全文获取类型
收费全文 | 179955篇 |
免费 | 8725篇 |
国内免费 | 3157篇 |
专业分类
电工技术 | 4895篇 |
技术理论 | 4篇 |
综合类 | 5916篇 |
化学工业 | 28684篇 |
金属工艺 | 9645篇 |
机械仪表 | 9321篇 |
建筑科学 | 7292篇 |
矿业工程 | 2294篇 |
能源动力 | 4721篇 |
轻工业 | 10863篇 |
水利工程 | 2654篇 |
石油天然气 | 3203篇 |
武器工业 | 555篇 |
无线电 | 22301篇 |
一般工业技术 | 32269篇 |
冶金工业 | 8814篇 |
原子能技术 | 1669篇 |
自动化技术 | 36737篇 |
出版年
2024年 | 220篇 |
2023年 | 1415篇 |
2022年 | 2044篇 |
2021年 | 3690篇 |
2020年 | 2767篇 |
2019年 | 2620篇 |
2018年 | 16860篇 |
2017年 | 15919篇 |
2016年 | 12836篇 |
2015年 | 4054篇 |
2014年 | 5059篇 |
2013年 | 6397篇 |
2012年 | 9942篇 |
2011年 | 16627篇 |
2010年 | 14019篇 |
2009年 | 11440篇 |
2008年 | 12291篇 |
2007年 | 12533篇 |
2006年 | 4909篇 |
2005年 | 5200篇 |
2004年 | 4362篇 |
2003年 | 4198篇 |
2002年 | 3492篇 |
2001年 | 2677篇 |
2000年 | 2334篇 |
1999年 | 2107篇 |
1998年 | 2374篇 |
1997年 | 1628篇 |
1996年 | 1423篇 |
1995年 | 1070篇 |
1994年 | 831篇 |
1993年 | 719篇 |
1992年 | 542篇 |
1991年 | 463篇 |
1990年 | 392篇 |
1989年 | 326篇 |
1988年 | 307篇 |
1987年 | 211篇 |
1986年 | 174篇 |
1985年 | 139篇 |
1984年 | 113篇 |
1983年 | 74篇 |
1982年 | 50篇 |
1981年 | 46篇 |
1976年 | 63篇 |
1968年 | 47篇 |
1966年 | 45篇 |
1965年 | 47篇 |
1955年 | 63篇 |
1954年 | 68篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
In this paper, we consider the classical finite mixture model, which is an effective tool for modeling lifetime distributions for random samples from heterogeneous populations. We discuss new results on stochastic comparison for two finite mixtures when each of them is drawn from one of the following semiparametric families, i.e., proportional hazards, accelerated lifetime and proportional reversed hazards. 相似文献
72.
73.
74.
Variations of Incomplete Open Cubes is the major project by the twentieth-century conceptual artist Sol LeWitt. In this paper we interpret the enumerative component of the project as embeddings of graphs. This formulation permits use of an algorithm to check the completeness of the list of the structures produced by the artist. Our conclusion is that the artist found the correct number of structures (that is, 122), but that his list contains a mistake in the presentation of a pair of incomplete cubes, a discovery that appears not to have been noted before. 相似文献
75.
Peer-to-Peer Networking and Applications - Recently, as the P2P service environment repeats evolution, its usage in mobile is rapidly increasing. Applications are being developed in various mobile... 相似文献
76.
The increased concentration of CO2 due to continuous breathing and no discharge of human beings in the manned closed space, like spacecraft and submarines, can be a threat to health and safety. Effective removal of low concentration CO2 from the manned closed space is essential to meet the requirements of long-term space or deep-sea exploration, which is an international frontier and trend. Ionic liquids (ILs), as a widespread and green solvent, already showed its excellent performance on CO2 capture and absorption, indicating its potential application in low concentration CO2 capture. In this review, we first summarized the current methods and strategies for direct capture from low concentration CO2 in both the atmosphere and manned closed spaces. Then, the multi-scale simulation methods of CO2 capture by ionic liquids are described in detail, including screening ionic liquids by COSMO-RS methods, capture mechanism by density functional theory and molecular dynamics simulation, and absorption process by computational fluid dynamics simulation. Lastly, some typical IL-based green technologies for low concentration CO2 capture, such as functionalized ILs, co-solvent systems with ILs, and supported materials based on ILs, are introduced, and analyzed the subtle possibility in manned closed spaces. Finally, we look forward to the technology and development of low concentration CO2 capture, which can meet the needs of human survival in closed space and proposed that supported materials with ionic liquids have great advantages and infinite possibilities in the vital area. 相似文献
77.
Zhuo Shi Ningning Dong Dingfeng Zhang Xiaofang Jiang Guanxin Du Shichao Lv Jiejie Chen Jun Wang Shifeng Zhou 《Journal of the American Ceramic Society》2019,102(7):3965-3971
The construction of nonlinear optical materials featuring asymmetric transmission of light is of great technological importance for various applications, including optical switching and optical power limiting. A significant challenge is the scalable fabrication of material candidates with good photochemical stability, high optical transmittance, and excellent optical limiting performance. Here, we present a nanocrystallization avenue for constructing hybrid optical limiting materials that exhibit ultrafast and robust optical limiting performance. The experimental results show that the controllable relaxation of a niobate glass may lead to the clustering of Nb-O units and contracting of the bandgap. It results in the notable improvement in nonlinear optical properties, including the enhanced saturation irradiance (380 GW/cm2), doubly increased nonlinear coefficient, and decreased limiting threshold (200 GW/cm2). Our results suggest a promising material that exhibits promising applications for protecting eyes and sensitive components from laser-induced damage. 相似文献
78.
79.
80.
棋盘格图像在摄像机标定中有非常广泛的应用,对于复杂环境且测量精度要求非常高的场合,会需要特定的且有一定复杂度的算法,但通常情况下,使用这样的标定系统是没有必要的,且会让初次应用的人觉得困难。这里提供一套应用简单,快速,对棋盘格图像具有旋转不变性,良好的鲁棒性,且对非复杂环境具有高精度的标定系统。所有算法均是在前辈们的算法上稍作改变而来,应用效果非常好。 相似文献