全文获取类型
收费全文 | 5018篇 |
免费 | 188篇 |
国内免费 | 107篇 |
专业分类
电工技术 | 1305篇 |
综合类 | 398篇 |
化学工业 | 159篇 |
金属工艺 | 7篇 |
机械仪表 | 113篇 |
建筑科学 | 1595篇 |
矿业工程 | 69篇 |
能源动力 | 122篇 |
轻工业 | 78篇 |
水利工程 | 29篇 |
石油天然气 | 21篇 |
武器工业 | 4篇 |
无线电 | 450篇 |
一般工业技术 | 211篇 |
冶金工业 | 106篇 |
原子能技术 | 3篇 |
自动化技术 | 643篇 |
出版年
2024年 | 6篇 |
2023年 | 30篇 |
2022年 | 75篇 |
2021年 | 78篇 |
2020年 | 120篇 |
2019年 | 53篇 |
2018年 | 41篇 |
2017年 | 105篇 |
2016年 | 118篇 |
2015年 | 130篇 |
2014年 | 532篇 |
2013年 | 321篇 |
2012年 | 482篇 |
2011年 | 476篇 |
2010年 | 467篇 |
2009年 | 379篇 |
2008年 | 304篇 |
2007年 | 341篇 |
2006年 | 264篇 |
2005年 | 196篇 |
2004年 | 147篇 |
2003年 | 135篇 |
2002年 | 118篇 |
2001年 | 78篇 |
2000年 | 65篇 |
1999年 | 52篇 |
1998年 | 34篇 |
1997年 | 25篇 |
1996年 | 33篇 |
1995年 | 14篇 |
1994年 | 20篇 |
1993年 | 17篇 |
1992年 | 3篇 |
1991年 | 9篇 |
1990年 | 3篇 |
1989年 | 4篇 |
1988年 | 11篇 |
1987年 | 4篇 |
1985年 | 2篇 |
1984年 | 5篇 |
1983年 | 3篇 |
1982年 | 5篇 |
1981年 | 2篇 |
1965年 | 1篇 |
1964年 | 1篇 |
1962年 | 1篇 |
1957年 | 1篇 |
1956年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有5313条查询结果,搜索用时 15 毫秒
11.
杨光 《上海电机学院学报》2003,6(4):20-22
我国照明用电量占全国发电总量的12%左右,节约照明用电不仅减轻国家电力供应的压力,而且还保护了环境。大、中型商场照明用电量一般都很大,设计商场时,怎样才能做到投产后节约电能,通过多年设计实践总结出几点措施。 相似文献
12.
13.
Abdullah Zeid Ayssa 《Renewable Energy》1996,8(1-4)
The traditional Yemeni window is considered to be one of the most important elements that characterize the yemeni architecture. The beauty of the traditional Yemeni window comes from its four main components which combined the functions of view, lighting, ventilation, protection, and privacy. These functions can be controlled by the occupants according to their social and environmental needs. The four main components are the lower part (Taqah), the fanlight (Qamariyah), the wooden external overhang (Konnah), and the small vent (Shaquos). Since fanlights provide natural lighting during day-time, the area of the lower part can be reduced and its exterior shutters can be closed without the need for artificial lighting. The internal natural lighting that is provided by the upper and lower parts of the window was investigated to see its quality. In this investigation, there were two main goals. The first is the contribution and quality of the internal light provided by the Qamariyah when shutters are closed. The second is the effect of the internal simple white cloth curtains, in the lower part, in the internal light quality. Visual measurements were taken in a typical room of a traditional house of the Old City of Sana'a, Yemen. From the findings, it was found that the fanlights (Qamariyat) provide low and soft homogeneous internal lighting which was as low as 22 lux average. However, the occupants have the ability to increase level of lighting to as high as 600 or 700 lux. This can be done simply by deciding which shutter to open and how many of them to be opened. In this paper, the methodology and findings will be presented and discussed. 相似文献
14.
15.
Stephen Dain 《Color research and application》2007,32(6):428-432
There are anecdotal reports of color vision deficient medical practitioners (particularly deuteranopes) having difficulty in recognizing cyanosis. An understanding of the color changes in oxygenated blood has led to a better understanding of the lighting needs for hospitals. Using the same database, this article investigates the propensity for color vision deficient observers to make mistakes with cyanotic patients. The possibilities for helping the observer with appropriate color of lighting are considered. The spectral reflectances of blood at varying oxygenation levels previously reported were used 7 ; 8 to calculate chromaticity and lightness. The direction of the chromaticity change was compared with the protanopic and deuteranopic confusion lines. An attempt was made to identify sources that enhanced color changes for the color deficient. The color change of blood oxygenation is closely aligned with the confusion lines of congenital dichromats (particularly protanopia) showing the potential for difficulty in making this decision. No source could be demonstrated to solve the problem or even reduce it significantly. © 2007 Wiley Periodicals, Inc. Col Res Appl, 32, 428–432, 2007 相似文献
17.
XU Shun dou 《中国邮电高校学报(英文版)》2002,9(2)
1 IntroductionInordertoimprovethequalityofpostalserviceandtakeadvantageofautomatedmailsortingequip ments,ithasbeendeterminedtoconstructthepostalareacenterofficesysteminChinaPostalSer vice (CPS) .ThecruxoftheproblemfacedbyCPSistoredesignthepostalcommunica… 相似文献
18.
19.
20.
Long-Wen Chang Shui-kung Chuag Shang-shung Yu 《Multidimensional Systems and Signal Processing》1994,5(3):319-330
The compression of Chinese characters is very important for Chinese office automation and desktop publishing. In this paper, various methods are used to compress 13,051 Chinese characters losslessly by coding their skeleton points. The skeleton points are composed of isolated points and curves. To trace every point in a curve once and consecutively is a NP problem. Therefore, we use contour path following and revisiting algorithms to trace skeleton curves with chain codes. The remaining isolated skeleton points are encoded by an Elias code. Our coding method has a better compression rate than that of conventional skeleton coding. 相似文献