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81.
82.
Basil Mohammed Al-Hadithi Antonio Javier Barragán José Manuel Andújar Agustín Jiménez 《Applied Soft Computing》2013,13(12):4802-4812
In this paper, a fuzzy based Variable Structure Control (VSC) with guaranteed stability is presented. The main objective is to obtain an improved performance of highly non-linear unstable systems. The main contribution of this work is that, firstly, new functions for chattering reduction and error convergence without sacrificing invariant properties are proposed, which is considered the main drawback of the VSC control. Secondly, the global stability of the controlled system is guaranteed.The well known weighting parameters approach, is used in this paper to optimize local and global approximation and modeling capability of T-S fuzzy model.A one link robot is chosen as a nonlinear unstable system to evaluate the robustness, effectiveness and remarkable performance of optimization approach and the high accuracy obtained in approximating nonlinear systems in comparison with the original T-S model. Simulation results indicate the potential and generality of the algorithm. The application of the proposed FLC-VSC shows that both alleviation of chattering and robust performance are achieved with the proposed FLC-VSC controller. The effectiveness of the proposed controller is proven infront of disturbances and noise effects. 相似文献
83.
Ana Carolina Lorena André C. P. L. F. de Carvalho João M. P. Gama 《Artificial Intelligence Review》2008,30(1-4):19-37
Several real problems involve the classification of data into categories or classes. Given a data set containing data whose classes are known, Machine Learning algorithms can be employed for the induction of a classifier able to predict the class of new data from the same domain, performing the desired discrimination. Some learning techniques are originally conceived for the solution of problems with only two classes, also named binary classification problems. However, many problems require the discrimination of examples into more than two categories or classes. This paper presents a survey on the main strategies for the generalization of binary classifiers to problems with more than two classes, known as multiclass classification problems. The focus is on strategies that decompose the original multiclass problem into multiple binary subtasks, whose outputs are combined to obtain the final prediction. 相似文献
84.
Brain reading using full brain support vector machines for object recognition: there is no "face" identification area 总被引:1,自引:0,他引:1
Over the past decade, object recognition work has confounded voxel response detection with potential voxel class identification. Consequently, the claim that there are areas of the brain that are necessary and sufficient for object identification cannot be resolved with existing associative methods (e.g., the general linear model) that are dominant in brain imaging methods. In order to explore this controversy we trained full brain (40,000 voxels) single TR (repetition time) classifiers on data from 10 subjects in two different recognition tasks on the most controversial classes of stimuli (house and face) and show 97.4% median out-of-sample (unseen TRs) generalization. This performance allowed us to reliably and uniquely assay the classifier's voxel diagnosticity in all individual subjects' brains. In this two-class case, there may be specific areas diagnostic for house stimuli (e.g., LO) or for face stimuli (e.g., STS); however, in contrast to the detection results common in this literature, neither the fusiform face area nor parahippocampal place area is shown to be uniquely diagnostic for faces or places, respectively. 相似文献
85.
Mag. Dr. René Riedl Dipl.-Wirtsch.-Inf. Univ. Maximilian Kobler o. Univ.-Prof. Mag. Dr. Friedrich Roithmayr 《WIRTSCHAFTSINFORMATIK》2008,50(2):111-128
On the Rate of Board Members with IT Responsibilities in Firms Listed on the Stock Exchange: Results of a Content Analysis: This article reports on a content analysis that investigates the rate of board members with IT responsibilities in firms listed on the stock exchange in the German speaking countries. Furthermore, the study ascertains the correlation of six factors – which become evident through content analysis – with the rate of board members with IT responsibilities. A total of 679 annual reports of German, Austrian, and Swiss corporations have been analyzed. The results show that in Germany and Switzerland 26 percent of the firms investigated have a board member with IT responsibilities, in Austria the rate is 23 percent. Additionally, the results show that turnover and number of employees are highly positively correlated with the rate of board members with IT responsibilities. Furthermore, the data show a correlation between industry and the rate of board members with IT responsibilities. 相似文献
86.
In this paper we propose a nonlinear control approach for the path‐tracking of an autonomous underactuated airship. A backstepping controller is designed from the airship nonlinear dynamic model including wind disturbances, and further enhanced to consider actuators saturation. Control implementation issues related to airship underactuation are also addressed, namely control allocation and an attitude reference shaping to obtain a faster error correction with smoother input requests. The results obtained demonstrate the capacity of an underactuated unmanned airship to execute a realistic mission including vertical take‐off and landing, stabilization and path‐tracking, in the presence of wind disturbances, with a single robust control law. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
87.
