. Involving users throughout the design and development process is an essential part of any project. Computer-based interviewing has been found to be a valuable tool in eliciting information, which can also enhance interpersonal communication afterwards. This paper discusses the development of a computer interviewing tool to facilitate the gathering of user requirements and conducting user evaluations. 相似文献
45.
Tea Tušar Peter Korošec Gregor Papa Bogdan Filipič Jurij Šilc 《Applied Intelligence》2007,27(2):101-111
The efficiency of universal electric motors that are widely used in home appliances can be improved by optimizing the geometry
of the rotor and the stator. Expert designers traditionally approach this task by iteratively evaluating candidate designs
and improving them according to their experience. However, the existence of reliable numerical simulators and powerful stochastic
optimization techniques make it possible to automate the design procedure. We present a comparative study of six stochastic
optimization algorithms in designing optimal rotor and stator geometries of a universal electric motor where the primary objective
is to minimize the motor power losses. We compare three methods from the domain of evolutionary computation, generational
evolutionary algorithm, steady-state evolutionary algorithm and differential evolution, two particle-based methods, particle-swarm
optimization and electromagnetism-like algorithm, and a recently proposed multilevel ant stigmergy algorithm. By comparing
their performance, the most efficient method for solving the problem is identified and an explanation of its success is offered. 相似文献
46.
Simeon Keates Ray Adams Cathy Bodine Sara Czaja Wayne Gordon Peter Gregor Emily Hacker Vicki Hanson John Kemp Mark Laff Clayton Lewis Michael Pieper John Richards David Rose Anthony Savidis Greg Schultz Paul Snayd Shari Trewin Philip Varker 《Universal Access in the Information Society》2007,5(4):329-339
In October 2005, the IBM Human Ability and Accessibility Center and T.J. Watson Research Center hosted a symposium on “cognitive
and learning difficulties and how they affect access to IT systems”. The central premise of the symposium was the recognition
that cognitive and learning difficulties have a profound impact on a person’s ability to interact with information technology
(IT) systems, but that little support is currently being offered by those systems. By bringing together internationally renowned
experts from a variety of different, but complementary, research fields, the symposium aimed to provide a complete overview
of the issues related to this topic. This paper summarises the discussions and findings of the symposium. 相似文献
47.
Prolate elements are a “plug-compatible” modification of spectral elements in which Legendre polynomials are replaced by prolate spheroidal wave functions of order zero. Prolate functions contain a“bandwidth parameter” $c \ge 0 $ c ≥ 0 whose value is crucial to numerical performance; the prolate functions reduce to Legendre polynomials for $c\,=\,0$ c = 0 . We show that the optimal bandwidth parameter $c$ c not only depends on the number of prolate modes per element $N$ N , but also on the element widths $h$ h . We prove that prolate elements lack $h$ h -convergence for fixed $c$ c in the sense that the error does not go to zero as the element size $h$ h is made smaller and smaller. Furthermore, the theoretical predictions that Chebyshev and Legendre polynomials require $\pi $ π degrees of freedom per wavelength to resolve sinusoidal functions while prolate series need only 2 degrees of freedom per wavelength are asymptotic limits as $N \rightarrow \infty $ N → ∞ ; we investigate the rather different behavior when $N \sim O(4-10)$ N ~ O ( 4 ? 10 ) as appropriate for spectral elements and prolate elements. On the other hand, our investigations show that there are certain combinations of $N,\,h$ N , h and $c>0$ c > 0 where a prolate basis clearly outperforms the Legendre polynomial approximation. 相似文献
48.
An initiative was introduced in one of the production facilities of Germany’s E.G.O. Group in order to enhance its SAP information system with a custom-made application for production-scheduling optimization. The goal of the optimization is to find a production schedule that satisfies different, contradictory production and business constraints. We show the challenges faced in the application of the multi-objective optimization approach, which is gaining influence in the management of production scheduling. We implement a memetic version of the Indicator-Based Evolutionary Algorithm with customized reproduction operators and local search procedures to find a set of feasible, non-dominated solutions. Such a memetic algorithm was applied to two real order lists from the production company. Additionally, we also lay out an efficient presentation of the multi-objective results for an expert’s support in decision making. This provides the management with the possibility to gain additional insights into how the production schedule dynamically reacts to changes in the decision criteria. We show that the multi-objective approach is able to find high-quality solutions, which enables flexibility when it comes to quickly adapting to specific business conditions. 相似文献
49.
Nonlinear modelling approaches such as neural networks, fuzzy models and multiple model networks have been proposed for model based control, to improve the poor transient response of adaptive control techniques. The quality of control is known to be strongly related to the accuracy of the model which represents the process. A Bayesian Gaussian process (GP) approach provides an analytic prediction of the model uncertainty, which makes the GP model an ideal candidate for model based control strategies. This article extends the use of the GP model for nonlinear internal model control. The invertibility of the GP model is discussed and the use of predicted variance is illustrated on a simulated example. 相似文献
50.
The rigorous application of design science in information and communications technology (ICT) research is growing rapidly
and producing exciting results. The five papers published in this special issue reflect some of the most recent ideas and
research projects in ICT design science research (DSR). This introduction begins with concise summaries of the published papers.
We then reflect on three key design science issues, using the published papers to illustrate our views. The three issues are:
(1) the nature of the artifacts/problems studied in DSR in ICT disciplines; (2) the research approaches that are used; and
(3) the nature of the research contributions that are made. We explain why we believe that these issues are interdependent
and why thinking about these three issues as a whole can support an improved understanding of the goals and processes of design
science research. 相似文献