全文获取类型
收费全文 | 1737篇 |
免费 | 67篇 |
专业分类
电工技术 | 16篇 |
综合类 | 3篇 |
化学工业 | 583篇 |
金属工艺 | 33篇 |
机械仪表 | 28篇 |
建筑科学 | 137篇 |
矿业工程 | 5篇 |
能源动力 | 40篇 |
轻工业 | 184篇 |
水利工程 | 5篇 |
石油天然气 | 1篇 |
无线电 | 95篇 |
一般工业技术 | 333篇 |
冶金工业 | 223篇 |
原子能技术 | 15篇 |
自动化技术 | 103篇 |
出版年
2021年 | 23篇 |
2019年 | 22篇 |
2018年 | 24篇 |
2017年 | 28篇 |
2016年 | 39篇 |
2015年 | 39篇 |
2014年 | 43篇 |
2013年 | 68篇 |
2012年 | 62篇 |
2011年 | 76篇 |
2010年 | 45篇 |
2009年 | 60篇 |
2008年 | 63篇 |
2007年 | 56篇 |
2006年 | 51篇 |
2005年 | 53篇 |
2004年 | 54篇 |
2003年 | 34篇 |
2002年 | 38篇 |
2001年 | 31篇 |
2000年 | 28篇 |
1999年 | 19篇 |
1998年 | 30篇 |
1997年 | 32篇 |
1996年 | 38篇 |
1995年 | 26篇 |
1994年 | 21篇 |
1993年 | 36篇 |
1992年 | 19篇 |
1991年 | 29篇 |
1990年 | 25篇 |
1989年 | 29篇 |
1988年 | 16篇 |
1987年 | 18篇 |
1985年 | 33篇 |
1984年 | 35篇 |
1983年 | 28篇 |
1982年 | 28篇 |
1981年 | 30篇 |
1980年 | 29篇 |
1979年 | 25篇 |
1978年 | 27篇 |
1976年 | 19篇 |
1975年 | 20篇 |
1974年 | 29篇 |
1973年 | 20篇 |
1972年 | 19篇 |
1971年 | 17篇 |
1970年 | 16篇 |
1969年 | 17篇 |
排序方式: 共有1804条查询结果,搜索用时 0 毫秒
41.
42.
Pauline Hibon Heinz von Seggern Hsin-Rong Tseng Christoph Leonhard Manuel Hamburger Gaëlle Béalle 《应用聚合物科学杂志》2020,137(29):48895
Interface control remains a top challenge of solution-processed organic light emitting diodes (OLED) stacks since the device performance heavily relies on it. Film stability of an inkjet deposited and crosslinked layer against subsequent exposure to a suitable inkjet printed solvent has been investigated. Impact of processing solvent (solvent used to prepare the polymer layer) on solution-cast thin film properties has already been shown for polymer films. To our knowledge, this study is the first one analyzing thin films stability against solvent exposure using technology relevant materials processed via inkjet printing (IJP). The outcome of this research showed that the stability of the crosslinked films is affected by the solvent used for ink formulation. These findings are of great interest for multilayered semiconductors devices, such as OLEDs, field-effect transistors and dye-sensitized solar cells. Differential scanning calorimetry (DSC) was used to quantify the efficiency of the polymer crosslinking reaction in pure powder and in thin films, as processed from different solvents. Crosslinking efficiency measured by DSC correlated well with the deformation induced by the solvent and observed on layer surfaces. The interaction in solution between polymer and solvent has also been evaluated to explain its impact on thin film stability against successive solvent printing. © 2020 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48895. 相似文献
43.
Transformation of Free and Dipeptide‐Bound Glycated Amino Acids by Two Strains of Saccharomyces cerevisiae 下载免费PDF全文
Dr. Michael Hellwig Marie Börner Falco Beer Prof. Dr. Karl‐Heinz van Pée Prof. Dr. Thomas Henle 《Chembiochem : a European journal of chemical biology》2017,18(3):266-275
The yeast Saccharomyces cerevisiae transforms branched‐chain and aromatic amino acids into higher alcohols in the Ehrlich pathway. During microbiological culturing and industrial fermentations, this yeast is confronted with amino acids modified by reducing sugars in the Maillard reaction (glycation). In order to gain some preliminary insight into the physiological “handling” of glycated amino acids by yeasts, individual Maillard reaction products (MRPs: fructosyllysine, carboxymethyllysine, pyrraline, formyline, maltosine, methylglyoxal‐derived hydroimidazolone) were administered to two strains of S. cerevisiae in a rich medium. Only formyline was converted into the corresponding α‐hydroxy acid, to a small extent (10 %). Dipeptide‐bound pyrraline and maltosine were removed from the medium with concomitant emergence of several metabolites. Pyrraline was mainly converted into the corresponding Ehrlich alcohol (20–60 %) and maltosine into the corresponding α‐hydroxy acid (40–60 %). Five specific metabolites of glycated amino acids were synthesized and characterized. We show for the first time that S. cerevisiae can use glycated amino acids as a nitrogen source and transform them into new metabolites, provided that the substances can be transported across the cell membrane. 相似文献
44.
