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41.
42.
Victor D. Fachinotti Steven Le Corre Nicolas Triolet Manuel Bobadilla Michel Bellet 《International journal for numerical methods in engineering》2006,67(10):1341-1384
As an approach towards a better modelling of solidification problems, we introduce a thermo‐mechanical and macrosegregation model that considers a solidifying alloy as a binary mixture made of a liquid and a solid phase. Macroscopic conservation laws for mass, momentum and solute are obtained by spatial averaging of the respective microscopic conservation equations. Assuming local thermal equilibrium, a single equation for the conservation of the mixture energy is then written. A single equation can be obtained for the solute as well by invoking a proper microsegregation rule. The numerical implementation in a two‐dimensional finite element code is then detailed. Lastly, some examples of simulations of academic tests as well as industrial applications for continuous casting of steel slabs are discussed. They particularly enlighten the ability of the formulation to describe the formation of central macrosegregation during the secondary cooling of slab continuous casting processes. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
43.
Novel GaInSbAs/GaSb multiple-quantum-well lasers operating near room temperature have been successfully used for tunable diode laser absorption spectroscopy in the vicinity of 2.35 mum. Continuous current tuning over a more than 150-GHz frequency range has been realized. Direct absorption measurements have been carried out on the R, R, R, and R lines of carbon monoxide. Traces of carbon monoxide at the level of 0.3 part in 10(6) in volume at 100 Torr could be detected by the low-frequency wavelength-modulation technique and an astigmatic multipass cell. These results show a potential use of these diode lasers in portable low-cost trace-pollutant sensors. 相似文献
44.
Christophe Daux Nicolas Moës John Dolbow Natarajan Sukumar Ted Belytschko 《International journal for numerical methods in engineering》2000,48(12):1741-1760
Extensions of a new technique for the finite element modelling of cracks with multiple branches, multiple holes and cracks emanating from holes are presented. This extended finite element method (X‐FEM) allows the representation of crack discontinuities and voids independently of the mesh. A standard displacement‐based approximation is enriched by incorporating discontinuous fields through a partition of unity method. A methodology that constructs the enriched approximation based on the interaction of the discontinuous geometric features with the mesh is developed. Computation of the stress intensity factors (SIF) in different examples involving branched and intersecting cracks as well as cracks emanating from holes are presented to demonstrate the accuracy and the robustness of the proposed technique. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
45.
This paper presents the results of an extensive analytical investigation on the mechanisms involved in filtration of biological sludges by studying the changes in the “bound water” content of activated and mixed digested sludges when they were subjected to several physical, and chemical processes. A new method for determining bound water in sludges, based on differential thermal analysis (DTA), was developed which proved reliable and fast. Water in sludges exist in two states, as “free” or bulk water and as “bound” water which is held by the solid state either by sorption on specific sites, i.e. functional groups of the proteins and other macromolecules and/or restricted within pores and capillaries. Water binding by sludge displayed similar behaviour to the absorption of ions.All chemical coagulants (FeCl3, AlCl3, FeSO4) and cationic polyelectrolytes resulted in a reduction of the specific resistance and the bound water content of the sludge which was due to the replacement of water molecules by the adsorbed coagulant. Heat treatment of activated and digested sludge at 130°C resulted in a reduction of bound water by 30% whereas freezing and thawing reduced bound water by 70%. 相似文献
46.
