全文获取类型
收费全文 | 1373篇 |
免费 | 56篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 51篇 |
化学工业 | 299篇 |
金属工艺 | 32篇 |
机械仪表 | 29篇 |
建筑科学 | 20篇 |
矿业工程 | 1篇 |
能源动力 | 129篇 |
轻工业 | 70篇 |
水利工程 | 7篇 |
石油天然气 | 6篇 |
无线电 | 140篇 |
一般工业技术 | 274篇 |
冶金工业 | 159篇 |
原子能技术 | 17篇 |
自动化技术 | 200篇 |
出版年
2024年 | 6篇 |
2023年 | 19篇 |
2022年 | 31篇 |
2021年 | 57篇 |
2020年 | 48篇 |
2019年 | 53篇 |
2018年 | 54篇 |
2017年 | 46篇 |
2016年 | 53篇 |
2015年 | 39篇 |
2014年 | 44篇 |
2013年 | 112篇 |
2012年 | 60篇 |
2011年 | 82篇 |
2010年 | 68篇 |
2009年 | 66篇 |
2008年 | 47篇 |
2007年 | 53篇 |
2006年 | 41篇 |
2005年 | 28篇 |
2004年 | 27篇 |
2003年 | 37篇 |
2002年 | 19篇 |
2001年 | 23篇 |
2000年 | 27篇 |
1999年 | 17篇 |
1998年 | 37篇 |
1997年 | 32篇 |
1996年 | 26篇 |
1995年 | 12篇 |
1994年 | 18篇 |
1993年 | 14篇 |
1992年 | 15篇 |
1991年 | 12篇 |
1990年 | 7篇 |
1989年 | 9篇 |
1988年 | 9篇 |
1987年 | 6篇 |
1986年 | 4篇 |
1985年 | 9篇 |
1984年 | 7篇 |
1983年 | 5篇 |
1981年 | 5篇 |
1980年 | 6篇 |
1979年 | 8篇 |
1978年 | 6篇 |
1977年 | 8篇 |
1976年 | 6篇 |
1975年 | 3篇 |
1974年 | 3篇 |
排序方式: 共有1434条查询结果,搜索用时 0 毫秒
11.
MODELING AND PREDICTIVE CONTROL OF MIMO NONLINEAR SYSTEMS USING WIENER-LAGUERRE MODELS 总被引:1,自引:0,他引:1
Prabirkumar Saha S. H. Krishnan V. S. R. Rao Sachin C. Patwardhan 《Chemical Engineering Communications》2004,191(8):1083-1119
In this work, a Weiner-type nonlinear black box model was developed for capturing dynamics of open loop stable MIMO nonlinear systems with deterministic inputs. The linear dynamic component of the model was parameterized using orthogonal Laguerre filters while the nonlinear state output map was constructed either using quadratic polynomial functions or artificial neural networks. The properties of the resulting model, such as open loop stability and steady-state behavior, are discussed in detail. The identified Weiner-Laguerre model was further used to formulate a nonlinear model predictive control (NMPC) scheme. The efficacy of the proposed modeling and control scheme was demonstrated using two benchmark control problems: (a) a simulation study involving control of a continuously operated fermenter at its optimum (singular) operating point and (b) experimental verification involving control of pH at the critical point of a neutralization process. It was observed that the proposed Weiner-Laguerre model is able to capture both the dynamic and steady-state characteristics of the continuous fermenter as well as the neutralization process reasonably accurately over wide operating ranges. The proposed NMPC scheme achieved a smooth transition from a suboptimal operating point to the optimum (singular) operating point of the fermenter without causing large variation in manipulated inputs. The proposed NMPC scheme was also found to be robust in the face of moderate perturbation in the unmeasured disturbances. In the case of experimental verification using the neutralization process, the proposed control scheme was found to achieve much faster transition to a set point close to the critical point when compared to a conventional gain-scheduled PID controller. 相似文献
12.
K. C. A. Alam B. B. Saha A. Akisawa T. Kashiwagi 《Chemical Engineering Communications》2004,191(7):981-997
This article aims at clarifying the possible design and operating conditions for silica gel-water adsorption refrigeration cycles driven by near-ambient temperature waste heat sources (between 45 and 75°C) with relatively small regenerating temperature lifts (15 to 45 K). A two-stage silica gel-water advanced adsorption chiller is introduced and a simulation model of the chiller was developed to analyze the influence of operating and design conditions on the system performance (coefficient of performance, COP, and cooling capacity). It was hypothesized that the proposed chiller can be driven by low temperature waste heat at 55°C to produce effective cooling. Simulation results show that the operating conditions such as cycle time and hot and cooling water inlet temperature have an influential effect on cooling capacity and COP. COP is proportional to cycle time and heat transfer coefficient as well as inversely proportional to the cooling water inlet temperature, while there are optimum values of hot water temperature and silica gel weight for maximum COP. Cooling capacity mainly improves with the addition of silica gel weight and decreases as cooling water temperature increases. Simulation results also revealed that the system performance can be improved significantly by setting the design and operating conditions optimally. 相似文献
13.
The rates of absorption of CO2 into water and 0.1 kmol/m3 aqueous solutions of MEA, DEA and AMP were measured in a stirred cell with a flat gas-liquid interface in the presence of fine activated carbon particles. Experiments showed that the rates of absorption increased significantly with increases in the loading of activated carbon up to about 6 kg/m3 and thereafter remained constant. 相似文献
14.
