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111.
The origin of the main electron trap (0.83 eV) in GaAs is investigated by creating conditions to favour the formation of Ga-vacancy-oxygen complex in the material. Two specific schemes have been used, (1) Liquid phase epitaxial (LPE) growth of the material at high temperatures (≈1000°C) with oxygen doping and (2) Electron bombardment of LPE material and subsequent annealing. The traps have been characterised by transient capacitance technique. The results show that the main electron trap cannot be produced by either of the schemes thereby implying that a complex involving Ga-vacancy and oxygen may not be responsible for the trap. 相似文献
112.
J. S. Arora E. J. Haug 《International journal for numerical methods in engineering》1976,10(4):747-766
The purpose of this paper is to present refinements in a steepest descent algorithm for optimal design of structures and numerical experience that demonstrates its numerical efficiency. The algorithm is based on a state space optimization technique that was initially developed and applied to optimal control problems. Design constraints are divided into four distinct subsets, the special characteristics of which are exploited to improve computational efficiency of the algorithm. Some further improvements in structural analysis, design sensitivity analysis, and constrained steepest descent programming calculations are presented. Optimum designs for three test problems are obtained and convergence rates are compared with results presented in the literature. 相似文献
113.
In this paper, an implementation scheme involving decoders and residue adders has been suggested to convert input data in fixed radix representation to residue representation. A method dealing with the reverse process is also demonstrated. A comparison has been made with the methods known hitherto. 相似文献
114.
Ashok D. Belegundu Jasbir S. Arora 《International journal for numerical methods in engineering》1984,20(5):803-816
Recursive quadratic programming methods have become popular in the field of mathematical programming owing to their excellent convergence characteristics. There are two recursive quadratic programming methods that have been published in the literature. One is by Han and the other is by Pshenichny, published in 1977 and 1970, respectively. The algorithm of Pshenichny had been undiscovered until now, and is examined here for the first time. It is found that the proof of global convergence by Han requires computing sensitivity coefficients (derivatives) of all constraint functions of the problem at every iteration. This is prohibitively expensive for large-scale applications in optimal design. In contrast, Pshenichny has proved global convergence of his algorithm using only an active-set strategy. This is clearly preferable for large-scale applications. The method of Pshenichny has been coded into a FORTRAN program. Applications of this method to four example problems are presented. The method is found to be very reliable. However, the method is found to be very sensitive to local minima, i.e. it converges to a local minimum nearest to the starting design. Thus, for optimal design problems (which usually possess multiple local minima) it is suggested that Pshenichny's method be used as part of a hybrid method. 相似文献
115.
Su L.T. Antoniadis D.A. Arora N.D. Doyle B.S. Krakauer D.B. 《Electron Device Letters, IEEE》1994,15(10):374-376
A simple methodology to accurately extract constant temperature model parameters from static measurements of fully-depleted SOI MOSFET current-voltage characteristics is demonstrated. Self-heating is included in an existing physically-based, short-channel bulk MOSFET model, PCIM, by allowing the temperature to change linearly with power dissipation at each bias point. Only a simple modification of the channel bulk charge in PCIM is necessary to adapt it for SOI. The temperature dependence of the physical parameters (mobility, flatband voltage, and saturation velocity) are also fitted and included in the model. Excellent fit to experimental fully-depleted SOI data is shown over a large range of bias conditions and channel lengths. Once the static SOI data is fitted, the constant temperature model parameters appropriate for circuit simulation are easily extracted 相似文献
116.
This paper presents methods of design sensitivity analysis and optimization of dynamic response of mechanical and structural systems. The point-wise state variable constraint function is divided into time sub-domains such that each sub-domain contains only one local maximum point. Then, the original constraint is replaced by a number of equivalent functional constraints. Each functional constraint is the integration of the positive value of the original constraint over its own time sub-domain. A direct differentiation method and three adjoint variable methods of design sensitivity analysis are presented. All of these methods are discussed and compared. It turns out that two of the adjoint variable methods are more efficient than others. A hybrid optimization algorithm based on these methods is proposed in detail. Two problems are solved for optimal design. Comparisons of results with those available in the literature are made. Numerical experience with the proposed method is discussed in detail. It is concluded that the new formulation is extremely efficient and converges to either optimal or near optimal solutions without any difficulty. 相似文献
117.
Utkarsh Deshmukh Sumit Arora Deepika Kathuria Ashish Kumar Singh Shaik Abdul Hussain Richa Singh 《International Journal of Dairy Technology》2023,76(3):533-543
Changes in techno-functional properties of buffalo milk were evaluated due to variation in calcium content. Decalcification resulted in significant variation in ζ-potential, casein size, colour and ηapp. However, calcium addition only influenced ζ-potential of milk. In case of acid gelation, the time and temperature required for coagulation decreased significantly for both calcium-depleted and -added milks. However, during chymosin gelation, only 20%–30% of calcium-depleted milk coagulated with an increased clotting time. Furthermore, calcium addition increased firmness, consistency and cohesiveness of both chymosin and acid-induced gelation. 相似文献
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