全文获取类型
收费全文 | 219969篇 |
免费 | 13949篇 |
国内免费 | 7521篇 |
专业分类
电工技术 | 9518篇 |
技术理论 | 3篇 |
综合类 | 11842篇 |
化学工业 | 32579篇 |
金属工艺 | 12319篇 |
机械仪表 | 11259篇 |
建筑科学 | 12264篇 |
矿业工程 | 3687篇 |
能源动力 | 4853篇 |
轻工业 | 15962篇 |
水利工程 | 4166篇 |
石油天然气 | 6145篇 |
武器工业 | 1131篇 |
无线电 | 26550篇 |
一般工业技术 | 32885篇 |
冶金工业 | 9091篇 |
原子能技术 | 1830篇 |
自动化技术 | 45355篇 |
出版年
2024年 | 636篇 |
2023年 | 2152篇 |
2022年 | 4122篇 |
2021年 | 5548篇 |
2020年 | 4027篇 |
2019年 | 3420篇 |
2018年 | 17837篇 |
2017年 | 17393篇 |
2016年 | 13674篇 |
2015年 | 6070篇 |
2014年 | 7309篇 |
2013年 | 9068篇 |
2012年 | 12766篇 |
2011年 | 20009篇 |
2010年 | 17654篇 |
2009年 | 14695篇 |
2008年 | 15678篇 |
2007年 | 16219篇 |
2006年 | 8245篇 |
2005年 | 7834篇 |
2004年 | 5724篇 |
2003年 | 4866篇 |
2002年 | 4194篇 |
2001年 | 3211篇 |
2000年 | 2900篇 |
1999年 | 2627篇 |
1998年 | 2252篇 |
1997年 | 1912篇 |
1996年 | 1712篇 |
1995年 | 1398篇 |
1994年 | 1102篇 |
1993年 | 914篇 |
1992年 | 727篇 |
1991年 | 574篇 |
1990年 | 446篇 |
1989年 | 349篇 |
1988年 | 298篇 |
1987年 | 217篇 |
1986年 | 178篇 |
1985年 | 152篇 |
1984年 | 111篇 |
1983年 | 86篇 |
1982年 | 82篇 |
1981年 | 61篇 |
1980年 | 58篇 |
1979年 | 46篇 |
1976年 | 66篇 |
1968年 | 50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
51.
This paper presents an integrated passive damping approach in hybrid metal-CFRP parts for structural applications. In this concept a viscoelastic material is embedded in the joint zone of the hybrid component. To examine the connection strength single-lap-joint specimens were produced and tested and the influence of the used material combinations, different surface structures, and different process parameters i.e. the moment of cross-linking were evaluated. Afterwards, the metal-CFRP hybrids were tested in quasi-static tests to assess their connection strength and failure behaviour. Dynamic cyclic tensile tests with step-wise increased loading conditions were performed to determine the specimens damping behaviour and to estimate their fatigue performance. Finally, these results are compared to a state of the art metal-CFRP hybrid with rivets connecting both materials. 相似文献
52.
煤电平均供电煤耗作为评价能源系统效率的指标已在行业内广泛应用。但该项指标无法很好地反映一个国家、地区的用电结构与用电能耗水平。为此,参照行业内普遍采用的火电厂发电煤耗和供电煤耗指标,定义“综合用电煤耗”,即用户每用1 kW?h电“消耗”的标准煤量(单位:g/(kW?h))。在此基础上,提出“综合发电煤耗”与“综合供电煤耗”的概念,形成完整的指标评价体系。对近年典型省份指标值的研究表明,该指标体系能够很好地反映供给侧国家、省区或企业的发电结构与电能生产能耗水平。这一指标体系能够为正确理解和计算用电、输电与电能替代项目的化石能源消耗量及其排放量提供依据。 相似文献
53.
54.
Mingchang Lin Yufei Zhang Guosong Chen Ming Jiang 《Small (Weinheim an der Bergstrasse, Germany)》2015,11(45):6065-6070
Glyco‐mimicking nanoparticles (glyco‐NPs) with Förster resonance energy transfer (FRET) donor and acceptor groups formed via dynamic covalent bond of benzoboroxole and sugar from two complementary polymers are prepared. The glyco‐NPs are proved to be quite stable under physiological conditions but sensitive to pH. So the glyco‐NPs can be internalized by dendritic cells with integrity and nontoxicity and then dissociate within the acidic organelles. This particle dissociation is directly observed and visualized in vitro, for the first time via the FRET measurements and fluorescent microscopy. This feature makes controlled release of drug or protein by glyco‐NPs possible, i.e., when model antigen Ovalbumin is loaded in the glyco‐NPs, the released Ovalbumin in dendritic cells stimulates T cells more efficiently than the free Ovalbumin itself as a result of the enhanced antigen processing and presentation. Thus, the results enlighten a bright future of the glyco‐NPs in immunotherapy. 相似文献
55.
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
56.
57.
58.
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
59.
60.