全文获取类型
收费全文 | 1374篇 |
免费 | 51篇 |
国内免费 | 4篇 |
学科分类
工业技术 | 1429篇 |
出版年
2023年 | 10篇 |
2022年 | 16篇 |
2021年 | 22篇 |
2020年 | 10篇 |
2019年 | 17篇 |
2018年 | 18篇 |
2017年 | 23篇 |
2016年 | 30篇 |
2015年 | 37篇 |
2014年 | 40篇 |
2013年 | 48篇 |
2012年 | 79篇 |
2011年 | 87篇 |
2010年 | 68篇 |
2009年 | 64篇 |
2008年 | 79篇 |
2007年 | 76篇 |
2006年 | 46篇 |
2005年 | 44篇 |
2004年 | 43篇 |
2003年 | 31篇 |
2002年 | 34篇 |
2001年 | 21篇 |
2000年 | 33篇 |
1999年 | 23篇 |
1998年 | 25篇 |
1997年 | 37篇 |
1996年 | 10篇 |
1995年 | 23篇 |
1994年 | 20篇 |
1993年 | 21篇 |
1992年 | 13篇 |
1991年 | 15篇 |
1990年 | 21篇 |
1989年 | 19篇 |
1988年 | 20篇 |
1987年 | 8篇 |
1986年 | 9篇 |
1985年 | 14篇 |
1984年 | 18篇 |
1983年 | 21篇 |
1982年 | 11篇 |
1981年 | 15篇 |
1980年 | 19篇 |
1979年 | 12篇 |
1978年 | 16篇 |
1977年 | 11篇 |
1975年 | 8篇 |
1973年 | 9篇 |
1971年 | 8篇 |
排序方式: 共有1429条查询结果,搜索用时 15 毫秒
1.
Patricia Mortreau Reinhard Berndt 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2004,530(3):559-567
The traditional method used to non-destructively determine the uranium enrichment with an NaI detector is based on the “enrichment meter principle” (Progress report LA-4605-MS, Los Alamos National Laboratory, NNM, 1970, p. 19), which involves measuring the intensity of the 186 keV line of 235U by selecting two regions of interest for the peak and the background. This type of method suffers from several limitations, the most limiting of which are the impossibility to make wall thickness correction or to take the inference of foreign radioisotopes into account. The NaIGEM software (A guide for using NaIGEM code, version 1.5 for DOS and Windows, 2001; Nucl. Instr. and Meth. A 458 (2001) 196) was developed to overcome these limitations by calculating the 186 keV line intensity with a fitting procedure. The code was tested in different measurement conditions on the wide variety of certified samples, in particular, on reprocessed uranium and on depleted material with thick steel filters interposed between the source and the detector. The results are presented to illustrate the performance and limitations of the tested version (A guide for using NaIGEM code, version 1.5 for DOS and Windows, 2001). The general performance is good except in the case of low-enriched uranium in thick containers. 相似文献
2.
3.
Das Autobahnmautgesetz zeichnet sich durch eine strenge Zweckbindung für die Mautdaten aus. Diese dürfen ausschlie?lich für
die Zwecke des Mautgesetzes erhoben und verarbeitet werden. Diese Vorgabe hat das LG Magdeburg in einem Beschluss richtungsweisend
auch für die Verbindungsdaten der GSM-Kommunikation best?tigt. 相似文献
4.
Reinhard Effenberger 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1993,58(2):129-133
The preparation of 2,6-dibromophenol is described. This compound, useful as raw material for brominated poly(phenyleneoxide) and pyrogallol or derived pharmaceuticals/pesticides, was prepared in 80% (isolated) yield by a transalkylation reaction between tetrabromobisphenol-A and toluene. The catalyst, trifluoromethanesulphonic acid, can be simply recovered and recycled. Perfluorinated resin sulphonic acid (NAFION-H®, DuPont) did not effectively catalyse this transalkylation. 相似文献
5.
Mena, a relative of VASP and Drosophila Enabled, is implicated in the control of microfilament dynamics 总被引:3,自引:0,他引:3
FB Gertler K Niebuhr M Reinhard J Wehland P Soriano 《Canadian Metallurgical Quarterly》1996,87(2):227-239
This paper examines the effects of exposure to mass media messages promoting family planning on the reproductive behaviour of married women in Nigeria using cross-sectional data. Longitudinal data are also used to ensure that exposure to media messages pre-dates the indicators of reproductive behaviour. Cross-sectional analysis suggests that: (1) contraceptive use and intention are positively associated with exposure to mass media messages, and (2) women who are exposed to media messages are more likely to desire fewer children than those who are not exposed to such messages. Similarly, analysis of the longitudinal data shows that exposure to mass media messages is a significant predictor of contraceptive use. Thus, exposure to mass media messages about family planning may be a powerful tool for influencing reproductive behaviour in Nigeria. 相似文献
6.
