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241.
BACKGROUND: Progressive deterioration and ensuing death following a neurosurgical procedure often represents a diagnostic challenge to the team responsible for patient care. Many, but not all, causes are treatable if a diagnosis is made early. METHODS: A 69-year-old woman who died 6 weeks post-operatively following a meningioma resection is reported. An initial routine post-operative course became complicated by progressive neurological deterioration 3-4 weeks later. Despite extensive investigation she died 6 weeks post-operatively without a diagnosis. RESULTS: Autopsy demonstrated extensive Candida meningitis. A review of the literature demonstrates this to be a reported complication in high risk patients, difficult to diagnose, but treatable when identified. CONCLUSIONS: Fungal meningitis should be high in the differential diagnosis in the post-operative patient with delayed, unexplained neurological deterioration, especially when associated with negative CSF cultures.  相似文献   
242.
An in-situ formed nano-composite consisting of silicon nitride and amorphous silicon oxynitride has been developed using conventional ceramic processing techniques. The phases present have been identified using x-ray diffraction, electron diffraction and Raman spectroscopy. The chemical composition has been determined using quantitative chemical analysis. The microstructure has been characterized using TEM. Results have shown a material having 300 nm sized gmins of silicon nitride surrounded by 20-50 nm grains of silicon nitride and amorphous silicon oxynitride. The material has a low bulk density of (2.6 g/cc), a Vickers Hardness of 1165 Kg/mm2 and a modulus of rupture of 200 MPa with an elastic modulus of 150 GPa. The fracture toughness is 1.5 MPa m1/2. Based on the fracture analysis, it is expected that the strength can be improved substantially. The material has a thermal expansion less than 2 × 10-6/C and a dielectric constant of 4.8 at room temperature.  相似文献   
243.

Photostriction is a multiphysics phenomenon comprising of both photovoltaic effect and converse piezoelectric effect. The extensively researched photostrictive material is lead lanthanum zirconate titanate, i.e., Pb0.92La0.08(Zr0.65Ti0.35)0.98O3 (PLZT) ceramic. In contrast to the traditional approaches of improving deflection response, the current study proposes a 0–3 composite model to substantially enhance the effective material properties, which in turn significantly improves the deflection response. A computational framework based on finite element analysis is employed to 0–3 photostrictive composite of PLZT as matrix and Pb(Mg1/3Nb2/3)O3-0.35PbTiO3 (PMN-35PT) as the inclusions. The representative volume element (RVE) or unit cell technique is used to incorporate the local variation of constituent properties and to calculate photostrictive properties such as effective elastic, dielectric, piezoelectric, and pyroelectric properties. An opto-electro-thermo-mechanical finite element formulation was engaged to get the actuation response of photostrictive material bonded to cantilever and simply supported beam. The maximum deflection for cantilever beam attached to photostrictive composite patch having 25% inclusions volume fraction in 0–3 composite is found to be 38% more in comparison to pure PLZT material. It is established that the opto-electro-mechanical 0–3 composite actuators possess high potential in lightweight, compact and wireless actuation applications.

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244.
Coherence, being at the heart of interference phenomena, is found to be an useful resource in quantum information theory. Here we want to understand quantum coherence under the combination of two fundamentally dual processes, viz., cloning and deleting. We found the role of quantum cloning and deletion machines with the consumption and generation of quantum coherence. We establish cloning as a cohering process and deletion as a decohering process. Fidelity of the process will be shown to have connection with coherence generation and consumption of the processes.  相似文献   
245.
Multimodal biometrics has gained interest in the recent past due to its improved recognition rate over unibiometric and unimodal systems. Fusion at feature level is considered here for the purpose of recognition. The biometrics considered for fusion are face and iris. Here, new face images along with iris images are generated, and they are included in the training set. Feature-level fusion is incorporated. The recognition rates of the classification algorithm thus obtained are statistically found to be significantly better than the existing feature-level fusion and classification techniques.  相似文献   
246.
Various blends of ultra-high molecular weight polyethylene (UHMWPE) with linear low-density polyethylene (LLDPE) were prepared in an internal (Banbury type) mixer, a static mixer, and by solvent blending. Two mixing techniques, namely simultaneous and sequential loading methods, were employed with the internal mixer. In the former case, the two polymer components were simultaneously loaded at 180°C and mixed. The latter method allowed the UHMWPE component to diffuse at 250°C and cooled it down to 180°C, then the LLDPE component was added subsequently and mixed. Rheological and mechanical properties of these blends are profoundly affected by the mixing techniques used. Rheological results shows yield characteristics of UHMWPE/LLDPE blends, in particular in blends of high UHMWPE contents. Tensile properties of sequentially loaded blends vary more or less linearly with blend compositions. However, negative or positive deviations are seen in the simultaneously prepared blends. Differential scanning calorimetry (DSC) studies indicate that co-crystallization takes place between UHMWPE and LLDPE components in sequentially mixed blends. DSC and small-angle light scattering (SALS) studies show that separate crystallization takes place in simultaneously blended compounds as a result of poor mixing. It seems that the sequential loading method provides more homogeneous compounds than those of simultaneous blending.  相似文献   
247.