An extension of the Cauer ladder development for synthesizing singly terminated filters with symmetric and asymmetric responses is presented. Basically, a driving‐point immittance including reactive constant elements is carried out in such a way that provides the transmission zeros. The reactive constant elements are introduced into the synthesis for two reasons. The first is to consider the possibility of the asymmetric position of transmission zeros in the real frequency axis. The second one is to obtain canonical forms, i.e. networks with the minimum number of elements in the case of symmetrical responses. To validate the proposed method, a filter with asymmetrical response has been synthesized, comparing different topologies for its use in multiplexers. This fact is illustrated with a Ku‐band elliptic response diplexer designed in H‐plane rectangular waveguide. © 2009 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009. 相似文献
88.
Guilherme T. de Assis Alberto H. F. Laender Marcos André Gonçalves Altigran S. da Silva 《World Wide Web》2009,12(3):285-319
Focused crawlers have as their main goal to crawl Web pages that are relevant to a specific topic or user interest, playing
an important role for a great variety of applications. In general, they work by trying to find and crawl all kinds of pages
deemed as related to an implicitly declared topic. However, users are often not simply interested in any document about a
topic, but instead they may want only documents of a given type or genre on that topic to be retrieved. In this article, we
describe an approach to focused crawling that exploits not only content-related information but also genre information present
in Web pages to guide the crawling process. This approach has been designed to address situations in which the specific topic
of interest can be expressed by specifying two sets of terms, the first describing genre aspects of the desired pages and
the second related to the subject or content of these pages, thus requiring no training or any kind of preprocessing. The
effectiveness, efficiency and scalability of the proposed approach are demonstrated by a set of experiments involving the
crawling of pages related to syllabi of computer science courses, job offers in the computer science field and sale offers
of computer equipments. These experiments show that focused crawlers constructed according to our genre-aware approach achieve
levels of F1 superior to 88%, requiring the analysis of no more than 65% of the visited pages in order to find 90% of the
relevant pages. In addition, we experimentally analyze the impact of term selection on our approach and evaluate a proposed
strategy for semi-automatic generation of such terms. This analysis shows that a small set of terms selected by an expert
or a set of terms specified by a typical user familiar with the topic is usually enough to produce good results and that such
a semi-automatic strategy is very effective in supporting the task of selecting the sets of terms required to guide a crawling
process. 相似文献
89.
Adaptation and application of multi-objective evolutionary algorithms for rule reduction and parameter tuning of fuzzy rule-based systems 总被引:7,自引:7,他引:0
María José Gacto Rafael Alcalá Francisco Herrera 《Soft Computing - A Fusion of Foundations, Methodologies and Applications》2009,13(5):419-436
Recently, multi-objective evolutionary algorithms have been applied to improve the difficult tradeoff between interpretability
and accuracy of fuzzy rule-based systems. It is known that both requirements are usually contradictory, however, these kinds
of algorithms can obtain a set of solutions with different trade-offs. This contribution analyzes different application alternatives
in order to attain the desired accuracy/interpr-etability balance by maintaining the improved accuracy that a tuning of membership
functions could give but trying to obtain more compact models. In this way, we propose the use of multi-objective evolutionary
algorithms as a tool to get almost one improved solution with respect to a classic single objective approach (a solution that
could dominate the one obtained by such algorithm in terms of the system error and number of rules). To do that, this work
presents and analyzes the application of six different multi-objective evolutionary algorithms to obtain simpler and still
accurate linguistic fuzzy models by performing rule selection and a tuning of the membership functions. The results on two
different scenarios show that the use of expert knowledge in the algorithm design process significantly improves the search
ability of these algorithms and that they are able to improve both objectives together, obtaining more accurate and at the
same time simpler models with respect to the single objective based approach.
相似文献
María José Gacto (Corresponding author)Email: |
Rafael AlcaláEmail: |
Francisco HerreraEmail: |
90.
José de Oliveira Guimarães 《Computer Languages, Systems and Structures》2009,35(4):435-447
A programming language that considers basic values and classes as objects brings more opportunities of code reuse and it is easier to use than a language that does not support this feature. However, popular statically typed object-oriented languages do not consider classes as first-class objects because this concept is difficult to integrate with static type checking. They also do not consider basic values as objects for sake of efficiency. This article presents the Green language type system which supports classes as classless objects and offers a mechanism to treat basic values as objects. The result is a reasonably simple type system which is statically typed and easy to implement. It simplifies several other language mechanisms and prevents any infinite regression of metaclasses. 相似文献