全文获取类型
收费全文 | 988篇 |
免费 | 42篇 |
国内免费 | 48篇 |
学科分类
工业技术 | 1078篇 |
出版年
2024年 | 1篇 |
2023年 | 5篇 |
2022年 | 9篇 |
2021年 | 15篇 |
2020年 | 11篇 |
2019年 | 4篇 |
2018年 | 9篇 |
2017年 | 9篇 |
2016年 | 10篇 |
2015年 | 19篇 |
2014年 | 58篇 |
2013年 | 46篇 |
2012年 | 57篇 |
2011年 | 89篇 |
2010年 | 61篇 |
2009年 | 59篇 |
2008年 | 67篇 |
2007年 | 93篇 |
2006年 | 62篇 |
2005年 | 72篇 |
2004年 | 49篇 |
2003年 | 62篇 |
2002年 | 27篇 |
2001年 | 27篇 |
2000年 | 28篇 |
1999年 | 21篇 |
1998年 | 16篇 |
1997年 | 19篇 |
1996年 | 7篇 |
1995年 | 16篇 |
1994年 | 14篇 |
1993年 | 9篇 |
1992年 | 6篇 |
1991年 | 5篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1974年 | 1篇 |
排序方式: 共有1078条查询结果,搜索用时 15 毫秒
61.
陈海辉 《昆明理工大学学报(自然科学版)》2004,29(2):45-48
分析地铁屏蔽门系统的用电负荷特点及其供电要求,设计出智能高频开关模块、免维护铅酸蓄电池的直流供电方案,采用TN-S接地方式、门体与钢轨保持等电位、门体与站台结构绝缘的系统保护措施.将一次开/关门循环定为一次短暂电流冲击,以确定蓄电池放电时间.以费用为目标函数进行优化计算,选取最佳数量的高频模块及电池组,并给出了一个实例. 相似文献
62.
基于Webmin的安全网管系统开发 总被引:1,自引:0,他引:1
网络应用日益广泛,安全问题也随之突出,因此开发一种安全网络管理系统成为必要。文章在介绍Webmin及其特点的基础上论述了如何利用Webmin的框架结构以及它的模块开发方法来构建一个基于Web的安全网络管理系统,并给出这种方法构建系统的优点。 相似文献
63.
64.
This paper presents the first IEEE 802.16m medium access control (MAC) protocol module embedded in the network simulator version 3 (ns-3). The designed module provides a validation tool for researchers to verify simulated results related to the IEEE 802.16m. This module supports the basic MAC functions which includes an initial ranging (IR) function; four types of bandwidth request (BR) procedures; five types of standard-specified quality-of-service (QoS); a QoS-based transmission scheduler; an adaptive modulation and coding (AMC) selection function; a physical (PHY) layer with a channel propagation model. The designed module provides modification flexibility to adapt to other simulation modules. Various scenarios are simulated to show the capacity of the implemented IEEE 802.16m module in details. Results of different types of traffic are tested with the path loss effect on transmission to visualize the numeric capability of the module. 相似文献
65.
《International Journal of Hydrogen Energy》2019,44(33):18461-18471
In the second part of this study, a new analytical model for catalyst layers (CLs) compression is developed using effective medium theory, using a geometric “unit cell”, to accurately predict the deformation of CLs under compression. Based on SEM images, a representative unit cell is proposed using microstructural properties of CL such as porosity, pore size distribution, and ionomer to carbon weight ratio (I/C) to simplify the random complex structure of CLs. Deformation of the ionomer film that covers carbon agglomerates is found to be the main deformation compared to other mechanisms such as Hertzian compliance of carbon particles and deformation of agglomerates. The present model is validated using the experimental results obtained for five different CL designs, presented in Part 1 of this study. The analytical model is capable of predicting the non-linear compressive behaviour of CLs with a reasonable accuracy since a continuous change of CL porosity is considered in the model. The proposed geometrical model has also been used for other properties of CL in our group and successfully predicted thermal conductivity and gas diffusivity of CL. 相似文献
66.
本文主要通过与传统电视结构的简单对比介绍了液晶电视整机模组的一体化结构设计的技术特征,并在原有一体化结构设计的基础上提出了一种优化结构。 相似文献
67.
