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981.
982.
983.
In this paper, we consider the problem of flocking and shape‐orientation control of multi‐agent systems with inter‐agent and obstacle collision avoidance. We first consider the problem of forcing a set of autonomous agents to form a desired formation shape and orientation while avoiding inter‐agent collision and collision with convex obstacles, and following a trajectory known to only one of the agents, namely the leader of the formation. Then we build upon the solution given to this problem and solve the problem of guaranteeing obstacle collision avoidance by changing the size and the orientation of the formation. Changing the size and the orientation of the formation is helpful when the agents want to go through a narrow passage while the existing size or orientation of the formation does not allow this. We also propose collision avoidance algorithms that temporarily change the shape of the formation to avoid collision with stationary or moving nonconvex obstacles. Simulation results are presented to show the performance of the proposed control laws. 相似文献
984.
We present a new type of calorimeter in which we couple an unknown heat capacity with the aid of Peltier elements to an electrical circuit. The use of an electrical inductance and an amplifier in the circuit allows us to achieve autonomous oscillations, and the measurement of the corresponding resonance frequency makes it possible to accurately measure the heat capacity with an intrinsic statistical uncertainty that decreases as ~t(m)(-3/2) with measuring time t(m), as opposed to a corresponding uncertainty ~t(m)(-1/2) in the conventional alternating current method to measure heat capacities. We have built a demonstration experiment to show the feasibility of the new technique, and we have tested it on a gadolinium sample at its transition to the ferromagnetic state. 相似文献
985.
Balderas-López JA Díaz-Reyes J Zelaya-Angel O 《The Review of scientific instruments》2011,82(12):124901
A photoacoustic (PA) methodology, in the transmission configuration, for simultaneous measurements of thermal effusivity and molar absorption coefficient (absorptivity) for pigments in liquid solution is introduced. The analytical treatment involves a self-normalization procedure for the PA signal, as a function of the modulation frequency, for a strong absorbing material in the thermally thin regime, when the light travels across the sample under study. Two fitted parameters are obtained from the analysis of the self-normalized PA amplitude and phase, one of them proportional to the sample's optical absorption coefficient and from which, taking it for a series of samples at different concentrations, the pigment's absorptivity in liquid solution can be measured, the other one yields the sample's thermal effusivity. Methylene blue's absorptivity in distilled water was measured with this methodology at 658 nm, finding good agreement with the corresponding one reported in the literature. 相似文献
986.
Tholén EA Platz D Forchheimer D Schuler V Tholén MO Hutter C Haviland DB 《The Review of scientific instruments》2011,82(2):026109
Nonlinear systems can be probed by driving them with two or more pure tones while measuring the intermodulation products of the drive tones in the response. We describe a digital lockin analyzer which is designed explicitly for this purpose. The analyzer is implemented on a field-programmable gate array, providing speed in analysis, real-time feedback, and stability in operation. The use of the analyzer is demonstrated for intermodulation atomic force microscopy. A generalization of the intermodulation spectral technique to arbitrary drive waveforms is discussed. 相似文献
987.
M. Esbjörnsson O. Juhlin A. Weilenmann 《International journal of human-computer interaction》2013,29(1-2):37-58
Abstract Mobile phone use in cars is a highly debated issue. Legislation and policy discussions flourish in many countries and coincide with an increased effort in design of new in-car technologies. The studies that influence policy and design decisions use experimental approaches and are based on a cognitive perspective. This article discusses why this is a problematic approach. Further, the article provides data and initial results from an ethnographic study of mobile phone use in traffic, where the aim is to investigate the interactional adaptation by which the driver fit the involvement with the phone with driving and vice versa. By taking part of drivers'daily work and video recording their activities of driving and handling the mobile phone, details are revealed that could not be found in experimental studies with a constructed setup. The article ends with a discussion of the benefits of this method and how it can be developed further. 相似文献
988.
The solution to the nonlinear output regulation problem requires one to solve a first‐order partial differential equation, known as the Francis–Byrnes–Isidori equations. In this paper, we propose a method to compute approximate solutions to the Francis–Byrnes–Isidori equations when the zero dynamics of the plant are hyperbolic and the exosystem is two dimensional. With our method, we are able to produce approximations that converge uniformly to the true solution. Our method relies on the periodic nature of two‐dimensional analytic center manifolds. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
989.
The problem of finding the optimal control over the portfolio for an investor in (B, S)-market is considered. Clark’s model is taken as a model for the stock price evolution. The cases of risk-loving, risk-neutral, and risk-averse investors are considered. 相似文献
990.
A. I. Kibzun M. N. Krasil’shchikov V. L. Miroshkin K. I. Sypalo 《Journal of Computer and Systems Sciences International》2013,52(4):628-636
An approach to the control of the motion of the center of mass of a high altitude hypervelocity flying vehicle whose engine thrust and aerodynamics strongly depend on the angle of attack in the midcourse active phase of the flight is proposed. This approach provides a basis for the method of the trajectory control of motion. The motion of this flying vehicle is simulated with regard to the disturbed atmosphere. It is shown that the proposed approach can be used to form launching zones of high altitude hypervelocity flying vehicles. 相似文献