In this paper, optimal sets of filter coefficients are searched by a meta-heuristic optimization technique called Harmony Search (HS) algorithm for infinite impulse response (IIR) system identification problem. For different optimization problems, HS algorithm undergoes three basic rules; namely Random Selection (RS), Harmony Memory Consideration (HMC), and Pitch Adjustment (PA) rules, which are inspired from the process that the musicians use to improvise a perfect state of harmony with the consummate skill of blending notes in tune. With the help of the properly selected control parameters, a perfect balance is achieved in exploration and exploitation in searching phases. The detailed analysis of simulation results emphasizes the strength of HS algorithm to find the near-global optimal solution, quality of convergence profile and the speed of convergence while tested against standard benchmark examples for same and reduced order models. 相似文献
15.
Influence of Distributed Particle Size on the Determination of the Parabolic Rate Constant for Oxidation by the Powder Method 总被引:1,自引:0,他引:1
The established analysis for the study of oxidation using powder specimens is based on the assumption of monosized particles. The experiments, however, are conducted on powders with a distributed particle size. Here we present a statistical approach for the calculation of the rate constant for oxidation. The results of the analysis are applied to new data on oxidation studies of dense powders of silicon carbonitride amorphous ceramics. The monosized model requires a wide range of values for the rate constant to fit the short term and the long-term data, leading to considerable ambiguity in the estimate of the parabolic rate constant, k p , for oxidation. In contrast the statistical model fits over the entire range of data, yielding a much more reliable value for k p . For example, the monosized approach gave a value in the range 19.7 × 10−18 < k p < 2.7 × 10−18 m2 /s. In contrast, the statistical model yields a specific value of 4.5 × 10−18 m2 /s. 相似文献
16.
17.
Quantum information processing is largely dependent on the robustness of non-classical correlations, such as entanglement and quantum discord. However, all the realistic quantum systems are thermodynamically open and lose their coherence with time through environmental interaction. The time evolution of quantum entanglement, discord, and the respective classical correlation for a single, spin-1/2 particle under spin and energy degrees of freedom, with an initial Werner state, has been investigated in the present study. The present intra-particle system is considered to be easier to produce than its inter-particle counterpart. Experimentally, this type of system may be realized in the well-known Penning trap. The most stable correlation was identified through maximization of a system-specific global objective function. Quantum discord was found to be the most stable, followed by the classical correlation. Moreover, all the correlations were observed to attain highest robustness under initial Bell state, with minimum possible dephasing and decoherence parameters. 相似文献
18.
Multifocus image fusion is the process of obtaining a single image from multiple partially focused images such that the newly formed image consists of the well-defined information extracted from each source image. This paper proposes the use of saliency of the source images based on Mutual Spectral Residual. Spectral Residual brings out the unique/salient features of an image in frequency domain. The idea of proposed mutual spectral residual is to emphasize the relative unique features of a source image with respect to the other source images. The relative unique features are utilized to form saliency maps for each source image. These saliency maps can clearly indicate the focused and defocused parts of an image. Based on the saliency maps obtained, the image fusion takes place in spatial domain. Visual inspection and quantitative evaluation of the fused images obtained by the proposed method, using different evaluation metrics, demonstrate its effectiveness over several existing image fusion methods. 相似文献
19.
Probir Saha Debashis Tarafdar Surjya K. Pal Partha Saha Ashok K. Srivastava Karabi Das 《Applied Soft Computing》2013,13(4):2065-2074
This paper proposed a Neuro-Genetic technique to optimize the multi-response of wire electro-discharge machining (WEDM) process. The technique was developed through hybridization of a radial basis function network (RBFN) and non-dominated sorting genetic algorithm (NSGA-II). The machining was done on 5 vol% titanium carbide (TiC) reinforced austenitic manganese steel metal matrix composite (MMC). The proposed Neuro-Genetic technique was found to be potential in finding several optimal input machining conditions which can satisfy wide requirements of a process engineer and help in efficient utilization of WEDM in industry. 相似文献
20.
Irfan Ahmad Rather Gulshan Kumar Rahul Saha 《International Journal of Communication Systems》2023,36(9):e5473
In heterogeneous access network, Multiple-Input Multiple-Output (MIMO) radio-over-fiber (RoF) system is an efficient approach for multiple signal transmission with low cost and complexity. The performance of RoF fronthaul system in MIMO system will be varied with different nonlinear effects. By adjusting various transmission parameters, such as the input signal power or the laser bias current, the nonlinear impacts produced by the RoF system can be reduced. In this paper, a novel algorithm Improved Aquila Optimization (IAO) is proposed to optimize transmission circumstances of MIMO RoF system. It determines the appropriate bias current for both lasers and Radio Frequency (RF) signal power in a short period. The input signals are wavelength multiplexed with Intensity Modulation and Direct Detection (IM/DD) applied. The carrier as well as transmission frequency is governed by the MIMO-Long-Term Evolution (LTE) standard. The proposed system is implemented in MATLAB, and the performance is evaluated. The experimental results show that fast convergence and trade-off between noise and nonlinearity are obtained with varying bandwidth. In the experimental scenario, the maximum Error Vector Magnitude (EVM) of 1.88, 3.14, and signal-to-noise ratio (SNR) of 3.204, and 2.698 was attained for both quadrature phase shift keying (QPSK) and quadrature amplitude modulation (QAM) modulation. [Correction added on 24 April 2023, after first online publication: the SNR values were corrected in the preceding sentence.] For 100 iterations, the processing time was reduced to 0.137 s. When compared with the conventional state-of-the-art approaches, the accuracy and computational complexity of the proposed approach are improved. 相似文献