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951.
This paper studies the stabilisability and the performance of stochastic disturbance attenuation of a Markov jump linear system whose feedback channel is subject to an additive white Gaussian noise. First an inequality of differential entropy of random vectors under Markov switching is presented. Then by the concept of entropy power and the theory of information, a necessary condition to stabilise the system is obtained. This requires that the signal-to-noise ratio in the feedback channel is bigger than a specified value. Furthermore, to evaluate the performance of disturbance attenuation, a lower bound of the maximum fluctuation of the system state is presented.  相似文献   
952.
A neural/fuzzy optimal process model for robotic part assembly   总被引:1,自引:0,他引:1  
A process model for part assembly task, using robotic manipulators, is introduced. A neural network control strategy, based on measured force and moment data, for avoiding jamming during part insertion is presented. Fuzzy set theory, well-suited to the management of uncertainty, is introduced to address the uncertainty problem associated with the part insertion procedure. The degree of uncertainty associated with the part insertion is used as an optimality criterion for a specific task execution. The proposed technique is applicable to a wide range of robotic tasks including part mating with various shaped parts.  相似文献   
953.
The use of ontologies for knowledge sharing and distributed collaboration has been widely recognised in the knowledge modelling community, but the lack of a systematic and constructive methodology for developing manufacturing ontologies has impeded their wide usage for knowledge reuse in distributed manufacturing environments. This paper presents a constructive, two-level knowledge modelling approach to systematically develop manufacturing ontologies using both software engineering and Semantic Web paradigms. The UML/OCL (Unified Modeling Language/Object Constraint Language)-based object modelling is used first to serve as a graphical and structured basis for conceptual communication between domain experts and knowledge engineers. The OWL/SWRL (Web Ontology Language/Semantic Web Rule Language)-based ontology modelling then extends the UML/OCL-based object models with added semantics using a progressive, semantics-oriented knowledge acquisition method. An illustrative example for manufacturing ontology development in the manufacturing industry for producing electronic connectors is used to demonstrate the practicality of the proposed approach.  相似文献   
954.
In this work, the method of moments is used for solution of population balance equations appearing in modeling of emulsion polymerization (EP). The zero-one model without coagulation effect and the pseudo-bulk model including coagulation effect are investigated as two common approaches for modeling EP processes. The fixed quadrature method is used to close the set of moment equations, and the maximum entropy approach is applied to reconstruct the particle size distribution from a finite number of its moments. Comparing the results with those obtained by the high-precision finite volume technique indicates that, despite the low computational load of the moment method, it has an acceptable accuracy. These features support use of the moment technique for other applications such as on-line control or optimization in particulate processes.  相似文献   
955.
Causality inference and root cause analysis are important for fault diagnosis in the chemical industry. Due to the increasing scale and complexity of chemical processes, data-driven methods become indispensable in causality inference. This paper proposes an approach based on the concept of transfer entropy which was presented by Schreiber in 2000 to generate a causal map. To get a better performance in estimating the time delay of causal relations, a modified form of the transfer entropy is presented in this paper. Case studies on two simulated chemical processes, including the benchmark Tennessee Eastman process are performed to illustrate the effectiveness of this approach.  相似文献   
956.
The biological pharmaceutical market is one of the fastest growing sectors in the health care business. Sales of biologic drugs reached $120 billion in 2008 [1] and the worldwide market of biologics continues to grow (IMS Health). As patents on first generation of biologic drugs, including epoetin, insulin granulocyte colony-stimulating factor (G-CSF) and interferon alpha, will soon expire, if they have not already, and patents on some of the second generation of biological drugs, such as antibody drugs, are going to be expire in the next few years, there exists a great opportunity in developing biosimilars, especially for large pharmaceutical companies which face great challenges in developing new blockbuster drugs. In the past few years, the United States, Canada, and Japan have debated or passed legislation on biosimilars with active involvement from top pharmaceutical and generic drug companies. The successful leader in this field will be the one that has the foresight and resources to position themselves well to gain in the future. So what are biosimilars? What are the technological differences between biosimilars and small molecule generic drugs? Finally, what are the considerations for biosimilars in terms of patent searching? An example on a biosimilar study is given here.  相似文献   
957.
958.
Melting of solid chemical elements has recently been explained by electronic transitions. Due to such transitions into higher energy levels the wave‐functions and their local charge distributions are changed. Since the occupation of the electronic states and the corresponding charge distribution change at random with time, the core ions are continuously driven to new positions. If the forces are strong enough and the core ions relax to their new positions within the lifetime of the excited states, the changing arrangement of the core ions corresponds to a melt. These considerations are extended from elements to chemical compounds as one‐component systems. The melting entropy and the specific heat capacities near the melting temperature have been normalised to the number of atoms in the formula unit of the one‐component systems. The heat capacities exceed 3R, which is the value expected for vibrations, and accumulate surprisingly at special values as well as the melting entropies. This seems to support the idea of melting as an electronically induced effect. The distributions of the electronic energy levels in the molten state and in the crystalline solid are different. If the forces of the electronic distribution in the relaxed low energy states of the undercooled melt are too weak to attract the core ions to regular lattice positions, the disorder is frozen‐in during cooling and a glass transition takes place. Sufficiently strong directional bonds between neighbouring ions and low melting entropy per particle favour such a transition.  相似文献   
959.
本文计算了环丙烷-1-丁烯体系的化工热力学数据,分析了45%环丙烷-55%1-丁烯在制冷循环中的应用,认为:该体系用于制冷循环比氟利昂R12节能5.4%。  相似文献   
960.
地震资料的双约束频谱补偿方法   总被引:4,自引:0,他引:4  
孙成禹 《石油物探》2000,39(1):35-41
指出了现行的最小熵高频外推方法存在的一些问题,在此基础上首次提出“理论记录+熵”约束的频谱补偿方法,并给予了具体实现。该方法以往的“最小熵”为“熵约束”,利用对数锭义的熵模,要求频率补偿后 约束条件靠近的同时,记录的 向约束条件的熵模靠近,并且保持有效频带内的频率成分不变。这一方法有效地保证了弱小反射不被压制,且同相轴原有的基本特征保持不变。理论模型和实际资料的处理都证明了该方法的正确性。  相似文献   
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