全文获取类型
收费全文 | 5875篇 |
免费 | 254篇 |
国内免费 | 21篇 |
专业分类
电工技术 | 57篇 |
综合类 | 23篇 |
化学工业 | 1145篇 |
金属工艺 | 91篇 |
机械仪表 | 128篇 |
建筑科学 | 304篇 |
矿业工程 | 10篇 |
能源动力 | 240篇 |
轻工业 | 360篇 |
水利工程 | 56篇 |
石油天然气 | 31篇 |
无线电 | 534篇 |
一般工业技术 | 1179篇 |
冶金工业 | 846篇 |
原子能技术 | 46篇 |
自动化技术 | 1100篇 |
出版年
2023年 | 56篇 |
2022年 | 118篇 |
2021年 | 186篇 |
2020年 | 133篇 |
2019年 | 178篇 |
2018年 | 214篇 |
2017年 | 139篇 |
2016年 | 167篇 |
2015年 | 133篇 |
2014年 | 199篇 |
2013年 | 353篇 |
2012年 | 315篇 |
2011年 | 353篇 |
2010年 | 258篇 |
2009年 | 265篇 |
2008年 | 274篇 |
2007年 | 277篇 |
2006年 | 202篇 |
2005年 | 194篇 |
2004年 | 169篇 |
2003年 | 175篇 |
2002年 | 145篇 |
2001年 | 86篇 |
2000年 | 101篇 |
1999年 | 75篇 |
1998年 | 237篇 |
1997年 | 164篇 |
1996年 | 99篇 |
1995年 | 108篇 |
1994年 | 80篇 |
1993年 | 71篇 |
1992年 | 60篇 |
1991年 | 45篇 |
1990年 | 32篇 |
1989年 | 32篇 |
1988年 | 39篇 |
1987年 | 35篇 |
1986年 | 19篇 |
1985年 | 29篇 |
1984年 | 20篇 |
1983年 | 15篇 |
1982年 | 26篇 |
1981年 | 29篇 |
1980年 | 22篇 |
1979年 | 21篇 |
1978年 | 17篇 |
1977年 | 26篇 |
1976年 | 49篇 |
1975年 | 14篇 |
1972年 | 13篇 |
排序方式: 共有6150条查询结果,搜索用时 9 毫秒
931.
932.
Nathalie Ouellet Louis‐Simon Lussier France Beaupr 《Propellants, Explosives, Pyrotechnics》2003,28(3):138-144
Quantitative analysis of multi‐component mixtures such as propellant powders is not trivial since it usually requires separation of the mixture constituents. Multivariate calibration combined to the use of semi‐synthetic data sets can eliminate the need for standard solutions preparation, and therefore allow the rapid determination of mixtures provided no intermolecular interactions occur in the systems. Multivariate compositional analyses of FTIR spectra of low‐vulnerability (LOVA), high‐energy low‐vulnerability (HELOVA) and energetic thermoplastic elastomer (ETPE) propellant powder systems were performed using the partial least‐squares (PLS) regression algorithm. All constituents except ethyl centralite (EC) were quantified. Concentrations were predicted within 1% error for the major component (1,3,5‐trinitro‐1,3,5‐triazacyclohexane or RDX), and within 5% error for the minor components (between 12 and 2% nominally by weight). LOVA, HELOVA, and ETPE gun powder samples concentrations were estimated and compared to expected compositions. 相似文献
933.
Emmanuel Batsa Tetteh Tobias Loffler Tsvetan Tarnev Thomas Quast Patrick Wilde Harshitha Barike Aiyappa Simon Schumacher Corina Andronescu Richard D.Tilley Xingxing Chen Wolfgang Schuhmann 《Nano Research》2022,(2):1564-1569
Scanning electrochemical cell microscopy(SECCM)is increasingly applied to determine the intrinsic catalytic activity of single electrocatalyst particle.This is especially feasible if the catalyst nanoparticles are large enough that they can be found and counted in post-SECCM scanning electron microscopy images.Evidently,this becomes impossible for very small nanoparticles and hence,a catalytic current measured in one landing zone of the SECCM droplet cannot be correlated to the exact number of catalyst particles.We show,that by introducing a ruler method employing a carbon nanoelectrode decorated with a countable number of the same catalyst particles from which the catalytic activity can be determined,the activity determined using SECCM from many spots can be converted in the intrinsic catalytic activity of a certain number of catalyst nanoparticles. 相似文献
934.
Marie Bisconti Jean-Franois Simon Sarah Grassi Baptiste Leroy Baptiste Martinet Vanessa Arcolia Vladimir Isachenko Elise Hennebert 《International journal of molecular sciences》2021,22(23)
Male infertility is a common health problem that can be influenced by a host of lifestyle risk factors such as environment, nutrition, smoking, stress, and endocrine disruptors. These effects have been largely demonstrated on sperm parameters (e.g., motility, numeration, vitality, DNA integrity). In addition, several studies showed the deregulation of sperm proteins in relation to some of these factors. This review inventories the literature related to the identification of sperm proteins showing abundance variations in response to the four risk factors for male infertility that are the most investigated in this context: obesity, diabetes, tobacco smoking, and exposure to bisphenol-A (BPA). First, we provide an overview of the techniques used to identify deregulated proteins. Then, we summarise the main results obtained in the different studies and provide a compiled list of deregulated proteins in relation to each risk factor. Gene ontology analysis of these deregulated proteins shows that oxidative stress and immune and inflammatory responses are common mechanisms involved in sperm alterations encountered in relation to the risk factors. 相似文献
935.
Liang Deng Long Zhang Konrad Kosiba René Limbach Lothar Wondraczek Gang Wang Dongdong Gu Uta Kühn Simon Pauly 《材料科学技术学报》2021,81(22):139-150
Monolithic bulk metallic glass and glass matrix composites with a relative density above 98 % were produced by processing Cu46Zr46Al8 (at.%) via selective laser melting (SLM).Their microstructures and mechanical properties were systematically examined.B2 CuZr nanocrystals (30-100 nm in diameter) are uniformly dispersed in the glassy matrix when SLM is conducted at an intermediate energy input.These B2 CuZr nanocrystals nucleate the oxygen-stabilized big cube phase during a remelting step.The presence of these nanocrystals increases the structural heterogeneity as indirectly revealed by mircrohardness and nanoindentation measurements.The corresponding maps in combination with calorimetric data indicate that the glassy phase is altered by the processing conditions.Despite the formation of crystals and a high overall free volume content,all additively manufactured samples fail at lower stress than the as-cast glass and without any plastic strain.The inherent brittleness is attributed to the presence of relatively large pores and the increased oxygen content after selective laser melting. 相似文献
936.
937.
938.
939.
940.