Reinhard Fritsch 《真空研究与实践》1990,2(2):104-112
In Part 1 (Henning, Materials used in Vacuum Technology), the application possibilities of different materials in vacuum technology were described. Part 2 describes the most important non-detachable connections of these materials to produce components that can be used in vacuum technology. The following processes are suitable for this purpose:
- ○ Welding
- ○ Soldering
- ○ Glueing
- ○ Fusion
7.
Reinhard Hainisch Margit Gfoehler M. Zubayer-Ul-Karim Marcus G. Pandy 《Multibody System Dynamics》2012,28(1-2):143-156
Accurate knowledge of muscle-tendon parameters in biomechanical models is critical for accurate simulation and analyses of human movement. An excellent example of this is the creation of subject-specific models from magnetic resonance imaging (MRI). When Hill-type muscle models are used to calculate muscle forces, the determination of muscle attachment points, optimal fiber length, tendon slack length and maximum isometric force all have a significant influence on the joint moment-angle behavior of the model. In the present study a method was developed for customizing the values of muscle-tendon parameters in a generic model to create subject-specific biomechanical models from MRI. The method was applied by generating musculoskeletal models for the biomechanical simulation platform OpenSim, but the workflow is equally well applicable to other simulation platforms. New computational algorithms are described for identifying joint centers and for reconstructing the centroids of the muscle bellies from MRI. A?process is also described for the extraction of the muscle paths and for identifying the positions of ??via-points?? used to model muscles wrapping over bones. Finally, a new algorithm is described for adjusting the values of optimal fiber length, tendon slack length and maximum isometric force based on a comparison of the model results with experiment. We tested our computational algorithms by developing subject-specific biomechanical models of five typically developed children (age 9.5±1.7?years) from MRI. The joint moment-angle relationships calculated for the subject-specific models were similar to those determined for corresponding scaled generic models. The results indicate that the proposed methodology is suitable for developing subject-specific models of healthy children. Future studies should investigate how abnormalities of the musculoskeletal system, such as tibial torsion and muscle spasticity, can be integrated into the modeling process. 相似文献
8.
Reinhard Silwar und Roland Tressl 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1989,189(3):205-211
Zusammenfassung Das Modellsystem Cystein/Methionin/Furfural lieferte unter Röstbedingungen ein komplexes Reaktionsgemisch, das sich mittels Adsorptionschromatographie auf Kieselgel und Capillar-GC in ca. 130 Komponenten auftrennen ließ, von denen 85 capillargaschromatographisch-massenspektrometrisch charakterisiert wurden. Furfural und die aus Cystein und Methionin resultierenden reaktiven Abbauprodukte H2S, Cysteamin und Methylmercaptan sind wichtige Precursor für heterocyclische Flavorkomponenten. Neben Furanen, (Furan)-aldiminen und schwefelsubstituierten Furanderivaten werden auchN-Furfurylpyrrole, Pyridine, Thiazole, Thiazoline, Thiazolidine, Thiophene sowie aliphatische Schwefelverbindungen und cyclische Methylenpolysulfide gebildet. Beim Kaffeerösten entsteht Furfural als eine der Furanhauptkomponenten und spielt bei der Genese wesentlicher Kaffeearomastoffe eine zentrale Rolle.
Poster-Präsentation beim Deutschen Lebensmittelchemikertag in Bremen (14.–16. Sept. 1988) 相似文献
Gaschromatographic-mass spectrometric investigation of aroma compounds from the reaction of cysteine and methionine with furfural under roasting conditions
Summary The model-system cysteine/methionine/furfural produced under roasting conditions a complex mixture of compounds which was separated by adsorption chromatography on silica gel, according to the increasing polarity of the components, into six fractions. The fractions were investigated by capillary gas chromatography with and without mass spectrometry. Of the approx. 130 compounds detected, 85 were identified and quantified. Furfural and the reactive degradation products H2S, cysteamine and methylmercaptan, resulting from cysteine and methionine, are important precursors for heterocyclic flavor components. Besides furans, (furan)aldimines, and sulphur-substituted furan derivates, the following compounds are also formed:N-furfurylpyrroles, pyridines, thiazoles, thiazolines, thiazolidines, thiophenes, as well as aliphatic sulphur compounds and cyclic methylene polysulfides. During coffee roasting, furfural is produced as one of the major components of the furans and is essential for the formation of important coffee aroma constituents.
Poster-Präsentation beim Deutschen Lebensmittelchemikertag in Bremen (14.–16. Sept. 1988) 相似文献
9.
10.
Summary Novel oxycarbonyl isocyanate telechelic polyisobutylenes have been prepared by conversion of hydroxylterminated polyisobutylenes with N-chlorocarbonyl isocyanate. This reaction is free from side-reactions and provides highly reactive isocyanate-terminated polyisobutylene prepolymers. Conversion of these prepolymers with glycol, urea, pentaerythritol, and polyethylene glycol led to linear chain extension, crosslinking, and multiblock copolymer formation, respectively. 相似文献