全文获取类型
收费全文 | 384篇 |
免费 | 10篇 |
国内免费 | 1篇 |
专业分类
化学 | 276篇 |
晶体学 | 1篇 |
力学 | 20篇 |
数学 | 30篇 |
物理学 | 68篇 |
出版年
2022年 | 6篇 |
2021年 | 13篇 |
2020年 | 9篇 |
2019年 | 10篇 |
2018年 | 11篇 |
2017年 | 3篇 |
2016年 | 16篇 |
2015年 | 10篇 |
2014年 | 10篇 |
2013年 | 19篇 |
2012年 | 20篇 |
2011年 | 12篇 |
2010年 | 15篇 |
2009年 | 9篇 |
2008年 | 10篇 |
2007年 | 13篇 |
2006年 | 18篇 |
2005年 | 16篇 |
2004年 | 12篇 |
2003年 | 10篇 |
2002年 | 17篇 |
2001年 | 3篇 |
2000年 | 4篇 |
1999年 | 2篇 |
1998年 | 4篇 |
1996年 | 6篇 |
1995年 | 4篇 |
1994年 | 6篇 |
1993年 | 5篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1989年 | 2篇 |
1988年 | 7篇 |
1986年 | 2篇 |
1985年 | 6篇 |
1984年 | 5篇 |
1983年 | 7篇 |
1982年 | 6篇 |
1981年 | 10篇 |
1980年 | 6篇 |
1979年 | 3篇 |
1978年 | 6篇 |
1977年 | 9篇 |
1976年 | 6篇 |
1975年 | 9篇 |
1974年 | 2篇 |
1973年 | 3篇 |
1936年 | 1篇 |
1930年 | 1篇 |
1869年 | 1篇 |
排序方式: 共有395条查询结果,搜索用时 15 毫秒
91.
Summary The synthesis and characterization of disodium 3-hydroxy-4-[(6-methyl-2-pyridyl)azo]-2, 7-naphthalenedisulfonateN-oxide and its application to the spectrophotometric determination of trace amounts of copper are described. The effects due to pH, time, reagent concentration and diverse ions are reported. The reagent exhibits good specificity for copper. Beer's law is obeyed and the molar absorbance coefficient at 536 nm is 1.8×104.
Die spektrophotometrische Bestimmung von Kupfer mit Dinatrium-3-hydroxy-4-[(6-methyl-2-pyridyl)azo]-2, 7-napbthalindisulfonat-N-oxid
Zusammenfassung Die Synthese und die Eigenschaften von Dinatrium-3-hydroxy-4-[(6-methyl-2-pyridyl)azo]-2, 7-naphthalindisulfonat-N-oxid sowie dessen Anwendung zur spektrophotometrischen Bestimmung von Kupferspuren wurden beschrieben. Die Einflüsse von pH, Zeit, Reagenskonzentration und von verschiedenen Ionen wurden angegeben. Das Reagens zeigt gute Spezifität gegenüber Kupfer. Das Beersche Gesetz wird befolgt. Der molare Extinktionskoeffizient bei 536 nm beträgt 1,8·104.相似文献
92.
Panagiota Papaspyridakou Michail Lykouras Christos Kontoyannis Malvina Orkoula 《Molecules (Basel, Switzerland)》2022,27(10)
Vibrational spectroscopic techniques and especially Raman spectroscopy are gaining ground in substituting the officially established chromatographic methods in the identification of ethanol and other volatile substances in body fluids, such as blood, urine, saliva, semen, and vaginal fluids. Although a couple of different carriers and substrates have been employed for the biochemical analysis of these samples, most of them are suffering from important weaknesses as far as the analysis of volatile compounds is concerned. For this reason, in this study three carriers are proposed, and the respective sample preparation methods are described for the determination of ethanol in human urine samples. More specifically, a droplet of the sample on a highly reflective carrier of gold layer, a commercially available cuvette with a mirror to enhance backscattered radiation sealed with a lid, and a home designed microscope slide with a cavity coated with gold layer and covered with transparent cling film have been evaluated. Among the three proposed carriers, the last one achieved a quick, simple, and inexpensive identification of ethanol, which was used as a case study for the volatile compound, in the biological samples. The limit of detection (LoD) was found to be 1.00 μL/mL, while at the same time evaporation of ethanol was prevented. 相似文献
93.
