全文获取类型
收费全文 | 2753篇 |
免费 | 132篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 29篇 |
综合类 | 6篇 |
化学工业 | 798篇 |
金属工艺 | 57篇 |
机械仪表 | 43篇 |
建筑科学 | 245篇 |
矿业工程 | 7篇 |
能源动力 | 80篇 |
轻工业 | 231篇 |
水利工程 | 9篇 |
石油天然气 | 1篇 |
武器工业 | 1篇 |
无线电 | 165篇 |
一般工业技术 | 515篇 |
冶金工业 | 300篇 |
原子能技术 | 24篇 |
自动化技术 | 375篇 |
出版年
2023年 | 24篇 |
2022年 | 25篇 |
2021年 | 76篇 |
2020年 | 39篇 |
2019年 | 50篇 |
2018年 | 67篇 |
2017年 | 59篇 |
2016年 | 86篇 |
2015年 | 77篇 |
2014年 | 108篇 |
2013年 | 130篇 |
2012年 | 129篇 |
2011年 | 163篇 |
2010年 | 107篇 |
2009年 | 124篇 |
2008年 | 113篇 |
2007年 | 104篇 |
2006年 | 78篇 |
2005年 | 92篇 |
2004年 | 82篇 |
2003年 | 47篇 |
2002年 | 51篇 |
2001年 | 51篇 |
2000年 | 32篇 |
1999年 | 32篇 |
1998年 | 47篇 |
1997年 | 53篇 |
1996年 | 52篇 |
1995年 | 40篇 |
1994年 | 26篇 |
1993年 | 46篇 |
1992年 | 26篇 |
1991年 | 31篇 |
1990年 | 26篇 |
1989年 | 31篇 |
1986年 | 18篇 |
1985年 | 34篇 |
1984年 | 40篇 |
1983年 | 31篇 |
1982年 | 28篇 |
1981年 | 34篇 |
1980年 | 29篇 |
1979年 | 25篇 |
1978年 | 28篇 |
1976年 | 20篇 |
1975年 | 20篇 |
1974年 | 32篇 |
1973年 | 21篇 |
1971年 | 18篇 |
1969年 | 19篇 |
排序方式: 共有2886条查询结果,搜索用时 15 毫秒
1.
Landsiedel Justus Root Waleri Schramm Christian Menzel Alexander Witzleben Steffen Bechtold Thomas Pham Tung 《Nano Research》2020,13(10):2658-2664
Nano Research - Development of colored surfaces by formation of nano-structured aggregates is a widely used strategy in nature to color lightweight structures (e.g. butterflies) without the use of... 相似文献
2.
Annika Jahn Anton Hoffmann Luisa Blaesing Fabian Kunde Martin Bertau Martina Bremer Steffen Fischer 《化学,工程师,技术》2020,92(11):1733-1740
The enzymatic conversion of lignins, possibly in combination with electrochemical oxidation, makes aromatics such as syringol, guaiacol, vanillin and catechol available in the qualities required by the fragrance industry. The lignins were obtained by soda digestion from wheat straw and Miscanthus, characterized and then converted with laccases. The overall yield amounted up to 9 wt % with a product spectrum confined to four substances. Catechol was the major product, with a fraction of ≈75 %. It can easily be isolated by extraction with acetone. 相似文献
3.
Steffen Vojacek Lukas Schulig Nathalie Wössner Norman Geist Prof. Dr. Walter Langel Prof. Dr. Manfred Jung Prof. Dr. Dennis Schade Prof. Dr. Andreas Link 《ChemMedChem》2019,14(8):853-864
Indoles are privileged structures in medicinal and bioorganic chemistry that are particularly well suited to serve as platforms for diversity. Among many other therapeutic areas, the indole scaffold has been used to design aromatic compounds useful to interfere with enzymes engaged in the regulation of substrate acylation status, such as sirtuins. However, the planarity of the indole ring is not necessarily optimal for all target enzymes, especially when functionalization with aromatic side chains is required. Replacement of flat scaffolds by nonplanar molecular cores dominated by sp3 hybridization is a common strategy to avoid the disadvantages associated with poor solubility and high promiscuity, while covering less-well-explored areas of chemical space. Thus, we synthesized fragment-like tetrahydroindoles suitable for fragment-based drug discovery as well as a well-characterized small library intended as multipurpose screening compounds. For proof of principle, these compounds were screened against sirtuins 1–3, enzymes known to be addressable by indoles. We found that 2,6,6-trimethyl-4-oxo-4,5,6,7-tetrahydro-1H-indole-3-carboxamides are potent and selective SIRT2 inhibitors. Compound 16 t displayed an IC50 value of 0.98 μm and could serve as exquisite starting point for hit-to-lead profiling. 相似文献
4.
The commercial success of the German Federal Ministry's materials research program “Mafto” (1985–1994) was recently evaluated to determine the effectiveness of the direct-funding model in supporting innovative industrial research. Based on the results of a questionnaire, where a 97% return rate was achieved, it was found that the results obtained in 27% of the projects have already been commercialized to some degree, for 26% of the projects a commercialization of the results is planned but has not yet taken place, and for 54% of the projects no commercialization is planned. This study included only projects where at least four years had elapsed since project completion. The reasons why scientifically and technically successfully projects were not commercialized were also surveyed. 相似文献
5.
Heinz Blenke Beate Farys-Kahle Carl-Max Freiherr Von Meysenbug Helmut Weimer 《化学,工程师,技术》1985,57(5):381-390
Rationalizing drawings for chemical apparatus . For small and medium-sized manufacturers of apparatus, producing drawings may constitute a disproportionate waste of time and personnel, particularly when no new designs are involved but only modification or improvement of drawings supplied by the customer. One possibility for rationalizing drawing is to simplify the old-fashioned approach by using symbols for frequently drawn or standard items, or by listing alphanumerically. This presumes a kind of systematization permitting determination of those symbols and their reasonable use, as well facilitating rationalization by means of data processing. There are different approaches to computer-aided drawing (from computer controlled drawing-board to interactive screens); here a CAD programme is presented which was especially developed for graphic presentation of chemical apparatus, and which can be used without learning a programming language. 相似文献
6.
7.
Peter Horn Peter Schaaf Brigitte Holbach Stefan Hölzl Heinz Eschnauer 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1993,196(5):407-409
For provenance assignments of wines strontium isotope ratios can be used because soils from different wine-growing regions, and hence the wines grown there, each show specific ratios. Some successful applications are demonstrated.
87Sr/86Sr aus Gestein und Boden in Rebe und Wein
Zusammenfassung Zur Herkunftsbestimmung von Weinen können Strontium-Isotopenverhältnisse herangezogen werden, da die Böden verschiedener Weinbaugebiete, und damit die dort gezogenen Weine, jeweils spezifische Verhältnisse aufweisen. Einige erfolgreiche Anwendungen werden demonstriert.相似文献
8.
9.
10.
Decision support for AIDS control programmes in Eastern Africa 总被引:1,自引:1,他引:0
Steffen Fleßa 《OR Spectrum》2003,25(2):265-291
The Acquired Immune Deficiency Syndrome (AIDS) constitutes the worst hazard to health care systems in Eastern Africa. Misallocation
of scarce resources of AIDS Control Programmes will unavoidably lead to additional infections and casualties. The following
paper discusses a system dynamics model which allows to assess the impact of different interventions on a pattern population
in Eastern Africa. It becomes obvious that short- and long-term consequences of these programmes differ significantly. The
optimal allocation of resources, therefore, is highly complex and calls for decision support systems to sustain AIDS control
programmes. 相似文献