全文获取类型
收费全文 | 328篇 |
免费 | 19篇 |
学科分类
工业技术 | 347篇 |
出版年
2023年 | 4篇 |
2022年 | 3篇 |
2021年 | 9篇 |
2020年 | 4篇 |
2019年 | 7篇 |
2017年 | 10篇 |
2016年 | 15篇 |
2015年 | 8篇 |
2014年 | 11篇 |
2013年 | 28篇 |
2012年 | 12篇 |
2011年 | 19篇 |
2010年 | 9篇 |
2009年 | 14篇 |
2008年 | 17篇 |
2007年 | 14篇 |
2006年 | 6篇 |
2005年 | 5篇 |
2003年 | 3篇 |
2002年 | 3篇 |
2001年 | 5篇 |
2000年 | 3篇 |
1999年 | 17篇 |
1998年 | 8篇 |
1997年 | 11篇 |
1996年 | 5篇 |
1995年 | 7篇 |
1994年 | 13篇 |
1993年 | 2篇 |
1992年 | 4篇 |
1991年 | 2篇 |
1989年 | 2篇 |
1988年 | 6篇 |
1987年 | 3篇 |
1986年 | 6篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1976年 | 5篇 |
1975年 | 3篇 |
1971年 | 2篇 |
1970年 | 5篇 |
1969年 | 2篇 |
1944年 | 2篇 |
排序方式: 共有347条查询结果,搜索用时 343 毫秒
1.
Diffusion induced grain boundary migration (DIGM) was observed to occur in a Ni-48.5 wt pct Cu alloy during oxidation at 450
°C, 500 °C, 600 °C, and 707 °C in air. The DIGM zones are Cu enriched. A Ni depleted zone, consisting of small recrystallized
grains, formed in the matrix beneath the metal-oxide interface during oxidation at 600 °C and 707 °C. This process is referred
to as oxidation-induced recrystallization (OIR). Growth of the small OIR grains was observed to be associated with Cu-rich
DIGM. No Cu-rich DIGM was found in the same alloy when annealed in Ar at 707 °C. Oxidation of this alloy in air resulted in
the formation of a duplex oxide: an inner NiO layer and an outer CuO layer. The NiO layer was observed to grow at a faster
rate than the CuO layer. The occurrence of Cu-rich DIGM is interpreted in terms of this preferential oxidation of Ni. 相似文献
2.
The GKSS-Forschungszentrum has simulated within an extensive PSS (Pressure Suppression System) program small break LOCA situations in a large scale multivent PSS test arrangement. The gained experimental information indicates that the simulated small break LOCA in a BWR-PSS which initiates steam condensation in the wetwell pool at the vent pipe outlets, gives strong cyclic pressure pulses from chugging events over a long time period. 相似文献
3.
Paula Bracco Hein J. Wijma Bastian Nicolai Jhon Alexander Rodriguez Buitrago Thomas Klünemann Agustina Vila Patrick Schrepfer Wulf Blankenfeldt Dick B. Janssen Prof. Dr. Anett Schallmey 《Chembiochem : a European journal of chemical biology》2021,22(6):1099-1110
CYP154C5 from Nocardia farcinica is a P450 monooxygenase able to hydroxylate a range of steroids with high regio- and stereoselectivity at the 16α-position. Using protein engineering and substrate modifications based on the crystal structure of CYP154C5, an altered regioselectivity of the enzyme in steroid hydroxylation had been achieved. Thus, conversion of progesterone by mutant CYP154C5 F92A resulted in formation of the corresponding 21-hydroxylated product 11-deoxycorticosterone in addition to 16α-hydroxylation. Using MD simulation, this altered regioselectivity appeared to result from an alternative binding mode of the steroid in the active site of mutant F92A. MD simulation further suggested that the entrance of water to the active site caused higher uncoupling in this mutant. Moreover, exclusive 15α-hydroxylation was observed for wild-type CYP154C5 in the conversion of 5α-androstan-3-one, lacking an oxy-functional group at C17. Overall, our data give valuable insight into the structure–function relationship of this cytochrome P450 monooxygenase for steroid hydroxylation. 相似文献
4.
