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   29135篇
  免费   4191篇
  国内免费   1774篇
电工技术   3723篇
综合类   3669篇
化学工业   798篇
金属工艺   503篇
机械仪表   2573篇
建筑科学   583篇
矿业工程   588篇
能源动力   588篇
轻工业   566篇
水利工程   467篇
石油天然气   1135篇
武器工业   426篇
无线电   6770篇
一般工业技术   2451篇
冶金工业   187篇
原子能技术   138篇
自动化技术   9935篇
  2025年   120篇
  2024年   360篇
  2023年   426篇
  2022年   552篇
  2021年   650篇
  2020年   747篇
  2019年   649篇
  2018年   646篇
  2017年   868篇
  2016年   1104篇
  2015年   1185篇
  2014年   1606篇
  2013年   1642篇
  2012年   2144篇
  2011年   2343篇
  2010年   2051篇
  2009年   2062篇
  2008年   2302篇
  2007年   2662篇
  2006年   2138篇
  2005年   1872篇
  2004年   1511篇
  2003年   1243篇
  2002年   885篇
  2001年   774篇
  2000年   629篇
  1999年   451篇
  1998年   381篇
  1997年   284篇
  1996年   192篇
  1995年   145篇
  1994年   103篇
  1993年   82篇
  1992年   59篇
  1991年   43篇
  1990年   51篇
  1989年   34篇
  1988年   16篇
  1987年   12篇
  1986年   8篇
  1985年   15篇
  1984年   12篇
  1983年   13篇
  1982年   4篇
  1981年   11篇
  1980年   4篇
  1979年   2篇
  1978年   2篇
  1975年   1篇
  1973年   3篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
Currently there are design barriers inhibiting the implementation of high-precision digital signal processing (DSP) objects with field programmable logic (FPL) devices. This paper explores overcoming these barriers by fusing together the popular distributed arithmetic (DA) method with the residue number system (RNS) for use in FPL-centric designs. The new design paradigm is studied in the context of a high-performance filter bank and a discrete wavelet transform (DWT). The proposed design paradigm is facilitated by a new RNS accumulator structure based on a carry save adder (CSA). The reported methodology also introduces a polyphase filter structure that results in a reduced look-up table (LUT) budget. The 2C-DA and RNS-DA are compared, in the context of a FPL implementation strategy, using a discrete wavelet transform (DWT) filter bank as a common design theme. The results show that the RNS-DA, compared to a traditional 2C-DA design, enjoys a performance advantage that increases with precision (wordlength).  相似文献   
2.
3.
针对重力测定反问题,提出将其离散为线性不适定问题,利用小波变换方法进行数值求解.该方法将小波变换和正则化方法相结合,选取小波函数作为一组基底,将原不适定问题转化为粗子空间上的适定问题,并给出选取粗子空间基的方法.通过数值模拟已有方法和小波变换方法求解结果的比较,表明了小波变换方法的可行性和有效性.  相似文献   
4.
This paper describes a novel model for fetal heart rate (FHR) monitoring from single-lead mother?s abdomen ECG (AECG) measurements. This novel method is divided in two stages: the first step consists on a one-step wavelet-based preprocessing for simultaneous baseline and high-frequency noise suppression, while the second stage efficiently detects fetal QRS complexes allowing FHR monitoring. The presented structure has been simplified as much as possible, in order to reduce computational cost and thus enable possible custom hardware implementations. Moreover, the proposed scheme and its fixed-point modeling have been tested using real abdominal ECG signals, which allow the validation of the presented approach and provide high accuracy.  相似文献   
5.
To provide both a high payload capacity and a good stego-image quality, a high payload frequency-based reversible image hiding (HPFRIH) method was presented in this paper. These performances can be achieved by transforming a cover image from the spatial domain into the frequency domain through Haar digital wavelet transform (HDWT) method followed by an adaptive arithmetic coding method to encode the HDWT coefficients in a high-frequency band. The HPFRIH method was used to conceal both the compressed data and the secret data in the high-frequency band. This simple method can completely reconstruct the cover image only from the stego-image. Moreover, experimental results showed that the HPFRIH method offers both impressive hiding capacity and satisfied stego-image quality.  相似文献   
6.
In this paper we present new edge detection algorithms which are motivated by recent developments on edge-adapted reconstruction techniques [F. Aràndiga, A. Cohen, R. Donat, N. Dyn, B. Matei, Approximation of piecewise smooth functions and images by edge-adapted (ENO-EA) nonlinear multiresolution techniques, Appl. Comput. Harmon. Anal. 24 (2) (2008) 225–250]. They are based on comparing local quantities rather than on filtering and thresholding. This comparison process is invariant under certain transformations that model light changes in the image, hence we obtain edge detection algorithms which are insensitive to changes in illumination.  相似文献   
7.
8.
A supported framework of a gyroscope's rotor is designed and the B-Spline wavelet finite element model of nonlinear supported magnetic field is worked out. A new finite element space is studied in which the scaling function of the B-spline wavelet is considered as the shape function of a tetrahedton. The magnetic field is spited by an artificial absorbing body which used the condition of field radiating, so the solution is unique. The resolution is improved via the varying gradient of the B-spline function under the condition of unchanging gridding. So there are some advantages in dealing with the focus flux and a high varying gradient result from a nonlinear magnetic field. The result is more practical. Plots of flux and in the space is studied via simulating the supported system model. The results of the study are useful in the research of the supported magnetic system for the gyroscope rotor.  相似文献   
9.
二维小波变换理论在地震信号去噪中的应用   总被引:3,自引:0,他引:3  
针对地震信号随机干扰和规则干扰的特点,运用二维小波变换的理论,设计了相应的变换域去噪滤波器。理论记录和实际野外记录试算表明,二维小波变换具有较强的信噪分离作用。只要运用得当就能取得满意的效果。  相似文献   
10.
On neuro-wavelet modeling   总被引:1,自引:0,他引:1  
We survey a number of applications of the wavelet transform in time series prediction. The Haar à trous wavelet transform is proposed as a means of handling time series data when future data is unknown. Results are exemplified on financial futures and S&P500 data. Nonlinear and linear multiresolution autoregressionmodels are studied. Experimentally, we show that multiresolution approaches can outperform the traditional single resolution approach to modeling and prediction.  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