全文获取类型
收费全文 | 3294篇 |
免费 | 256篇 |
国内免费 | 175篇 |
专业分类
电工技术 | 450篇 |
综合类 | 315篇 |
化学工业 | 78篇 |
金属工艺 | 113篇 |
机械仪表 | 344篇 |
建筑科学 | 90篇 |
矿业工程 | 81篇 |
能源动力 | 62篇 |
轻工业 | 129篇 |
水利工程 | 21篇 |
石油天然气 | 20篇 |
武器工业 | 11篇 |
无线电 | 211篇 |
一般工业技术 | 293篇 |
冶金工业 | 44篇 |
原子能技术 | 3篇 |
自动化技术 | 1460篇 |
出版年
2024年 | 4篇 |
2023年 | 17篇 |
2022年 | 42篇 |
2021年 | 44篇 |
2020年 | 47篇 |
2019年 | 49篇 |
2018年 | 79篇 |
2017年 | 82篇 |
2016年 | 93篇 |
2015年 | 124篇 |
2014年 | 190篇 |
2013年 | 196篇 |
2012年 | 220篇 |
2011年 | 239篇 |
2010年 | 183篇 |
2009年 | 227篇 |
2008年 | 221篇 |
2007年 | 283篇 |
2006年 | 241篇 |
2005年 | 213篇 |
2004年 | 154篇 |
2003年 | 127篇 |
2002年 | 95篇 |
2001年 | 72篇 |
2000年 | 58篇 |
1999年 | 42篇 |
1998年 | 50篇 |
1997年 | 37篇 |
1996年 | 40篇 |
1995年 | 39篇 |
1994年 | 38篇 |
1993年 | 16篇 |
1992年 | 24篇 |
1991年 | 15篇 |
1990年 | 13篇 |
1989年 | 17篇 |
1988年 | 14篇 |
1987年 | 9篇 |
1986年 | 7篇 |
1985年 | 8篇 |
1984年 | 8篇 |
1983年 | 8篇 |
1982年 | 10篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1977年 | 4篇 |
1975年 | 2篇 |
1963年 | 2篇 |
1961年 | 3篇 |
排序方式: 共有3725条查询结果,搜索用时 46 毫秒
1.
Effects of Winding Attachment Positions on Output Characteristics of Flux‐Modulating Synchronous Machines 下载免费PDF全文
Hirofumi Aoki Tadashi Fukami Kazuo Shima Toshihiro Tsuda Mitsuhiro Kawamura 《Electrical Engineering in Japan》2015,191(3):40-49
The flux‐modulating synchronous machine (FMSM) is a new type of multipole SM with nonoverlapping concentrated armature and field windings on the stator. This paper compares the output characteristics of two FMSMs through finite element analysis (FEA) and experiments. In both of the FMSMs, the attachment positions of the armature and field windings are swapped. To determine the reason for the discrepancies in their output characteristics, unsaturated inductances were calculated using a d‐‐q equivalent circuit. In addition, the calculated results of the inductances were confirmed through a visualization of the leakage fluxes using FEA. The results of the study show that the synchronous inductance can be reduced by attaching the armature winding to the air‐gap side of the stator teeth and that the reduction leads to an increase in output power. 相似文献
2.
The aim of the research is evaluating the classification performances of eight different machine-learning methods on the antepartum cardiotocography (CTG) data. The classification is necessary to predict newborn health, especially for the critical cases. Cardiotocography is used for assisting the obstetricians’ to obtain detailed information during the pregnancy as a technique of measuring fetal well-being, essentially in pregnant women having potential complications. The obstetricians describe CTG shortly as a continuous electronic record of the baby's heart rate took from the mother's abdomen. The acquired information is necessary to visualize unhealthiness of the embryo and gives an opportunity for early intervention prior to happening a permanent impairment to the embryo. The aim of the machine learning methods is by using attributes of data obtained from the uterine contraction (UC) and fetal heart rate (FHR) signals to classify as pathological or normal. The dataset contains 1831 instances with 21 attributes, examined by applying the methods. In the paper, the highest accuracy displayed as 99.2%. 相似文献
3.