Lissette Iturburu;Xiaoyu Liu;Xin Zhang;Benjamin E. Wogen;Juan Nicolas Villamizar;Shirley J. Dyke;Julio Ramirez;Jongseong Brad Choi;Gianella Valencia;Sergio M. Alcocer; 《The Structural Design of Tall and Special Buildings》2024,33(13):e2120
The automated identification of building characteristics for seismic vulnerability remains a challenge for governments due to the high number of buildings in cities. The diverse architectural styles of these buildings complicate the automated identification of building information (e.g., number of stories, structural system, and material type). Deep learning techniques lose accuracy as they generalize information, while the visual contents of a building exhibit a considerable range and diversity. This study leverages the pose detection technique to tackle such issues by focusing on a common construction style: reinforced concrete buildings representing columns, beams, or floors on the façade. With an aim to enable the assessment of seismic vulnerability, the technique developed herein is conceived for buildings with up to six stories that are more likely to be moment-frame buildings. The AI-enabled proposed framework starts with collecting building images and categorizing those containing this specific building type. A bounding box detector is then used to isolate building facades, for the subsequent identification of the structural frame with the High-Resolution Network (HR-Net). For demonstration, we illustrate this technique by identifying the structural frame on concrete buildings with a sample dataset developed based on buildings found in Mexico City in a pre-earthquake event state. 相似文献
47.
John Fahlteich Dr. Matthias Fahland Dr. Steffen Straach Steffen Günther Dr. Nicolas Schiller Dr. 《真空研究与实践》2011,23(4):29-37
Transparent permeation barrier layers on flexible polymer substrates This paper reviews different vacuum based technologies for manufacturing transparent permeation barrier layers and layer stacks on flexible polymer substrates. With plasma assisted reactive evaporation, a cost‐efficient, highly productive process for food packaging applications is presented. Reactive dual magnetron sputtering is a technology for the deposition of oxide layers with a very low water vapor and oxygen transmission rate at a reasonable deposition rate. Many groups suggest multilayer stacks for the encapsulation of flexible electronic devices. In this paper, an all‐in‐vacuum inline concept for manufacturing such multilayers is presented. It is based on the combination of reactively sputtered barrier layers with interlayers grown by using a magnetron based PECVD process (Magnetron‐PECVD). Both, process parameters, such as deposition rate and process pressure, and important layer properties, such as morphology and the water vapor and oxygen transmission rate are compared for the different single and multi layer technologies. 相似文献
48.
Simoens François Meilhan Jérôme Nicolas Jean-Alain 《Journal of Infrared, Millimeter and Terahertz Waves》2015,36(10):961-985
Journal of Infrared, Millimeter, and Terahertz Waves - Sensitive and large-format terahertz focal plane arrays (FPAs) integrated in compact and hand-held cameras that deliver real-time terahertz... 相似文献
49.
Nicolas Vivas Guy Bourgeois Christiane Vitry Yves Glories Victor de Freitas 《Journal of the science of food and agriculture》1996,72(3):309-317
The composition of various commercial tannin extracts were determined by liquid secondary ion mass spectrometry (LSIMS). Spectra were obtained directly from tannin extracts without any pre-separation. Eight different tannin powders were analysed: three gallotannins (Chinese, Turkish, tara), three ellagitannins (sweet chestnut, pendunculata oak, sessile oak), one mixed hydrolysable tannin (myrabolans) and one proanthocyanidin (grape seeds). This method enabled the main molecules in these powders to be identified. 相似文献
50.
Andreas Mettler Nicolas Wyrsch Michael Goetz Arvind Shah 《Solar Energy Materials & Solar Cells》1994,34(1-4)
We present systematic measurements of CPM on two independent series of slightly phosphorous and boron doped films. For “n-type” samples of both series, the CPM deep defect absorption is proportional to the square root of the gas dopant ratio. For these samples we discuss the influence of Fermi level on the CPM spectra. For slightly “p-type” samples, CPM deep defect absorption as evaluated by CPM becomes higher than the corresponding PDS-values. This fundamental problem can be traced back to the violation of two basic conditions necessary for a correct evaluation of the absorption from CPM measurements: (1) the power law exponent γ (Rose factor) of the photoconductivity must be spectrally independent, and (2) the generation rate G, which corresponds to the CPM photocurrent, also has to be spectrally independent. Further, we compare the annealed and the “saturated” light soaked states of selected slightly doped samples and an undoped sample: the variations in the CPM deep defect absorption and in photoconductivity due to light-soaking are discussed. 相似文献