全文获取类型
收费全文 | 15532篇 |
免费 | 832篇 |
国内免费 | 29篇 |
专业分类
电工技术 | 169篇 |
综合类 | 43篇 |
化学工业 | 3342篇 |
金属工艺 | 307篇 |
机械仪表 | 316篇 |
建筑科学 | 687篇 |
矿业工程 | 45篇 |
能源动力 | 503篇 |
轻工业 | 1232篇 |
水利工程 | 124篇 |
石油天然气 | 52篇 |
无线电 | 1112篇 |
一般工业技术 | 2976篇 |
冶金工业 | 2239篇 |
原子能技术 | 117篇 |
自动化技术 | 3129篇 |
出版年
2023年 | 166篇 |
2022年 | 359篇 |
2021年 | 574篇 |
2020年 | 385篇 |
2019年 | 380篇 |
2018年 | 496篇 |
2017年 | 461篇 |
2016年 | 532篇 |
2015年 | 465篇 |
2014年 | 594篇 |
2013年 | 1060篇 |
2012年 | 971篇 |
2011年 | 1155篇 |
2010年 | 807篇 |
2009年 | 747篇 |
2008年 | 788篇 |
2007年 | 774篇 |
2006年 | 581篇 |
2005年 | 504篇 |
2004年 | 371篇 |
2003年 | 381篇 |
2002年 | 338篇 |
2001年 | 213篇 |
2000年 | 186篇 |
1999年 | 205篇 |
1998年 | 211篇 |
1997年 | 185篇 |
1996年 | 183篇 |
1995年 | 177篇 |
1994年 | 153篇 |
1993年 | 147篇 |
1992年 | 119篇 |
1991年 | 74篇 |
1990年 | 122篇 |
1989年 | 116篇 |
1988年 | 80篇 |
1987年 | 93篇 |
1986年 | 100篇 |
1985年 | 100篇 |
1984年 | 88篇 |
1983年 | 76篇 |
1982年 | 96篇 |
1981年 | 90篇 |
1980年 | 71篇 |
1979年 | 70篇 |
1978年 | 62篇 |
1977年 | 74篇 |
1976年 | 61篇 |
1975年 | 45篇 |
1974年 | 41篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
In the first half of the 21st century, a redistribution of the energy data should occur, where nuclear will play a more important role, particularly as coal will become more and more costly to extract.On a worldwide basis, the unability of oil to be replaced in some areas like transportation, and the difficulty of developing countries to find substitutes for this energy source, could also lead developed countries to keep the energy resources for a better utilization, and give the countries which have no access to other resources, a possibility to develop.Thus, France has extensively enhanced nuclear energy for its electricity production, and, consequently, makes the necessary efforts for the knowledge of the whole fuel cycle. 相似文献
12.
V Daniel 《Canadian Metallurgical Quarterly》1995,120(34-35):1171-1174
13.
In a study of how aviation expertise influences age differences in narrative processing, young and older pilots and nonpilots read and recalled aviation and general narratives. They chose referents for sentences referring to a protagonist or minor character mentioned 1 sentence (recent character) or 3 sentences (distant character) before this target sentence. All groups chose referents less accurately for sentences about distant and minor characters than about recent and protagonist characters, perhaps because these referents were less likely to be in working memory. Young readers and pilots were more accurate for distant and minor character target sentences in aviation narratives and recalled aviation narratives more accurately. Expertise did not reduce age differences. Expertise differences may reflect decreased demands on working memory capacity, and age declines may reflect reduced capacity. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
14.
The transition from basic automation to flexible manufacturing is an expensive and tedious procedure. It requires meticulous planning and almost clairvoyant forecasting to insure that the initial flexibility obtained is sufficient to allow growth and expansion in the future. This paper will suggest a systematic and methodological approach to achieve optimal flexibility and describe the present results of its application to an ongoing system transformation.
Conclusions based on existing levels of completion are presented along with identification of critical and non critical flexibility requirements. The considerations and steps taken are summarized in a procedural format which may then be applied to a wide variety of system transformations. 相似文献
15.
It's no longer just black hats or white hats in computer security. The more someone has to lose, the less likely they should be to trust the computer. It means that all people, all programs, all transactions are shades of grey. Black and white are just a memory. 相似文献
16.
Daniel Bethge 《真空研究与实践》1996,8(2):84-87
The distillation in the fine and high vacuum range requires not only appropriate vacuum pumps but also special apparatus and machines. The principle and the design of laboratory and industrial plants are explained. New mathematical methods are supporting laboratory and pilot testing required for process development and plant layout. An example was chosen for demonstration purposes. 相似文献
17.
18.
Prem Kalra Angelo Mangili Nadia Magnenat Thalmann Daniel Thalmann 《Computer Graphics Forum》1992,11(3):59-69
This paper describes interactive facilities for simulating abstract muscle actions using Rational Free Form Deformations (RFFD). The particular muscle action is simulated as the displacement of the control points of the control-unit for an RFFD defined on a region of interest. One or several simulated muscle actions constitute a Minimum Perceptible Action (MPA), which is defined as the atomic action unit, similar to Action Unit (AU) of the Facial Action Coding System (FACS), to build an expression. 相似文献
19.
20.
Next-generation broadband promises to usher in a digital future in which it will be possible, for instance, to have a high-definition videoconference examination with your doctor from the comfort of your own home. Japan and Korea in particular are much closer to this sort of digital future than most countries, including the US. Public policy must play an important role in making tomorrow's broadband a reality in America. 相似文献