全文获取类型
收费全文 | 1496篇 |
免费 | 83篇 |
国内免费 | 8篇 |
学科分类
工业技术 | 1587篇 |
出版年
2023年 | 29篇 |
2022年 | 18篇 |
2021年 | 53篇 |
2020年 | 33篇 |
2019年 | 31篇 |
2018年 | 42篇 |
2017年 | 29篇 |
2016年 | 61篇 |
2015年 | 45篇 |
2014年 | 63篇 |
2013年 | 86篇 |
2012年 | 84篇 |
2011年 | 99篇 |
2010年 | 60篇 |
2009年 | 66篇 |
2008年 | 78篇 |
2007年 | 71篇 |
2006年 | 61篇 |
2005年 | 53篇 |
2004年 | 39篇 |
2003年 | 34篇 |
2002年 | 43篇 |
2001年 | 16篇 |
2000年 | 31篇 |
1999年 | 27篇 |
1998年 | 21篇 |
1997年 | 28篇 |
1996年 | 16篇 |
1995年 | 14篇 |
1994年 | 21篇 |
1993年 | 15篇 |
1992年 | 13篇 |
1991年 | 18篇 |
1990年 | 14篇 |
1989年 | 8篇 |
1988年 | 7篇 |
1987年 | 9篇 |
1986年 | 7篇 |
1985年 | 14篇 |
1984年 | 16篇 |
1983年 | 15篇 |
1982年 | 10篇 |
1981年 | 9篇 |
1979年 | 13篇 |
1978年 | 5篇 |
1976年 | 7篇 |
1975年 | 6篇 |
1974年 | 12篇 |
1973年 | 6篇 |
1969年 | 6篇 |
排序方式: 共有1587条查询结果,搜索用时 46 毫秒
61.
62.
63.
Datenschutz und Datensicherheit - DuD - 相似文献
64.
65.
The Effect of Gradual Fluorination on the Properties of FnZnPc Thin Films and FnZnPc/C60 Bilayer Photovoltaic Cells 下载免费PDF全文
Michael Brendel Stefan Krause Andreas Steindamm Anna Katharina Topczak Sudhakar Sundarraj Peter Erk Steffen Höhla Norbert Fruehauf Norbert Koch Jens Pflaum 《Advanced functional materials》2015,25(10):1565-1573
Motivated by the possibility of modifying energy levels of a molecule without substantially changing its band gap, the impact of gradual fluorination on the optical and structural properties of zinc phthalocyanine (FnZnPc) thin films and the electronic characteristics of FnZnPc/C60 (n = 0, 4, 8, 16) bilayer cells is investigated. UV–vis measurements reveal similar Q‐ and B‐band absorption of FnZnPc thin films with n = 0, 4, 8, whereas for F16ZnPc a different absorption pattern is detected. A correlation between structure and electronic transport is deduced. For F4ZnPc/C60 cells, the enhanced long range order supports fill factors of 55% and an increase of the short circuit current density by 18%, compared to ZnPc/C60. As a parameter being sensitive to the organic/organic interface energetics, the open circuit voltage is analyzed. An enhancement of this quantity by 27% and 50% is detected for F4ZnPc‐ and F8ZnPc‐based devices, respectively, and is attributed to an increase of the quasi‐Fermi level splitting at the donor/acceptor interface. In contrast, for F16ZnPc/C60 a decrease of the open circuit voltage is observed. Complementary photoelectron spectroscopy, external quantum efficiency, and photoluminescence measurements reveal a different working principle, which is ascribed to the particular energy level alignment at the interface of the photoactive materials. 相似文献
66.
67.
Microstructure of poly(isobutyl acrylate) (PiBuA) and poly(sec-butyl acrylate) (PsBuA), prepared by free radical and anionic polymerization, was investigated by 13C NMR spectroscopy. The carbonyl signal in the 100 MHz 13C NMR spectra of both homopolymers provided sufficient resolution to perform detailed analysis of distribution of configurational sequences at the pentad/heptad level. Application of Bernoulli and first order Markov statistics to determine probabilities of configurational sequences and incremental calculation to estimate chemical shifts of the individual sequences allowed for positive simulation of carbonyl signals. 相似文献
68.
Seven novel high refractive index (HRI) acrylic monomers, comprising the quinolinone structural motive, have been synthesized and characterized. Cross-linked homo- as well as copolymers were prepared by photochemical bulk polymerization. The homopolymers show refractive indices at 589 nm (n 589) ranging from 1.60 up to 1.68, glass transition temperatures (T g) from 52 to 76 °C, and Abbe numbers (ν Abbe) of 19 to 25. Due to these parameters, the homopolymers are not suitable to be used directly for intraocular lens (IOL) manufacture, but the quinolinone monomers may be used as high refractive index components in copolymers. Potential mixtures were calculated theoretically and one example, a copolymer with PEA and PEGPEA, was prepared and characterized. The experimentally found values were T g?=?24 °C, n 589?=?1.593, and ν Abbe?=?28.3. Interestingly, the quinolinone compound which does not have any spacer between the polymerizable group and the high refractive index group appears to be the most useful one. The lightfastness of the new material fulfills the demands for IOLs. Quinolinone derivatives are promising new comonomers for high refractive index copolymers. 相似文献
69.
Dr.‐Ing. Andrea Ohle Michael Obst Prof. Dr.‐Ing. Norbert Mollekopf Prof. Dr.‐Ing. Leon Urbas 《化学,工程师,技术》2014,86(5):640-648
Modularization has been identified as one of the research fields of the ?50 % idea”?. A development methodology for modules must consider both the economies of scale for investment costs and costs of operation and maintenance. In this paper, the impact of an absorber module, which is offered as discretized diameter scaling, on the total process is investigated at the example of the CO2 separation from biogas. The simulation shows the effect of this approach to the stripper diameter and the energy demand of the process. The calculations form the basis for applying cost models. 相似文献
70.
Christian Monsé Christian Monz Dirk Dahmann Christof Asbach Burkhard Stahlmecke Norbert Lichtenstein 《Aerosol science and technology》2014,48(4):418-426
In the EU there is an increasing need for regulatory agencies to derive health based threshold limits based on human inhalation studies with airborne particles. A necessary prerequisite for such projects is the development of a suitable generator system to produce nanoparticle test aerosols for human whole-body inhalation studies. We decided to use a generator with flame-based heating of aqueous precursor solutions. Validation of the test system was done by generating zinc oxide (ZnO) nanoparticles with minimal contamination of trace gases, i.e., nitric oxides or carbon monoxide that could confound the effects seen in exposed subjects. ZnO was selected based on the uncertainties surrounding its health effects after exposure at the workplace. The generation process of the developed flame generator yields ZnO nanoparticles with monomodal size distribution and very good temporal stability. The maximum target exposure mass concentration of 2 mg/m3 ZnO, with a resulting median particle diameter of 57 nm, is attainable in our human exposure laboratory. The morphological examination shows typical agglomerates and aggregates formed by high temperature processes. Overall, the performed experiments confirm that a constant exposure can be provided for all subjects at all times.
Copyright 2014 American Association for Aerosol Research 相似文献