首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   88414篇
  免费   9961篇
  国内免费   7507篇
电工技术   6542篇
技术理论   11篇
综合类   8634篇
化学工业   6597篇
金属工艺   2860篇
机械仪表   4633篇
建筑科学   4958篇
矿业工程   2631篇
能源动力   3904篇
轻工业   1733篇
水利工程   2142篇
石油天然气   4756篇
武器工业   961篇
无线电   12578篇
一般工业技术   6352篇
冶金工业   2187篇
原子能技术   1269篇
自动化技术   33134篇
  2024年   442篇
  2023年   1351篇
  2022年   2538篇
  2021年   3077篇
  2020年   3291篇
  2019年   2675篇
  2018年   2342篇
  2017年   2947篇
  2016年   3169篇
  2015年   3514篇
  2014年   5620篇
  2013年   5374篇
  2012年   6448篇
  2011年   6952篇
  2010年   5303篇
  2009年   5280篇
  2008年   5626篇
  2007年   6411篇
  2006年   5596篇
  2005年   4931篇
  2004年   4249篇
  2003年   3651篇
  2002年   2859篇
  2001年   2277篇
  2000年   1960篇
  1999年   1456篇
  1998年   1141篇
  1997年   965篇
  1996年   791篇
  1995年   702篇
  1994年   536篇
  1993年   437篇
  1992年   338篇
  1991年   293篇
  1990年   213篇
  1989年   174篇
  1988年   140篇
  1987年   114篇
  1986年   91篇
  1985年   113篇
  1984年   90篇
  1983年   92篇
  1982年   70篇
  1981年   46篇
  1980年   23篇
  1979年   42篇
  1978年   14篇
  1977年   20篇
  1976年   15篇
  1959年   9篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
该文介绍了设计Logo时对剪贴图层创建图层样式的方法。  相似文献   
92.
提出一种以词性为参考值的文本挖掘算法,能有效挖掘与种子词有关的关联规则。基于Bootstrapping算法思想,既减少了预处理阶段对于词根还原的依赖,能处理日志中出现的中文词汇。增加了对于日志文本上下的理解,提高了关联规则的有效性,并应用与IDS日志挖掘之中,有效改善挖掘效率,为规则库提供关联规则。  相似文献   
93.
94.
This paper addresses a novel hybrid data-fusion system for damage detection by integrating the data fusion technique, probabilistic neural network (PNN) models and measured modal data. The hybrid system proposed consists of three models, i.e. a feature-level fusion model, a decision-level fusion model and a single PNN classifier model without data fusion. Underlying this system is the idea that we can choose any of these models for damage detection under different circumstances, i.e. the feature-level model is preferable to other models when enormous data are made available through multi-sensors, whereas the confidence level for each of multi-sensors must be determined (as a prerequisite) before the adoption of the decision-level model, and lastly, the single model is applicable only when data collected is somehow limited as in the cases when few sensors have been installed or are known to be functioning properly. The hybrid system is suitable for damage detection and identification of a complex structure, especially when a huge volume of measured data, often with uncertainties, are involved, such as the data available from a large-scale structural health monitoring system. The numerical simulations conducted by applying the proposed system to detect both single- and multi-damage patterns of a 7-storey steel frame show that the hybrid data-fusion system cannot only reliably identify damage with different noise levels, but also have excellent anti-noise capability and robustness.  相似文献   
95.
Most of the current approaches to mixture modeling consider mixture components from a few families of probability distributions, in particular from the Gaussian family. The reasons of these preferences can be traced to their training algorithms, typically versions of the Expectation-Maximization (EM) method. The re-estimation equations needed by this method become very complex as the mixture components depart from the simplest cases. Here we propose to use a stochastic approximation method for probabilistic mixture learning. Under this method it is straightforward to train mixtures composed by a wide range of mixture components from different families. Hence, it is a flexible alternative for mixture learning. Experimental results are presented to show the probability density and missing value estimation capabilities of our proposal.  相似文献   
96.
政务信息资源中心框架设计及关键技术研究   总被引:1,自引:0,他引:1  
目前国内有关政务信息资源共享的研究及应用还停留在网络互联互通、信息资源整合、点对点数据交换阶段,并没有达到"协同工作"的要求.鉴于此,提出了政务信息资源中心的概念,实现政务信息资源的统一获取、统一管理、规则化和规模化服务.结合工作实践,对其组成、总体框架、技术架构进行了设计,并就实现时需要解决的关键技术进行了研究.  相似文献   
97.
为满足非接触化、小型化、集成化、数字化、智能化等现代检测技术的发展要求,从成本、工作原理、灵敏度等方面综合考虑,现采用以光电定位模块为核心的光电定位技术,以无线传感器网络作为数据传输与管理的技术手段,构建了无线光电定位网络,并进行了实验分析.可实现多点实时监测、异地显示测量数据、数据网络化管理等特殊需求;涵盖了多学科领...  相似文献   
98.
In China’s first lunar exploration project, Chang-E 1 (CE-1), a multi-channel microwave radiometer was aboard the satellite, with the purpose of measuring microwave brightness temperature from lunar surface and surveying the global distribution of lunar regolith layer thickness. In this paper, the primary 621 tracks of swath data measured by Chang-E 1 microwave radiometer from November 2007 to February 2008 are collected and analyzed. Using nearest neighbor interpolation based on the sun incidence angle in ...  相似文献   
99.
Copyright protection and information security have become serious problems due to the ever growing amount of digital data over the Internet. Reversible data hiding is a special type of data hiding technique that guarantees not only the secret data but also the cover media can be reconstructed without any distortion. Traditional schemes are based on spatial, discrete cosine transformation (DCT) and discrete wavelet transformation (DWT) domains. Recently, some vector quantization (VQ) based reversible data hiding schemes have been proposed. This paper proposes an improved reversible data hiding scheme based on VQ-index residual value coding. Experimental results show that our scheme outperforms two recently proposed schemes, namely side-match vector quantization (SMVQ)-based data hiding and modified fast correlation vector quantization (MFCVQ)-based data hiding.  相似文献   
100.
In this paper, we present a hybrid multi-criteria decision-making (MCDM) model to evaluate the competence of the firms. According to the competence-based theory reveals that firm competencies are recognized from exclusive and unique capabilities that each firm enjoy in marketplace and are tightly intertwined within different business functions throughout the company. Therefore, competence in the firm is a composite of various attributes. Among them many intangible and tangible attributes are difficult to measure. In order to overcome the issue, we invite fuzzy set theory into the measurement of performance. In this paper first we calculate the weight of each criterion through adaptive analytic hierarchy process (AHP) approach (A3) method, and then we appraise the performance of firms via linguistic variables which are expressed as trapezoidal fuzzy numbers. In the next step we transform these fuzzy numbers into interval data by means of α-cut. Then considering different values for α we rank the firms through TOPSIS method with interval data. Since there are different ranks for different α values, we apply linear assignment method to obtain final rank for alternatives.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号