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991.

Recently, skin detection has been employed in multifarious applications of computer vision including face detection, gesture recognition, etc. This is mainly due to the appealing characteristics of skin color and its potency to segment objects. However, there are certain challenges involved in utilizing human complexion as a feature to detect faces, and they have led to the inefficiency of many methods. In order to counteract these factors, in this paper, a skin segmentation method which exploits a multi step diffusion algorithm to detect skin regions is presented. The method starts with conservative extraction of skin seeds in each frame which is accomplished by using fusion of ternary-based human motion detection, modified Bayesian classifier, and a feedback mechanism. Subsequently, these candidate skin pixels are utilized in a 2-stage diffusion scheme to detect other skin pixels. Both quantitative and qualitative results demonstrate the effectiveness of the proposed system in comparison with other works.

  相似文献   
992.

This paper study the stabilization of mechanical system with impulse effects around a hybrid limit cycle, the proposed control approach is based on LaSalle’s invariance principle for hybrid systems and Layounov constraint based method. Theorem 2 shows necessary and sufficient condition of the existence and the uniqueness of the developed controller which leads to a system of partial differential equations (PDE) whose solutions are the kinetic and potential energy of smooth Lyapunov function, furthermore Theorem 3 gave an alternative existence condition which states that the largest positively invariant set should be nowhere dense and closed and it is none other than the hybrid limit cycle itself.

