全文获取类型
收费全文 | 69990篇 |
免费 | 6190篇 |
国内免费 | 3701篇 |
专业分类
电工技术 | 5242篇 |
综合类 | 5440篇 |
化学工业 | 11445篇 |
金属工艺 | 7616篇 |
机械仪表 | 4111篇 |
建筑科学 | 6131篇 |
矿业工程 | 1745篇 |
能源动力 | 4331篇 |
轻工业 | 4538篇 |
水利工程 | 1662篇 |
石油天然气 | 3544篇 |
武器工业 | 627篇 |
无线电 | 5885篇 |
一般工业技术 | 7824篇 |
冶金工业 | 5027篇 |
原子能技术 | 1307篇 |
自动化技术 | 3406篇 |
出版年
2024年 | 302篇 |
2023年 | 982篇 |
2022年 | 1870篇 |
2021年 | 2237篇 |
2020年 | 2385篇 |
2019年 | 1923篇 |
2018年 | 1812篇 |
2017年 | 2423篇 |
2016年 | 2560篇 |
2015年 | 2651篇 |
2014年 | 4118篇 |
2013年 | 4303篇 |
2012年 | 5102篇 |
2011年 | 5512篇 |
2010年 | 3834篇 |
2009年 | 4016篇 |
2008年 | 3543篇 |
2007年 | 4568篇 |
2006年 | 4197篇 |
2005年 | 3406篇 |
2004年 | 3011篇 |
2003年 | 2575篇 |
2002年 | 2132篇 |
2001年 | 1900篇 |
2000年 | 1558篇 |
1999年 | 1235篇 |
1998年 | 997篇 |
1997年 | 866篇 |
1996年 | 769篇 |
1995年 | 591篇 |
1994年 | 518篇 |
1993年 | 362篇 |
1992年 | 355篇 |
1991年 | 305篇 |
1990年 | 232篇 |
1989年 | 151篇 |
1988年 | 128篇 |
1987年 | 75篇 |
1986年 | 79篇 |
1985年 | 64篇 |
1984年 | 57篇 |
1983年 | 43篇 |
1982年 | 29篇 |
1981年 | 17篇 |
1980年 | 24篇 |
1979年 | 17篇 |
1977年 | 8篇 |
1975年 | 4篇 |
1959年 | 13篇 |
1951年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
11.
在气敏温度区域内研究了α-Fe_2O_3(SO_4~(2-),Sn)材料的电阻-温度特性,认为表面结构的变化导致温度特性出现峰值并呈现气敏性。可利用空气中电阻温度特性提供的信息改性或发现新的气敏材料。 相似文献
12.
13.
Naoki Takinami Takashi Chino Shotaro Yoshida Isao Miura Kazuo Watanabe Kazuo Amano 《Electrical Engineering in Japan》1994,114(6):1-12
When ground-fault problems occur on a cable line, immediate fault location and restoration are required. Therefore, various new methods to locate the fault point instantaneously have been investigated to replace such conventional methods as the Murray loop method and the pulse radar method [1]. These methods require a long time to locate the fault point. One possible fault location method is to sense the temperature rise following a ground fault using a fiber optic distributed temperature sensor. Application of this method was found feasible through sensing the temperature rise at a ground-fault test using a thermocouple as a temperature sensor with test cables [4]. A power/optical composite cable was prepared experimentally and after verifying its thermal mechanical performance, the temperature rise at an incidence of a fault was determined and the anticipated performance was demonstrated in a ground-fault test. This article describes the outline of the test. 相似文献
14.
G. SAID 《Fatigue & Fracture of Engineering Materials & Structures》2006,29(8):606-614
Costs of ASTM E399 and ASTM E1921 tests, which were developed to determine the fracture toughness (KIc) and the ductile–brittle transition temperature of ferritic steels, respectively, are considered high and the procedures are also very complicated. In this study, a method, which is more cost‐effective and easier to carry out, is proposed. 相似文献
15.
16.
The thermal stress on building‐integrated photovoltaic modules (BIPV) in Espoo, Finland, was studied with field‐testing of amorphous silicon modules. Based on these results, the thermal stress at two other European locations (Paris and Lisbon) was estimated. The estimation procedure entailed thermal modelling of heat transfer in the façade with meteorological data as input. The results indicate that the thermal stress on BIPV modules in Lisbon is, in this case, approximately 50% higher that in Espoo and between 80 and 200% higher than in Paris, depending on the activation energy of the degradation process. The difference in stress between a BIPV module and a free‐standing module in Espoo was 50–200%. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
17.
18.
本文主要完成了液态金属钠高温沸腾实验回路的应力分析与计算,确定了回路高温区连接管系的布置型式和支吊架系统,是该回路总体设计的重要组成部分。 相似文献
19.
J. R. Prez-Correa F. R. Sepúlveda M. A. Duarte 《International Journal of Adaptive Control and Signal Processing》1995,9(2):183-197
This paper presents experimental results obtained in temperature adaptive control of a heating vessel. A non-linear model of the process showed that the feed flow rate causes severe variations in time constant and process gain. An extended horizon self-tuning controller and two different model reference adaptive controllers were tested. The influence of design parameters on control performance for each algorithm was assessed. The control system was disturbed with load and setpoint changes. 相似文献
20.
The paper describes the development and evaluation of temperature compensated high elongation resistance strain gauges for use from room temperature to 250°C. These gauges could be temperature-compensated on steels with coefficient of thermal expansion α = 11 ppm/°C. Thermal output within 250°C was about 1 μm/m/°C and maximum standard deviation of 5 gauges was 34 μm/m. Strain limit was > 4% at room temperature and at 250°C. Gauge factors of different strain ranges at R.T. and at 250°C are tabulated. Some applications are stated. 相似文献