全文获取类型
收费全文 | 210860篇 |
免费 | 23224篇 |
国内免费 | 7690篇 |
专业分类
电工技术 | 12275篇 |
技术理论 | 16篇 |
综合类 | 11555篇 |
化学工业 | 42771篇 |
金属工艺 | 9532篇 |
机械仪表 | 11333篇 |
建筑科学 | 15225篇 |
矿业工程 | 4537篇 |
能源动力 | 6037篇 |
轻工业 | 19664篇 |
水利工程 | 3620篇 |
石油天然气 | 7878篇 |
武器工业 | 1463篇 |
无线电 | 27315篇 |
一般工业技术 | 30793篇 |
冶金工业 | 7979篇 |
原子能技术 | 1745篇 |
自动化技术 | 28036篇 |
出版年
2025年 | 48篇 |
2024年 | 3438篇 |
2023年 | 3812篇 |
2022年 | 6064篇 |
2021年 | 8329篇 |
2020年 | 8261篇 |
2019年 | 9167篇 |
2018年 | 7809篇 |
2017年 | 8602篇 |
2016年 | 8962篇 |
2015年 | 10361篇 |
2014年 | 12023篇 |
2013年 | 14632篇 |
2012年 | 13646篇 |
2011年 | 13733篇 |
2010年 | 12647篇 |
2009年 | 12050篇 |
2008年 | 11181篇 |
2007年 | 10647篇 |
2006年 | 10108篇 |
2005年 | 8636篇 |
2004年 | 6445篇 |
2003年 | 5936篇 |
2002年 | 5873篇 |
2001年 | 5171篇 |
2000年 | 4627篇 |
1999年 | 3891篇 |
1998年 | 2903篇 |
1997年 | 2381篇 |
1996年 | 2113篇 |
1995年 | 1757篇 |
1994年 | 1472篇 |
1993年 | 1085篇 |
1992年 | 814篇 |
1991年 | 662篇 |
1990年 | 508篇 |
1989年 | 420篇 |
1988年 | 373篇 |
1987年 | 216篇 |
1986年 | 210篇 |
1985年 | 130篇 |
1984年 | 112篇 |
1983年 | 74篇 |
1982年 | 86篇 |
1981年 | 67篇 |
1980年 | 65篇 |
1979年 | 46篇 |
1977年 | 37篇 |
1976年 | 24篇 |
1975年 | 16篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
The simultaneous contrast effect is investigated in this article. A total of 174 and 154 test/induction combinations were studied for CRT and surface colours respectively. Each combination was assessed by nine observers using a matching technique. The test and induction colours used for CRT colours were similar to surface colours using fabric samples. The results indicated a strong lightness contrast effect for both CRT and surface media; that is, the lightness of a test colour surrounded by a lighter induction colour was reduced for both CRT and surface colours. However, the effect in CRT medium was more pronounced than in the surface medium. © 2004 Wiley Periodicals, Inc. Col Res Appl, 30, 13–20, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20074 相似文献
102.
The growth of Li1+xMn2O4 via detonation reaction was investigated with respect to the presence of an energetic precursor, such as the metallic nitrate and the degree of confinement of the explosive charge. The detonation products were characterized by scanning electron microscopy. Powder X-ray diffraction and transmission electron microscopy were used to characterize the products. Li1+xMn2O4 with 1-2 μm spherical morphology and more uniform secondary particles, but with smaller primary particles of diameters from 20 to 60 nm and a variety of morphologies were found. The oxides produced by this cheap method affirmed the validity of detonation synthesis of nano-size powders. 相似文献
103.
Jens‐Peter Heinß Dr. 《真空研究与实践》2007,19(5):20-23
Hydrogen free amorphous carbon coatings ‐ deposited with plasma‐activated high‐rate evaporation By using the technology of the plasmaactivated electron beam evaporation we deposited hydrogen free amorphous carbon coatings with deposition rates of up to 100 μm/h. The results of the mechanical and tribological investigations show the potential of these layers for the use in case of wear resistance. Hardnesses of up to 16GPa were proved. The actual state of the characterisation of the coatings is described and the outlook onto possibilities of further optimisation is given. 相似文献
104.
105.
D. Surek Prof. Dr.‐Ing. habil. 《真空研究与实践》2007,19(3):32-36
Helium leak test devices for the quality inspection of housings for vacuum compressors The well‐known and wide‐spread helium leak test method is a safe and fast quality testing method for construction units of any kind. Due to its safe examination and the short time of examination it is predominantly inserted into automated production lines as e.g. in the automobile supporting industry up to the examination by Airbags and rims of wheel. Likewise in addition, for the construction units, machines and devices of the vacuum engineering. From this the demand results simple and in particular economical devices for the helium leak test of construction units with small numbers of items of under 200 pieces per day. For these manufacturing profiles economical ways for the helium leak test are pointed out. 相似文献
106.
107.
108.
109.
110.
Imperfection in information can be considered a crosscutting concern that manifests itself in diverse kinds of imprecision, uncertainty, or inconsistency in the data models of a software system. The extension of existing programming and querying interfaces for the different aspects of information imperfection requires a proper modularization of the different concerns of numerical imprecision handling, so that the extensions do not interfere with existing programming practices and do not obscure the original design. Aspect‐oriented design (AOD) enables such a form of nonintrusive extensions to be added to existing software libraries, clearly separating fuzziness or other imperfections in data as a differentiated concern that can be considered from the early phases of development. In this article, a general framework for aspect‐based extension of data models and fuzzy databases is described, and some design and implementation issues of such AOD‐based extensions on OJB database libraries are described as a case study. © 2006 Wiley Periodicals, Inc. Int J Int Syst 21: 1199–1216, 2006. 相似文献