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121.
122.
Zdragas A Partheniou P Kotzamanidis C Psoni L Koutita O Moraitou E Tzanetakis N Yiangou M 《Water research》2008,42(4-5):1274-1280
Enterococcus includes species that may pose emerging health risks and has been used as biomarkers for environmental contamination while little is known concerning their occurrence in marine water. Classification of enterococci in environmental samples can be problematic and requires polyphasic taxonomy. In this study, we investigated the presence of vancomycin-resistant enterococci (VRE) in the inner bay of Thermaikos Gulf in Northern Greece. Based on physiological and biochemical criteria, 121 presumptive enterococcal strains were identified. High-level VRE were undetectable in seawater and only 35 vancomycin gene-negative strains possessed low-level vancomycin resistance. Genotyping by pulsed field gel electrophoresis (PFGE) proved to be more reliable for marine enterococcal discrimination and revealed distinguished characteristics of the seawater enterococci, indicating high genetic diversity. Random amplified polymorphic DNA-PCR (RAPD-PCR) was unable to separate distinct species analyzed in this study. This study indicates the need of polyphasic taxonomy for seawater enterococcal species' identification and provides information for future biomonitoring programs of Thermaikos Gulf. 相似文献
123.
Eleni I. Vlahogianni Matthew G. Karlaftis & John C. Golias 《Computer-Aided Civil and Infrastructure Engineering》2008,23(7):536-548
Abstract: Recognizing temporal patterns in traffic flow has been an important consideration in short-term traffic forecasting research. However, little work has been conducted on identifying and associating traffic pattern occurrence with prevailing traffic conditions. We propose a multilayer strategy that first identifies patterns of traffic based on their structure and evolution in time and then clusters the pattern-based evolution of traffic flow with respect to prevailing traffic flow conditions. Temporal pattern identification is based on the statistical treatment of the recurrent behavior of jointly considered volume and occupancy series; clustering is done via a two-level neural network approach. Results on urban signalized arterial 90-second traffic volume and occupancy data indicate that traffic pattern propagation exhibits variability with respect to its statistical characteristics such as deterministic structure and nonlinear evolution. Further, traffic pattern clustering uncovers four distinct classes of traffic pattern evolution, whereas transitional traffic conditions can be straightforwardly identified . 相似文献
124.
In this work the radial basis function neural network architecture is used to model the dynamics of Distributed Parameter Systems (DPSs). Two pure data driving schemes which do not require knowledge of the governing equations are described and compared. In the first method, the neural network methodology generates the full model of the system that is able to predict the process outputs at any spatial point. Past values of the process inputs and the coordinates of the specific location provide the input information to the model. The second method uses empirical basis functions produced by the Singular Value Decomposition (SVD) on the snapshot matrix to describe the spatial behavior of the system, while the neural network model is used to estimate only the temporal coefficients. The models produced by both methods are then implemented in Model Predictive Control (MPC) configurations, suitable for constrained DPSs. The accuracies of the modeling methodologies and the efficiencies of the proposed MPC formulations are tested in a tubular reactor and produce encouraging results. 相似文献
125.
Dimitris S. Achilias Iliana Kanellopoulou Panagiotis Megalokonomos Eleni Antonakou Angelos A. Lappas 《大分子材料与工程》2007,292(8):923-934
The potential use of the liquid product obtained from the pyrolysis of polystyrene as a raw material for the reproduction of the polymer was investigated in this study. Catalytic and non‐catalytic pyrolysis experiments were carried out in a fixed bed reactor using either model polymer or commercial waste products as the feedstock. The liquid fraction produced from all the pyrolysis experiments consisted mainly of the styrene monomer and this was subjected to re‐polymerization without any further purification, in a DSC with AIBN initiator. It was found that the pyrolysis oil fraction could be re‐polymerized to again produce polymer. However, aromatic compounds included in this fraction may act as chain transfer agents, resulting in alterations in the shape of the reaction rate curve and lowering significantly the average molecular weight and the Tg of the polymer produced.
126.
Antoniadis A Poulios I Nikolakaki E Mantzavinos D 《Journal of hazardous materials》2007,146(3):492-495
The application of high intensity, low frequency ultrasound for the disinfection of simulated and septic tank wastewaters is evaluated in this work. Laboratory scale experiments were conducted at 24 and 80kHz ultrasound frequency with horn-type sonicators capable of operating in continuous and pulsed irradiation modes at nominal ultrasound intensities up to 450W. For the experiments with simulated wastewaters, Escherichia coli were used as biological indicator of disinfection efficiency, while for the experiments with septic tank wastewaters, the total microbiological load was used. Complete elimination of E. coli could be achieved within 20-30min of irradiation at 24kHz and 450W with the efficiency decreasing with decreasing intensity and frequency. Moreover, continuous irradiation was more effective than intermittent treatment based on a common energy input. Irradiation of the septic tank effluent prior to biological treatment at 24kHz and 450W for 30min resulted in a three-log total microbiological load reduction, and this was nearly equal to the reduction that could be achieved during biological treatment. Bacterial cell elimination upon irradiation was irreversible as no reappearance of the microorganisms occurred after 24h. 相似文献
127.
Taylor J Galanis E Wilcott L Hoang L Stone J Ekkert J Quibell D Huddleston M McCormick R Whitfield Y Adhikari B Grant CC Sharma D;Salmonella Chester Outbreak Investigation Team 《Journal of food protection》2012,75(4):738-742
Salmonella Chester infection has rarely been reported in the literature. In 2010, 33 case patients were reported in 2 months in four Canadian provinces. We conducted an outbreak investigation in collaboration with public health agencies, food safety specialists, regulatory agencies, grocery store chains, and the product distributor. We used case patient interviews, customer loyalty cards, and microbiological testing of clinical and food samples to identify nationally distributed head cheese as the food vehicle responsible for the outbreak. The rare serotype, a limited affected demographic group, and an uncommon exposure led to the rapid identification of the source. Control measures were implemented within 9 days of notification of the outbreak. 相似文献
128.
Volatile profile of Greek dried white figs (Ficus carica L.) and investigation of the role of β‐damascenone in aroma formation in fig liquors 下载免费PDF全文
129.