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121.
Chiral terpenes in orange juices were examined by solid-phase microextraction-gas chromatography-mass spectrometry to study the dependence of their enantiomeric composition on the thermal treatment applied during the industrial manufacture. The experimental conditions used in the isolation and concentration of the compounds of interest produced relative standard deviations ranging from 2.9 to 15.1% when absolute areas were used and from 1.7 to 18.3% when normalized areas were used. Recovery varied between 8.8 and 56.1%, and detection limits ranged from 0.11 to 0.32 microg/ml. The enantiomeric compositions of the majority of the chiral terpenes varied within a reasonably narrow range. Nevertheless, the enantiomeric ratio of two monoterpene alcohols, alpha-terpineol and linalool, exhibited considerable variation according to the thermal treatment used in the manufacture of the juices. Therefore, the knowledge of the enantiomeric composition of alpha-terpineol and linalool might be useful for thermal treatment control purposes. 相似文献
122.
Millán Jdel R Renkens F Mouriño J Gerstner W 《IEEE transactions on bio-medical engineering》2004,51(6):1026-1033
Brain activity recorded noninvasively is sufficient to control a mobile robot if advanced robotics is used in combination with asynchronous electroencephalogram (EEG) analysis and machine learning techniques. Until now brain-actuated control has mainly relied on implanted electrodes, since EEG-based systems have been considered too slow for controlling rapid and complex sequences of movements. We show that two human subjects successfully moved a robot between several rooms by mental control only, using an EEG-based brain-machine interface that recognized three mental states. Mental control was comparable to manual control on the same task with a performance ratio of 0.74. 相似文献
123.
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125.
S. Dueñas H. Castán J. Barbolla E. San Andrés A. del Prado I. Mártil G. González-Díaz 《Journal of Materials Science: Materials in Electronics》2003,14(5-7):375-378
In this work we present a new method to fabricate improved TiO2 films by using a high-pressure sputtering system. In order to minimize the damage induced in the substrate surface by the ion bombardment, a high chamber pressure of 100 Pa is used, which is very much higher than typical values in conventional systems. We present results obtained by X-ray diffraction and FTIR spectroscopy. Moreover, we will compare the properties of the resulting TiO2-insulator-metal capacitors with those of anodic Ta2O5. Very thin films of TiO2 have been obtained with a very promising quality for future electron device fabrication. 相似文献
126.
This paper deals with the inference of finite populations quantiles by using auxiliary information. The population information
considered on the proposed estimatiors is a population quantile of the auxiliary variable with the same order as that of the
quantile of the main variable to be estimated. A simulation study based on three real finite populations is performed and
comparisons of the proposed estimators with other common estimators for quantile estimation are carried out. 相似文献
127.
J. González-Hernández V. Castaño A. del Real E. Morales-Sánchez E. García-García A. Mendoza-Galván E. F. Prokhorov Yu. V. Vorobiev 《Inorganic Materials》2000,36(12):1219-1227
The kinetics of the amorphous-to-crystalline phase transformation in alloys with compositions around Ge2Sb2Te5, used as erasable optical memories, was investigated by electric impedance, Raman spectroscopy, and optical and transmission electron microscopy. To induce the transformation, isothermal and isokinetic experiments were carried out at various temperatures and various heating rates. The results obtained agree with the Johnson–Mehl–Avrami model and show that the overall activation energy for the transition is about 8 eV, which exceeds previous estimations. The nucleation process changes during the transition and depends on both temperature and heating rate. The available data indicate that nuclei are formed both in the bulk and at the surface of crystallites, and that the structural details of the material (the crystallite size, in particular) depend greatly on the transformation conditions. Intercrystalline inclusions, which appear after the transition, contain Te precipitates within a structurally disordered phase. These inclusions have electrical and optical properties essentially different as compared to the rest of the sample; they could be residual phases formed due to the nonstoichiometric nature of the samples. 相似文献
128.
Francisco J. López Fraguas Mario Rodríguez Artalejo Rafael del Vado Vírseda 《Higher-Order and Symbolic Computation》2007,20(1-2):73-122
In this paper we propose a new generic scheme CFLP풟, intended as a logical and semantic framework for lazy Constraint Functional Logic Programming over a parametrically given
constraint domain 풟. As in the case of the well known CLP풟 scheme for Constraint Logic Programming, 풟 is assumed to provide domain specific data values and constraints. CFLP풟 programs are presented as sets of constrained rewrite rules that define the behavior of possibly higher order and/or non-deterministic
lazy functions over 풟. As a main novelty w.r.t. previous related work, we present a Constraint Rewriting Logic CRWL풟 which provides a declarative semantics for CFLP풟 programs. This logic relies on a new formalization of constraint domains and program interpretations, which allows a flexible
combination of domain specific data values and user defined data constructors, as well as a functional view of constraints.
This research has been partially supported by the Spanish National Projects MELODIAS (TIC2002-01167), MERIT-FORMS (TIN2005-09207-C03-03)
and PROMESAS-CAM (S-0505/TIC/0407). 相似文献
129.
Douglas D. Gransberg Carla Lopez del Puerto Daniel Humphrey 《Canadian Metallurgical Quarterly》2007,133(6):404-408
Intuitively, there should be a relationship between the size of the design fee for a transportation project and the quality of the resulting design. This study sought that relationship by looking at the fee expressed as a percentage of the construction cost and the final construction cost growth from the engineer’s initial estimate of the construction cost at the time the design contract was awarded. The research team analyzed 31 projects from the Oklahoma Turnpike Authority with a total construction value of $90 million. The projects were divided into road and bridge projects. Based on the results of the analysis, it seems that as the design fee decreases, the absolute percentage of construction cost growth from the engineer’s early estimate increases. The relationship is strongest for bridge projects, which tend to be more technically complex to design than roadway projects. This confirms for U.S. projects the result of an earlier study in Saudi Arabia. This paper concludes that the design fee should be viewed as an investment at a point in time where the ability to impact the project is the highest and can accrue the benefit of reduced cost growth. 相似文献
130.
The effect of brittle failures on the elastic wave propagation along cylindrical bars is analysed. From experimental observations provided by spalling tests of ceramic materials, a theoretical analysis is carried out based on a finite elements simulation of the experiments and a mathematical analysis of the pulses by means of Fourier Transform techniques. Differences between the propagating waves before and after the material failure are revealed. After failure, the pulse is influenced by dispersion effects and its shape changes during propagation. To correct this effect, a procedure based on Bancroft's curves is suggested. Finally, some clues about the way to get consistent results from spalling tests are given. 相似文献