全文获取类型
收费全文 | 496090篇 |
免费 | 48812篇 |
国内免费 | 22456篇 |
专业分类
电工技术 | 30364篇 |
技术理论 | 48篇 |
综合类 | 35190篇 |
化学工业 | 88566篇 |
金属工艺 | 28089篇 |
机械仪表 | 30580篇 |
建筑科学 | 36978篇 |
矿业工程 | 15046篇 |
能源动力 | 13534篇 |
轻工业 | 38606篇 |
水利工程 | 9893篇 |
石油天然气 | 28194篇 |
武器工业 | 4207篇 |
无线电 | 56033篇 |
一般工业技术 | 58487篇 |
冶金工业 | 23889篇 |
原子能技术 | 4973篇 |
自动化技术 | 64681篇 |
出版年
2024年 | 1830篇 |
2023年 | 6620篇 |
2022年 | 12407篇 |
2021年 | 17581篇 |
2020年 | 14191篇 |
2019年 | 13118篇 |
2018年 | 14740篇 |
2017年 | 16688篇 |
2016年 | 16046篇 |
2015年 | 21296篇 |
2014年 | 26101篇 |
2013年 | 31616篇 |
2012年 | 33047篇 |
2011年 | 35700篇 |
2010年 | 32776篇 |
2009年 | 31230篇 |
2008年 | 30626篇 |
2007年 | 29323篇 |
2006年 | 28737篇 |
2005年 | 24901篇 |
2004年 | 17767篇 |
2003年 | 15699篇 |
2002年 | 14905篇 |
2001年 | 13227篇 |
2000年 | 12035篇 |
1999年 | 11302篇 |
1998年 | 8083篇 |
1997年 | 6959篇 |
1996年 | 6472篇 |
1995年 | 5315篇 |
1994年 | 4364篇 |
1993年 | 2926篇 |
1992年 | 2308篇 |
1991年 | 1745篇 |
1990年 | 1370篇 |
1989年 | 1117篇 |
1988年 | 905篇 |
1987年 | 586篇 |
1986年 | 454篇 |
1985年 | 271篇 |
1984年 | 223篇 |
1983年 | 182篇 |
1982年 | 141篇 |
1981年 | 91篇 |
1980年 | 108篇 |
1979年 | 50篇 |
1978年 | 21篇 |
1977年 | 26篇 |
1976年 | 29篇 |
1959年 | 16篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
111.
The texture effect on visual colour difference evaluation was investigated in this study. Five colour centers were selected and textured colour pairs were generated using scanned textile woven fabrics and colour‐mapping technique. The textured and solid colour pairs were then displayed on a characterized cathode ray tube (CRT) monitor for colour difference evaluation. The colour difference values for the pairs with texture patterns are equal to 5.0 CIELAB units in lightness direction. The texture level was represented by the half‐width of histogram, which is called texture strength in this study. High correlation was found between texture strength and visual colour difference for textured colour pairs, which indicates that an increasing of 10 units of texture strength in luminance would cause a decreasing of 0.25 units visual difference for the five colour centers. The ratio of visual difference between textured and solid colour pairs also indicates a high parametric effect of texture. © 2005 Wiley Periodicals, Inc. Col Res Appl, 30, 341–347, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col. 相似文献
112.
Yong Ma Yong‐zhen Peng Xiao‐lian Wang Shu‐ying Wang 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2005,80(10):1118-1124
The laboratory scale anaerobic–anoxic–aerobic (A2O) process fed with synthetic brewage wastewater was designed to investigate the effects of changing feed C/P ratio on the performance of biological nutrient removal (BNR) processes. In the experiment, the influent chemical oxygen demand (COD) concentration was kept at approximately 300 mg L?1 while the total phosphorus concentration was varied to obtain the desired C/P ratio. Results showed that when the C/P ratio was lower than 32, phosphorus removal efficiency increased as C/P ratio increased linearly, while when the C/P ratio was higher than 32, the P removal efficiency was maintained at 90–98%, and effluent P concentration was lower than 0.5 mg L?1. However, regardless of the C/P ratio, excellent COD removal (90% or higher) and good total nitrogen removal (75–84%) were maintained throughout the experiments. It was also found that very good linear correlation was obtained between COD uptake per unit P released in the anaerobic zone and C/P ratio. In addition, the P content in the wasted activated sludge increased with the decrease in the C/P ratio. Based on the results, it was recommended that the wastewater C/P ratio and its effects be incorporated into BNR design and operational procedures, appropriate C/P ratios were used to achieve the effluent treatment goals. Copyright © 2005 Society of Chemical Industry 相似文献
113.
Gang Chen Zhonghua Yang Chor Ping Low 《Industrial Informatics, IEEE Transactions on》2006,2(4):269-280
In this paper, we address agent coordination from a dynamic systems perspective and propose a dynamic coordination model, which is inspired by biological metabolic systems. A new coordination mechanism through dynamic local adjustment (CDLA) is presented, and coordination is achieved when every agent utilizes explicitly the global system dynamics and performs iteratively a dynamic local adjustment procedure. The CDLA mechanism is investigated in an example multiagent shop floor system. The results show that the example manufacturing process is well-coordinated and the coordination approach is practically applicable and effective 相似文献
114.
115.
介绍成品油传统汽运发货流程.指出其中的弊端,提出采用计算机网络化管理的思路,并对计算机成品油汽运发货系统的优点和功能进行了介绍,然后详细讨论了该系统的开发过程和功能实现,最后提出改进和发展方向。 相似文献
116.
117.
118.
Different qualities of concrete have been fire tested using different geometries of the specimens as well as different load levels and load configurations. The main objective with the study was to examine a test methodology consisting of a full‐scale test and different small scale‐tests for determining the probability of spalling and the amount of spalling of fire exposed concrete structures. A reference specimen was defined as a one‐sided fire exposed slab with the dimensions 1800 × 1200 mm2 giving an exposed area of 1500 × 1200 mm2. A number of concrete qualities with different probabilities for spalling, were tested using the reference specimen. These tests showed that the reference specimens worked well giving the expected test results. Small specimens were manufactured in different shapes with the same concrete as the one used in the reference tests. These small specimens were tested either at the same time as the reference specimens in the large furnace or afterwards on a small‐scale furnace where the fire exposed surface was 450 × 360 mm2. The test results clearly show the increased probability and the increased amount of spalling by using external compressive loading. The results also show that by using pre‐stress through bars or wires the load can be lost due to heating of the bars/wires which results in a decreased amount of spalling. The boundary of the specimen also affects the amount of spalling. The spalling around the edges was in all tests less than the spalling on the central parts of the exposed area. It could also be noted that the spalling did not pass completely through any of the specimens. The reason for this is probably that the water/vapour could migrate out from the unexposed surface of the specimen. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
119.
戴力农 《艺术与设计.数码设计》2007,(5)
在上海地铁研究中,我们发现了许多使用者的不满。这些不满来自于设计师对使用者的缺乏了解和缺乏关注。通过对上海地铁真实的使用者、真实的地点和真实的时间的调研,我们分析出25项上海地铁使用者的需求。并提出希望设计师能够从这些使用者的需求出发,去作为使用者带来良好体验的设计。 相似文献
120.