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61.
In this paper, a prediction model is presented that estimates the evacuation time in an emergency situation for hospitals. The model is generic enough to be used in various hospital settings. This model can provide incident managers with estimates of the evacuation times of different types of patients and can offer support to the managers with their resource allocation decisions in emergency situations. The major advantage of the prediction model is that the computation time is very short and the model does not need a lengthy and costly design. The model was applied for several different evacuation scenarios and the results were compared with those of a simulation model which had already been designed for use by the hospital. The comparison shows that the prediction model can provide estimates of the evacuation time that are similar to the results found by using costly and time-consuming simulation models. 相似文献
62.
Saeideh Samani Ming Ye Fan Zhang Yong-zhen Pei Guo-ping Tang Ahmed Elshall Asghar A. Moghaddam 《水科学与水工程》2018,11(2):89-100
This study used the marginal likelihood and Bayesian posterior model probability for evaluation of model complexity in order to avoid using over-complex models for numerical simulations. It focused on investigation of the impacts of prior parameter distributions (involved in calculating the marginal likelihood) on the evaluation of model complexity. We argue that prior parameter distributions should define the parameter space in which numerical simulations are made. New perspectives on the prior parameter distribution and posterior model probability were demonstrated in an example of groundwater solute transport modeling with four models, each simulating four column experiments. The models had different levels of complexity in terms of their model structures and numbers of calibrated parameters. The posterior model probability was evaluated for four cases with different prior parameter distributions. While the distributions substantially impacted model ranking, the model ranking in each case was reasonable for the specific circumstances in which numerical simulations were made. For evaluation of model complexity, it is thus necessary to determine the parameter spaces for modeling, which can be done by conducting numerical simulation and using engineering judgment based on understanding of the system being studied. 相似文献
63.
64.
Siavash Amin-Nejad Tayyebeh Asgari Gashteroodkhani Katayoon Basharkhah 《Wireless Personal Communications》2018,98(2):1913-1929
Adaptive beamformers are designed with the aim of detection of noise and intentional destructive interference and then removing them from the desired signal. This is done by placing high attenuation in the direction of the destructive signal in the radiation pattern of antenna arrays without attenuating the signal from a known direction. Minimum variance distortionless response and linearly constrained minimum variance are among such algorithms in mobile communications. A short explanation of the theory and weights formulae of these beamformers will be given. Two designs for weights calculations in Simulink with the added library of DSP-Builder tool from Altera will be presented. Quadrature Rectangular decomposition with Modified Gram-Schmidt algorithm is used instead of the direct matrix inversion. All calculations are done in single floating point mode for the required high accuracy. Modelsim has been used for hardware simulation and measuring the required clock cycles. The target FPGA is Aria10 from Altera which has floating point DSP blocks for high-performance computations. Hardware resources usage, power consumption, maximum clock frequency and update rate for different matrix sizes of these two beamformers are compared and discussed. The results are also compared with some other relevant reported works. 相似文献
65.
A. H. Golmohammadi 《Virtual and Physical Prototyping》2019,14(1):19-36
In additive manufacturing processes, the part build orientation (PBO) is one of the most important factors that can affect the characteristics of the quality product such as the amount of support structure and the surface roughness. In most previous methods, the optimal PBO cannot be determined with high precision and accuracy in 3D space. In this paper, to find the precise and accurate optimal PBO with a desired angular accuracy, a new Taguchi-based method, called the Zooming-Taguchi method, is proposed. The proposed simulation-based method can precisely find the optimal PBO in absence of the noise effects. In order to find the optimal PBO with the desired angular resolution, the zooming procedure is iteratively carried out on factor levels through a clustering strategy. Finally, to validate the proposed method, two case studies are considered and the obtained results are compared with conventional methods in the literature and the experimental results. 相似文献
66.
The time-to-market and cost constraints of designing VLSI circuits, together with increasing complexity, necessitate a structured design methodology. Such a methodology should be based on an extensive use of libraries of generic components and previously designed macro blocks. An ideal library for modern design strategies that are based on a top-down structured approach is described. The concepts of portability, migratability, and interoperability of libraries are discussed. It is shown that libraries capitalize on knowledge gained over generations of designs, and successful libraries demand a serious effort at standardization 相似文献
67.
Overall performance of a peer‐to‐peer system can be highly variable and unpredictable as there is no central authority to set and coordinate the amount of resource contributions made by constituent peers. In this paper, we address the problem of optimal cooperation policy setting for individual peers by taking into account their rationality, and with respect to a set of overall constraints imposed by resource‐driven requirements of the system. We formalize distributed cooperation policy setting as an asynchronous distributed decision making (ADDM) process and represent an integrated design for this process in two top‐down and bottom‐up phases. In top‐down design, we specify the overall objective and constraints and in line with them, we synthesize the local objectives of individual peers. We show that the rational peers should continuously adapt their cooperation policies asynchronously and autonomously according to the policies of the other participants in order to maximize their local objectives. To this end, we devise a self‐organizing interaction mechanism in the bottom‐up phase and demonstrate that it coordinates asynchronous distributed decisions of individual peers with respect to the overall objective and constraints through local interactions. ©2012 Wiley Periodicals, Inc. Syst Eng 16 相似文献
68.
