全文获取类型
收费全文 | 13713篇 |
免费 | 1394篇 |
国内免费 | 956篇 |
专业分类
电工技术 | 2060篇 |
综合类 | 1322篇 |
化学工业 | 1070篇 |
金属工艺 | 347篇 |
机械仪表 | 995篇 |
建筑科学 | 787篇 |
矿业工程 | 315篇 |
能源动力 | 418篇 |
轻工业 | 281篇 |
水利工程 | 339篇 |
石油天然气 | 378篇 |
武器工业 | 112篇 |
无线电 | 1492篇 |
一般工业技术 | 988篇 |
冶金工业 | 407篇 |
原子能技术 | 202篇 |
自动化技术 | 4550篇 |
出版年
2024年 | 24篇 |
2023年 | 115篇 |
2022年 | 288篇 |
2021年 | 314篇 |
2020年 | 348篇 |
2019年 | 354篇 |
2018年 | 319篇 |
2017年 | 389篇 |
2016年 | 469篇 |
2015年 | 546篇 |
2014年 | 821篇 |
2013年 | 816篇 |
2012年 | 929篇 |
2011年 | 1118篇 |
2010年 | 787篇 |
2009年 | 873篇 |
2008年 | 853篇 |
2007年 | 1013篇 |
2006年 | 796篇 |
2005年 | 698篇 |
2004年 | 629篇 |
2003年 | 500篇 |
2002年 | 448篇 |
2001年 | 374篇 |
2000年 | 322篇 |
1999年 | 314篇 |
1998年 | 265篇 |
1997年 | 223篇 |
1996年 | 177篇 |
1995年 | 167篇 |
1994年 | 126篇 |
1993年 | 114篇 |
1992年 | 86篇 |
1991年 | 68篇 |
1990年 | 59篇 |
1989年 | 66篇 |
1988年 | 48篇 |
1987年 | 34篇 |
1986年 | 29篇 |
1985年 | 17篇 |
1984年 | 24篇 |
1983年 | 22篇 |
1982年 | 24篇 |
1981年 | 15篇 |
1980年 | 11篇 |
1979年 | 7篇 |
1978年 | 5篇 |
1976年 | 7篇 |
1963年 | 3篇 |
1962年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
A serious problem in motion control is the occurrence of torque ripple. Since a direct drive (DD) motor with a magnet rotor uses a rare-earth magnet, the torque ripple is more serious than that of conventional servomotors. This paper presents an auto-compensation of torque ripple using a software-implemented torque observer. The frequency and amplitude of torque ripple can be obtained in the controller by using the estimated torque from an observer, and the autonomous generation of a compensating current component for a torque ripple is possible. The proposed algorithm has been verified by experiments. 相似文献
32.
Trends in Hydrological Parameters of a Southern Brazilian Watershed and its Relation to Human Induced Changes 总被引:5,自引:1,他引:4
Moraes Jorge M. Pellegrino Giampaolo Q. Ballester Maria V. Martinelli Luiz A. Victoria Reynaldo L. Krusche Alex V. 《Water Resources Management》1998,12(4):295-311
The Piracicaba river basin is a subtropical watershed located in the southeastern region of Brazil. With an area of 12 400 km2, the basin is a typical example of new landscape resulting from development in tropical and sub-tropical regions: establishment of intensive industrial and agricultural processes were followed by significant population growth and water management. This scenario has led to significant increase in water demand and decrease in water quality. The main objective of this study is the detection of changes in the patterns of flow and precipitation in the basin, and its possible relation to man-induced changes. Statistical analyses were performed on records of precipitation, evapotranspiration and streamflow, from 1947 to 1991. Precipitation and evapotranspiration totals showed significant increasing trends for the entire basin. From eight streamflow gauge stations, half showed significant decreasing trend. The most probable cause of such trends is the export of water from the basin to the metropolitan region of São Paulo city. 相似文献
33.
34.
Hao Yin Chuang Lin Berton Sebastien Bo Li Geyong Min 《International Journal of Communication Systems》2005,18(8):711-729
Fast and accurate methods for predicting traffic properties and trend are essential for dynamic network resource management and congestion control. With the aim of performing online and feasible prediction of network traffic, this paper proposes a novel time series model, named adaptive autoregressive (AAR). This model is built upon an adaptive memory‐shortening technique and an adaptive‐order selection method originally developed by this study. Compared to the conventional one‐step ahead prediction using traditional Box–Jenkins time series models (e.g. AR, MA, ARMA, ARIMA and ARFIMA), performance results obtained from actual Internet traffic traces have demonstrated that the proposed AAR model is able to support online prediction of dynamic network traffic with reasonable accuracy and relatively low computation complexity. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
35.
本文介绍了由微道板构成的透射型定时探测器,得到的飞行时间系统的时间分辨为280ps。并对进一步改善时间特性作了讨论。 相似文献
36.
现场总线控制系统中GPS精确校时的实现 总被引:1,自引:0,他引:1
针对现场总线控制系统精确校时和时间统一的要求,提出了3种利用GPS授时功能对总线式系统进行校时的方案.以GPSDEC授时型接收机为例,其校时可通过RS-232接口端ASCII码信息和DCF77信号、及输出端自定义脉冲信号实现.开放性要求高的大中型总线网络及通用的智能设备,当总线系统中的通讯协议具有时钟功能时,可采用广播式校时法对设备逐个校时.顺序式校时主要针对下层智能设备种类较多的大型总线系统内的前置通讯,并按通讯机的先后依次校时.对时间精度要求较高且下层智能仪表具有时钟同步信号接口的小型总线系统,宜采用单点式校时. 相似文献
37.
This paper is concerned with (1) an explicit solution of a minimum variance control law for linear time-variant (LTV) processes in the transfer function form, and (2) performance assessment of LTV processes using minimum variance control as the benchmark. It is shown that there exists a time-variant, absolute lower bound of process variance that is achievable under LTV minimum variance control and can be estimated from routine operating data. This lower bound can subsequently be used to assess the benefit of implementing LTV control such as adaptive control. The proposed methods are illustrated through simulated examples and an industrial case study. 相似文献
38.
孙锋 《数字社区&智能家居》2006,(11):142-143
简要介绍了数据挖掘及其在给水管网安全中的应用。提出了一种基于数据挖掘的时间序列相似性查询方法。通过对事故症候相似性查询,建立安全预警系统,为调度员提供事故预警信息。 相似文献
39.
A method for the time suboptimal control of an industrial manipulator from an initial position and orientation to a final
position and orientation as it moves along a specified path is proposed. Nonlinear system equations that describe the manipulator
motion are linearized at each time step along the path. A method which gives the control inputs (joint angular velocities)
for time suboptimal control of the manipulator is developed. In the formulation, joint angular velocity and acceleration limitations
are also taken into consideration. A six degree of freedom elbow type manipulator is used in numerical examples to verify
the method developed. 相似文献
40.
本文对PKIX依从系统中增量CRLs的应用进行了一些研究,包括:增量CRL的时间跨度对性能的影响及其最优选择;基于完全CRL与增量CRL检查证书状态以及构造新的完全CRL的算法。 相似文献