《Fusion Engineering and Design》2014,89(7-8):1284-1288
In order to determine the forces acting on the EU-Helium Cooled Pebble Bed Test Blanket Module (HCPB-TBM) during operation, a measurement system is developed. Therefore, two force reconstruction (FR) methods using measured strain signals are selected that are suitable for the application to the TBM. The first one, the augmented Kalman filter is a combined deterministic-stochastic approach. A second FR method based on the concept of a model predictive controller is proposed in this paper, which uses an optimization algorithm. In order to test the selected methods a testing device has been built which can be used to apply different force excitations on a reduced sized TBM mock up and measure the resulting strain signals of 16 strain gages. A simple tube mock up has been designed and manufactured to test and calibrate the FR algorithms. In addition, a second TBM mock up with attachment system is described. Finally, first results of the FR of a worst-case test case from simulated strain data of the simple tube mock up are presented. 相似文献
68.
Dong-Hyuck Seo Tae-Seong Roh Dong-Whan Choi 《Journal of Mechanical Science and Technology》2009,23(3):677-685
A hybrid method of an artificial neural network (ANN) and a support vector machine (SVM) has been used for a health monitoring
algorithm of a gas turbine engine. The method has the advantage of reducing learning data and converging time without any
loss of estimation accuracy, because the SVM classifies the defect location and reduces the learning data range. In off-design
condition, however, the operation region of the engine becomes wide and the nonlinearity of learning data increases considerably.
Therefore, an improved hybrid method with the module system and the advanced SVM has been suggested to solve the problems.
The module system divides the whole operating region into reasonably small-sized sections, and the advanced SVM has two steps
of the classification. The proposed algorithm has been proven to reliably and effectively diagnose the simultaneous defects
of the triple components as well as the defects of the single and dual components of the gas turbine engine in off-design
condition.
This paper was recommended for publication in revised form by Associate Editor Tong Seop Kim
Tae-Seong Roh received his B.S. and M.S. degrees in Aeronautical Engineering from Seoul National University in 1984 and 1986. He then went
on to receive his Ph.D. degree from Pennsylvania State University in 1995. Dr. Roh is currently a Professor at the department
of Aerospace Engi-neering at Inha University in Incheon, Korea. His research interests are in the area of combustion instabilities,
rocket and jet propulsions, interior ballistics, and gas turbine engine defect diagnostics.
Dong-Whan Choi received his B.S. degree in Aeronautical Engineering from Seoul National University in 1974. He then went on to receive his
M.S. and Ph.D. degrees from University of Washington in 1978 and 1983. Dr. Choi served three years as a President of Korea
Aerospace Research Institute from 1999. He is currently a professor at the department of Aerospace Engineering at Inha University
in Incheon, Korea. His research interests are in the area of turbulence, jet propulsions, and gas turbine defect diagnostics. 相似文献
69.
Ritesh Tipnis Jan Bernkopf Shijun Jia John Krieg Sergey Li Mark Storch Darin Laird 《Solar Energy Materials & Solar Cells》2009,93(4):442-446
Here we describe the fabrication of the largest (233 cm2 total area) organic photovoltaic (OPV) module (polymer:fullerene) to be certified by the National Renewable Energy Laboratory (NREL). OPV solar cells were fabricated at Plextronics by spin coating a blend of poly 3-hexylthiophene-2,5 diyl (P3HT) and [6,6] phenyl C61 butyric acid methyl ester (PCBM) on top of our hole transport layer (HTL), Plexcore® OC. In laboratory-scale devices (0.09 cm2), this system routinely exhibits power conversion efficiencies exceeding 3.7%. This P3HT:PCBM active layer and HTL ink system was used to scale up to the larger area module (15.2 cm×15.2 cm module size, i.e. 233 cm2 total area; 108 cm2 active area), which was certified by NREL as having 1.1% total area efficiency (3.4% active area efficiency). 相似文献
70.
.NET平台是应用非常广泛的平台,文中结合SQL Server2005数据库来开发某高职院校的设备管理信息系统.系统的运行,极大的提高了设备管理工作的质量和效益,减少差错,减轻劳动强度,从而提高学校的整体管理水平. 相似文献