Siavash Ghavami Bahman Abolhassani 《International Journal of Communication Systems》2012,25(2):121-145
In this paper, a two‐phase algorithm for the spectrum sensing and power/rate control of a secondary user (S‐user) or cognitive radio is proposed. In the first phase, the primary base station (P‐BS), which is conscious of both the number and the data rate of primary active users (P‐user), broadcasts theitusage capacity percentage (UCP) of its cell. Since knowing only the UCP is not enough to guarantee that the total load (of P‐users and S‐users) is less than a maximum permissible load, the S‐user must measure the total interference received from both the P‐users and other S‐users. In this direction, using both the UCP and measurement of the interference received from the P‐users and the S‐users by the S‐user or secondary base station (S‐BS), we mathematically derive an equation for issuing data transmission permission, which if it is held then the second phase of the algorithm: the transmit power/rate control starts. In this phase, the S‐user and the S‐BS look for feasible values for the transmit power level and transmission rate. If there are feasible values, it starts its transmission at these feasible transmit power and rate. Since both the location of the S‐user and the channel condition vary in time, the whole algorithm is iterated periodically with a period faster than the coherence time of the channel. Furthermore, we consider the down link of the above system with cooperation among neighboring S‐users to overcome fading channels and we investigate the amount of improvement in the reliability of the issuing data transmission permission. As well, we consider the uplink of the system with multiple antennas in the S‐BS to investigate the improvement in the same parameter over spatially correlated and independent fading channels. Theoretical analysis is validated using computer simulations. Both theoretical analysis and computer simulations show that the proposed cooperative spectrum sensing algorithm performs properly at SNR = ?5dB in flat Nakagami‐m fading channels with m = 1 even in correlated fading channels. We also address the improvement of the reliability of the issuing data transmission permission in the uplink in case of using multiple antennas only in the S‐BS. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
69.
Siavash Partow Verena Siewers Sara Bjørn Jens Nielsen Jérôme Maury 《Yeast (Chichester, England)》2010,27(11):955-964
The widely used pESC vector series (Stratagene, La Jolla, CA, USA) with the bidirectional GAL1/GAL10 promoter provides the possibility of simultaneously expressing two different genes from a single vector in Saccharomyces cerevisiae. This system can be induced by galactose and is repressed by glucose. Since S. cerevisiae prefers glucose as a carbon source, and since its growth rate is higher in glucose than in galactose‐containing media, we compared and evaluated seven different promoters expressed during growth on glucose (pTEF1, pADH1, pTPI1, pHXT7, pTDH3, pPGK1 and pPYK1) with two strong galactose‐induced promoters (pGAL1 and pGAL10), using lacZ as a reporter gene and measuring LacZ activity in batch and continuous cultivation. TEF1 and PGK1 promoters showed the most constant activity pattern at different glucose concentrations. Based on these results, we designed and constructed two new expression vectors which contain the two constitutive promoters, TEF1 and PGK1, in opposite orientation to each other. These new vectors retain all the features from the pESC–URA plasmid except that gene expression is mediated by constitutive promoters. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
70.
Abdollah Golmohammadi Amir H. Afkari-Sayyah 《International Journal of Food Properties》2013,16(1):104-113
Determination of physical properties of agricultural products, such as the potato, and their variations during long-term storage, is an important feature in achieving high product quality and consumer acceptance. Physical properties of potatoes (Agria, Satina, and Caesar cultivars), including surface area, volume, moisture content, weight, and three main diameters of tuber, were measured and then other properties, such as sphericity, roundness, geometric mean diameter, volume mean diameter, aspect ratio, effective diameter, and real density during storage time, were calculated. The measurements were done every 15 days for a period of 22 weeks and analyzed based on a completely randomized block design in ten replications. Significant differences were observed among three potato cultivars according to major diameter, shape characteristics, mass, volume, and surface area of tubers. In this relation, Satina was larger in size compared to the two other cultivars. However, the Agria cultivar was closer to a sphere in shape. Also, it was found that the surface area of each potato could be estimated based on its mass and volume by a power law equation with a high coefficient of determination. According to the results, real density of tubers increased as a function of storage time based on a polynomial equation with R2 = 0.99. During storage time, moisture content of tubers decreased according to a linear model and was probably the major rationale for decrease in tuber size. Density, size, and moisture content are the major physical characteristics of potato tubers, which change dramatically during long-term storage. Considerable differences in physical properties of different cultivars persuade researchers to carry out further studies on other popular potato cultivars. 相似文献