Filip Tintchev Uwe Kuhlmann Hainer Wackerbarth Stefan Töpfl Volker Heinz Dietrich Knorr Peter Hildebrandt 《Food chemistry》2009
Non-thermal food preservation technology is based on the application of high pressures up to 600 MPa. Here we report a resonance Raman (RR) spectroscopic analysis of smoked salmon meat after high pressure processing. High quality spectra, which can be obtained even from packed salmon without spectral interference of the packing foil, allow determining pressure-dependent irreversible changes of the main RR-active components of salmon meat, astaxanthin and myoglobin/haemoglobin. High pressure-treatment causes a decrease of the relative RR intensities of astaxanthin as probed with 514 nm excitation which is in line with a slight attenuation of the originally intense red colour of the salmon meat. 413-nm excited RR spectra indicate a heterogeneous broadening of astaxanthin bands accompanied by the formation of deoxy-myoglobin or deoxy-haemoglobin. The results suggest that pressure-treatment facilitates the oxidative degradation of astaxanthin coupled to the reduction of metmyoglobin (methaemoglobin). 相似文献
45.
46.
47.
Ralph Ohr Dipl.‐Phys. Marc Neuhüuser Dipl.‐Phys. Heinz Hilgers Dr. Peter Pokrowsky Prof. Dr. Gerd Schönhense Prof. Dr. Georg Dittmar Dr. 《真空研究与实践》2001,13(5):277-285
Spectroscopic Ellipsometry is a fast, non‐destructive and reliable method for characterizing thin films, based on interaction between incident light and a multilayer system. For our investigations, light in the visible spectral range has been used to characterize protective carbon coatings with thicknesses of 2‐7nm on magnetic hard disks. The specific disk layer stack has been described with an adequate one‐layer model. With regard to an accurate analysis of the covering carbon coating a reproducible procedure for determining the underlying metallic material has been developed. The measured ellipsometric parameters (ψ, Δ) display a linear dependence on carbon film thickness which shows an appropriate application of the used model down to a thickness of 2 nm. By means of simulation calculations, criteria for the selection of optimized wavelengths with respect to film characterization has been established. Furthermore, an increasing extinction coefficient κ with rising nitrogen content in the carbon coating could be stated. Apparent time instabilities in the determination of layer thickness d and extinction coefficient κ of the carbon film could be explained as due to adsorption processes on the surface. 相似文献
48.
49.
Heinz Lange 《International Journal of Communication Systems》1989,2(2):73-79
This paper describes the realization in West Germany of a 450 MHz cable TV system, which matches into the infrastructure already formed by the existing 300 MHz systems. The studies and developments done to achieve this are described, and the results of a field trial detailed. Finally the impact of the new MAC standard is discussed. 相似文献
50.
硅烷膏体浸渍剂在保护混凝土中的实际应用 总被引:8,自引:4,他引:8
渗透型有机硅成功用于保护混凝土在国外已有数十年的历史。用于保护钢筋混凝土,它可防止水分及氯离子的渗透,从而对于防止混凝土的腐蚀与破坏起到关键的作用。这种浸渍剂一般都由硅烷或硅氧烷组成。通常情况下,由于这些低粘度的液体非常容易挥发。尤其在桥梁底面及立面施工时,有效成分大量流失。为了避免出现这种情况,德国瓦克化学有限公司成功开发了一种新型的硅烷乳膏状产品。这种材料施工简单,只需一步完成,具有很高的遮盖率,由于不流淌,活性组分不会损失。与混凝土表面接触时间长,保证了在高等级混凝土中的渗透深度,而且在其表面不会残留任何痕迹。 相似文献