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   407篇
  免费   20篇
  国内免费   9篇
电工技术   28篇
综合类   14篇
化学工业   48篇
金属工艺   21篇
机械仪表   19篇
建筑科学   70篇
矿业工程   4篇
能源动力   34篇
轻工业   10篇
石油天然气   13篇
武器工业   2篇
无线电   54篇
一般工业技术   15篇
冶金工业   9篇
原子能技术   13篇
自动化技术   82篇
  2023年   5篇
  2022年   9篇
  2021年   6篇
  2020年   3篇
  2019年   7篇
  2018年   10篇
  2017年   9篇
  2016年   19篇
  2015年   21篇
  2014年   14篇
  2013年   18篇
  2012年   20篇
  2011年   44篇
  2010年   20篇
  2009年   38篇
  2008年   29篇
  2007年   32篇
  2006年   24篇
  2005年   22篇
  2004年   17篇
  2003年   16篇
  2002年   16篇
  2001年   9篇
  2000年   7篇
  1999年   3篇
  1998年   4篇
  1997年   4篇
  1996年   3篇
  1995年   4篇
  1994年   1篇
  1992年   1篇
  1986年   1篇
排序方式: 共有436条查询结果,搜索用时 15 毫秒
1.
宁会生 《石油仪器》2006,20(5):12-13
新一代深度张力面板不仅具有基本的深度、张力采集、处理、显示功能,同时还具有多种报警及通讯功能.其最大的特点是采用了液晶显示屏和触摸屏,使得信息的显示更加丰富、直观和醒目.同时,触摸屏的采用,省去了传统的按钮、开关及键盘操作模式,使操作更加方便简洁、自然.该面板可以单独工作,也可以配备于测井、录井地面系统中使用.  相似文献   
2.
The features extracted from the cardiac sound signals are commonly used for detection and identification of heart valve disorders. In this paper, we present a new method for classification of cardiac sound signals using constrained tunable-Q wavelet transform (TQWT). The proposed method begins with a constrained TQWT based segmentation of cardiac sound signals into heart beat cycles. The features obtained from heart beat cycles of separately reconstructed heart sounds and murmur can better represent the various types of cardiac sound signals than that from containing both. Therefore, heart sounds and murmur have been separated using constrained TQWT. Then the proposed novel raw feature set has been created by the parameters that have been optimized while constraining the output of TQWT together with that of extracted by using time-domain representation and Fourier–Bessel (FB) expansion of separated heart sounds and murmur. However, the adaptively selected features have been used to obtain the final feature set for subsequent classification of cardiac sound signals using least squares support vector machine (LS-SVM) with various kernel functions. The performance of the proposed method has been validated with publicly available datasets and the results have been compared with the existing short-time Fourier transform (STFT) based method. The proposed method shows higher percentage classification accuracy of 94.01 as compared to 93.53 of STFT based method. In comparison with STFT based method, it is noteworthy that the proposed method uses well defined and lower dimensionality of feature vector that can reduce the computational complexity.  相似文献   
3.
由数字式湿度温度传感器SHT75的原理,设计了一种多功能数字显示温湿度计。该温湿度计具有精密度高、性能稳定、由CRC校验据保证了数据的可靠性;在实时温度和湿度数字显示的同时,能够计算对应露点;且具备电源选择功能。该设计的特点是:USB接口等实现多种数据输出,为温湿度计与其它功能模块结合使用提供了条件,也为温度和湿度的自动控制提供了方便。该温湿度计还能够进一步开发温度和湿度远程自动控制系统。  相似文献   
4.
针对碱回收蒸发工段的工艺特点和控制要求,设计了S7-300PLC控制系统。对黑液浓度采取软测量方法,提出了黑液浓度-压力串级控制策略;对温度控制对象采用了具有自整定功能的温度控制功能块FB58,并从硬件配置和软件设计等方面对系统进行详细论述。  相似文献   
5.
The purpose of the present study was to examine the prevalence of cyber-bullying through Facebook in a sample of 226 Greek university undergraduates, and to explore whether big five personality characteristics, narcissism, as well as attitudes toward Facebook, technological knowledge and skills were predictive of such behavior. Participants completed a self-report questionnaire measuring the above constructs. Results indicated that almost one third of the sample reported Facebook bullying engagement at least once during the past month, with male students reporting more frequent involvement than females. Bullying through Facebook was predicted by low Agreeableness and more time spent on Facebook only for males, whereas for females none of the studied variables predicted engagement in Facebook bullying. Findings are discussed in terms of prevention and intervention strategies.  相似文献   
6.
Based on the method of (n,k)-universal sets, we present a deterministic parameterized algorithm for the weighted rd-matching problem with time complexity O(4(r−1)k+o(k)), improving the previous best upper bound O(4rk+o(k)). In particular, the algorithm applied to the unweighted 3d-matching problem results in a deterministic algorithm with time O(16k+o(k)), improving the previous best result O(21.26k). For the weighted r-set packing problem, we present a deterministic parameterized algorithm with time complexity O(2(2r−1)k+o(k)), improving the previous best result O(22rk+o(k)). The algorithm, when applied to the unweighted 3-set packing problem, has running time O(32k+o(k)), improving the previous best result O(43.62k+o(k)). Moreover, for the weighted r-set packing and weighted rd-matching problems, we give a kernel of size O(kr), which is the first kernelization algorithm for the problems on weighted versions.  相似文献   
7.
We show that for some special functions (called k-multigrid equidistributed functions), we can compute the limit of the frequency of patterns in the discretization of their graph, when the resolution tends to zero. This result is applied to parabolas. We deduce also that local length estimators almost never converge to the length for the parabolas.  相似文献   
8.
该文设计的淋浴节水控制器,可根据消费者实际的洗浴时间长短计时收费,实现节能节水.采用RC500作为IC卡操作模块.经485接口与微机进行实时通信.采用先扣钱后供水的消费模式.定时收费,费率可通过软件设置.在空闲模式下,控制器显示当前时间;在淋浴过程中,显示消费金额及卡中余额,并可以通过红外传感器,根据需要暂停出水及计费...  相似文献   
9.
Density functional calculations and minimization techniques have been employed to characterize the structural and electronic properties of [5,6]-heterofullerene-C58Si-C2v. Since it has odd number of atoms and a near planar tetracoordinate Si atom on the skeleton of the cage, it has odd number of atoms assembling a cage and is a novel molecule. Vibrational frequencies of the molecule have been calculated at the B3LYP/6-31G* level of theory. The absence of imaginary vibrational frequency confirms that the molecule corresponds to a true minimum on the potential energy hypersurface. Sixteen 13C nuclear magnetic resonance (NMR) spectral signals of C58Si are characterized, and its heat of formation was estimated in this work.  相似文献   
10.
简要的介绍了循环流化床锅炉以及其保护系统FSSS的基本知识。以越南林同铝厂热电站的DCS控制系统项目为背景较为详细地介绍了如何在Honeywell的DCS系统中实现FSSS系统的功能,并且对FSSS系统的具体逻辑实现进行了详细的讲解。  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