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排序方式: 共有1913条查询结果,搜索用时 0 毫秒
991.
G.D Sorita A Santamaria-Echart A.M Gozzo O.H Gonçalves F.V Leimann E Bona Y Manrique I.P.M Fernandes I.C.F.R Ferreira M.F Barreiro 《Advanced Powder Technology》2021,32(5):1710-1722
Spray-congealing, a technique based on the fast solidification of sprayed molten lipids, is considered a novel strategy to encapsulate natural products. Among others, it is a safe, low cost, fast and reproducible technique, with rising interest for several applications (e.g. food applications). One of the key parameters for the application of this technique is the lipid solidification temperature, which can be modulated by optimizing the lipid composition. In this work, three lipid components (beeswax, carnauba wax, and medium-chain triglycerides (Miglyol 812)) were selected, and the mixture composition modelled using a simplex-centroid experimental design. Three different lipid compositions were chosen to validate the proposed model, then tested in the preparation of curcumin-loaded microparticles (1.5%, w/w). The produced microparticles were analysed in terms of colour, morphology, particle size, encapsulation efficiency and load, physicochemical, crystalline, and thermal properties. Results evidenced that microparticle’s properties, including encapsulation efficiency, vary according to the used lipid mixture, supporting their tailoring role. This fact brings advantages in the design of microencapsulation systems based on spray congealing processes, broadening their applicability. Moreover, lipid composition optimisation was proved to be an important tool to precede the development of spray-congealing applications. 相似文献
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994.
Rubens Fernandes Nunes Creto Augusto Vidal Joaquim Bento Cavalcante-Neto 《The Visual computer》2007,23(9-11):823-832
In this paper, we propose a flexible representation of controllers that uses high-level sensors and possesses a general and intuitive structure that offers several types of parameters, which can be modified either automatically or with the animator’s intervention. This structure, with the feedback signals provided by its sensors, allows several state machines to act simultaneously on the model, or in a subset of its actuators. The sensors can be optimized, facilitating their definition and use. The representation also permits the animator to define procedures with general instructions that can be automatically executed by the controller during the dynamics simulation. 相似文献
995.
Anastasios Gounaris Rizos Sakellariou Norman W. Paton Alvaro A. A. Fernandes 《Distributed and Parallel Databases》2006,19(2-3):87-106
Advances in network technologies and the emergence of Grid computing have both increased the need and provided the infrastructure
for computation and data intensive applications to run over collections of heterogeneous and autonomous nodes. In the context
of database query processing, existing parallelisation techniques cannot operate well in Grid environments because the way
they select machines and allocate tasks compromises partitioned parallelism. The main contribution of this paper is the proposal
of a low-complexity, practical resource selection and scheduling algorithm that enables queries to employ partitioned parallelism,
in order to achieve better performance in a Grid setting. The evaluation results show that the scheduler proposed outperforms
current techniques without sacrificing the efficiency of resource utilisation.
Recommended by: Ioannis Vlahavas 相似文献
996.
V.C. Salustiano N.J. Andrade N.F.F. Soares J.C. Lima P.C. Bernardes L.M.P. Luiz P.E. Fernandes 《Food Control》2009,20(4):439-442
Over the last decade, increased transportation of refrigerated raw milk from farms to factories has raised concerns over Bacillus cereus contamination in the Brazilian dairy industry. Twelve isolates from pasteurized milk and 30 isolates from the post-pasteurization equipment surfaces of a dairy processing unit were characterized as B. cereus. Seven ribotypes were identified, demonstrating the genetic variability of this microorganism. Most of the isolates belonged to the same ribogroup (RIBO1222-73-S4), and they were found on four surfaces and also in the milk, indicating the role of the equipment surfaces as reservoirs for milk recontamination. 相似文献
997.
Multidimensional, mapping-based complex wavelet transforms. 总被引:4,自引:0,他引:4
Felix C A Fernandes Rutger L C van Spaendonck C Sidney Burrus 《IEEE transactions on image processing》2005,14(1):110-124
Although the discrete wavelet transform (DWT) is a powerful tool for signal and image processing, it has three serious disadvantages: shift sensitivity, poor directionality, and lack of phase information. To overcome these disadvantages, we introduce multidimensional, mapping-based, complex wavelet transforms that consist of a mapping onto a complex function space followed by a DWT of the complex mapping. Unlike other popular transforms that also mitigate DWT shortcomings, the decoupled implementation of our transforms has two important advantages. First, the controllable redundancy of the mapping stage offers a balance between degree of shift sensitivity and transform redundancy. This allows us to create a directional, nonredundant, complex wavelet transform with potential benefits for image coding systems. To the best of our knowledge, no other complex wavelet transform is simultaneously directional and nonredundant. The second advantage of our approach is the flexibility to use any DWT in the transform implementation. As an example, we exploit this flexibility to create the complex double-density DWT: a shift-insensitive, directional, complex wavelet transform with a low redundancy of (3M - 1)/(2M - 1) in M dimensions. No other transform achieves all these properties at a lower redundancy, to the best of our knowledge. By exploiting the advantages of our multidimensional, mapping-based complex wavelet transforms in seismic signal-processing applications, we have demonstrated state-of-the-art results. 相似文献
998.
Marcio Schwaab 《Chemical engineering science》2007,62(10):2750-2764
The Arrhenius equation is one of the most well-known equations in the chemical field and is widely used to describe the temperature dependence of kinetic constants. This equation contains two parameters, the frequency factor and the activation energy, which are usually estimated from experimental data. However, the correlation between the two parameter estimates is usually very high and in many cases is practically equal to one. This makes the precise identification of the parameter values very difficult. The high parameter correlation can be diminished through reparameterization of the Arrhenius equation and definition of a reference temperature. For problems involving a single kinetic constant, it is shown here both analytically and through numerical examples that the proper definition of the reference temperature allows for estimation of the parameters of the Arrhenius equation without correlation and with minimum relative error, leading to improvement of the parameter estimation procedure. 相似文献
999.
Francisco das Chagas Fernandes Guerra Wellington Santos Mota 《Power Delivery, IEEE Transactions on》2007,22(1):187-194
This paper presents a current-transformer (CT) model that is useful for low-frequency applications. To describe the iron-core magnetic behavior, a hysteresis model is proposed, which is able to generate minor asymmetric loops and remanent flux. The effects of classic eddy current losses and anomalous losses are represented by linear and nonlinear resistors, respectively. The obtained results are compared with those calculated by the Preisach's model and measured in the laboratory. This model may be applied in power system protection studies, as it is the case of numeric correction of distorted secondary currents in current transformers (CTs) 相似文献
1000.
Marcio Milititsky Bruno C. Decooman John G. Speer Nico De Wispelaere Nuri Akdut 《Metallurgical and Materials Transactions A》2006,37(7):2117-2123
The room-temperature aging behavior of two duplex stainless alloys with different austenite stability was investigated. Both
alloys readily aged at room temperature. Even for aging times as short as 30 seconds, the originally continuous yielding behavior
becomes discontinuous upon reloading after prestraining. The magnitude of the stress increase due to aging was higher in the
presence of strain-induced martensite, even though it was shown that aging also occurred in the austenite phase. The aging
response was shown to be thermally activated, with increasing age hardening associated with increasing aging times. The results
could be explained by the combination of aging phenomena in the bcc phases by interstitials and the aging by interstitial-vacancy
complexes in the fcc phase, where the interstitials are thought to be immobile during the short aging times used and aging
would occur due to short-range migration of vacancies instead. 相似文献