Cesar Mendoza-Martinez Michail Papadourakis Salom Llabrs Arun A. Gupta Paul N. Barlow Julien Michel 《Chemical science》2022,13(18):5220
Many proteins recognise other proteins via mechanisms that involve the folding of intrinsically disordered regions upon complex formation. Here we investigate how the selectivity of a drug-like small molecule arises from its modulation of a protein disorder-to-order transition. Binding of the compound AM-7209 has been reported to confer order upon an intrinsically disordered ‘lid’ region of the oncoprotein MDM2. Calorimetric measurements revealed that truncation of the lid region of MDM2 increases the apparent dissociation constant of AM-7209 250-fold. By contrast, lid truncation has little effect on the binding of the ligand Nutlin-3a. Insights into these differential binding energetics were obtained via a complete thermodynamic analysis that featured adaptive absolute alchemical free energy of binding calculations with enhanced-sampling molecular dynamics simulations. The simulations reveal that in apo MDM2 the ordered lid state is energetically disfavoured. AM-7209, but not Nutlin-3a, shows a significant energetic preference for ordered lid conformations, thus shifting the balance towards ordering of the lid in the AM-7209/MDM2 complex. The methodology reported herein should facilitate broader targeting of intrinsically disordered regions in medicinal chemistry.Molecular simulations and biophysical measurements elucidate why the ligand AM-7209 orders a disordered region of the protein MDM2 on binding. This work expands strategies available to medicinal chemists for targeting disordered proteins. 相似文献
94.
95.
Michail N. Elinson Ruslan F. Nasybullin Gennady I. Nikishin 《Comptes Rendus Chimie》2013,16(9):789-794
Sodium acetate catalyzed multicomponent reaction of aryl aldehydes, 2-pyrazolin-5-ones, and malononitrile or alkyl cyanoacetates in alcohols results in the formation of substituted 3-(5-hydroxy-3-methylpyrazol-4-yl)-3-arylpropionitriles in 80–99% yields. The developed efficient catalytic approach to the substituted 3-(5-hydroxy-3-methylpyrazol-4-yl)-3-arylpropionitriles – the promising compounds for human cardiovascular diseases therapy and different biomedical applications – is beneficial from the viewpoint of diversity-oriented large-scale processes and represents facile, efficient and environmentally benign synthetic concept for multicomponent reactions strategy. 相似文献
96.
Michail N. Elinson Sergey K. Feducovich Anatolii N. Vereshchagin 《Tetrahedron》2004,60(51):11743-11749
Electrolysis of arylidenemalononitriles and malononitrile in alcohols in an undivided cell in the presence of sodium bromide as mediator results in the stereoselective formation of (1R,2S,6R)*-6-aryl-2-amino-4,4-dialkoxy-1,5-dicyano-3-azabicyclo[3.1.0]hex-2-enes in 60-80% yields. 相似文献
97.
98.
Dr. Dmitry S. Perekalin Dr. Valentin V. Novikov Alexander A. Pavlov Igor A. Ivanov Dr. Natalia Yu. Anisimova Alexey N. Kopylov Dr. Dmitry S. Volkov Dr. Irina F. Seregina Prof. Dr. Michail A. Bolshov Prof. Dr. Alexander R. Kudinov 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(13):4923-4925
Melittin is a membrane‐active peptide from bee venom with promising antimicrobial and anticancer activity. Herein we report on a simple and selective method for labeling of the tryptophan residue in melittin by the organometallic fragment [(C5H5)Ru]+ in aqueous solution and in air. Ruthenium coordination does not disturb the secondary structure of the peptide (as verified by 2D NMR spectroscopy), but changes the pattern of its intermolecular interactions resulting in an 11‐fold decrease of hemolytic activity. The high stability of the organometallic conjugate allowed the establishment of the biodistribution of the labeled melittin in mice by inductively coupled plasma MS analysis of ruthenium. 相似文献
99.
100.
Michail O. Danilov Gennady Ya. Kolbasov 《Journal of Solid State Electrochemistry》2010,14(12):2169-2172
An electrochemical method for the preparation of nanostructured composites based on multiwalled carbon nanotubes and chromium
oxide is proposed. The method involves electrodeposition of chromium oxides from a solution of hexavalent chromium oxide in
sulfuric acid on carbon nanotubes. By varying the electrolysis conditions one can obtain deposited—catalyst particles of different
size and vary the amount of catalyst. Oxygen electrodes have been made from the materials obtained for fuel cells with alkaline
electrolyte, which showed good electrocatalytic properties. 相似文献