This article presents a comprehensive parametric study with experimental characterization of an inductively coupled CPW-fed slot antenna on a GaAs substrate for MMIC applications. The length, width, and feed inset of the antenna are varied and their influences on the input impedance, bandwidth, and gain are investigated. The parametric study reveals that the slot length is the prime factor for determining the resonant frequency, while the width is used for fine-tuning of resonant frequency and gain-bandwidth product. For the fixed slot dimensions, the feed inset tremendously affects both resonant frequency and input match. The manufactured antenna resonates at 22.4 GHz with a 6.1% impedance bandwidth, 2% gain bandwidth, 2.5-dBi boresight gain, and 5-dB front-to-back (F/B) radiation level. The antenna exhibits bidirectional radiation patterns with almost omnidirectional patterns in the E-plane and a wide beamwidth of 84° 3-dB beam width in the H-plane. © 2003 Wiley Periodicals, Inc. Int J RF and Microwave CAE 14, 4–14, 2004  相似文献   
248.
Chemical Looping Combustion (CLC) in two interconnected fluidized beds, i.e., the air reactor and the fuel reactor has been recognized to be promising. As the CLC setup design is critical and sensitive to oxygen carrier (OC) materials, it is very much essential to investigate hydrodynamics in a specially fabricated cold model set up for the successful development and operational control of corresponding large-scale hot model. In this study, a pilot-scale cold flow model CLC system has been designed and tested. The riser and fuel reactor were operated at circulated fluidized bed and bubbling fluidized bed conditions, respectively and the control of solid circulation between two reactors was done by two loop seals operated in bubbling fluidized bed conditions. The effect of fluidization velocity in the riser on the voidage profiles, solid circulation rate, and pressure profiles were investigated using Indian ilmenite (150–212?µm) as OC. The stable operation of the system was established under various operational conditions. The results will be useful for the development of ilmenite based hot model CLC system. Moreover, the achievable variations of solid circulation rate in the present study in cold model setup will determine obtainable limit of extent of oxygen transport and thermal energy.  相似文献   
249.
This paper proposes an IoT-enabled soil monitoring system using wireless sensor network for automatic irrigation in agricultural applications, especially for lemongrass plants, where an automated control system is required for irrigation applications. This can solve the problem of the water crisis, which is faced by the farmers during the cultivation of the crop in the field. This controls the water supply in the irrigation process using an IoT communication system. A system architecture for soil monitoring and controlling irrigation using IoT technique is designed where the different sensors and actuators like humidity, soil moisture, temperature, pump, and so forth are connected with a node microcontrol unit and message queuing telemetry transport (MQTT) protocol for enhancing communication capabilities. This wireless sensor network gives feedback to the system. This provides automation by the on/off pump system during drip irrigation. The sensor data are displayed on a PC or mobile phone through wireless communication and an IoT cloud platform. An experimental testing setup is developed and the experimental performance of a soil monitoring system using IoT technique for automatic drip irrigation has been carried out and soil moisture data are also stored in a cloud server for analytics. The performance shows that the MQTT protocol sends data within 48 s to the IoT cloud so that the data can be acquired in a faster manner. This shows that this kind of soil monitoring system is suitable for automatic drip irrigation, which enhances the farming process and overcomes the water crises in the agricultural system by reducing the wastage of water.  相似文献   
250.
Simulation is a cost effective, fast and flexible alternative to test-beds or practical deployment for evaluating the characteristics and potential of mobile ad hoc networks. Since environmental context and mobility have a great impact on the accuracy and efficacy of performance measurement, it is of paramount importance how closely the mobility of a node resembles its movement pattern in a real-world scenario. The existing mobility models mostly assume either free space for deployment and random node movement or the movement pattern does not emulate real-world situation properly in the presence of obstacles because of their generation of restricted paths. This demands for the development of a node movement pattern with accurately representing any obstacle and existing path in a complex and realistic deployment scenario. In this paper, we propose a general mobility model capable of creating a more realistic node movement pattern by exploiting the concept of flexible positioning of anchors. Since the model places anchors depending upon the context of the environment through which nodes are guided to move towards the destination, it is capable of representing any terrain realistically. Furthermore, obstacles of arbitrary shapes with or without doorways and any existing pathways in full or part of the terrain can be incorporated which makes the simulation environment more realistic. A detailed computational complexity has been analyzed and the characteristics of the proposed mobility model in the presence of obstacles in a university campus map with and without signal attenuation are presented which illustrates its significant impact on performance evaluation of wireless ad hoc networks.  相似文献   
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