全文获取类型
收费全文 | 316篇 |
免费 | 24篇 |
专业分类
电工技术 | 4篇 |
化学工业 | 87篇 |
金属工艺 | 10篇 |
机械仪表 | 7篇 |
建筑科学 | 21篇 |
能源动力 | 22篇 |
轻工业 | 22篇 |
水利工程 | 3篇 |
无线电 | 22篇 |
一般工业技术 | 68篇 |
冶金工业 | 12篇 |
原子能技术 | 3篇 |
自动化技术 | 59篇 |
出版年
2023年 | 5篇 |
2022年 | 2篇 |
2021年 | 7篇 |
2020年 | 10篇 |
2019年 | 5篇 |
2018年 | 13篇 |
2017年 | 5篇 |
2016年 | 11篇 |
2015年 | 11篇 |
2014年 | 20篇 |
2013年 | 20篇 |
2012年 | 21篇 |
2011年 | 18篇 |
2010年 | 20篇 |
2009年 | 17篇 |
2008年 | 20篇 |
2007年 | 18篇 |
2006年 | 12篇 |
2005年 | 14篇 |
2004年 | 11篇 |
2003年 | 6篇 |
2002年 | 8篇 |
2001年 | 7篇 |
1999年 | 4篇 |
1998年 | 5篇 |
1997年 | 3篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1994年 | 5篇 |
1993年 | 4篇 |
1992年 | 4篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1969年 | 1篇 |
1963年 | 1篇 |
排序方式: 共有340条查询结果,搜索用时 14 毫秒
1.
Knaust Thiemo Felnhofer Anna Kothgassner Oswald D. Hllmer Helge Gorzka Robert-Jacek Schulz Holger 《Virtual Reality》2022,26(3):925-938
Virtual Reality - It is generally accepted that natural environments reduce stress and improve mood. Since access to natural environments is sometimes limited, virtual natural environments,... 相似文献
2.
Nonribosomal Peptides Produced by Minimal and Engineered Synthetases with Terminal Reductase Domains
Andreas Tietze Dr. Yan-Ni Shi Dr. Max Kronenwerth Prof. Dr. Helge B. Bode 《Chembiochem : a European journal of chemical biology》2020,21(19):2750-2754
Nonribosomal peptide synthetases (NRPSs) use terminal reductase domains for 2-electron reduction of the enzyme-bound thioester releasing the generated peptides as C-terminal aldehydes. Herein, we reveal the biosynthesis of a pyrazine that originates from an aldehyde-generating minimal NRPS termed ATRed in entomopathogenic Xenorhabdus indica. Reductase domains were also investigated in terms of NRPS engineering and, although no general applicable approach was deduced, we show that they can indeed be used for the production of similar natural and unnatural pyrazinones. 相似文献
3.
Helge Kragh 《Centaurus; international magazine of the history of science and medicine》2019,61(4):329-344
Like other scientific concepts, the idea of a chemical element has changed considerably over time, since it was first established in the Enlightenment era. In Dmitri Mendeleev's construction of the periodic system, he distinguished between simple substances and elements as defined by their atomic weights. The foundation of the periodic system on the latter concept led to several challenges. For example, the system seemed unable to accommodate the radioactive substances eventually recognised as isotopes. Around 1920, elements were consequently redefined in terms of their atomic numbers, a nuclear property that could be determined by X‐ray spectroscopy. Although this understanding of an element has stood the test of time, new questions turned up relating to the concept of an element following the syntheses of transuranic elements since the early 1940s. These syntheses of very heavy elements have additionally led chemists and physicists to reconsider the criteria for the discovery of a new element. Recently, elements have been officially recognised on the sole ground that a small number of very heavy atomic nuclei were identified. The paper discusses how the notion of an element was modified during different periods of time, the reasons for the modifications, and the values ascribed to them in the communities of chemists and physicists. 相似文献
4.
5.
6.
Lei Zhao Tien Duy Vo Marcel Kaiser Prof. Dr. Helge B. Bode 《Chembiochem : a European journal of chemical biology》2020,21(9):1288-1292
A new cyclic lipopeptide, phototemtide A ( 1 ), was isolated from Escherichia coli expressing the biosynthetic gene cluster pttABC from Photorhabdus temperata Meg1. The structure of 1 was elucidated by HR-ESI-MS and NMR experiments. The absolute configurations of amino acids and 3-hydroxyoctanoic acid in 1 were determined by using the advanced Marfey's method and comparison after total synthesis of 1 , respectively. Additionally, three new minor derivatives, phototemtides B–D ( 2 – 4 ), were identified by detailed HPLC–MS analysis. Phototemtide A ( 1 ) showed weak antiprotozoal activity against Plasmodium falciparum, with an IC50 value of 9.8 μm . The biosynthesis of phototemtides A–D ( 1 – 4 ) was also proposed. 相似文献
7.
Dr. Carsten Kegler Friederike I. Nollmann Tilman Ahrendt Florian Fleischhacker Edna Bode Prof. Dr. Helge B. Bode 《Chembiochem : a European journal of chemical biology》2014,15(6):826-828
An E. coli strain with deletions in five transaminases (ΔaspC ΔilvE ΔtyrB ΔavtA ΔybfQ) was constructed to be unable to degrade several amino acids. This strain was used as an expression host for the analysis of the amino acid configuration of nonribosomally synthesized peptides, including the novel peptide “xenotetrapeptide” from Xenorhabdus nematophila, by using a combination of labeling experiments and mass spectrometry. Additionally, the number of D ‐amino acids in the produced peptide was assigned following simple cultivation of the expression strain in D2O. 相似文献
8.
9.
10.