全文获取类型
收费全文 | 117篇 |
免费 | 8篇 |
专业分类
化学 | 97篇 |
力学 | 1篇 |
数学 | 9篇 |
物理学 | 18篇 |
出版年
2023年 | 3篇 |
2022年 | 5篇 |
2021年 | 1篇 |
2020年 | 3篇 |
2019年 | 3篇 |
2018年 | 1篇 |
2017年 | 1篇 |
2016年 | 5篇 |
2015年 | 6篇 |
2014年 | 3篇 |
2013年 | 7篇 |
2012年 | 5篇 |
2011年 | 5篇 |
2010年 | 5篇 |
2008年 | 5篇 |
2007年 | 3篇 |
2006年 | 9篇 |
2005年 | 4篇 |
2004年 | 5篇 |
2003年 | 2篇 |
2002年 | 2篇 |
2001年 | 1篇 |
2000年 | 2篇 |
1995年 | 2篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1978年 | 3篇 |
1976年 | 3篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1972年 | 2篇 |
1971年 | 3篇 |
1970年 | 1篇 |
1967年 | 2篇 |
1966年 | 3篇 |
1964年 | 2篇 |
1956年 | 1篇 |
1955年 | 2篇 |
1937年 | 1篇 |
排序方式: 共有125条查询结果,搜索用时 15 毫秒
31.
32.
V. V. Dzenis A. A. Merten V. K. Bernkhard V. V. Shumskii 《Mechanics of Composite Materials》1975,11(4):580-584
A method of determining the ultrasonic surface-wave velocity by means of exponential concentrators is proposed for determining the properties of human tibia in vitro. The effect of the radiation frequency and the thickness of the surface layer of bone tissue on the surface-wave propagation velocity is studied. For measurement purposes the tibia is divided into 24–28 vertical levels and six to seven horizontal zones. The variation of the surface-wave velocity with the measuring point is investigated. Relations are established between the distribution of surface-wave velocities and the statistical parameters characterizing the dispersion of the results, on the one hand, and biological age and the source of the bone (right or left leg), on the other. 相似文献
33.
Dr. Michal S. Andrä Lukas Schifferer Dr. Corina H. Pollok Dr. Christian Merten Prof. Dr. Lukas J. Gooßen Prof. Dr. Jin-Quan Yu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(36):8503-8507
A complementary set of chiral N,N-ligands enables the Pd-catalyzed β-C−H arylation of unbiased internal methylene groups in good yield and with high levels of enantio- and diastereoinduction. Both the dia- and enantioselectivity can be reversed, thus allowing the selective arylation of any of the four β-C−H bonds in cycloalkanecarboxamides of various ring sizes. The method is applicable to a broad range of aryl iodides with electron-withdrawing and -donating substituents in the o-, m-, or p-position. 相似文献
34.
Patrick Emond Sylvie Mavel Nacima Aïdoud Lydie Nadal-Desbarats Frédéric Montigny Frédérique Bonnet-Brilhault Catherine Barthélémy Marc Merten Pierre Sarda Frédéric Laumonnier Patrick Vourc’h Hélène Blasco Christian R. Andres 《Analytical and bioanalytical chemistry》2013,405(15):5291-5300
Autism spectrum disorders (ASD) are a group of neurodevelopmental disorders resulting from multiple factors. Diagnosis is based on behavioural and developmental signs detected before 3 years of age, and there is no reliable biological marker. The purpose of this study was to evaluate the value of gas chromatography combined with mass spectroscopy (GC-MS) associated with multivariate statistical modeling to capture the global biochemical signature of autistic individuals. GC-MS urinary metabolic profiles of 26 autistic and 24 healthy children were obtained by liq/liq extraction, and were or were not subjected to an oximation step, and then were subjected to a persilylation step. These metabolic profiles were then processed by multivariate analysis, in particular orthogonal partial least-squares discriminant analysis (OPLS-DA, R 2Y(cum) = 0.97, Q 2(cum) = 0.88). Discriminating metabolites were identified. The relative concentrations of the succinate and glycolate were higher for autistic than healthy children, whereas those of hippurate, 3-hydroxyphenylacetate, vanillylhydracrylate, 3-hydroxyhippurate, 4-hydroxyphenyl-2-hydroxyacetate, 1H-indole-3-acetate, phosphate, palmitate, stearate, and 3-methyladipate were lower. Eight other metabolites, which were not identified but characterized by a retention time plus a quantifier and its qualifier ion masses, were found to differ between the two groups. Comparison of statistical models leads to the conclusion that the combination of data obtained from both derivatization techniques leads to the model best discriminating between autistic and healthy groups of children. 相似文献
35.
Merten Jabben Klaus Heihoff Silvia E. Braslavsky Kurt Schaffner 《Photochemistry and photobiology》1984,40(3):361-367
After excitation at room temperature with a 15 ns dye laser pulse, phytochrome (60 kDalton) from etiolated oat seedlings was studied by optoacoustic spectroscopy, which records the heat emission caused by non-radiative deactivation processes of the photoexcited molecule. The action spectrum for the heat emitted by Pr deviates from the absorption spectrum around 610 and 695 nm, indicating the build-up of photoproduct(s) within 15 ns after excitation. It is proposed that the 695 nm product is identical with I700 and lumi-R known to be the first intermediate on the Pr× Pfr pathway, and that the photochemical back reaction of I700 to Pr occurs on the same time scale. About 90% of the absorbed light energy was lost by radiationless deactivation. Values for the rate constants of excited state deactivation of Pr and for the internal energy content difference of the primary photoproducts are calculated. 相似文献
36.
37.
D. Merten U. Löring K. Kretzschmar B. Metsch H.-R. Petry 《The European Physical Journal A - Hadrons and Nuclei》2002,14(4):477-489
We compute electroweak form factors of the nucleon and photon transition form factors of non-strange baryon resonances up
to the third resonance region in a model with instanton-induced interaction. The calculation is based on the Bethe-Salpeter
equation for three light constituent quarks and is fully relativistic (U. L?ring et al., Eur. Phys. J. A 10, 309 (2001)). Static nucleon properties and photon resonance couplings are in good agreement with experiment and the Q2 behaviour of the experimentally known form factors up to large momentum transfer is accounted for.
Received: 4 April 2002 / Accepted: 2 May 2002 相似文献
38.
39.
40.
Dr. Christian Merten Corina H. Pollok Dr. Saihu Liao Prof. Dr. Benjamin List 《Angewandte Chemie (International ed. in English)》2015,54(30):8841-8845
Ionic interactions are increasingly appreciated as a key, asymmetry‐inducing factor in enantioselective catalytic transformations, including those involving Brønsted acid or base catalysis, phase‐transfer catalysis, and related processes. However, a detailed understanding of these interactions is often lacking. Herein, we show how an enantiopure anion enforces a chiral conformation onto a catalytically relevant achiral cation. Specifically, we use vibrational circular dichroism (VCD) spectroscopy to monitor the transmission of stereochemical information from a chiral phosphate anion to a flexible manganese(III)–salen cation. We show that VCD can be used to study solvent effects and that the obtained chiroptical data directly and quantitatively correlate with the experimentally observed enantioselectivity in an asymmetric olefin epoxidation reaction. 相似文献