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61.
By modeling mass transfer phenomena, we simulate solids and liquids dissolving or changing to other substances. We also deal with the very small‐scale phenomena that occur when a fluid spreads out at the interface of another fluid. We model the pressure at the interfaces between fluids with Darcy's Law and represent the viscous fingering phenomenon in which a fluid interface spreads out with a fractal‐like shape. We use hybrid grid‐based simulation and smoothed particle hydrodynamics (SPH) to simulate intermolecular diffusion and attraction using particles at a computable scale. We have produced animations showing fluids mixing and objects dissolving. 相似文献
62.
63.
A telebiometric system mechanism model and biometric network protocol for the security of networked manufacturing 总被引:1,自引:1,他引:0
Networked manufacturing changes conventional enterprise activities. With a networked manufacturing system, enterprises are
able to perform a range of activities, such as product planning, design, production, and marketing, in collaboration with
international partners, regardless of geographical location. However, strict security measures are required, as the authentication
and information transfers for networked manufacturing are conducted over a network. With the development of biometric technology,
more and more enterprises are using the unique biometric data of individuals to verify the identity of users, in order to
restrict and provide access to technology research centers or factory facilities. This paper analyzes the vulnerabilities
of the biometric system used for access control and the authentication of access to confidential information in the networked
manufacturing system. In addition, the biometric systems that can be built in an open network environment are classified into
9 general models, and a biometric network protocol is suggested that is secure and compatible with international standards. 相似文献
64.
Examining influencing factors of post-adoption usage of mobile internet: Focus on the user perception of supplier-side attributes 总被引:1,自引:0,他引:1
Young Mee Shin Seung Chang Lee Bongsik Shin Ho Geun Lee 《Information Systems Frontiers》2010,12(5):595-606
Key supplier-side factors that affect the usage level of mobile Internet were identified and the procedural mechanism among
the independent and dependent variables was investigated. For this, a research model was introduced to describe associations
among four external variables (access quality, service variety, cost rationality, and ease of use), an intermediate variable
(usefulness) and a dependent variable (the usage level of mobile Internet). Through the on-line survey, data were gathered
from actual mobile Internet users. Confirmatory factor analysis and path analysis were applied to test the overall integrity
of the research model and of proposed hypotheses. All four external variables affected user perceptions on the usefulness
of mobile Internet. Among them, service variety and cost rationality had a relatively larger influence on perceived usefulness.
Perceived usefulness of the mobile Internet had a positive effect on its usage, confirming the important role of usefulness
as a significant mediator between the four external variables and the dependent variable. Meanwhile, the cost rationality
was the only external variable with direct influence on the MI usage. Theoretical and practical implications of the study
results are discussed. 相似文献
65.
The conventional approach to reducing control signal chattering in sliding mode control is to use the boundary layer design. However, when there is high‐level measurement noise, the boundary layer design becomes ineffective in chattering reduction. This paper, therefore, proposes a new design for chattering reduction by low‐pass filtering the control signal. The new design is non‐trivial since it requires estimation of the sliding variable via a disturbance estimator. The new sliding mode control has the same performance as the boundary layer design in noise‐free environments, and outperforms the boundary layer design in noisy environments. Copyright © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society 相似文献
66.
Wonseok Lee Young-bong Bang Kyung-min Lee Bu-hyun Shin Jamie Kyujin Paik In-su Kim 《International Journal of Control, Automation and Systems》2010,8(5):1072-1081
Conventional robot motion teaching methods use a teaching pendant or a motion capture device and are not the most convenient
or intuitive ways to teach a robot sophisticated and fluid movements such as martial arts motions. Ideally, a robot could
be set up as if it were a clothing mannequin that has light limbs and flexible yet frictional joints which can be positioned
at desirable shape and hold all the positions. To do the same with a robot, an operator could pull or push the links with
minor forces until the desired robot posture is attained. For this, a robot should measure the applied external force by using
torque sensors at the robot joints. However, torque sensors are bulky and expensive to install in every DOF joints while keeping
a compact design, which is essential to humanoid robots. In this paper, we use only motor current readings to acquire joint
torques. The equations used to compensate for the effect of gravity on the joint torques and the self-calibration method to
earn link parameters are presented. Additionally, kinematic restrictions can be imposed on the robot’s arms to simplify the
motion teaching. Here, we teach the Kendo training robot with this method and the robot’s learnt martial art motions are demonstrated. 相似文献
67.
