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971.
本文在运用模糊数学和概率统计原理的基础上,结合Mathematic软件的回归计算功能,初步探索了一种由配电网主要结构参数和运行参数构成的简单实用的线损计算模型。并对某市配电网线损进行了计算分析,结果满意。  相似文献   
972.
基于遗传算法的电力系统聚类模糊稳定器的设计   总被引:2,自引:2,他引:2  
为了抑制电力系统因负阻尼而产生的低频振荡,提高系统稳定性,将具有自学习能力的聚类算法和常规模糊控制相结合,提出了一种新型的聚类自适应模糊控制方案,应用于非线性和强耦合的电力系统中,并用一种加速搜索过程的改进遗传算法将常规模糊控制器的隶属参数进行了优化。仿真结果表明,该方案的自适应性、实时性、鲁棒性都很强。  相似文献   
973.
基于模糊聚类的神经网络模型及其在渗流分析中的应用   总被引:5,自引:0,他引:5  
本文采用模糊聚类理论方法对因子集进行模糊聚类 ,然后利用神经网络的方法建立样本因子集类别变量特征值与样本观测值之间的预测模型 ,提出了将模糊聚类、模糊模式识别以及神经网络三者有机结合的预测理论。并通过某大坝渗流计算实例对传统的统计预报模型和基于模糊聚类的神经网络预测模型进行了比较 ,结果表明后者的预报精度比前者要高。  相似文献   
974.
R. A.  F. J.  E. 《Pattern recognition》2002,35(12):2771-2782
A generalized prototype-based classification scheme founded on hierarchical clustering is proposed. The basic idea is to obtain a condensed 1-NN classification rule by merging the two same-class nearest clusters, provided that the set of cluster representatives correctly classifies all the original points. Apart from the quality of the obtained sets and its flexibility which comes from the fact that different intercluster measures and criteria can be used, the proposed scheme includes a very efficient four-stage procedure which conveniently exploits geometric cluster properties to decide about each possible merge. Empirical results demonstrate the merits of the proposed algorithm taking into account the size of the condensed sets of prototypes, the accuracy of the corresponding condensed 1-NN classification rule and the computing time.  相似文献   
975.
从电力与环境的关系入手,分析电力生产的环境影响问题及其改善途径。简介日趋势严格的国际性环保条约、规定和有关排放标准,以及由引而导电力工业生产技术改进与发展趋势。最后展望了我国未来电力与环境协调发展的规划和前景。  相似文献   
976.
0~adosAdesignmethodisselectedaccoldingtotheobjectandtheenvironmentfortheconealengineeringandsimulahonsystem.ThemathematicalmodelingisalmoStimPOssibleforsomecomplexcontrolsystem.fothefuZZycontroliswidelyappliedforitSindependenceofthemathematicalmodelingOftheobject["'].However,expertcontrolrulesaregenelallyreqUiredforsystemdesign.Whatcanbeobtainedinsomecasesarenumericalsampledatafromcontroloperationsensorsratherthansuchcontrolrules.ThisreqUirestheextractionof"if-then"fUZZyconealrulesfromthe…  相似文献   
977.
Although peer reviewing of writing is a way to create more writing opportunities in college and university settings, the validity and reliability of peer-generated grades are a major concern. This study investigated the validity and reliability of peer-generated writing grades of 708 students across 16 different courses from 4 universities in a particular scaffolded reviewing context: Students were given guidance on peer assessment, used carefully constructed rubrics, and were provided clear incentives to take the assessment task seriously. Distinguishing between instructor and student perspectives of reliability and validity, the analyses suggest that the aggregate ratings of at least 4 peers on a piece of writing are both highly reliable and as valid as instructor ratings while (paradoxically) producing very low estimates of reliability and validity from the student perspective. The results suggest that instructor concerns about peer evaluation reliability and validity should not be a barrier to implementing peer evaluations, at least with appropriate scaffolds. Future research needs to investigate how to address student concerns about reliability and validity and to identify scaffolds that may ensure high levels of reliability and validity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
978.
Summary In this paper we consider the problem of partitioning the set of nodes in a graph in at mostp classes, such that the sum of node weights in any class is not greater than the class capacityb, and such that the sum of edge weights, for edges connecting nodes in the same class, is maximal. This problem can be formulated as a MILP, which turns out to be completely symmetrical with respect to thep classes, and the gap between the relaxed LP solution and the optimal solution is the largest one possible. These two properties make it very difficult to solve even smaller problems. In this paper it is shown how it is possible to preassign certain nodes to certain classes, thus reducing both the symmetric nature of the formulation, the number of variables and constraints and the gap. It is also shown how the gap can be reduced even further by introducing combinatorial cuts. Computational results based on the two formulations of the problem and combinatorial cuts are presented.  相似文献   
979.
Neural networks have recently been proposed for the construction of navigation interfaces for Information Retrieval systems. In this paper, we give an overview of some current research in this area. Most of the cited approaches use (variants) of the well-known Kohonen network. The Kohonen network implements a topology-preserving dimensionality-reducing mapping, which can be applied for information visualization. We identify a number of problems in the application of Kohonen networks for Information Retrieval, most notably scalability, reliability and retrieval effectiveness. To solve these problems we propose to use the Growing Cell Structures network, a variant of the Kohonen network which shows a more flexible adaptation to the domain structure.This network was tested on two standard test-collections, using a combined recall and precision measure, and compared to traditional IR methods such as the Vector Space Model and various clustering algorithms. The network performs at a competitive level of effectiveness, and is suitable for visualization purposes. However, the incremental training procedures for the networks result in a reliability problem, and the approach is computationally intensive. Also, the utility of the resulting maps for navigation will need further improvement.  相似文献   
980.
Bax-induced cell death in Candida albicans   总被引:1,自引:0,他引:1  
Bax is a pro-apoptotic member of the Bcl-2 family of proteins involved in the regulation of genetically programmed cell death in mammalian cells. It has been shown that heterologous expression of Bax in several yeast species, such as Saccharomyces cerevisiae, Schizosaccharomyces pombe and Pichia pastoris, also induces cell death. In this study we investigated the effects of Bax expression in the pathogenic yeast Candida albicans. Cell death inducing expression of Bax required a synthetic BAX gene that was codon-optimized for expression in Candida albicans. Expression of this BAX gene resulted in growth inhibition and cell death. By fusing Bax with the yeast enhanced green fluorescent protein of Aequoria victoria, the cell death-inducing effect of Bax was increased due to reduced proteolytic degradation of Bax. Using this fusion protein we showed that, upon expression in C. albicans, Bax co-localizes with the mitochondria. Furthermore, we showed for the first time that expression of Bax in yeast causes the mitochondria, which are normally distributed throughout the cell, to cluster in the perinuclear region.  相似文献   
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