全文获取类型
收费全文 | 1378篇 |
免费 | 76篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 20篇 |
综合类 | 3篇 |
化学工业 | 357篇 |
金属工艺 | 31篇 |
机械仪表 | 17篇 |
建筑科学 | 119篇 |
矿业工程 | 2篇 |
能源动力 | 45篇 |
轻工业 | 86篇 |
水利工程 | 8篇 |
石油天然气 | 10篇 |
武器工业 | 1篇 |
无线电 | 88篇 |
一般工业技术 | 224篇 |
冶金工业 | 135篇 |
原子能技术 | 9篇 |
自动化技术 | 300篇 |
出版年
2023年 | 20篇 |
2022年 | 12篇 |
2021年 | 66篇 |
2020年 | 32篇 |
2019年 | 30篇 |
2018年 | 47篇 |
2017年 | 34篇 |
2016年 | 58篇 |
2015年 | 49篇 |
2014年 | 68篇 |
2013年 | 68篇 |
2012年 | 72篇 |
2011年 | 98篇 |
2010年 | 68篇 |
2009年 | 67篇 |
2008年 | 55篇 |
2007年 | 63篇 |
2006年 | 39篇 |
2005年 | 49篇 |
2004年 | 35篇 |
2003年 | 18篇 |
2002年 | 23篇 |
2001年 | 25篇 |
2000年 | 12篇 |
1999年 | 21篇 |
1998年 | 44篇 |
1997年 | 36篇 |
1996年 | 25篇 |
1995年 | 19篇 |
1994年 | 14篇 |
1993年 | 23篇 |
1992年 | 10篇 |
1991年 | 6篇 |
1990年 | 10篇 |
1989年 | 11篇 |
1988年 | 7篇 |
1987年 | 6篇 |
1986年 | 5篇 |
1985年 | 9篇 |
1984年 | 10篇 |
1983年 | 7篇 |
1982年 | 4篇 |
1981年 | 11篇 |
1979年 | 5篇 |
1978年 | 4篇 |
1977年 | 5篇 |
1976年 | 6篇 |
1975年 | 6篇 |
1974年 | 4篇 |
1971年 | 5篇 |
排序方式: 共有1455条查询结果,搜索用时 93 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.
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
6.
Zhufang Liu Mohammad Shamsuzzoha Earl T. Ada W. Matthew Reichert David E. Nikles 《Journal of power sources》2007
Well-dispersed Pt nanoparticles with controlled size and narrow size distribution were prepared by polyalcohol reduction of platinum acetylacetonate, using oleylamine as a capping agent. The particle size was varied from 3.5 nm to 11.5 nm by decreasing the amount of oleylamine added in the synthesis. Size selection of the as-prepared particles by solvent fractionation yielded nearly monodispersed Pt particles. The as-prepared particles were loaded on a carbon support by physical deposition, but showed no electrocatalytic activity due to the oleylamine bound to the particle surface. The particles were activated for electrocatalysis after heating the particles in air at 185 °C for 5 h, conditions that gave no particle-sintering and no oxidation. Cyclic voltammetry showed that the particles after the heat treatment in air were electrocatalytically active for methanol oxidation. The smaller 3.5 nm and 4.0 nm Pt particles had a higher intrinsic activity for methanol oxidation, but a lower tolerance to CO poisoning, compared with 6.0 nm, 9.5 nm and 11.5 nm particles. CO-stripping results suggest that CO is more easily oxidized on larger Pt particles. 相似文献
7.
M Kay R Wyllie W Michener M Caulfield R Steffen 《Canadian Metallurgical Quarterly》1993,60(6):473-478
We report two young men with clinical and laboratory evidence of macroscopic ulcerative colitis, sclerosing cholangitis, and insulin-dependent diabetes mellitus. The first patient presented at age 15 with vomiting, abdominal pain, weight loss, and abnormal liver function test results. Liver biopsy and endoscopic retrograde cholangiopancreatography (ERCP) demonstrated sclerosing cholangitis. Colonoscopy with biopsy revealed ulcerative colitis which responded to sulfasalazine. Diabetes occurred at age 18 and insulin therapy was begun. The second patient was 19 at presentation with diarrhea, hematochezia, and weight loss. Proctosigmoidoscopy revealed ulcerative colitis, and sulfasalazine led to clinical remission. Three months later he developed diabetes requiring insulin therapy. At age 28, he developed elevated alkaline phosphatase, and ERCP revealed sclerosing cholangitis. At age 37 he expired from adenocarcinoma that metastasized to the liver. Literature review revealed only one possible case report of this association with microscopic asymptomatic ulcerative colitis in that patient. Statistical analysis suggests that this association is real rather than a chance occurrence. An autoimmune process may be involved and a specific histocompatibility locus antigen (HLA) type may exert a regulatory influence. 相似文献
8.
P. Balle H. Bockhorn B. Geiger N. Jan S. Kureti D. Reichert T. Schrder 《Chemical Engineering and Processing: Process Intensification》2006,45(12):1065-1073
This study deals with the development of a laboratory bench for the practical evaluation of catalysts that are useful for the direct conversion of NOx and soot in the exhaust of diesel engines. The employed model exhaust is generated by using a diffusion burner with additionally dosing some gaseous components to the burner gas to obtain a realistic feed composition. The produced soot is extensively characterized by employing thermogravimetry, transmission electron microscopy, N2 physisorption and temperature programmed techniques. The results of the different characterization methods show that the present soot is suitable for the intended catalytic investigations. The simultaneous conversion of NOx and soot is examined like in practice, i.e. the soot is separated from the tail gas by a diesel particulate filter (DPF) that is coated with the catalyst. The deposited soot is then catalytically converted by NOx and O2 to form N2 and CO2. The conversions of NOx and soot are measured by exclusively applying gas analysers, whereby a special experimental procedure is developed to determine the soot removal. Hence, additional soot related analytics are not required. To show the suitability of the constructed bench a Pt/Fe2O3/β-zeolite sample is taken as test catalyst that is reported to be very active in NOx/soot reaction. The measurements performed with and without catalyst clearly show the effect of the used sample in simultaneous NOx/soot conversion. We therefore consider the constructed laboratory bench to be a useful tool for testing and ranking catalytic materials. 相似文献
9.
Tiziana Margaria Bernhard Steffen 《International Journal on Software Tools for Technology Transfer (STTT)》2004,5(2-3):107-123
In this paper, our solution to the problem of modelling functionally complex communication systems at the application level, based on lightweight coordination, is extended to seamlessly capture system-level testing as well. This extension could be realized simply by self-application: the bulk of the work for integrating system-level testing into our development environment, the ABC, concerned domain modelling, which can be done using the ABC. Therefore, the extension of the ABC to cover system-level testing was merely an application development on the basis of the ABC, illustrated here in the domain of Computer Telephony Integration. Here the adoption of a coarse-grained approach to test design, which is central to the scalability of the overall testing environment, is the enabling aspect for system-level test automation. Together with our lightweight coordination approach this induces an understandable modelling paradigm of system-wide test cases that is adequate for the needs and requirements of industrial test engineers. In particular, it enables test engineers to graphically design complex test cases that, in addition, can even be automatically checked for their intended purposes via model checking. 相似文献
10.