  相似文献   
993.
An unprecedented increase in subscribers and demand for high-speed data are considered a critical step towards the new era of mobile wireless networks, i.e., Fifth Generation (5G), where the legacy mobile communication system will still be operational for a long time in the future. This has subsequently increased the overall energy consumption, operational costs and carbon footprint of cellular networks, due to increase the number of base stations (BSs), which consume the most energy. Switching BSs off/on in accordance with the traffic pattern variations is considered an effective method for improving energy efficiency. However, the main concerns from the network operators are the requirements to switched on/off the BSs, coverage issues and secured the radio service for the affected area. Hence, the main focus of this study is to develop an intelligent cooperation management (switch BSs on/off) within a multi-radio access technology (RAT) environment between a future generation 5G into the existing LTE and UMTS cellular network towards green cellular networks, while guaranteeing maximum cells coverage area during a switch off session. Particle swarm optimisation has been adopted in this study to maximize the cell coverage area under the constraints of the transmission power of the BS \((P_{tx})\), the total antenna gain (G), the bandwidth (BW), the signal-to-interference-plus-noise ratio (SINR), and shadow fading \((\sigma )\). Moreover, the modulation and coding scheme, the data rate, and the energy efficiency are considered. The results have shown that by applying the proposed a dynamic multi-RAT BSs switching off\(\backslash \)on strategy according to the traffic load variations, the daily energy savings of up to 42.3% can be achieved, with guaranteed maximum cells coverage area.  相似文献   
994.
The primary aim of this study was to recover base oil from used oil using solvent extraction followed by the adsorption method. Many effective variables were examined within the solvent extraction method, including using different solvents, solvent/used oil, temperature and speed of blending. Central composite design (CCD) was applied as the statistical method. Response surface methodology was then used to find the optimum conditions in the process of extraction: ratio of solvent/used oil 2.4 and 3.12 vol/vol, temperature=54 and 18 °C, and speed of mixing=569 and 739 rpm for 1-butanol and methyl ethyl ketone (MEK), respectively. Various flocculation agents were used with the solvent, such as Sodium hydroxide (NaOH), Potassium hydroxide (KOH) and Monoethylamine (MEA); they provided an increase in the separation efficiency. The best result was obtained when using 2 grams of MEA/kg solvent; this amount of MEA increases sludge removal from 12.6% to 14.7%. In the process of clay adsorption, the variables that were tested included the ratio of clay/extract oil, temperature and time of contact. The best conditions in the process of adsorption by activated bentonite were a ratio of clay/extract oil=15 wt/vol%, temperature=120 °C, and time of contact=150 minutes. The recovered base oil was analyzed by Fourier transform infrared spectroscopy (FTIR) and compared to Iraqi specifications of base oils. The recovered base oil specifications were analyzed, including, viscosity @100 °C 8.32, 9.22 cSt, pour point ?17.35, ?22.23 °C, flash point 210.12, 223.04 °C, total acid number (TAN) 0.25, nill, total base number (TBN) nill, nill, ash 0.031, 0.0019 wt% and color 3.0, 2.5 for two types of base oil recovered using MEK, 1-butanol with activated bentonite, respectively.  相似文献   
995.
The objective behind this study is to investigate the phenomenon and kinetics of Cd(II) ion biosorption by the algae fibers, as well as the development of mathematical model that would describe the phenomenon of ions transport through porous algae. The results obtained have shown an inter-particle rate constant of diffusion Kint = 0.188 (mg·g?1·min?1/2), R2 = 0.999, and adsorption amount at equilibrium QSeq = 1.87 mg·g?1. These results indicated that the diffusion of ions existed in the porous algae. The proposed mathematical model is used to optimize the biosorption of heavy metal ions by connecting the model parameters with the fiber performances.  相似文献   
996.
Composites of emeraldine form of polyaniline (PAni) and poly(methyl methacrylate) (PMMA) are prepared by emulsion polymerization method in definite ratios. The chemical structure of the samples and their morphologies have been investigated by different techniques including FTIR, UV–vis, XRD, SEM, and TGA. Enhancement in thermal stability of the obtained composites by PAni additions has been confirmed. Alpha analyzer, in frequency range 0.1 Hz to 20 MHz, was employed to investigate the molecular dynamics of the prepared samples and the accompanied electrical conductivity at temperatures ranging from 223 to 423 K. Conductivity investigations showed that mobility has the more dominant effect on the charge transportation. The dynamic peak at lower temperatures of the PMMA has high activation energy (83.8 kJ/mol). While, Maxwill‐Wagner‐Siller process due to the interfacial polarization in the composites has only 7.5 kJ/mol activation energy. This is a clear indication of the ease of the investigated dynamic. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45415.  相似文献   
997.
The profit potential for a given investment in fertilizer use can be estimated using representative crop nutrient response functions. Where response data is scarce, determination of representative response functions can be strengthened by using results from homologous crop growing conditions. Maize (Zea mays L.) nutrient response functions were selected from the Optimization of Fertilizer Recommendations in Africa (OFRA) database of 5500 georeferenced response functions determined from field research conducted in Sub-Saharan Africa. Three methods for defining inference domains for selection of response functions were compared. Use of the OFRA Inference Tool (OFRA-IT; http://agronomy.unl.edu/OFRA) resulted in greater specificity of maize N, P, and K response functions with higher R2 values indicating superiority compared with using the Harvest Choice Agroecological Zones (HC-AEZ) and the recommendation domains of the Global Yield Gap Atlas project (GYGA-RD). The OFRA-IT queries three soil properties in addition to climate-related properties while the latter two options use climate properties only. The OFRA-IT was generally insensitive to changes in criteria ranges of 20–25% used in queries suggesting value in using wider criteria ranges compared with the default for information scarce crop nutrient response functions.  相似文献   
998.
999.
Friction stir welding (FSW) of dissimilar alloys and materials is becoming progressively essential as it permits to take the benefits of both materials. Tensile strength is a measure of the weld quality, which mainly depends on machine variables and tool design. In this paper, FSW of dissimilar AA7075-AA6061 aluminium alloys was studied with respect to the welding speeds (rotational and axial), tool tilt angle and tool geometry by the response surface methodology (RSM) with central composite design (CCD). A reduced second-order polynomial equation was successfully developed and validated to adequately fit the observed results of the ultimate tensile strength (UTS). Respectable fitness and well agreement between the experimental and calculated values with an elevated regression coefficient and low deviation were detected for this model within the range of the operating variables. Five tools with concave shoulders and different probe profiles (cylindrical and tapered, smooth and threaded, flatted and non-flatted) and a self-designed backing plate and clamping system were fabricated for this study. It was found that the welding tool with a threaded truncated cone pin and single flat results in a sound weld with higher tensile strength, wide nugget area and smooth surface finish.  相似文献   
1000.
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