全文获取类型
收费全文 | 7428篇 |
免费 | 924篇 |
国内免费 | 155篇 |
专业分类
电工技术 | 31篇 |
综合类 | 322篇 |
化学工业 | 5962篇 |
金属工艺 | 102篇 |
机械仪表 | 35篇 |
建筑科学 | 33篇 |
矿业工程 | 47篇 |
能源动力 | 180篇 |
轻工业 | 250篇 |
水利工程 | 3篇 |
石油天然气 | 606篇 |
武器工业 | 29篇 |
无线电 | 232篇 |
一般工业技术 | 518篇 |
冶金工业 | 109篇 |
原子能技术 | 27篇 |
自动化技术 | 21篇 |
出版年
2024年 | 38篇 |
2023年 | 155篇 |
2022年 | 174篇 |
2021年 | 243篇 |
2020年 | 257篇 |
2019年 | 257篇 |
2018年 | 206篇 |
2017年 | 213篇 |
2016年 | 357篇 |
2015年 | 338篇 |
2014年 | 337篇 |
2013年 | 382篇 |
2012年 | 404篇 |
2011年 | 460篇 |
2010年 | 352篇 |
2009年 | 457篇 |
2008年 | 420篇 |
2007年 | 450篇 |
2006年 | 387篇 |
2005年 | 419篇 |
2004年 | 327篇 |
2003年 | 300篇 |
2002年 | 294篇 |
2001年 | 259篇 |
2000年 | 185篇 |
1999年 | 173篇 |
1998年 | 114篇 |
1997年 | 87篇 |
1996年 | 78篇 |
1995年 | 58篇 |
1994年 | 49篇 |
1993年 | 40篇 |
1992年 | 32篇 |
1991年 | 30篇 |
1990年 | 21篇 |
1989年 | 13篇 |
1988年 | 12篇 |
1987年 | 18篇 |
1986年 | 8篇 |
1985年 | 19篇 |
1984年 | 24篇 |
1983年 | 28篇 |
1982年 | 20篇 |
1981年 | 1篇 |
1951年 | 11篇 |
排序方式: 共有8507条查询结果,搜索用时 0 毫秒
1.
2.
Dr. Md Kausar Raza Aisha Noor Dr. Paresh Kumar Samantaray 《Chembiochem : a European journal of chemical biology》2021,22(23):3270-3272
Individually, photoredox catalysis (PC) and photodynamic therapy (PDT) are well-established concepts that have experienced a remarkable resurgence in recent years, leading to significant progress in organic synthesis for PC and clinical approval of anticancer drugs for PDT. But, very recently, new photoredox catalyst systems based on Ir(III) and Ru(II) complexes have garnered significant interest because they can simultaneously be used as PDT agents apart from their demonstrated PC activity. This highlight discusses the unique PC behavior of emerging Ir(III)- and Ru(II)-based systems while also examining their potential PDT activity in cancer treatment. 相似文献
3.
4.
5.
Yilin Yang Siddarth K. Achar John R. Kitchin 《American Institute of Chemical Engineers》2022,68(6):e17653
The degree of rate control (DRC) quantitatively identifies the kinetically relevant (sometimes known as rate-limiting) steps of a complex reaction network. This concept relies on derivatives which are commonly implemented numerically, for example, with finite differences (FDs). Numerical derivatives are tedious to implement, and can be problematic, and unstable or unreliable. In this study, we demonstrate the use of automatic differentiation (AD) in the evaluation of the DRC. AD libraries are increasingly available through modern machine learning frameworks. Compared with the FDs, AD provides solutions with higher accuracy with lower computational cost. We demonstrate applications in steady-state and transient kinetics. Furthermore, we illustrate a hybrid local-global sensitivity analysis method, the distributed evaluation of local sensitivity analysis, to assess the importance of kinetic parameters over an uncertain space. This method also benefits from AD to obtain high-quality results efficiently. 相似文献
6.
Dr. Alexander Fries Dr. Laura S. Mazzaferro Dr. Björn Grüning Dr. Philippe Bisel Karin Stibal Patrick C. F. Buchholz Prof. Dr. Jürgen Pleiss Prof. Dr. Georg A. Sprenger Prof. Dr. Michael Müller 《Chembiochem : a European journal of chemical biology》2019,20(13):1672-1677
Chorismate and isochorismate constitute branch-point intermediates in the biosynthesis of many aromatic metabolites in microorganisms and plants. To obtain unnatural compounds, we modified the route to menaquinone in Escherichia coli. We propose a model for the binding of isochorismate to the active site of MenD ((1R,2S, 5S,6S)-2-succinyl-5-enolpyruvyl-6-hydroxycyclohex-3-ene-1-carboxylate (SEPHCHC) synthase) that explains the outcome of the native reaction with α-ketoglutarate. We have rationally designed variants of MenD for the conversion of several isochorismate analogues. The double-variant Asn117Arg–Leu478Thr preferentially converts (5S,6S)-5,6-dihydroxycyclohexa-1,3-diene-1-carboxylate (2,3-trans-CHD), the hydrolysis product of isochorismate, with a >70-fold higher ratio than that for the wild type. The single-variant Arg107Ile uses (5S,6S)-6-amino-5-hydroxycyclohexa-1,3-diene-1-carboxylate (2,3-trans-CHA) as substrate with >6-fold conversion compared to wild-type MenD. The novel compounds have been made accessible in vivo (up to 5.3 g L−1). Unexpectedly, as the identified residues such as Arg107 are highly conserved (>94 %), some of the designed variations can be found in wild-type SEPHCHC synthases from other bacteria (Arg107Lys, 0.3 %). This raises the question for the possible natural occurrence of as yet unexplored branches of the shikimate pathway. 相似文献
7.
8.
9.
10.