The ensemble learning paradigm has proved to be relevant to solving most challenging industrial problems. Despite its successful application especially in the Bioinformatics, the petroleum industry has not benefited enough from the promises of this machine learning technology. The petroleum industry, with its persistent quest for high-performance predictive models, is in great need of this new learning methodology. A marginal improvement in the prediction indices of petroleum reservoir properties could have huge positive impact on the success of exploration, drilling and the overall reservoir management portfolio. Support vector machines (SVM) is one of the promising machine learning tools that have performed excellently well in most prediction problems. However, its performance is a function of the prudent choice of its tuning parameters most especially the regularization parameter, C. Reports have shown that this parameter has significant impact on the performance of SVM. Understandably, no specific value has been recommended for it. This paper proposes a stacked generalization ensemble model of SVM that incorporates different expert opinions on the optimal values of this parameter in the prediction of porosity and permeability of petroleum reservoirs using datasets from diverse geological formations. The performance of the proposed SVM ensemble was compared to that of conventional SVM technique, another SVM implemented with the bagging method, and Random Forest technique. The results showed that the proposed ensemble model, in most cases, outperformed the others with the highest correlation coefficient, and the lowest mean and absolute errors. The study indicated that there is a great potential for ensemble learning in petroleum reservoir characterization to improve the accuracy of reservoir properties predictions for more successful explorations and increased production of petroleum resources. The results also confirmed that ensemble models perform better than the conventional SVM implementation. 相似文献
4.
In this paper, we study scheduling games under mixed coordination mechanisms on hierarchical machines. The two scheduling policies involved are ‐ and ‐, where ‐ (resp., ‐) policy sequences jobs in nondecreasing order of their hierarchies, and jobs of the same hierarchy in nonincreasing (resp., nondecreasing) order of their processing times. We first show the existence of a Nash equilibrium. Then we present the price of anarchy and the price of stability for the games with social costs of minimizing the makespan and maximizing the minimum machine load. All the bounds given in this paper are tight. 相似文献
5.
邱文平 《理化检验(物理分册)》2003,39(8):409-410
介绍了一种用三点弯曲试验法测定高性能大尺寸粘接永磁体粘合强度的方法,及利用布氏硬度计的加载系统,实现100%检验粘接质量的方法。 相似文献
6.
In this paper,a sequential algorithm computing the aww vertex pair distance matrix D and the path matrix Pis given.On a PRAM EREW model with p,1≤p≤n^2,processors,a parallel version of the sequential algorithm is shown.This method can also be used to get a parallel algorithm to compute transitive closure array A^* of an undirected graph.The time complexity of the parallel algorithm is O(n^3/p).If D,P and A^* are known,it is shown that the problems to find all connected components,to compute the diameter of an undirected graph,to determine the center of a directed graph and to search for a directed cycle with the minimum(maximum)length in a directed graph can all be solved in O(n^2/p logp)time. 相似文献
7.
介绍了某化纤厂引进意大利十二台粘胶连续纺丝机车间与以往的纺丝车间相比,空调设计中的节能途径,体现了既满足工艺要求,又降低生产成本的设计目的。 相似文献
8.
Melt index is considered an important quality variable determining product specifications. Reliable prediction of melt index (MI) is crucial in quality control of practical propylene polymerization processes. In this paper a least squares support vector machines (LS‐SVM) soft‐sensor model of propylene polymerization process is developed to infer the MI of polypropylene from other process variables. Considering the use of a SSE cost function without regularization might lead to less robust estimates; the weighted least squares support vector machines (weighted LS‐SVM) approach of propylene polymerization process is further proposed to obtain a robust estimation of melt index. The performance of standard SVM model is taken as a basis of comparison. A detailed comparison research among the standard SVM, LS‐SVM, and weighted LS‐SVM models is carried out. The research results confirm the effectiveness of the presented methods. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 285–289, 2006 相似文献
9.
Support vector clustering involves three steps—solving an optimization problem, identification of clusters and tuning of hyper-parameters. In this paper, we introduce a pre-processing step that eliminates data points from the training data that are not crucial for clustering. Pre-processing is efficiently implemented using the R*-tree data structure. Experiments on real-world and synthetic datasets show that pre-processing drastically decreases the run-time of the clustering algorithm. Also, in many cases reduction in the number of support vectors is achieved. Further, we suggest an improvement for the step of identification of clusters. 相似文献
10.