Angelika Elsner G. Mieth W. Engst L. Aust H.-J. Leverenz 《European Journal of Lipid Science and Technology》1991,93(8):290-293
Sucrose carboxylic acid polyesters are in dependence of the degree of acylation and fatty acid composition more or less undigestible or emulsifying fat substitutes and functional additives for foods. In this connection the relationships between their molecular parameters and functional properties are discussed. New procedures of the solvent-free synthesis are presented. Furthermore, open biochemical and toxicological problems of pinocytosis and accumulation of intact polyesters in organs and tissue being still under investigations are considered. 相似文献
5.
6.
Vitamin E dependent inhibition of rat liver microsomal lipid peroxidation in an NADPH and ADP-Fe+3 containing system occurred at lower vitamin E concentrations in the presence of glutathione (GSH). Using microsomes from
rats fed a vitamin E deficient diet, vitamin E was shown to be rquired for inhibition. Inhibition also required the presence
of a storage labile microsomal component, since no inhibition was observed when using microsomes that had been stored for
one moth. This observation provides evidence that direct reduction of reversibly oxidized vitamin E by GSH does not appear
to contribute significantly to inhibition of peroxidation. During GSH and vitamin E dependent inhibition of lipid peroxidation,
vitamin E (reduced form) concentrations remained constant, indicating that GSH maintained vitamin E concentrations. Without
GSH, vitamin E concentrations dropped rapidly. By adding vitamin E to microsomes, it was found that inhibition of lipid peroxidation
in the presence of GSH occurred at about five-fold less vitamin E than in the absence of GSH. Inhibition at these lower levels
of vitamin E was 85–90% complete. Results indicate that GSH can be used to maintain vitamin E (reduced form) concentrations,
thereby lowering the concentration of vitamin E necessary to inhibit microsomal lipid peroxidation. 相似文献
7.
8.
Bolette Sandford Pedersen Sanni Nimb Jørg Asmussen Nicolai Hartvig Sørensen Lars Trap-Jensen Henrik Lorentzen 《Language Resources and Evaluation》2009,43(3):269-299
This paper is a contribution to the discussion on compiling computational lexical resources from conventional dictionaries.
It describes the theoretical as well as practical problems that are encountered when reusing a conventional dictionary for
compiling a lexical-semantic resource in terms of a wordnet. More specifically, it describes the methodological issues of
compiling a wordnet for Danish, DanNet, from a monolingual basis, and not—as is often seen—by applying the translational expansion method with Princeton WordNet as the English source.
Thus, we apply as our basis a large, corpus-based printed dictionary of modern Danish. Using this approach, we discuss the
issues of readjusting inconsistent and/or underspecified hyponymy hierarchies taken from the conventional dictionary, sense
distinctions as opposed to the synonym sets of wordnets, generating semantic wordnet relations on the basis of sense definitions,
and finally, supplementing missing or implicit information. 相似文献
9.
Localized Synthesis of Iron Oxide Nanowires and Fabrication of High Performance Nanosensors Based on a Single Fe2O3 Nanowire 下载免费PDF全文
Oleg Lupan Vasile Postica Niklas Wolff Oleksandr Polonskyi Viola Duppel Victor Kaidas Eugen Lazari Nicolai Ababii Franz Faupel Lorenz Kienle Rainer Adelung 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(16)
A composed morphology of iron oxide microstructures covered with very thin nanowires (NWs) with diameter of 15–50 nm has been presented. By oxidizing metallic Fe microparticles at 255 °C for 12 and 24 h, dense iron oxide NW networks bridging prepatterned Au/Cr pads are obtained. X‐ray photoelectron spectroscopy studies reveal formation of α‐Fe2O3 and Fe3O4 on the surface and it is confirmed by detailed high‐resolution transmission electron microscopy and selected area electron diffraction (SAED) investigations that NWs are single phase α‐Fe2O3 and some domains of single phase Fe3O4. Localized synthesis of such nano‐ and microparticles directly on sensor platform/structure at 255 °C for 24 h and reoxidation at 650 °C for 0.2–2 h, yield in highly performance and reliable detection of acetone vapor with fast response and recovery times. First nanosensors on a single α‐Fe2O3 nanowire are fabricated and studied showing excellent performances and an increase in acetone response by decrease of their diameter was developed. The facile technological approach enables this nanomaterial as candidate for a range of applications in the field of nanoelectronics such as nanosensors and biomedicine devices, especially for breath analysis in the treatment of diabetes patients. 相似文献
10.