Sangmun Shin Nguyen Khoa Viet Truong Byung Rae Cho Sung Hoon Hong 《Computers & Industrial Engineering》2011
Robust design (RD) and tolerance design (TD) have received much attention from researchers and practitioners for more than two decades, and a number of methodologies for modeling and optimizing the RD and TD processes have been studied. However, there is ample room for improvement. Because most existing research considers RD and TD as separate research fields, the primary objective of this paper is to develop a sequential robust–tolerance design method to jointly determine the best factor settings and the closed-form solutions for the optimal specification limits. We then apply the proposed method to a destructive quality characteristic. Finally, a case study and sensitivity analyses are performed for verification purposes, and further studies are discussed. 相似文献
68.
Juyoung Wy Sangwon Jeong Byung-In Kim Junhyuk Park Jaejoon Shin Hyunjoong Yoon Sujeong Lee 《Computers & Industrial Engineering》2011
Simulation has been used to evaluate various aspects of manufacturing systems. However, building a simulation model of a manufacturing system is time-consuming and error-prone because of the complexity of the systems. This paper introduces a generic simulation modeling framework to reduce the simulation model build time. The framework consists of layout modeling software and a data-driven generic simulation model. The generic simulation model was developed considering the processing as well as the logistics aspects of assembly manufacturing systems. The framework can be used to quickly develop an integrated simulation model of the production schedule, operation processes and logistics of a system. The framework was validated by developing simulation models of cellular and conveyor manufacturing systems. 相似文献
69.
This paper presents an evolutionary algorithm, called the multi-objective symbiotic evolutionary algorithm (MOSEA), to solve a multi-objective FMS process planning (MFPP) problem with various flexibilities. The MFPP problem simultaneously considers four types of flexibilities related to machine, tool, sequence, and process and takes into account three objectives: balancing the machine workload, minimizing part movements, and minimizing tool changes. The MOSEA is modeled as a two-leveled structure to find a set of well-distributed solutions close to the true Pareto optimal solutions. To promote the search capability of such solutions, two main processes imitating symbiotic evolution and endosymbiotic evolution are introduced, together with an elitist strategy and a fitness sharing scheme. Evolutionary components suitable for the MFPP problem are provided. With a variety of test-bed problems, the performance of the proposed MOSEA is compared with those of existing multi-objective evolutionary algorithms. The experimental results show that the MOSEA is promising in solution convergence and diversity. 相似文献
70.
Usage of frequency based error correction methods for repetitive disturbances becomes popular in data storage devices that use a rotating mechanical power plant. Two distinct disturbance cancellation methods, disturbance observer (DOB) and adaptive feed forward control (AFC) are the most popular approaches used for current drive servo integration. DOB reduces error using a predetermined function that is calculated thorough a complicated process. Generally the response to disturbance and initiation of control action of DOB is relatively fast even if the amount of error reduction is limited. Meanwhile the error elimination capability of AFC for the repetitive disturbance is normally better than DOB as it utilizes a Fourier coefficients updating feature that supports an enhanced fine adaptation of a certain frequency disturbance. Of course, AFC suffers for disturbances that have neighboring close frequencies due to the inherent fundamental frequency dependencies of AFC formulation. In the present work, an attempt for combining benefits of AFC and DOB is made. This might enables control action not only to generate fast response to disturbance but also perform an accurate error rejection. This feature also provides to the closed loop system a frequency selection for enabling a strategic selective error rejection. The proposed method named Hybrid Disturbance Observer (HDOB) is compared to the traditional AFC and DOB. 相似文献