全文获取类型
收费全文 | 38140篇 |
免费 | 2897篇 |
国内免费 | 1578篇 |
专业分类
电工技术 | 1894篇 |
技术理论 | 2篇 |
综合类 | 2266篇 |
化学工业 | 6495篇 |
金属工艺 | 2266篇 |
机械仪表 | 2298篇 |
建筑科学 | 2982篇 |
矿业工程 | 933篇 |
能源动力 | 888篇 |
轻工业 | 2301篇 |
水利工程 | 536篇 |
石油天然气 | 2640篇 |
武器工业 | 211篇 |
无线电 | 4620篇 |
一般工业技术 | 4807篇 |
冶金工业 | 2105篇 |
原子能技术 | 402篇 |
自动化技术 | 4969篇 |
出版年
2024年 | 148篇 |
2023年 | 644篇 |
2022年 | 975篇 |
2021年 | 1451篇 |
2020年 | 1089篇 |
2019年 | 909篇 |
2018年 | 986篇 |
2017年 | 1178篇 |
2016年 | 1061篇 |
2015年 | 1386篇 |
2014年 | 1743篇 |
2013年 | 2224篇 |
2012年 | 2179篇 |
2011年 | 2474篇 |
2010年 | 2235篇 |
2009年 | 2047篇 |
2008年 | 2037篇 |
2007年 | 2032篇 |
2006年 | 2049篇 |
2005年 | 1777篇 |
2004年 | 1215篇 |
2003年 | 1051篇 |
2002年 | 1020篇 |
2001年 | 882篇 |
2000年 | 926篇 |
1999年 | 1103篇 |
1998年 | 956篇 |
1997年 | 846篇 |
1996年 | 828篇 |
1995年 | 636篇 |
1994年 | 561篇 |
1993年 | 389篇 |
1992年 | 349篇 |
1991年 | 258篇 |
1990年 | 195篇 |
1989年 | 169篇 |
1988年 | 137篇 |
1987年 | 104篇 |
1986年 | 78篇 |
1985年 | 59篇 |
1984年 | 57篇 |
1983年 | 30篇 |
1982年 | 37篇 |
1981年 | 24篇 |
1980年 | 18篇 |
1979年 | 11篇 |
1977年 | 7篇 |
1976年 | 7篇 |
1973年 | 5篇 |
1970年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Co-evolution as a computational and cognitive model of design 总被引:6,自引:0,他引:6
Co-evolutionary design has been developed as a computational model that assumes two parallel search spaces: the problem space
and the solution space. The design process iteratively searches each space using the other space as the basis for a fitness
function when evaluating the alternatives. Co-evolutionary design can also be developed as a cognitive model of design by
characterizing the way in which designers iteratively search for a design solution, making revisions to the problem specification.
This paper presents the computational model of co-evolutionary design and then describes a protocol study of human designers
looking for evidence of co-evolution of problem specifications and design solutions. The study shows that co-evolutionary
design is a good cognitive model of design and highlights the similarities and differences between the computational model
and the cognitive model. The results show that the two kinds of co-evolutionary design complement each other, having strengths
in different aspects of the design process.
Electronic Publication 相似文献
102.
103.
Xiaohui Tang Reckinger N. Bayot V. Krzeminski C. Dubois E. Villaret A. Bensahel D.-C. 《Nanotechnology, IEEE Transactions on》2006,5(6):649-656
Self-aligned single-dot memory devices and arrays were fabricated based on arsenic-assisted etching and oxidation effects. The resulting device has a floating gate of about 5-10 nm, presenting single-electron memory operation at room temperature. In order to realize the final single-electron memory circuit, this paper investigates process repeatability, device uniformity in single-dot memory arrays, device scalability, and process transferability to an industrial application 相似文献
104.
This article focuses on the detailed microstructural investigation of the oxide scale formed on a 304 steel in the presence of oxygen and water vapour (40%) at 600 °C. The work has been carried out using a combination of microanalytical techniques including FIB, TEM, EDX and electron diffraction. The local breakdown of the initially protective oxide scale and the growth of island/crater oxide morphology are described. Special consideration is given to the influence of the microstructure of the steel and the oxide scale on the breakdown behaviour. 相似文献
105.
To investigate the effects of multiple weak interactions on the binding of phenolic compounds by polymeric adsorbents, macroporous polystyrene (PS) resin and PS‐based adsorbents with different hydrogen‐bond acceptor atoms (PS CH2( OCH2CH2)n OCH3, n = 0, 1, 2, and 3, denoted as PS‐EG0, PS‐EG1, PS‐EG2, and PS‐EG3) were prepared. The phenol adsorption strength order on these adsorbents was PS/PS‐EG0 < PS‐EG1 < PS‐EG2 < PS‐EG3, indicating that the adsorption on PS and PS‐EG0 was driven by hydrophobic and π–π interactions, and the adsorption on PS‐EG1, PS‐EG2, and PS‐EG3 was driven by a hydrogen bond in addition to hydrophobic and π–π interactions. PS‐EG2 may adsorb a second phenol molecule on each binding site and PS‐EG3 may adsorb second and third ones. The adsorption strength of resorcinol increased in the order of PS, PS‐EG1, and PS‐EG2, indicating that the adsorption was driven by 0, 1, and 2 hydrogen bonds in addition to hydrophobic and π–π interactions. Similarly, the adsorption of phloroglucinol on PS, PS‐EG1, PS‐EG2, and PS‐EG3 was driven by 0, 1, 2, and 3 hydrogen bonds in addition to hydrophobic and π–π interactions because the adsorption strength increased in this order. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4652–4658, 2006 相似文献
106.
107.
A shortcut model is developed for predicting the HETP of a structured packed distillation column operating at elevated pressure. The proposed model incorporates the geometrical parameters of the packing, physical properties of the vapor and liquid phases, and the hydrodynamics of the two‐phase flow. The proposed model is tested and validated by comparing the predicted results with the present experimental data and some published HETP data. The results show that the proposed model can predict the experimental data with a deviation smaller than 20 %. 相似文献
108.
简要地介绍了氢离子敏场效应晶体管(H~+-ISFET)的基本结构和工作原理,提出了一种新型背面接触式H~+-ISFET。对该结构在版图、工艺设计中的有关问题,进行了探讨。最后指出:它在pH值的测量中有较好的实用价值。 相似文献
109.
雨洪资源利用的必要性及其措施探讨 总被引:2,自引:0,他引:2
遵循水的规律,坚持防汛抗旱并举,实现防汛工作由单纯的洪水控制向洪水资源化转变和单一农业性抗旱向以保证包括城市供水为重点的全面抗旱转变是新时期治水新思路的重要观点之一.文章在回顾雨洪资源利用发展简史的基础上,就其必要性、可行性和利用方式进行了初步探讨. 相似文献
110.
分析了我厂两碱法原卤净化后,加热管内壁结碳酸钙垢的原因,探讨了我厂采取加盐酸、加阻垢剂、用超声波阻垢器的方法,以及对加热管内碳酸钙垢防治的情况和存在的问题. 相似文献