全文获取类型
收费全文 | 218340篇 |
免费 | 24183篇 |
国内免费 | 15140篇 |
专业分类
电工技术 | 18877篇 |
技术理论 | 4篇 |
综合类 | 19221篇 |
化学工业 | 29667篇 |
金属工艺 | 13684篇 |
机械仪表 | 14862篇 |
建筑科学 | 17768篇 |
矿业工程 | 7536篇 |
能源动力 | 6271篇 |
轻工业 | 19083篇 |
水利工程 | 6075篇 |
石油天然气 | 10332篇 |
武器工业 | 2775篇 |
无线电 | 25960篇 |
一般工业技术 | 20979篇 |
冶金工业 | 8842篇 |
原子能技术 | 3131篇 |
自动化技术 | 32596篇 |
出版年
2024年 | 1197篇 |
2023年 | 3653篇 |
2022年 | 7561篇 |
2021年 | 10173篇 |
2020年 | 7598篇 |
2019年 | 5684篇 |
2018年 | 6282篇 |
2017年 | 7373篇 |
2016年 | 6446篇 |
2015年 | 9832篇 |
2014年 | 12352篇 |
2013年 | 14582篇 |
2012年 | 17303篇 |
2011年 | 18080篇 |
2010年 | 17003篇 |
2009年 | 16207篇 |
2008年 | 16039篇 |
2007年 | 15328篇 |
2006年 | 13643篇 |
2005年 | 10833篇 |
2004年 | 7630篇 |
2003年 | 6024篇 |
2002年 | 5759篇 |
2001年 | 5237篇 |
2000年 | 4076篇 |
1999年 | 2847篇 |
1998年 | 1658篇 |
1997年 | 1378篇 |
1996年 | 1272篇 |
1995年 | 1084篇 |
1994年 | 876篇 |
1993年 | 557篇 |
1992年 | 446篇 |
1991年 | 324篇 |
1990年 | 266篇 |
1989年 | 239篇 |
1988年 | 158篇 |
1987年 | 109篇 |
1986年 | 107篇 |
1985年 | 41篇 |
1984年 | 41篇 |
1983年 | 35篇 |
1982年 | 33篇 |
1981年 | 53篇 |
1980年 | 51篇 |
1979年 | 33篇 |
1977年 | 9篇 |
1976年 | 10篇 |
1959年 | 16篇 |
1951年 | 33篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
42.
43.
Wang Lu-di Zhou Wei Xing Ying Liu Na Movahedipour Mahmood Zhou Xiao-guang 《浙江大学学报:C卷英文版》2019,20(3):405-413
Frontiers of Information Technology & Electronic Engineering - Reconstruction of a 12-lead electrocardiogram (ECG) from a serial 3-lead ECG has been researched in the past to satisfy the need... 相似文献
44.
A facile and effective method was proposed to prepare the molecularly imprinted fluorescence sensor with carbon quantum dots, which were modified vinyl groups by acrylic acid on the surface. The obtained fluorescence composite material was investigated by transmission electron microscope and Fourier transform infrared spectra. After the experimental conditions were optimized, a linear range of 1.0–60 μmol L−1 was obtained and the detection limit was 0.17 μmol L−1. The novel fluorescence sensor can be successfully used to detect tetracycline in real samples. This study provides a convenient strategy for selective recognition and rapid detection of tetracycline in the complex environment. 相似文献
45.
46.
47.
The molecular design of short peptides to achieve a tailor-made functional architecture has attracted attention during the past decade but remains challenging as a result of insufficient understanding of the relationship between peptide sequence and assembled supramolecular structures. We report a hybrid-resolution model to computationally explore the sequence–structure relationship of self-assembly for tripeptides containing only phenylalanine and isoleucine. We found that all these tripeptides have a tendency to assemble into nanofibers composed of laterally associated filaments. Molecular arrangements within the assemblies are diverse and vary depending on the sequences. This structural diversity originates from (1) distinct conformations of peptide building blocks that lead to different surface geometries of the filaments and (2) unique sidechain arrangements at the filament interfaces for each sequence. Many conformations are available for tripeptides in solution, but only an extended β-strand and another resembling a right-handed turn are observed in assemblies. It was found that the sequence dependence of these conformations and the packing of resulting filaments are determined by multiple competing noncovalent forces, with hydrophobic interactions involving Phe being particularly important. The sequence pattern for each type of assembly conformation and packing has been identified. These results highlight the importance of the interplay between conformation, molecular packing, and sequences for determining detailed nanostructures of peptides and provide a detailed insight to support a more precise design of peptide-based nanomaterials. 相似文献
48.
Jialong Tian M. Babar Shahzad Wei Wang Lichang Yin Zhouhua Jiang Ke Yang 《材料科学技术学报》2018,34(9):1671-1675
The effect of Co addition on the formation of Ni-Ti clusters in maraging stainless steel was studied by three dimensional atom probe (3DAP) and first-principles calculation. The cluster analysis based on the maximum separation approach showed an increase in size but a decrease in density of Ni-Ti clusters with increasing the Co content. The first-principles calculation indicated weaker Co-Ni (Co-Ti) interactions than Co-Ti (Fe-Ti) interactions, which should be the essential reason for the change of distribution characteristics of Ni-Ti clusters in bcc Fe caused by Co addition. 相似文献
49.
Yejun Wu Bowen Yan Juan Zhou Huizhang Lian Xiaojun Yu Jianxin Zhao Hao Zhang Wei Chen Daming Fan 《Journal of food science》2020,85(10):3282-3292